Tech Arsenal 1/Tech Arsenal (Arsenal Computer).ISO/tek-04/inter36a.zip/INTERRUP.C

Text File | 1993-08-01 | 290KB | 7,882 lines

Interrupt List, part 3 of 10
This compilation is Copyright (c) 1989,1990,1991,1992,1993 Ralf Brown
--------B-1600-------------------------------
INT 16 - KEYBOARD - GET KEYSTROKE
    AH = 00h
Return: AH = BIOS scan code
    AL = ASCII character
Notes:    on extended keyboards, this function discards any extended keystrokes,
      returning only when a non-extended keystroke is available
    the BIOS scan code is usually, but not always, the same as the hardware
      scan code processed by INT 09.  It is the same for ASCII keystrokes
      and most unshifted special keys (F-keys, arrow keys, etc.), but
      differs for shifted special keys.
SeeAlso: AH=01h,AH=05h,AH=10h,AH=20h,INT 18/AH=00h
--------B-1601-------------------------------
INT 16 - KEYBOARD - CHECK FOR KEYSTROKE
    AH = 01h
Return: ZF set if no keystroke available
    ZF clear if keystroke available
        AH = BIOS scan code
        AL = ASCII character
Note:    if a keystroke is present, it is not removed from the keyboard buffer;
      however, any extended keystrokes which are not compatible with 83/84-
      key keyboards are removed in the process of checking whether a
      non-extended keystroke is available
SeeAlso: AH=00h,AH=11h,AH=21h,INT 18/AH=01h
--------B-1602-------------------------------
INT 16 - KEYBOARD - GET SHIFT FLAGS
    AH = 02h
Return: AL = shift flags (see below)
SeeAlso: AH=12h,AH=22h,INT 17/AH=0Dh,INT 18/AH=02h

Bitfields for shift flags:
 bit 7    Insert active
 bit 6    CapsLock active
 bit 5    NumLock active
 bit 4    ScrollLock active
 bit 3    Alt key pressed (either Alt on 101/102-key keyboards)
 bit 2    Ctrl key pressed (either Ctrl on 101/102-key keyboards)
 bit 1    left shift key pressed
 bit 0    right shift key pressed
--------B-1603-------------------------------
INT 16 - KEYBOARD - SET TYPEMATIC RATE AND DELAY
    AH = 03h
    AL = subfunction
        00h set default delay and rate (PCjr and some PS/2)
        01h increase delay before repeat (PCjr)
        02h decrease repeat rate by factor of 2 (PCjr)
        03h increase delay and decrease repeat rate (PCjr)
        04h turn off typematic repeat (PCjr and some PS/2)
        05h set repeat rate and delay (AT,PS)
        BH = delay value (00h = 250ms to 03h = 1000ms)
        BL = repeat rate (00h=30/sec to 0Ch=10/sec [def] to 1Fh=2/sec)
        06h get current typematic rate and delay (newer PS/2s)
        Return: BL = repeat rate (see above)
            BH = delay (see above)
Note:    use INT 16/AH=09h to determine whether some of the subfunctions are
      supported
SeeAlso: INT 16/AH=09h
--------B-1604-------------------------------
INT 16 - KEYBOARD - SET KEYCLICK (PCjr only)
    AH = 04h
    AL = keyclick state
        00h off
        01h on
SeeAlso: AH=03h
--------B-1605-------------------------------
INT 16 - KEYBOARD - STORE KEYSTROKE IN KEYBOARD BUFFER (AT/PS w enh keybd only)
    AH = 05h
    CH = scan code
    CL = ASCII character
Return: AL = 00h if successful
         01h if keyboard buffer full
Note:    under DESQview, the following "keystrokes" invoke the following
      actions when they are read from the keyboard buffer:
        38FBh or FB00h    switch to next window (only if main menu
                popped up)
        38FCh or FC00h    pop up DESQview main menu
        38FEh or FE00h    close the current window
        38FFh or FF00h    pop up DESQview learn menu
SeeAlso: AH=00h,AH=71h,AH=FFh,INT 15/AX=DE10h
--------B-1605-------------------------------
INT 16 - KEYBOARD - SELECT KEYBOARD LAYOUT (PCjr only)
    AH = 05h
    AL = function
        01h set keyboard layout to French
        02h set keyboard layout to German
        03h set keyboard layout to Italian
        04h set keyboard layout to Spanish
        05h set keyboard layout to UK
        80h check if function supported
        Return: AL <> 80h if supported
Return: ???
Note:    called by DOS 3.2 KEYBxx.COM
SeeAlso: AH=92h,AH=A2h
--------B-1609-------------------------------
INT 16 - KEYBOARD - GET KEYBOARD FUNCTIONALITY
    AH = 09h
Return: AL = supported keyboard functions (see below)
Note:    this function is only available if bit 6 of the second feature byte
      returned by INT 15/AH=C0h is set
SeeAlso: AH=03h,AH=0Ah,AH=10h,AH=11h,AH=12h,AH=20h,AH=21h,AH=22h,INT 15/AH=C0h

Bitfields for supported keyboard functions:
 bit 7    reserved
 bit 6    INT 16/AH=20h-22h supported (122-key keyboard support)
 bit 5    INT 16/AH=10h-12h supported (enhanced keyboard support)
 bit 4    INT 16/AH=0Ah supported
 bit 3    INT 16/AX=0306h supported
 bit 2    INT 16/AX=0305h supported
 bit 1    INT 16/AX=0304h supported
 bit 0    INT 16/AX=0300h supported
--------B-160A-------------------------------
INT 16 - KEYBOARD - GET KEYBOARD ID
    AH = 0Ah
Return: BX = keyboard ID or 0000h if no keyboard attached
Note:    check return value from AH=09h to determine whether this function is
      supported
SeeAlso: AH=09h
--------B-1610-------------------------------
INT 16 - KEYBOARD - GET ENHANCED KEYSTROKE (enhanced kbd support only)
    AH = 10h
Return: AH = BIOS scan code
    AL = ASCII character
Notes:    if no keystroke is available, this function waits until one is placed
      in the keyboard buffer
    the BIOS scan code is usually, but not always, the same as the hardware
      scan code processed by INT 09.  It is the same for ASCII keystrokes
      and most unshifted special keys (F-keys, arrow keys, etc.), but
      differs for shifted special keys.
    unlike AH=00h, this function does not discard extended keystrokes
    INT 16/AH=09h can be used to determine whether this function is
      supported, but only on later model PS/2s
SeeAlso: AH=00h,AH=09h,AH=11h,AH=20h
--------B-1611-------------------------------
INT 16 - KEYBOARD - CHECK FOR ENHANCED KEYSTROKE (enh kbd support only)
    AH = 11h
Return: ZF set if no keystroke available
    ZF clear if keystroke available
        AH = BIOS scan code
        AL = ASCII character
Notes:    if a keystroke is available, it is not removed from the keyboard buffer
    unlike AH=01h, this function does not discard extended keystrokes
    some versions of the IBM BIOS Technical Reference erroneously report
      that CF is returned instead of ZF
    INT 16/AH=09h can be used to determine whether this function is
      supported, but only on later model PS/2s
SeeAlso: AH=01h,AH=09h,AH=10h,AH=21h
--------B-1612-------------------------------
INT 16 - KEYBOARD - GET EXTENDED SHIFT STATES (enh kbd support only)
    AH = 12h
Return: AL = shift flags 1 (same as returned by AH=02h) (see below)
    AH = shift flags 2 (see below)
Notes:    AL bit 3 set only for left Alt key on many machines
    AH bits 7 through 4 always clear on a Compaq SLT/286
    INT 16/AH=09h can be used to determine whether this function is
      supported, but only on later model PS/2s
SeeAlso: AH=02h,AH=09h,AH=22h,AH=51h,INT 17/AH=0Dh

Bitfields for shift flags 1:
 bit 7    Insert active
 bit 6    CapsLock active
 bit 5    NumLock active
 bit 4    ScrollLock active
 bit 3    Alt key pressed (either Alt on 101/102-key keyboards)
 bit 2    Ctrl key pressed (either Ctrl on 101/102-key keyboards)
 bit 1    left shift key pressed
 bit 0    right shift key pressed

Bitfields for shift flags 2:
 bit 7    SysRq key pressed
 bit 6    CapsLock pressed
 bit 5    NumLock pressed
 bit 4    ScrollLock pressed
 bit 3    right Alt key pressed
 bit 2    right Ctrl key pressed
 bit 1    left Alt key pressed
 bit 0    left Ctrl key pressed
--------B-1620-------------------------------
INT 16 - KEYBOARD - GET 122-KEY KEYSTROKE (122-key kbd support only)
    AH = 20h
Return: AH = BIOS scan code (see AH=10h for details)
    AL = ASCII character
Note:    use AH=09h to determine whether this function is supported
SeeAlso: AH=00h,AH=09h,AH=10h,AH=21h,AH=22h
--------B-1621-------------------------------
INT 16 - KEYBOARD - CHECK FOR 122-KEY KEYSTROKE (122-key kbd support only)
    AH = 21h
Return: ZF set if no keystroke available
    ZF clear if keystroke available
        AH = BIOS scan code
        AL = ASCII character
Notes:    use AH=09h to determine whether this function is supported
    some versions of the IBM BIOS Technical Reference erroneously report
      that CF is returned instead of ZF
SeeAlso: AH=01h,AH=09h,AH=11h,AH=20h,AH=21h
--------B-1622-------------------------------
INT 16 - KEYBOARD - GET 122-KEY SHIFT STATUS (122-key kbd support only)
    AH = 22h
Return: AL = shift flags 1 (see AH=12h)
    AH = shift flags 2 (see AH=12h)
Note:    use AH=09h to determine whether this function is supported
SeeAlso: AH=02h,AH=09h,AH=12h,AH=20h,AH=21h
--------U-164252-----------------------------
INT 16 - TEXTCAP 2.0 - INSTALLATION CHECK
    AX = 4252h
Return: AX = 5242h if installed
Program: TEXTCAP 2.0 is a heavily modified (by Gisbert W. Selke) version of the
      PC Magazine utility CAPTURE written by Tom Kihlken
SeeAlso: AX=4253h,AX=4254h
--------U-164253-----------------------------
INT 16 - TEXTCAP 2.0 - UNINSTALL
    AX = 4253h
Return: AX = segment of resident code
Notes:    the uninstall code does not check whether interrupt vectors have been
      chained by other programs
    the caller must free the main memory block (using the returned segment)
SeeAlso: AX=4252h,AX=4254h
--------U-164254-----------------------------
INT 16 - TEXTCAP 2.0 - DUMP TEXT SCREEN TO FILE
    AX = 4254h
Return: AX = status
        4254h if screen dump will be written as soon as disk becomes idle
        5442h if screen dump written
SeeAlso: AX=4252h,AX=4253h
--------e-164500-----------------------------
INT 16 - Shamrock Software EMAIL - GET STATUS
    AX = 4500h
    DL = port number (01h = COM1)
    ES:BX -> 13-byte buffer for ASCIZ name
Return: AX = 4D00h if EMAIL installed on specified port
        ES:BX -> "" if no connection
          -> "*" if connection but caller has not identified name
          -> name otherwise
        CX = version (CH = major, CL = minor)
        DL = privilege level of user (00h = guest)
        DH = chosen language (00h German, 01h English)
SeeAlso: AX=4501h,AX=4502h
--------e-164501-----------------------------
INT 16 - Shamrock Software EMAIL - GET ELAPSED ONLINE TIME AND MAXIMUM TIME
    AX = 4501h
    DL = port number (01h = COM1)
Return: AX = 4D00h if EMAIL installed on specified port
        BX = maximum connect time in clock ticks
        CX = maximum connect time for guests (without name) in clock ticks
        DX = elapsed connect time of current user in clock ticks
SeeAlso: AX=4500h
--------e-164502-----------------------------
INT 16 - Shamrock Software EMAIL - GET CURRENT COMMUNICATIONS PARAMETERS
    AX = 4502h
    DL = port number (01h = COM1)
Return: AX = 4D00h if EMAIL installed on specified port
        BL = current value of serial port's Line Control Register
        BH = flags
        bit 0: ISO code
        bit 1: pause
        bit 2: linefeed
        bit 3: ANSI sequences
        CX = selected country code (33 = France, 49 = Germany, etc)
        DX = baudrate divisor (115200/DX = baudrate)
SeeAlso: AX=4500h
--------e-164503-----------------------------
INT 16 - Shamrock Software EMAIL - SPECIFY COMMAND-WORD FOR USER FUNCTION
    AX = 4503h
    DL = port number (01h = COM1)
    DH = maximum execution time in clock ticks (00h = 5 seconds)
    ES:BX -> ASCIZ string with new user command-word
Return: AX = 4D00h if EMAIL installed on specified port
Notes:    a single user command (consisting of only uppercase letters and digits)
      may be defined, and remains valid until it is overwritten or the
      EMAIL program terminates; the user command must be activated by
      calling AX=4504h at least once.
    an existing command word may be redefined with this function
SeeAlso: AX=4504h,AX=4505h
--------e-164504-----------------------------
INT 16 - Shamrock Software EMAIL - CHECK FOR USER FUNCTION COMMAND-WORD
    AX = 4504h
    DL = port number (01h = COM1)
    ES:BX -> 80-byte buffer for ASCIZ user input line
Return: AX = 4D00h if EMAIL installed on specified port
        DL = flags
        bit 0: user function supported (always set)
        bit 1: user entered user-function command word
        if DL bit 1 set,
        ES:BX buffer contains line entered by user which begins with
            the defined command word and has been converted to all
            caps
Note:    caller must process the returned commandline and invoke AX=4505h
      within five seconds with the result of that processing
SeeAlso: AX=4503h,AX=4505h
--------e-164505-----------------------------
INT 16 - Shamrock Software EMAIL - SEND RESULT OF USER FUNCTION
    AX = 4505h
    DL = port number (01h = COM1)
    DH = error flag
        bit 3: set on error
    ES:BX -> ASCIZ text to return to user, max 1024 bytes
Return: AH = 4Dh if EMAIL installed on specified port
    AL = status
        00h successful
        02h unable to perform function (timeout, prev call not complete)
        other error
Notes:    if the error flag in DH is set, the string is not sent and an error
      message is generated instead; if this function is not called within
      five seconds of AX=4504h, EMAIL automatically generates an error
      message
    the string is copied into an internal buffer, allowing this function's
      caller to continue immediately
SeeAlso: AX=4503h,AX=4504h,INT 17/AX=2400h
--------e-164506-----------------------------
INT 16 - Shamrock Software EMAIL - MONITOR XMODEM DOWNLOAD
    AX = 4506h
    DL = port number (01h = COM1)
    ES:BX -> 13-byte buffer for ASCIZ filename
Return: AX = 4D00h if EMAIL installed on specified port
        DH = Xmodem status
        00h no XGET command given
        01h XGET in progress
        02h XGET completed successfully
        ES:BX buffer filled with last filename given to XGET command
        (without path)
Note:    DH=02h will only be returned once per XGET; subsequent calls will
      return DH=00h
SeeAlso: AX=4500h,INT 17/AX=2408h
--------K-164D4F-----------------------------
INT 16 - M16_KBD.COM v5.6 - INSTALLATION CHECK
    AX = 4D4Fh
Return: AX = 6F6Dh if installed
        ES = segment of resident code
Program: M16_KBD is a shareware Cyrillic keyboard driver by I.V. Morozov
SeeAlso: INT 10/AX=1130h/BX=4D4Fh
--------J-165000-----------------------------
INT 16 - KEYBOARD - AX PC - SET KEYBOARD COUNTRY CODE
    AX = 5000h
    BX = country code
        0001h USA (English), 0051h Japan
Return: AL = status
        00h successful
        01h bad country code
        02h other error
SeeAlso: AX=5001h,INT 10/AX=5000h,INT 17/AX=5000h
--------J-165001-----------------------------
INT 16 - KEYBOARD - AX PC - GET KEYBOARD COUNTRY CODE
    AX = 5001h
Return: AL = status
        00h successful
        BX = country code
        02h error
SeeAlso: AX=5000h,INT 10/AX=5001h,INT 17/AX=5001h
--------J-1651-------------------------------
INT 16 - KEYBOARD - AX PC - READ SHIFT KEY STATUS
    AH = 51h
Return: AL = standard shift key states (see AH=12h)
    AH = Kana lock (00h off, 01h on)
SeeAlso: AH=02h,AH=12h,AH=22h
----------165453BX5242-----------------------
INT 16 - TSRBONES - INSTALLATION CHECK
    AX = 5453h ('TS')
    BX = 5242h ('RB')
    CX = 4F4Eh ('ON')
    DX = 4553h ('ES')
Return: AX = 4553h if installed
    BX = 4F4Eh if installed
    CX = 5242h if installed
    DX = 5453h if installed
Program: TSRBONES is a skeletal TSR framework by Robert Curtis Davis
Note:    these values are the default as the TSRBONES package is distributed,
      but will normally be changed when implementing an actual TSR with
      the TSRBONES skeleton
SeeAlso: INT 2D"AMIS"
--------A-165500-----------------------------
INT 16 C - Microsoft Word internal - MICROSOFT WORD COOPERATION WITH TSR
    AX = 5500h
Return: AX = 4D53h ('MS') if keyboard TSR present
Notes:    during startup, Microsoft Word tries to communicate with any TSRs
      that are present through this call.
    if the return is not 4D53h, Word installs its own INT 09 and INT 16
      handlers; otherwise it assumes that the TSR will handle the keyboard
SeeAlso: INT 1A/AX=3601h
----------165758BX4858-----------------------
INT 16 U - Netroom CACHECLK - INSTALLATION CHECK
    AX = 5758h
    BX = 4858h ('HX')
    DX = 4443h ('DC')
    CX <> 5758h
Return: BX = 6878h if installed
    CX = 6463h if installed
        AX = code segment of TSR
        CX = internal version??? (v3.00 returns 0100h)
Program: CACHECLK is a "cloaked" disk cache included with Netroom
Notes:    if CX=5758h on entry, CACHECLK returns with all registers unchanged
    the cache statistics are located early in the segment pointed at by
      AX on return
----------165758BX5754-----------------------
INT 16 U - Netroom ??? - ???
    AX = 5758h
    BX = 5754h
    ???
Return: ???
----------165758BX5754-----------------------
INT 16 U - Netroom ??? - ???
    AX = 5758h
    BX = 5755h
    DS:SI -> ???
Return: ???
----------165758BX5756-----------------------
INT 16 U - Netroom ??? - INSTALLATION CHECK
    AX = 5758h
    BX = 5756h
Return: BX <> 5756h if installed
----------165758BX5858-----------------------
INT 16 U - Netroom PRENET - GET OLD INTERRUPT VECTORS
    AX = 5758h
    BX = 5858h
Return: CF clear
    DX:BX -> saved copy of interrupt vector table
Note:    the installation check consists of calling this function and comparing
      BX against 5858h on return; if it has changed, PRENET is installed
SeeAlso: AX=5758h/BX=5859h
Index:    installation check;Netroom PRENET
----------165758BX5859-----------------------
INT 16 U - Netroom POSTNET - GET OLD INTERRUPT VECTORS
    AX = 5758h
    BX = 5859h
Return: CF clear
    DX:BX -> saved copy of interrupt vector table
Note:    the installation check consists of calling this function and comparing
      BX against 5859h on return; if it has changed, POSTNET is installed
SeeAlso: AX=5758h/BX=5858h
Index:    installation check;Netroom POSTNET
--------U-1655FF-----------------------------
INT 16 - Swap Utilities - ???
    AX = 55FFh
    BX >= 0004h
    CX = function
        0000h set ??? flag
        other clear ??? flag
Note:    present in SWAPSH and SWAPDT v1.77j, distributed with PC Tools v7, as
      well as the Trusted Access SCRNBLNK.COM; this may be part of the
      standard TesSeRact library
SeeAlso: INT 2F/AX=5453h
--------U-166969BX6968-----------------------
INT 16 - PC Tools v5.1+ BACKTALK - UNHOOK
    AX = 6969h
    BX = 6968h
Return: resident code unhooked, but not removed from memory
Index:    uninstall;BACKTALK
--------U-166969BX6969-----------------------
INT 16 - PC Tools v5.1+ BACKTALK - INSTALLATION CHECK
    AX = 6969h
    BX = 6969h
    DX = 0000h
Return: DX nonzero if installed
        BX = CS of resident code
        DX = PSP segment of resident code
        DS:SI -> ASCIZ identification string "CPoint Talk"
----------166A6B-----------------------------
INT 16 U - FastJuice - DISABLE/UNLOAD???
    AX = 6A6Bh
Return: ???
Program: FastJuice is a resident battery-power monitor by SeaSide Software
SeeAlso: AX=7463h
Index:    uninstall;FastJuice
--------G-166C63-----------------------------
INT 16 U - TMED v1.6a - INSTALLATION CHECK
    AX = 6C63h ('lc')
Return: AX = 4C43h ('LC') if installed
Program: TMED is a freeware resident memory editor by Liang Chen
--------b-166F00BX0000-----------------------
INT 16 - HP HIL Vectras - HP HIL Extended BIOS INSTALLATION CHECK
    AX = 6F00h
    BX = 0000h
Return: BX = 4850h if present
Notes:    called by recent MS Mouse drivers looking for an HP-HIL mouse
    supported by ES, QS, and RS series HP Vectras
SeeAlso: AX=6F0Dh
--------b-166F0D-----------------------------
INT 16 - HP HIL Vectras - GET HIL Extended BIOS INTERRUPT NUMBER
    AX = 6F0Dh
Return: AH = interrupt number (default 6Fh, 02h means 6Fh as well)
Note:    called by MS Windows HPSYSTEM.DRV and HPEBIOS.386 to support the HP-HIL
      input system
SeeAlso: AX=6F0Eh,INT 6F"HP"
--------b-166F0E-----------------------------
INT 16 - HP HIL Vectras - SET HIL Extended BIOS INTERRUPT NUMBER
    AX = 6F0Eh
    BL = new interrupt number (60h-6Fh,78h-7Fh)
Return: AH = status (00h = successful)
Desc:    allows the HIL Extended BIOS software to use a non-default interrupt
      number in case of an interrupt conflict with another application
Note:    called by MS Windows HPSYSTEM.DRV and HPEBIOS.386 to support the HP-HIL
      input system
SeeAlso: AX=6F0Dh,INT 6F"HP"
--------K-1670-------------------------------
INT 16 - FAKEY.COM - INSTALLATION CHECK
    AH = 70h
Return: AX = 1954h if installed
Program: FAKEY is a keystroke faking utility by System Enhancement Associates
--------K-1671-------------------------------
INT 16 - FAKEY.COM - PUSH KEYSTROKES
    AH = 71h
    CX = number of keystrokes
    DS:SI -> array of words containing keystrokes to be returned by AH=00h
Program: FAKEY is a keystroke faking utility by System Enhancement Associates
SeeAlso: AH=05h,AH=72h
--------K-1672-------------------------------
INT 16 - FAKEY.COM - CLEAR FAKED KEYSTROKES
    AH = 72h
Program: FAKEY is a keystroke faking utility by System Enhancement Associates
SeeAlso: AH=71h
--------K-1673-------------------------------
INT 16 - FAKEY.COM - PLAY TONES
    AH = 73h
    CX = number of tones to play
    DS:SI -> array of tones (see below)
Program: FAKEY is a keystroke faking utility by System Enhancement Associates
SeeAlso: INT 15/AX=1019h

Format of tone array entries:
Offset    Size    Description
 00h    WORD    divisor for timer channel 2
 02h    WORD    duration in clock ticks
----------167463-----------------------------
INT 16 U - FastJuice - INSTALLATION CHECK
    AX = 7463h ("tc")
Return: AX = 5443h ("TC") if installed
Program: FastJuice is a resident battery-power monitor by SeaSide Software
SeeAlso: AX=6A6Bh
--------R-1675-------------------------------
INT 16 - pcANYWHERE III - SET TICK COUNT FOR SCANNING
    AH = 75h
    AL = number of ticks between checks for new screen changes
--------R-1676-------------------------------
INT 16 - pcANYWHERE III - SET ERROR CHECKING TYPE
    AH = 76h
    AL = error checking type
        00h none
        01h fast
        02h slow
--------R-1677-------------------------------
INT 16 - pcANYWHERE III - LOG OFF
    AH = 77h
    AL = mode
        00h wait for another call
        01h leave in Memory Resident Mode
        02h leave in Automatic Mode
        FFh leave in current operating mode
--------U-167761-----------------------------
INT 16 - WATCH.COM v2.x-v3.0 - INSTALLATION CHECK
    AX = 7761h ('wa')
Return: AX = 5741h ('WA') if installed
Note:    WATCH.COM is part of the "TSR" package by Kim Kokkonen
SeeAlso: INT 21/AX=7761h
--------U-167788BX7789-----------------------
INT 16 - PC Magazine PUSHDIR.COM - INSTALLATION CHECK
    AX = 7788h
    BX = 7789h
    DS:SI -> signature "PUSHDIR VERSION 1.0"
Return: AX = 7789h if installed and signature correct
    BX = 7788h
    SI destroyed
--------R-1679-------------------------------
INT 16 - pcANYWHERE III - CHECK STATUS
    AH = 79h
Return: AX = status
        FFFFh if resident and active
        FFFEh if resident but not active
        FFFDh if in Memory Resident mode
        FFFCh if in Automatic mode
        other value if not resident
SeeAlso: AX=7B00h,INT 21/AX=2B44h
--------R-167A-------------------------------
INT 16 - pcANYWHERE III - CANCEL SESSION
    AH = 7Ah
--------R-167B00-----------------------------
INT 16 - pcANYWHERE III - SUSPEND
    AX = 7B00h
SeeAlso: AH=79h,AX=7B01h
--------R-167B01-----------------------------
INT 16 - pcANYWHERE III - RESUME
    AX = 7B01h
SeeAlso: AH=79h,AX=7B00h
--------R-167C-------------------------------
INT 16 - pcANYWHERE III - GET PORT CONFIGURATION
    AH = 7Ch
Return: AH = port number
    AL = baud rate
        00h = 50 baud
        01h = 75 baud
        02h = 110 baud
        03h = 134.5 baud
        04h = 150 baud
        05h = 300 baud
        06h = 600 baud
        07h = 1200 baud
        08h = 1800 baud
        09h = 2000 baud
        0Ah = 2400 baud
        0Bh = 4800 baud
        0Ch = 7200 baud
        0Dh = 9600 baud
        0Eh = 19200 baud
--------R-167D-------------------------------
INT 16 - pcANYWHERE III - GET/SET TERMINAL PARAMETERS
    AH = 7Dh
    AL = subfunction
        00h set terminal parameters
        01h get terminal parameters
        02h get configuration header and terminal parameters
    DS:CX -> terminal parameter block
--------R-167E-------------------------------
INT 16 - pcANYWHERE III - COMMUNICATIONS I/O THROUGH PORT
    AH = 7Eh
    AL = subfunction
        01h port input status
        Return AX = 0 if no characer ready,
               AX = 1 if character ready
        02h port input character
        Return AL = received character
        03h port output character in CX
        11h hang up phone
--------R-167F-------------------------------
INT 16 - pcANYWHERE III - SET KEYBOARD/SCREEN MODE
    AH = 7Fh
    AL = subfunction
        00h enable remote keyboard only
        01h enable host keyboard only
        02h enable both keyboards
        08h display top 24 lines
        09h display bottom 24 lines
        10h Hayes modem
        11h other modem
        12h direct connect
--------U-1680-------------------------------
INT 16 - MAKEY.COM - INSTALLATION CHECK
    AH = 80h
Return: AX = 1954h if installed
Program: MAKEY is a utility by System Enhancement Associates
--------U-168765BX4321-----------------------
INT 16 - AT.COM version 8/26/87 - API
    AX = 8765h
    BX = 4321h
    CX = ??? or FFFFh
    if CX = FFFFh
        DX = number of event to remove or FFFFh
Return: ES:BX -> event record array
Program: AT.COM is a resident scheduler by Bill Frolik

Format of event record:
Offset    Size    Description
 00h    BYTE    in-use flag (00h free, 01h in use, FFh end of array)
 01h    BYTE    day of date on which to trigger
 02h    BYTE    month of date on which to trigger
 03h    BYTE    trigger time, minute
 04h    BYTE    trigger time, hour
 05h    WORD    offset of command to be executed
----------1692-------------------------------
INT 16 - ???
    AH = 92h
Return: AH <= 80h if ???
Note:    called by DOS 3.2 KEYBxx.COM and DOS 5+ KEYB.COM
SeeAlso: AH=05h"PCjr",AH=A2h
--------U-1699-------------------------------
INT 16 - SCOUT v5.4 - GET ???
    AH = 99h
Return: AX = ABCDh
    BX:CX -> ??? (appears to be start of PSP for resident portion)
Program: Scout is a memory-resident file manager by New-Ware
SeeAlso: AH=9Eh
--------U-169E-------------------------------
INT 16 - SCOUT v5.4 - INSTALLATION CHECK
    AH = 9Eh
Return: AX = ABCDh if installed
Program: Scout is a memory-resident file manager by New-Ware
SeeAlso: AH=99h
----------16A2-------------------------------
INT 16 - ???
    AH = A2h
Return: AH <= 80h if ???
Note:    this function is called by DOS 5+ KEYB.COM
SeeAlso: AH=92h
--------V-16AA-------------------------------
INT 16 - PTxxx.COM - (xxx=CGA,EGA,VGA,HER...) CALL GATE FOR GRAPHICS
    AH = AAh
    Various registers set up by high level language.
Return: Graphics performed
Note:    PT stands for Paint Tools which is a graphics library for Turbo Pascal,
      Modula 2 and others from DataBiten in Sweden. The library is
      installed as a memory resident driver.
----------16AABBBXEEFF-----------------------
INT 16 U - JORJ v4.3 - INSTALLATION CHECK
    AX = AABBh
    BX = EEFFh
Return: AX = EEFFh if installed
    BX = AABBh if installed
        CL = hotkey name (default 6Ah 'j' for Alt-J)
Program: JORJ is a shareware dictionary with phonetic lookup by Jorj Software
      Co.
Index:    hotkeys;JORJ
--------K-16CA--BX736B-----------------------
INT 16 - CtrlAlt Associates STACKEY.COM v3.00 - API
    AH = CAh
    BX = 736Bh ("sk")
    CX = 736Bh
    AL = function
        00h installation check
        Return: DX = words available in keyboard buffer
        01h place keystroke in buffer
        DX = keystroke (DH = scan code, DL = ASCII character)
        Return: DX = words available in keyboard buffer
                FFFFh on error
        02h flush STACKEY and BIOS keyboard buffers
Return: AX = CAFFh if installed
        BX = segment of resident code
        CX = STACKEY version (CH = major, CL = minor)
Program: STACKEY is a shareware keyboard-input faking TSR
Index:    installation check;STACKEY
--------V-16CA00BX6570-----------------------
INT 16 - CtrlAlt Associates EGAPAL.COM v1.00 - INSTALLATION CHECK
    AX = CA00h
    BX = 6570h ("ep")
    CX = 6570h
Return: AX = CAFFh if installed
        BX = segment of resident code
        CX = ??? (0090h)
Program: EGAPAL is a TSR supplied with STACKEY which makes EGA palette settings
      permanent across mode switches
SeeAlso: AX=CA00h/BX=7670h
--------V-16CA00BX7670-----------------------
INT 16 - CtrlAlt Associates VGAPAL.COM v1.00 - INSTALLATION CHECK
    AX = CA00h
    BX = 7670h ("vp")
    CX = 7670h
Return: AX = CAFFh if installed
        BX = segment of resident code
        CX = ??? (0090h)
Program: VGAPAL is a TSR supplied with STACKEY which makes VGA palette settings
      permanent across mode switches
SeeAlso: AX=CA00h/BX=6570h
----------16D724CX00CB-----------------------
INT 16 U - APCAL v3.20 - GET ???
    AX = D724h
    CX = 00CBh
Return: AX = 0000h
    BX = 0000h
    DX:CX -> ??? or 0000h:0000h
Program: APCAL is an optionally-resident shareware appointment calendar by
      Gamma Software
SeeAlso: AX=D724h/CX=00CCh,AX=D724h/CX=00CDh
----------16D724CX00CC-----------------------
INT 16 U - APCAL v3.20 - GET ???
    AX = D724h
    CX = 00CCh
Return: AX = 0000h
    BX = 0000h
    DX:CX -> ??? (apparently an internal data area)
SeeAlso: AX=D724h/CX=00CBh,AX=D724h/CX=00CDh
----------16D724CX00CD-----------------------
INT 16 U - APCAL v3.20 - GET ???
    AX = D724h
    CX = 00CDh
Return: AX = ??? (5345h seen)
SeeAlso: AX=D724h/CX=00CBh,AX=D724h/CX=00CCh
--------t-16E0E0-----------------------------
INT 16 - TurboPower TSRs - ALTERNATE INSTALLATION CHECK
    AX = E0E0h
Return: AX = 1F1Fh if installed
        DWORD 0040h:00F0h -> last data block in TSR list (see AX=F0F0h)
Note:    the returned TSR list provides support for communication among TSRs
      built with TurboPower's Turbo Professional and Object Professional
      libraries for Turbo Pascal
SeeAlso: AX=F0F0h
--------U-16ED--BHED-------------------------
INT 16 - BORLAND TURBO LIGHTNING - API
    AH = EDh
    BH = EDh
    BL = function
        00h installation check
        Return: AX = 5205h
            CH = major version
            CL = minor version
        01h ???
        02h get resident CS
        Return: AX = code segment of resident portion
        03h get resident ???
        Return: AX = offset of some buffer in resident code seg
        04h ???
        05h set ???
        AL = 0 to 0Ch
        Return: AX = status
                0000h if OK
                0001h if out of range.
        06h ???
        07h ???
        08h ???
        AL = char???
        CX = ???
        DX = ???
        Return: AX = 0, 1 or 2
        09h ???
        0Ah ???
        CX = ???
        DX = ???
        Return: AX = ???
        0Bh ???
        DS:SI -> ???
        Return: AX = 0, 40h, 80h
        0Ch ???
        DS:SI -> ???
        Return: AH = 0
            AL = ???
        0Dh set ???
        (sets an internal flag)
        0Eh ???
        DS:SI -> ???
        Return: AX = 0, 1 or 2.
        0Fh ???
        10h ???
Notes:    AX in general returns an error code from most functions.
Index:    installation check;Turbo Lightning
----------16EF-------------------------------
INT 16 - CALCULATOR - INSTALLATION CHECK
    AH = EFh
Return: AX = 0088h if installed
Program: CALCULATOR is a shareware popup calculator by Andrzej Brzezinski and
      Marek Kosznik
--------b-16F0-------------------------------
INT 16 - Compaq 386 - SET CPU SPEED
    AH = F0h
    AL = speed
        00h equivalent to 6 MHz 80286 (COMMON)
        01h equivalent to 8 MHz 80286 (FAST)
        02h full 16 MHz (HIGH)
        03h toggles between 8 MHz-equivalent and speed set by system board
        switch (AUTO or HIGH)
        08h full 16 MHz except 8 MHz-equivalent during floppy disk access
        09h specify speed directly
        CX = speed value, 1 (slowest) to 50 (full), 3 ~= 8088
SeeAlso: AH=F1h,AH=F3h
--------t-16F0F0-----------------------------
INT 16 - TurboPower TSRs - INSTALLATION CHECK
    AX = F0F0h
Return: AX = 0F0Fh if installed
        ES:DI -> last data block in TSR list
Note:    the returned TSR list provides support for communication among TSRs
      built with TurboPower's Turbo Professional and Object Professional
      libraries for Turbo Pascal
SeeAlso: AX=E0E0h

Format of data block:
Offset    Size    Description
 00h    DWORD    pointer to program tag (counted ASCII string)
 04h    WORD    interface version number (0400h)
 06h    DWORD    pointer to command entry point
 0Ah    DWORD    pointer to previous data block (0000h:0000h if none)
 0Eh    DWORD    pointer to next data block (0000h:0000h if none)
---swappable TSRs only---
 12h    DWORD    pointer to swapping data
 16h    DWORD    pointer to user data
    more???
--------b-16F1-------------------------------
INT 16 - Compaq 386 - READ CURRENT CPU SPEED
    AH = F1h
Return: AL = speed code (see AH=F0h)
         if AL = 09h, CX = speed code
SeeAlso: AH=F0h,AH=F3h
--------b-16F2-------------------------------
INT 16 - Compaq 386 - DETERMINE ATTACHED KEYBOARD TYPE
    AH = F2h
Return: AL = type
        00h if 11-bit AT keyboard is in use
        01h if 9-bit PC keyboard is in use
--------b-16F3-------------------------------
INT 16 - Compaq 80286s - SET CPU SPEED LIMIT (OVERRIDE JUMPER)
    AH = F3h
    AL = 00h limit is 6 Mhz
       = 01h limit is 8 Mhz/6 Mhz
SeeAlso: AH=F0h,AH=F1h
--------U-16F398-----------------------------
INT 16 U - NORTON GUIDES - INSTALLATION CHECK
    AX = F398h
Return: AX = 6A73h ("js")
    BH = scan code of current hot key
    BL = ASCII code of current hot key
Note:    NG.EXE was written by John Socha
--------b-16F400-----------------------------
INT 16 - Compaq Systempro - CACHE CONTROLLER STATUS
    AX = F400h
Return: AH = E2h
    AL = status
        00h not present
        01h enabled
        02h disabled
SeeAlso: AX=F401h,AX=F402h
--------b-16F401-----------------------------
INT 16 - Compaq Systempro - ENABLE CACHE CONTROLLER
    AX = F401h
Return: AX = E201h
SeeAlso: AX=F400h,AX=F402h
--------b-16F402-----------------------------
INT 16 - Compaq Systempro - DISABLE CACHE CONTROLLER
    AX = F402h
Return: AX = E202h
SeeAlso: AX=F400h,AX=F401h
--------v-16FA00DX5945-----------------------
INT 16 U - PC Tools v8+ VSAFE, VWATCH - INSTALLATION CHECK???
    AX = FA00h
    DX = 5945h
Return: CF clear
    DI = 4559h
    BX = ??? (2F00h or FFFFh) (VSAFE only)
SeeAlso: INT 13/AH=FAh,INT 21/AH=FAh"VDEFEND",INT 2F/AX=6282h
--------v-16FA01DX5945-----------------------
INT 16 U - PC Tools v8+ VSAFE, VWATCH - UNINSTALL
    AX = FA01h
    DX = 5945h
Return: CF clear if successful
    DI = 4559h
SeeAlso: AX=FA00h
--------v-16FA02DX5945-----------------------
INT 16 U - PC Tools v8+ VSAFE, VWATCH - ???
    AX = FA02h
    DX = 5945h
    BL = ???
Return: CF clear
    DI = 4559h
    CL = old value of ???
--------v-16FA03DX5945-----------------------
INT 16 U - PC Tools v8+ VSAFE, VWATCH - ???
    AX = FA03h
    DX = 5945h
Return: CF clear
    DI = 4559h
    AX = 0002h
--------v-16FA04DX5945-----------------------
INT 16 U - PC Tools v8+ VSAFE - GET ???
    AX = FA04h
    DX = 5945h
Return: CF clear
    DI = 4559h
    BL = ???
Note:    this function is a NOP under VWATCH
SeeAlso: AX=FA05h
--------v-16FA05DX5945-----------------------
INT 16 U - PC Tools v8+ VSAFE - SET ???
    AX = FA05h
    DX = 5945h
    BL = ???
Return: CF clear
    DI = 4559h
Note:    this function is a NOP under VWATCH
SeeAlso: AX=FA04h
--------v-16FA06DX5945-----------------------
INT 16 U - PC Tools v8+ VSAFE, VWATCH - GET ???
    AX = FA06h
    DX = 5945h
Return: CF clear
    DI = 4559h
    BL = ???
SeeAlso: AX=FA07h
--------v-16FA07DX5945-----------------------
INT 16 U - PC Tools v8+ VSAFE, VWATCH - SET ???
    AX = FA07h
    DX = 5945h
    BL = ???
Return: CF clear
    DI = 4559h
SeeAlso: AX=FA00h,AX=FA06h
--------U-16FE55-----------------------------
INT 16 U - PC Tools v8+ DATAMON, DRIVEMAP, CPSCHED, CPTASK - ???
    AX = FE55h
    CX = segment of resident CPTASK or 0000h???
    DX = ???
    ???
Return: DX:AX -> ???
--------U-16FEA4-----------------------------
INT 16 U - PC Tools v7+ CPSCHED/DESKTOP - RESET ???
    AX = FEA4h
Return: nothing
Note:    this function is identical to AX=FFA4h, and is implemented by the same
      code in DESKTOP
SeeAlso: AX=FFA4h
--------U-16FEC6-----------------------------
INT 16 U - PC Tools v7+ CPSCHED - ENABLE/DISABLE CPSCHED API
    AX = FEC6h
    BL = new state (00h enabled, nonzero disabled)
Return: nothing
Desc:    specify whether CPSCHED API calls other than this one and AX=FE55h will
      be honored
--------U-16FED3-----------------------------
INT 16 U - PC Tools v7+ CPSCHED/DESKTOP - ???
    AX = FED3h
    DS:SI -> 92-byte data record for ???
Return: ???
Note:    this function is identical to AX=FFD3h, and is implemented by the same
      code in DESKTOP
SeeAlso: AX=FFD3h
--------U-16FEDC-----------------------------
INT 16 U - PC Tools v7+ CPSCHED - UNHOOK INTERRUPTS
    AX = FEDCh
Return: AX,DX destroyed
Index:    uninstall;CPSCHED
--------U-16FEEFCX0000-----------------------
INT 16 U - PC Tools v7+ CPSCHED/DESKTOP - INSTALLATION CHECK
    AX = FEEFh
    CX = 0000h
Return: CX = ABCDh if PC Tools scheduler (CPSCHED or DESKTOP) installed
        BX = segment of resident portion
        DX = (CPSCHED v8.0) resident CS
Note:    this function is identical to AX=FFD3h, and is implemented by the same
      code in DESKTOP
SeeAlso: AX=FFEFh
--------U-16FEF1-----------------------------
INT 16 U - PC Tools v7 only CPSCHED/DESKTOP - ALTERNATE INSTALLATION CHECK
    AX = FEF1h
    BX = ???
Return: CX = 5555h if PC Tools scheduler (CPSCHED or DESKTOP) installed
    DX = 5555h
Note:    this function is identical to AX=FFD3h, and is implemented by the same
      code in DESKTOP
SeeAlso: AX=FFF1h
--------K-16FF-------------------------------
INT 16 - KEYBOARD - KBUF extensions - ADD KEY TO TAIL OF KEYBOARD BUFFER
    AH = FFh
    DX = scan code
Return: AL = status
        00h success
        01h failure
Program: KBUF is a keyboard buffer expander by Mark Adler
SeeAlso: AH=05h
--------V-16FF-------------------------------
INT 16 - OPTIMA 1024 VGA-Sync,ET-3000 chipset - QUERY ZOOM INTERRUPT
    AH = FFh
Return: AL = interrupt number to which BIOS keyboard handler has been relocated
    AL+1 = Zoom interrupt number
    BX = hotkey
Notes:    the default interrupts are 60h for keyboard and 61h for Zoom interrupt;
      the default hot key is F10
    not all vendors include the Tseng TSR which supports these functions
SeeAlso: INT 60"OPTIMA"
Index:    hotkeys;OPTIMA 1024 VGA
--------d-16FF70-----------------------------
INT 16 U - PC Tools v8+ DRIVEMAP - API
    AX = FF70h
    BX = function (0000h-0002h)
        0000h installation check
        CX = 4C69h ('Li')
        DX = 6E6Bh ('nk')
        Return: AX = 0000h
            CX = 4350h ('CP')
            DH = major version
            DL = minor version
        0001h ???
        DL = ???
        Return: AX = ???
            DH = ???
        0002h ???
        BX = ???
        DX = ???
        Return: AX = ??? or FFFEh/FFFFh on error
            DL = ???
BUG:    this call will branch to random locations for BX values other than
      those listed above for v8.0 because a) the incorrect register is
      range-tested, resulting in BX=0003h-5CD6h being accepted as valid
      function numbers, and b) the conditional which branches on invalid
      function numbers jumps to the following instruction, becoming a NOP
SeeAlso: INT 2F/AX=9203h"DRIVEMAP"
Index:    installation check;DRIVEMAP
--------T-16FF80BX0000-----------------------
INT 16 U - PC Tools v8+ CPTASK - INSTALLATION CHECK
    AX = FF80h
    BX = 0000h
    CX = 0000h
    DX = 0000h
Return: CX = 5555h if installed
Program: CPTASK is a task switcher by Central Point Software
--------T-16FF80BX0001-----------------------
INT 16 U - PC Tools v8+ CPTASK - GET ???
    AX = FF80h
    BX = 0001h
    ???
Return: DX:SI -> task list???
    BX = ??? (PSP segment of resident code???)
--------T-16FF80BX0002-----------------------
INT 16 U - PC Tools v8+ CPTASK - GET ???
    AX = FF80h
    BX = 0002h
Return: DX:SI -> ???
--------T-16FF80BX0003-----------------------
INT 16 U - PC Tools v8+ CPTASK - GET ???
    AX = FF80h
    BX = 0003h
Return: AX = ???
--------T-16FF80BX0004-----------------------
INT 16 U - PC Tools v8+ CPTASK - SET ???
    AX = FF80h
    BX = 0004h
    CX = new value of ???
Return: ???
Note:    this function also sets the ??? flag
--------T-16FF80BX0005-----------------------
INT 16 U - PC Tools v8+ CPTASK - GET NUMBER OF ACTIVE TASKS???
    AX = FF80h
    BX = 0005h
Return: AX = number of active tasks???
--------T-16FF80BX0006-----------------------
INT 16 U - PC Tools v8+ CPTASK - GET AND CLEAR ??? FLAG
    AX = FF80h
    BX = 0006h
Return: AX = old state (0000h clear, 0001h set)
--------T-16FF80BX0007-----------------------
INT 16 U - PC Tools v8+ CPTASK - ???
    AX = FF80h
    BX = 0007h
    ES:DI -> ???
    ???
Return: ???
--------T-16FF80BX0008-----------------------
INT 16 U - PC Tools v8+ CPTASK - ???
    AX = FF80h
    BX = 0008h
    ???
Return: ???
--------T-16FF80BX0009-----------------------
INT 16 U - PC Tools v8+ CPTASK - GET ???
    AX = FF80h
    BX = 0009h
Return: CL = ???
    CH = ??? (01h or 02h)
--------T-16FF80BX4350-----------------------
INT 16 U - PC Tools v8+ CPTASK - ???
    AX = FF80h
    BX = 4350h ('CP')
    CX = 5354h ('ST')
    ???
Return: ???
--------U-16FF90-----------------------------
INT 16 U - PC Tools v8+ DESKTOP - ???
    AX = FF90h
    ???
Return: ???
Note:    available only when popped up
--------U-16FF91-----------------------------
INT 16 U - PC Tools v7+ DESKTOP - ???
    AX = FF91h
    ???
Return: AX = 0000h
Note:    calls AX=FFFDh after ???
SeeAlso: AX=FF92h,AX=FFFDh
--------U-16FF92-----------------------------
INT 16 U - PC Tools v7+ DESKTOP - ???
    AX = FF92h
    ???
Return: AX = 0000h
Note:    like AX=FF91h, but temporarily sets ??? to 3
SeeAlso: AX=FF91h,AX=FF92h
--------U-16FF93-----------------------------
INT 16 U - PC Tools v7+ DESKTOP - SET ??? FLAG
    AX = FF93h
--------U-16FF94-----------------------------
INT 16 U - PC Tools v7+ DESKTOP - SET ???
    AX = FF94h
    CX = ??? (default 0017h)
--------U-16FF95-----------------------------
INT 16 U - PC Tools v7+ DESKTOP - SET ???
    AX = FF95h
    BX = ???
--------U-16FF96-----------------------------
INT 16 U - PC Tools v7+ DESKTOP - ???
    AX = FF96h
    CL = ???
Return: AX = ???
--------U-16FF97-----------------------------
INT 16 U - PC Tools v7+ DESKTOP - ???
    AX = FF97h
    DS:DX -> buffer for ??? (see below)
Return: ???

Format of buffer:
Offset    Size    Description
 00h 48 BYTEs    ???
 30h 128 BYTEs    ???
--------U-16FF98-----------------------------
INT 16 U - PC Tools v7+ DESKTOP - OPEN \DESK.OVL FILE AND SEEK TO OVERLAY
    AX = FF98h
    DX = byte offset in file of overlay header
Return: BX = file handle for DESK.OVL file
Desc:    open the DESK.OVL file, seek to the specified offset, read in the
      overlay header, and seek to the offset specified by the header

Format of overlay header:
Offset    Size    Description
 00h 12 BYTEs    NUL-padded ASCII overlay filename
 0Ch    DWORD    offset within DESK.OVL file of actual overlay
--------U-16FF99-----------------------------
INT 16 U - PC Tools v7+ DESKTOP - ???
    AX = FF99h
    ???
Return: ???
--------U-16FF9A-----------------------------
INT 16 U - PC Tools v7+ DESKTOP - GET NAME OF COLOR SCHEME
    AX = FF9Ah
Return: ES:BX -> name of current color scheme
Note:    available even if not popped up
--------U-16FF9B-----------------------------
INT 16 U - PC Tools v7+ DESKTOP - UNUSED
    AX = FF9Bh
Return: ???
Note:    sounds triple-length beep
--------T-16FF9C-----------------------------
INT 16 U - PC Tools v8+ CPTASK - ???
    AX = FF9Ch
    BL = ??? (00h,01h,02h)
    ???
Return: ???
Note:    sounds triple-length beep
----------16FF9D-----------------------------
INT 16 U - PC Tools v8+ CPTASK, VSAFE - ???
    AX = FF9Dh
    ES:BX -> ??? word
Return: ???
Note:    if ES is non-zero, the word pointed at by ES:BX determines whether the
      ??? flag is cleared (word = 0000h) or set (word is nonzero).    The
      flag is always cleared if ES=0000h.
--------U-16FF9E-----------------------------
INT 16 U - PC Tools v7+ DESKTOP - ???
    AX = FF9Eh
    DL = ???
        bit 7: ???
        bits 6-0: function number??? (00h,01h,other)
    ???
Return: ???
--------U-16FFA1-----------------------------
INT 16 U - PC Tools v7+ DESKTOP - ???
    AX = FFA1h
    ???
Return: ???
Note:    same as AX=FFA2h, except ??? set to FFh
SeeAlso: AX=FFA2h
--------U-16FFA2-----------------------------
INT 16 U - PC Tools v7+ DESKTOP - ???
    AX = FFA2h
    ???
Return: ???
Note:    calls AX=FFC7h (remove window) and AX=FFFDh
SeeAlso: AX=FFA1h,AX=FFC7h,AX=FFFDh
--------y-16FFA3BX0000-----------------------
INT 16 U - PC Tools v7+ DATAMON - INSTALLATION CHECK
    AX = FFA3h
    BX = 0000h
    CX = 0000h
Return: AX = segment of resident code
    BX = 5555h
    CX = 5555h
SeeAlso: INT 21/AH=3Fh"NB.SYS",INT 21/AX=4101h
--------y-16FFA3BX0001-----------------------
INT 16 U - PC Tools v7+ DATAMON - GET ???
    AX = FFA3h
    BX = 0001h
    CX = 0001h
Return: AX:BX -> ???
    CX = BX
--------y-16FFA3BX0002-----------------------
INT 16 U - PC Tools v7+ DATAMON - GET ???
    AX = FFA3h
    BX = 0002h
    CX = 0002h
Return: AX = ??? (0 or 1)
    CX = BX = AX
--------y-16FFA3BX0003-----------------------
INT 16 U - PC Tools v7+ DATAMON - GET ???
    AX = FFA3h
    BX = 0003h
    CX = 0003h
Return: AX = ??? (0 or 1)
    CX = BX = AX
--------y-16FFA3BX0004-----------------------
INT 16 U - PC Tools v7+ DATAMON - SET ??? FLAG
    AX = FFA3h
    BX = 0004h
    CX = 0004h
SeeAlso: AX=FFA3h/BX=0005h
--------y-16FFA3BX0005-----------------------
INT 16 U - PC Tools v7+ DATAMON - CLEAR ??? FLAG
    AX = FFA3h
    BX = 0005h
    CX = 0005h
SeeAlso: AX=FFA3h/BX=0004h
--------y-16FFA3BX0006-----------------------
INT 16 U - PC Tools v7+ DATAMON - SET PSP SEGMENT ???
    AX = FFA3h
    BX = 0006h
    CX = 0006h
    DX = current PSP segment as known to DOS??? or 0000h
--------U-16FFA4-----------------------------
INT 16 U - PC Tools v7+ DESKTOP - ???
    AX = FFA4h
Return: ???
Notes:    available even when not popped up
    sets unknown flag if ??? conditions met
SeeAlso: AX=FEA4h
--------c-16FFA5CX1111-----------------------
INT 16 - PC-Cache v6+ - INSTALLATION CHECK
    AX = FFA5h
    CX = 1111h
Return: CH = 00h if installed
        ES:DI -> internal data (see below)
        CL = cache state
        01h enabled
        02h disabled
SeeAlso: INT 13/AH=27h,INT 13/AH=A0h,INT 21/AH=2Bh/CX=4358h

Format of internal data:
Offset    Size    Description
-1Ch 20 BYTEs    cached drive list, one byte per drive A: to T:
        each byte is either blank (20h) or drive letter (41h-54h)
 -8    BYTE    ???
 -7    WORD    number of physical transfers (scaled down to 0000h-7FFFh)
 -5    WORD    number of saved transfers (scaled down to 0000h-7FFFh)
 -3   3 BYTEs    ???
--------c-16FFA5CXAAAA-----------------------
INT 16 - PC-Cache v6+ - ENABLE DELAYED WRITES
    AX = FFA5h
    CX = AAAAh
Return: AX = ??? (apparently either 0000h or sectors_in_cache - 5)
SeeAlso: AX=FFA5h/CX=CCCCh
--------c-16FFA5CXCCCC-----------------------
INT 16 - PC-Cache v6+ - FLUSH CACHE AND DISABLE DELAYED WRITES
    AX = FFA5h
    CX = CCCCh
Return: AX = ??? (apparently either 0000h or sectors_in_cache - 5)
Note:    delayed writes are automatically disabled on EXECing
      (see INT 21/AH=4Bh) a program named either WIN.CO? or DV.E??;
      however, delayed writes are not automatically reenabled upon the
      program's termination in v6.
SeeAlso: AX=FFA5h/CX=AAAAh,AX=FFA5h/CX=FFFFh
--------c-16FFA5CXDDDD-----------------------
INT 16 - PC-Cache v6+ - FLUSH AND DISABLE CACHE
    AX = FFA5h
    CX = DDDDh
SeeAlso: AX=FFA5h/CX=EEEEh,AX=FFA5h/CX=FFFFh
--------c-16FFA5CXEEEE-----------------------
INT 16 - PC-Cache v6+ - ENABLE CACHE
    AX = FFA5h
    CX = EEEEh
SeeAlso: AX=FFA5h/CX=DDDDh
--------c-16FFA5CXFFFF-----------------------
INT 16 - PC-Cache v6+ - FLUSH CACHE
    AX = FFA5h
    CX = FFFFh
SeeAlso: AX=FFA5h/CX=CCCCh,AX=FFA5h/CX=DDDDh,INT 13/AH=A1h
--------U-16FFA6-----------------------------
INT 16 U - PC Tools v6.0+ DESKTOP API - GET ???
    AX = FFA6h
Return: DS:SI -> ???
Note:    available only when popped up
--------U-16FFA7-----------------------------
INT 16 U - PC Tools v6.0+ DESKTOP API - GET ??? PATH
    AX = FFA7h
Return: DS:SI -> ASCIZ path (directory from which PCTools was run???)
--------U-16FFA8-----------------------------
INT 16 U - PC Tools v6.0+ DESKTOP API - ???
    AX = FFA8h
    DS:SI -> three consecutive ASCIZ strings for ??? (max 256 bytes total)
    ???
Return: ???
Notes:    available only when popped up
    strings copied into internal buffer, among other actions
--------U-16FFA9-----------------------------
INT 16 U - PC Tools v6.0+ DESKTOP API - GET VERSION STRING
    AX = FFA9h
Return: DS:SI -> version string
--------U-16FFAA-----------------------------
INT 16 U - PC Tools v6.0+ DESKTOP API - ???
    AX = FFAAh
    ???
Return: ???
Note:    available only when popped up
--------U-16FFAB-----------------------------
INT 16 U - PC Tools v6.0+ DESKTOP API - GET EDITOR SETTINGS???
    AX = FFABh
Return: DS:SI -> editor setting strings???
--------U-16FFAC-----------------------------
INT 16 U - PC Tools v6.0+ DESKTOP API - SET ???
    AX = FFACh
    DL = ???
Note:    available only when popped up
--------U-16FFAD-----------------------------
INT 16 U - PC Tools v6.0+ DESKTOP API - SET ???
    AX = FFADh
    DL = ???
--------U-16FFAE-----------------------------
INT 16 U - PC Tools v6.0+ DESKTOP API - GET ???
    AX = FFAEh
Return: AL = ???
--------U-16FFAF-----------------------------
INT 16 U - PC Tools v6.0+ DESKTOP API - SET ???
    AX = FFAFh
    DL = ???
--------U-16FFB0-----------------------------
INT 16 U - PC Tools v6.0+ DESKTOP API - SET ???
    AX = FFB0h
    BL = ???
--------U-16FFB1-----------------------------
INT 16 U - PC Tools v6.0+ DESKTOP API - ???
    AX = FFB1h
    ???
Return: ???
--------U-16FFB2-----------------------------
INT 16 U - PC Tools v5.5+ DESKTOP API - GET ???
    AX = FFB2h
Return: DS:SI -> ???
--------U-16FFB3-----------------------------
INT 16 U - PC Tools v5.5+ DESKTOP API - ???
    AX = FFB3h
    ???
Return: ???
Note:    available only when popped up
--------U-16FFB4-----------------------------
INT 16 U - PC Tools v5.5+ DESKTOP API - SET ??? FLAG
    AX = FFB4h
Note:    available only when popped up
SeeAlso: AX=FFBBh
--------U-16FFB5-----------------------------
INT 16 U - PC Tools v5.5+ DESKTOP API - GET/SET WINDOW PARAMETERS
    AX = FFB5h
    BX = window specifier (000Fh to 0019h) (see below)
    DX = 0000h get, nonzero = set
    ES:DI -> window parameter buffer (see below)
SeeAlso: AX=FFCBh

Values for window specifier:
 000Fh    comm/FAX
 0014h    hotkey selection
 0015h    ASCII table
 0016h    system colors menu

Format of window parameters:
Offset    Size    Description
 00h    BYTE    rows in window, not counting frame
 01h    BYTE    columns in window, not counting frame
 02h    BYTE    row number of top of window
 03h    BYTE    2*column number of left of window
 04h    BYTE    character attribute for ???
 05h    BYTE    character attribute for background/border
 06h    BYTE    character attribute for ???
 07h    DWORD    pointer to ??? on screen
 0Bh  4 BYTEs    ???
 0Fh    BYTE    nonzero if window may be resized
Note:    if running in monochrome mode, character attributes at offsets 04h to
      06h are stored unchanged, but attributes other than 07h, 0Fh, or 70h
      are changed to 07h on reading
--------U-16FFB6-----------------------------
INT 16 U - PC Tools v5.5+ DESKTOP API - GET ???
    AX = FFB6h
Return: AH = ???
    AL = ???
--------U-16FFB7-----------------------------
INT 16 U - PC Tools v5.5+ DESKTOP API - GET/SET ???
    AX = FFB7h
    BX = direction
        0000h copy to buffer
        else  copy from buffer
    DS:SI -> 70-byte buffer with ???
Return: data copied
Note:    available only when popped up under v6.0+
--------U-16FFB8-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - GET/SET???
    AX = FFB8h
    BH = subfunction
        00h get
        Return: BL = old value of ???
            CL = old value of ??? (v6.0+)
            CH = old value of ??? (v6.0+)
        nonzero set
        BL = new value for ???
        CL = new value for ??? (v6.0+)
        CH = new value for ??? (v6.0+)
        DH = ???
        Return: AL = old value replaced by CL (v6.0+)
            AH = old value replaced by CH (v6.0+)
--------U-16FFB9-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFB9h
    ???
Return: AX = ???
    CX = ???
    DS:SI -> ???
    ES:DI -> ???
--------U-16FFBA-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFBAh
    ???
Return: AX = ???
Note:    available only when popped up
--------U-16FFBB-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - CLEAR ??? FLAG
    AX = FFBBh
Note:    available only when popped up
SeeAlso: AX=FFB4h
--------U-16FFBC-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - RESTORE ORIGINAL SCREEN???
    AX = FFBCh
--------U-16FFBD-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ??? DATABASE INDEXING MESSAGES
    AX = FFBDh
    ???
Return: ???
--------U-16FFBE-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFBEh
    ???
Return: ???
Note:    available only when popped up
--------U-16FFBF-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFBFh
    BX = DOS file handle to write on
    ???
Return: ???
Note:    available only when popped up
--------U-16FFC0-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFC0h
    ???
Return: AX = 0000h if successful
    AX = FFFFh on error
Note:    available only when popped up
--------U-16FFC1-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFC1h
    BL = ???
    ES:DI -> data structure (see below)
    ???
Return: AX = ???
Note:    available only when popped up
SeeAlso: AX=FFC2h,AX=FFC3h

Format of data structure:
Offset    Size    Description
 00h    WORD    ???
 02h    WORD    ???
 04h    WORD    ???
 06h    WORD    ???
 08h    WORD    ???
 0Ah    BYTE    ???
 0Bh    BYTE    ??? (zero/nonzero)
---v7.1---
 0Ch    WORD    ???
 0Eh    BYTE    ???
 0Fh    WORD    ???
 11h    WORD    ???
    ???
--------U-16FFC2-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFC2h
    BL = ???
    ES:DI -> data structure (see AX=FFC1h)
    ???
Return: AH = ???
    CX = ???
    DH = ???
    DL = ???
Note:    available only when popped up
SeeAlso: AX=FFC1h,AX=FFC3h
--------U-16FFC3-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFC3h
    BL = ???
    ES:DI -> data structure (see AX=FFC1h)
    ???
Return: AH = ???
    CX = ???
    DH = ???
    DL = ???
Note:    available only when popped up
SeeAlso: AX=FFC1h,AX=FFC2h
--------U-16FFC4-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - GET ???
    AX = FFC4h
Return: AL = ???
    BX = segment of scratch space???
    CX = segment of stored screen data (section covered by window???)
    DX = segment of window parameters for ???
    ES:BP -> ???
Note:    available only when popped up in versions prior to 6.0
--------U-16FFC5-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - CHECK WHETHER DESKTOP LOADED RESIDENT
    AX = FFC5h
Return: BL = nonzero if loaded resident
       = 00h if nonresident
Note:    available only when popped up; should call AX=FFEFh first to ensure
      that DESKTOP is active
SeeAlso: AX=FFEFh,AX=FFF3h
--------U-16FFC6-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - SET ???
    AX = FFC6h
    BL = new value for ???
--------U-16FFC7-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - REMOVE WINDOW
    AX = FFC7h
    ???
Return: ???
--------U-16FFC8-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - GET ???
    AX = FFC8h
Return: DS:SI -> ???
Note:    valid only while popped up
--------U-16FFC9-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - COPY DATA TO CLIPBOARD
    AX = FFC9h
    DS:SI -> characters to store in clipboard
    CX = size in bytes
Return: CF set on error
Notes:    available only when popped up
    while copying, bytes of 00h and 0Ah are skipped
--------U-16FFCA-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - SET ???
    AX = FFCAh
    DX = ???
Return: AX destroyed
Note:    available only when popped up
--------U-16FFCB-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - SELECT WINDOW PARAMETERS???
    AX = FFCBh
    DX = window specifier???
Return: AX destroyed
Note:    available only when popped up
SeeAlso: AX=FFB5h
--------U-16FFCC-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - DISPLAY ASCIZ STRING CENTERED IN WINDOW
    AX = FFCCh
    DS:SI -> ASCIZ string
Return: AX = ???
    CX = ???
    ES:DI -> address past last character displayed (v5.1/5.5)
          -> ??? on menu bar (v6.0)
--------U-16FFCD-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFCDh
    DS:DX -> ???
Return: ???
Note:    available only when popped up
--------U-16FFCE-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - SET ??? DELAYS
    AX = FFCEh
    CX = ???
Return: nothing???
--------U-16FFCF-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - CLOSE PRINTER/PRINT FILE
    AX = FFCFh
Note:    available only when popped up
--------U-16FFD0-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - PREPARE TO PRINT???
    AX = FFD0h
    ???
Return: ???
Note:    available only when popped up
--------U-16FFD1-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - DISPLAY PRINT OPTIONS MENU
    AX = FFD1h
Return: BX = number of copies
    DX = destination
        00h cancel
        01h LPT1
        02h LPT2
        03h LPT3
        04h COM1
        05h COM2
        06h disk file
Note:    available only when popped up
--------U-16FFD2-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFD2h
    BX = ???
Return: BL = ???
Note:    available only when popped up
--------U-16FFD3-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFD3h
    DS:SI -> 92-byte data record for ???
Return: ???
SeeAlso: AX=FED3h
--------U-16FFD4BH3C-------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - CREATE/OPEN/DELETE FILE
    AX = FFD4h
    BH = 3Ch create file (with no attributes)
         3Dh open file
         41h delete file
    BL = access mode
         00h read only
         01h write only
         02h read/write
    DS:SI -> ASCIZ filename
Return: BX = file handle
        0000h on error
Note:    operation is attempted in (in order) the directory from which the
      desktop was started/run???, the directory specified with the
      filename, X:\PCTOOLS\, and X:\
--------U-16FFD5-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFD5h
    ???
Return: ???
Note:    available only when popped up
--------U-16FFD6-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFD6h
    BX = ???
    CX = ???
    DX = offset in ???
    ???
Return: ???
Note:    available only when popped up
--------U-16FFD7-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFD7h
    ???
Return: BL = ???
Note:    available only when popped up
--------U-16FFD8-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - SAFE CREATE FILE
    AX = FFD8h
    DS:BX -> ASCIZ filename
Return: BX = file handle
        0000h on error
Note:    pops up confirmation menu if file already exists
    only available when popped up???
--------U-16FFD9-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - GET ???
    AX = FFD9h
Return: AX = ???
Note:    available only when popped up
--------U-16FFDA-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - GET NAME OF LAST FILE OPENED
    AX = FFDAh
    DS:SI -> ??? (v5.1/5.5 only)
Return: DS:SI -> filename
--------U-16FFDB-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - SET ???
    AX = FFDBh
    BL = ???
Note:    available only when popped up
--------U-16FFDC-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - UNHOOK
    AX = FFDCh
Return: interrupt vectors 09h, 10h (v6.0+), 16h, 1Ch, and 21h restored to
      original values
Index:    uninstall;PC Tools DESKTOP
--------U-16FFDDBX0000-----------------------
INT 16 U - PC Tools v5.1+ PCShell API - INSTALLATION CHECK
    AX = FFDDh
    BX = 0000h
Return: CX = 5555h
    DX = 5555h if PCShell installed in resident mode
--------U-16FFDDBX0001-----------------------
INT 16 U - PC Tools v5.1+ PCShell API - REQUEST POP-UP
    AX = FFDDh
    BX = 0001h
Return: CF clear if request successful (PCShell will pop up)
    CF set on error
SeeAlso: AX=FFDDh/BX=0003h
--------U-16FFDDBX0002-----------------------
INT 16 U - PC Tools v5.1-5.5 PCShell API - GET ???
    AX = FFDDh
    BX = 0002h
Return: AL =
        00h ???
        01h ???
Note:    PCShell v6.0+ displays the error message "Incorrect PCRUN version",
      awaits a keystroke, and aborts the current process
--------U-16FFDDBX0003-----------------------
INT 16 U - PC Tools v5.1+ PCShell API - REQUEST POP-UP
    AX = FFDDh
    BX = 0003h
SeeAlso: AX=FFDDh/BX=0001h
--------U-16FFDDBX0004-----------------------
INT 16 U - PC Tools v5.1+ PCShell API - GET ???
    AX = FFDDh
    BX = 0004h
Return: CF clear if successful
        DS:SI -> ???
--------U-16FFDDBX0005-----------------------
INT 16 U - PC Tools v5.1+ PCShell API - ???
    AX = FFDDh
    BX = 0005h
    ???
Return: ???
Note:    resets various variables if certain conditions are met
--------U-16FFDDBX0006-----------------------
INT 16 U - PC Tools v5.1+ PCShell API - ???
    AX = FFDDh
    BX = 0006h
    ???
Return: ???
Note:    resets various variables if certain conditions are met
--------U-16FFDDBX0007-----------------------
INT 16 U - PC Tools v5.1+ PCShell API - SET ??? FLAG
    AX = FFDDh
    BX = 0007h
Return: CF clear if successful
SeeAlso: AX=FFDDh/BX=0008h
--------U-16FFDDBX0008-----------------------
INT 16 U - PC Tools v5.1+ PCShell API - CLEAR ??? FLAG
    AX = FFDDh
    BX = 0008h
Return: CF undefined
SeeAlso: AX=FFDDh/BX=0007h
--------U-16FFDDBX0009-----------------------
INT 16 U - PC Tools v6.0+ PCShell API - GET PCRUN PARAMETERS
    AX = FFDDh
    BX = 0009h
Return: CF clear if successful
        DS:SI -> list of pointers (see below)

Format of returned pointer list:
Offset    Size    Description
 00h    WORD    offset of WORD containing ???
 02h    WORD    offset of name of program to execute
 04h    WORD    offset of 80-byte buffer for ???
 06h    WORD    offset of buffer for ??? (length in WORD preceding buffer)
 08h    WORD    offset of buffer for ??? (length in WORD preceding buffer)
--------U-16FFDDBX000A-----------------------
INT 16 U - PC Tools v6.0+ PCRUN API - INSTALLATION CHECK
    AX = FFDDh
    BX = 000Ah
Return: CX = 5555h if running
    DX = 5555h
Note:    also sets a flag
--------U-16FFDDBX000B-----------------------
INT 16 U - PC Tools v6.0+ PCRUN API - ???
    AX = FFDDh
    BX = 000Bh
    ???
Return: CX = 5555h if PCRUN active
    DX = 5555h
Note:    also clears flag set by AX=FFDDh/BX=000Ah
--------U-16FFDE-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - DISPLAY POPUP MENU
    AX = FFDEh
    DS:DX -> menu description (must be on a paragraph boundary)
Return: AX = ???
        AL seems to be the number of the selected button
Note:    available only when popped up
SeeAlso: AX=FFEEh
--------U-16FFDF-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFDFh
    ???
Return: ???
--------U-16FFE0-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFE0h
    CX = ???
    DX = ???
Note:    available only when popped up
--------U-16FFE1-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - BEEP
    AX = FFE1h
--------U-16FFE2-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFE2h
    DX = ???
Return: ???
Note:    available only when popped up
--------U-16FFE3-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - PRINT CHARACTER
    AX = FFE3h
    BL = character to print to currently open printer or print file
Return: CF set on error
Note:    available only when popped up
SeeAlso: INT 17/AH=00h
--------U-16FFE4-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFE4h
    DX = segment of ???
Return: ???
Note:    available only when popped up
--------U-16FFE5-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - POP UP FILE SELECTION MENU
    AX = FFE5h
    DS:SI -> ASCIZ wildcard filespec followed by ASCIZ menu title
    DX = segment of window parameters???
Return: AX = DOS file handle for file
        DS:DX -> filename???
       = FFFFh if cancelled by user
Note:    available only when popped up
SeeAlso: AX=FFDAh
--------U-16FFE6-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - CHECK FOR AND GET KEYSTROKE
    AX = FFE6h
Return: AX = 0000h if no key available
         else  BIOS keycode
Notes:    available only when popped up
    invokes INT 28 idle interrupt before checking for key
--------U-16FFE7-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFE7h
    BX = segment of ???
Return: ???
Note:    available only when popped up
--------U-16FFE8-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - DISPLAY NUMBER
    AX = FFE8h
    CX = number
    DH = attribute
    DS:SI -> destination for ASCII number
Return: DS:SI buffer filled in with alternating characters and attributes
--------U-16FFE9-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - GET FILE LIST???
    AX = FFE9h
Return: BX = segment of file/directory list (14 bytes per file, NUL-padded)
Note:    available only when popped up
--------U-16FFEA-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - DISPLAY COUNTED STRING
    AX = FFEAh
    DS:SI -> counted string (count byte followed by string)
Return: ???
Note:    available only when popped up
--------U-16FFEB-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFEBh
    ???
Return: ???
--------U-16FFEC-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - GET KEY
    AX = FFECh
    DS:SI -> FAR routine to ???
    BX = ???
    ???
Return: AX = keystroke
        FFFFh if F10 pressed to go to menu
Notes:    available only when popped up
    invokes INT 28 while waiting for keystroke
    F10 is hotkey to Desktop menu
Index:    hotkeys;PC Tools DESKTOP
--------U-16FFED-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - GET ???
    AX = FFEDh
Return: AX = ???
Note:    available only when popped up
--------U-16FFEE-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - DEFINE PULLDOWN MENUS
    AX = FFEEh
    DS:SI -> pulldown menu system description (see below)
Return: AX destroyed
Notes:    available only when popped up
    if the accessory does not need any menu items of its own, it should
      call AX=FFFAh instead
SeeAlso: AX=FFF7h,AX=FFFAh

Format of pulldown menu system description:
Offset    Size    Description
 00h    WORD    offset of menu bar contents (counted string)
 02h    WORD    number of items on menu bar
 04h 10 BYTEs    scan codes for hotkeying to each of up to ten menu items
 0Eh 10 BYTEs    which character to highlight in each menu item (01h=first)
 18h    WORD    offset of first menu definition (see below)
 1Ah    WORD    offset of second menu definition
    ...

Format of menu definition:
Offset    Size    Description
 00h    WORD    offset of menu contents (see below)
 02h    WORD    number of entries in menu
 04h    for each entry:
        Offset    Size    Description
         00h    BYTE    scancode of Alt-key to invoke entry
         01h    BYTE    character to highlight (01h=first, etc)
         02h    WORD    offset of FAR routine to handle selection

Format of menu contents:
Offset    Size    Description
 00h    BYTE    number of lines in menu
 01h    BYTE    width of menu
 02h  N BYTEs    counted strings, one for each line in menu
--------U-16FFEFCX0000-----------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - INSTALLATION CHECK
    AX = FFEFh
    CX = 0000h
Return: CX = ABCDh if PC Tools DESKTOP.EXE installed
        BX = segment of resident portion
        AX = ??? (v5.1/5.5 only)
SeeAlso: AX=FEEFh,AX=FFC5h,AX=FFF3h
--------U-16FFF0-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - SET ???
    AX = FFF0h
    DX = ???
Return: AX destroyed
Note:    available only when popped up
--------U-16FFF1BX0000-----------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ALTERNATE INSTALLATION CHECK
    AX = FFF1h
    BX = 0000h  leave ??? flag as is
        nonzero set ??? flag
Return: CX = 5555h if installed
    DX = 5555h
--------U-16FFF2-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - DISPLAY HELP LINE
    AX = FFF2h
    DS:SI -> ASCIZ function key label string (each label preceded by '[')
        or help text
Return: AX destroyed
Notes:    available only when popped up
    if the specified string does not start with '[', it is displayed
      centered on the bottom line, else the function key labels are shown
--------U-16FFF3-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - PREPARE TO UNLOAD RESIDENT DESKTOP
    AX = FFF3h
Note:    releases any EMS being used; restores video mode, page, and cursor
      shape; and restores interrupt vectors
SeeAlso: AX=FFC5h,AX=FFEFh
Index:    uninstall;PC Tools DESKTOP
--------U-16FFF4-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - ???
    AX = FFF4h
    ???
Return: ???
Note:    available only when popped up
SeeAlso: AX=FFF6h
--------U-16FFF5-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - GET SCREEN ATTRIBUTE ARRAY
    AX = FFF5h
Return: ES:BX -> screen attributes data structure (see below)
    AL = ??? (v6.0+)

Format of attribute data structure:
Offset    Size    Description
 -1    BYTE    attribute for desktop background
 00h    BYTE    attribute for normal characters on desktop menu
 01h    BYTE    attribute for highlighted characters on desktop menu
 02h  5 BYTEs    ???
 07h    BYTE    attribute for dialog boxes
 08h 15 BYTEs    ???
 17h    BYTE    attribute for message boxes
--------U-16FFF6-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - INVOKE NOTEPAD EDITOR
    AX = FFF6h
    DS = segment of editor buffer structure (see below)
    BX = ???
    DX = segment of window parameters structure (see AX=FFB5h)
Return: ???
Note:    available only when popped up
SeeAlso: AX=FFF4h

Format of editor buffer structure:
Offset    Size    Description
 00h    WORD    offset of current cursor position in buffer segment
 02h  2 BYTEs    ???
 04h    WORD    offset of beginning of file data in buffer segment
 06h 10 BYTEs    ???
 10h  N BYTEs    ASCIZ name of file being edited
--------U-16FFF7-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - PROCESS MENU BAR ENTRY???
    AX = FFF7h
    DS:SI -> ???
    ???
Return: ???
Notes:    available only when popped up
    performs input processing on the menu bar set up with AX=FFEEh
SeeAlso: AX=FFEEh,AX=FFFBh
--------U-16FFF8-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - DRAW EMPTY WINDOW
    AX = FFF8h
    DS:0000h -> window parameters structure (see AX=FFB5h)
    DS:BX -> DWORD to store address of ??? on screen
Return: ???
--------U-16FFF9-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - DEFINE SCREEN REFRESH ROUTINE
    AX = FFF9h
    ES:BX -> FAR routine to redisplay the utility's window
Note:    available only when popped up
--------U-16FFFA-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - DEFINE STANDARD PULLDOWN MENUS
    AX = FFFAh
Notes:    available only when popped up
    adds the "Window" option to the "Desktop" option which is the only one
      available when no accessories are active.  Unlike AX=FFEEh, no
      additional menu items are added between "Desktop" and "Window"
SeeAlso: AX=FFEEh,AX=FFFBh
--------U-16FFFB-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - PROCESS STANDARD MENU BAR
    AX = FFFBh
Return: ???
Notes:    available only when popped up
    performs input processing on the standard menu bar set up with AX=FFFAh
SeeAlso: AX=FFF7h
--------U-16FFFC-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - GET HOTKEYS AND KEYBOARD VECTOR
    AX = FFFCh
Return: ES:BX -> hotkey table (see below)
    DS:DX = original INT 09 vector

Format of hotkey table:
Offset    Size    Description
 00h  2 BYTEs    scancode/shift state for desktop hotkey
 02h  2 BYTEs    scancode/shift state for clipboard paste key
 04h  2 BYTEs    scancode/shift state for clipboard copy key
 06h  2 BYTEs    scancode/shift state for screen autodial key
--------U-16FFFD-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - COPY ???
    AX = FFFDh
Return: AX destroyed
Note:    copies 4000 bytes from ??? to ??? under certain circumstances
SeeAlso: AX=FF91h,AX=FF92h
--------M-16FFFE-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - SHOW MOUSE CURSOR
    AX = FFFEh
SeeAlso: AX=FFFFh,INT 33/AX=0001h
--------M-16FFFF-----------------------------
INT 16 U - PC Tools v5.1+ DESKTOP API - HIDE MOUSE CURSOR
    AX = FFFFh
SeeAlso: AX=FFFEh,INT 33/AX=0002h
--------P-17----DX0ABC-----------------------
INT 17 - PRINTER - LPTx v5.x INSTALLATION CHECK
    DX = 0ABCh
Return: AX = AAAAh
    DX = BAAAh
    ES = code segment of resident portion
--------P-17----DX0B90-----------------------
INT 17 - PRINTER - LPTx v6.x INSTALLATION CHECK
    DX = 0B90h
Return: DX = ABBBh
    ES = code segment of resident portion
--------P-17----DX0B91-----------------------
INT 17 - PRINTER - LPTx v7.x INSTALLATION CHECK
    DX = 0B91h
Return: DX = ABCBh
    ES = code segment of resident portion
--------P-17----DX0F5F-----------------------
INT 17 - PRINTER - LPTx v4.x INSTALLATION CHECK
    DX = 0F5Fh
Return: AX = AAAAh
    DX = F555h
    ES = code segment of resident portion
--------B-1700-------------------------------
INT 17 - PRINTER - WRITE CHARACTER
    AH = 00h
    AL = character to write
    DX = printer number (00h-02h)
Return: AH = printer status (see below)
SeeAlso: AH=02h,AH=84h"AX",AH=F1h,INT 16/AX=FFE3h,INT 1A/AH=11h"NEC"

Bitfields for printer status:
 bit 7    not busy
 bit 6    acknowledge
 bit 5    out of paper
 bit 4    selected
 bit 3    I/O error
 bits 2,1 unused
 bit 0    timeout
--------B-1701-------------------------------
INT 17 - PRINTER - INITIALIZE PORT
    AH = 01h
    DX = printer number (00h-02h)
Return: AH = printer status (see AH=00h)
Note:    some printers report that they are ready immediately after
      initialization when they actually are not; a more reliable result may
      be obtained by calling AH=02h after a brief delay
SeeAlso: AH=02h,AH=FFh"PC-MOS",INT 1A/AH=10h"NEC"
--------B-1702-------------------------------
INT 17 - PRINTER - GET STATUS
    AH = 02h
    DX = printer number (00h-02h)
Return: AH = printer status (see AH=00h)
Note:    PRINTFIX from MS-DOS 5.0 hooks this function and always returns AH=90h
SeeAlso: AH=01h,AH=F2h,INT 1A/AH=12h"NEC"
--------P-1702--DX0000-----------------------
INT 17 - INSET - INSTALLATION CHECK
    AH = 02h
    DX = 0000h
    CX = 07C3h (1987d)
Return: CX = 07C2h (1986d) if installed
Program: INSET is a text/graphics integration program
--------P-1703-------------------------------
INT 17 U - Emulaser ELTSR - INSTALL INTERRUPT HANDLERS
    AH = 03h
Return: BX = ???
    CX = ???
Program: ELTSR is the resident portion of the Emulaser PostScript emulator by
      Vertisoft Systems, Inc.
SeeAlso: AH=04h"Emulaser",AH=0Eh,INT 1A/AH=E5h
--------c-1703-------------------------------
INT 17 - PC-MOS/386 v5.01 - PRINT SPOOLER - PRINT STRING
    AH = 03h
    DX = printer port number
    CX = number of characters to print
    DS:SI -> string
Return: AH = printer status (see AH=00h)
    CX = number of characters actually printed
Desc:    send an entire string of chars to the print spooler with a single call
Program: PC-MOS/386 v5.01 is a multitasking, multiuser MS-DOS 5.0-compatible
      operating system by The Software Link, Inc.
SeeAlso: AH=00h,AH=01h,AH=02h,AH=FFh"PC-MOS"
--------P-1704-------------------------------
INT 17 U - Emulaser ELTSR - BEGIN CAPTURING OUTPUT
    AH = 04h
Note:    has no effect unless ELTSR is deactivated (see AX=0503h)
SeeAlso: AH=03h"Emulaser",AX=0503h,INT 1A/AH=E5h
--------P-170500-----------------------------
INT 17 U - Emulaser ELTSR - ???
    AX = 0500h
    ???
Return: AX = unload status (0001h safe to unload, 0002h not safe)
    BX = ???
    CX = PSP segment of ELTSR
    DX = activity flag (0000h disabled, 0001h capturing, 0002h ???printing)
    SI = ???
    DI = ???
SeeAlso: AH=04h,INT 1A/AH=E5h
--------P-170501-----------------------------
INT 17 U - Emulaser ELTSR - UNHOOK INTERRUPTS
    AX = 0501h
Return: (see AX=0500h)
Note:    restores interrupt vectors without checking whether they have been
      hooked by later programs; should only be called if ELTSR reports
      that it is safe to unload
SeeAlso: AH=04h,AX=0500h,AX=0503h,INT 1A/AH=E5h
Index:    uninstall;Emulaser ELTSR
--------P-170502-----------------------------
INT 17 U - Emulaser ELTSR - SET ???
    AX = 0502h
    BL = Emulaser port (31h = LPT1, 32h = LPT2, 33h = LPT3)
    CL = ???
    DL = ???
Return: (see AX=0500h)
SeeAlso: AH=04h,AX=0500h,INT 1A/AH=E5h
--------P-170503-----------------------------
INT 17 U - Emulaser ELTSR - DEACTIVATE???
    AX = 0503h
Return: (see AX=0500h)
SeeAlso: AH=04h,AX=0500h,AX=0501h,INT 1A/AH=E5h
--------P-1706-------------------------------
INT 17 U - Emulaser ELTSR - ???
    AH = 06h
    ???
Return: ???
SeeAlso: AH=05h,INT 1A/AH=E5h
--------P-1707-------------------------------
INT 17 U - Emulaser ELTSR - OPEN CAPTURE FILE
    AH = 07h
    ES:DX -> ASCIZ filename to be opened
Return: ???
Note:    new output will be appended to the specified file
SeeAlso: AH=08h,INT 1A/AH=E5h
--------P-1708-------------------------------
INT 17 U - Emulaser ELTSR - CLOSE CAPTURE FILE
    AH = 08h
    ???
Return: ???
Desc:    close the file previously opened by function 07h
SeeAlso: AH=07h,INT 1A/AH=E5h
--------P-1709-------------------------------
INT 17 U - Emulaser ELTSR - PRINT CAPTURE FILE???
    AH = 09h
    BX = ???
    CX = ???
    DX = printer port (01h COM1, 02h COM2, 05h LPT1, 06h LPT2)
Return: AX = status
        00h successful
        FFh failed
Program: ELTSR is the resident portion of the Emulaser PostScript emulator by
      Vertisoft Systems, Inc.
Note:    this function calls through to INT 1A/AX=E401h, and thus requires
      that either ELSPL or Disk Spool II be installed
SeeAlso: AH=0Ah,INT 1A/AX=E401h,INT 1A/AH=E5h
--------P-170A-------------------------------
INT 17 U - Emulaser ELTSR - SET ??? FILENAME
    AH = 0Ah
    ES:BX -> ??? buffer
    CX = length of ??? buffer
Return: ???
Note:    copies the specified name into the buffer passed to ELSPL as the
      filename by AH=09h
SeeAlso: AH=09h,INT 1A/AH=E5h
--------P-170B-------------------------------
INT 17 U - Emulaser ELTSR - GET ???
    AH = 0Bh
Return: AX:BX -> ???
SeeAlso: AH=0Ah,INT 1A/AH=E5h
--------P-170C-------------------------------
INT 17 U - Emulaser ELTSR - SET ??? FLAG
    AH = 0Ch
    ???
Return: ???
SeeAlso: AH=0Bh,INT 1A/AH=E5h
--------P-170D-------------------------------
INT 17 U - Emulaser ELTSR - GET TRUE ScrlLk STATE
    AH = 0Dh
Return: AX = state (0000h off, 0010h on)
Desc:    determine the actual state of ScrlLk even when Emulaser is controlling
      the ScrlLk light as its activity indicator
SeeAlso: AH=0Ch,INT 16/AH=02h,INT 1A/AH=E5h
--------P-170E-------------------------------
INT 17 U - Emulaser ELTSR - BACKGROUND PROCESSING
    AH = 0Eh
Program: ELTSR is the resident portion of the Emulaser PostScript emulator by
      Vertisoft Systems, Inc.
Note:    this function is called by ELTSR on every INT 08 to allow data to be
      processed in the background, but may also be called by applications
      to give Emulaser additional CPU time
SeeAlso: AH=0Dh,INT 1A/AH=E5h
--------P-172000-----------------------------
INT 17 - PC Paint Plus 2.0 - PRINTER DRIVER - INSTALLATION CHECK
    AX = 2000h
    BL = printer number???
Return:    AX = status (see below)
    BX = driver version number (BH=major,BL=minor)
    CH = ??? (00h)
    CL = ???
    DX = ??? (0100h)
Note:    also enables the remaining printer driver functions (2001h-2007h)
SeeAlso: AX=2001h,AX=2002h,AX=2003h,AX=2004h,AX=2005h,AX=2006h,AX=2007h

Values for status:
 0000h    successful
 0001h    invalid printer???
 0002h    ???
 0003h    invalid subfunction
 0005h    driver disabled, must call function 00h first
 0009h    unknown printer error
 000Bh    printer not selected
 000Ch    printer out of paper
 000Eh    error while writing to serial printer
 000Fh    ???
 0010h    invalid function number
 0011h    value out of range
--------P-172001-----------------------------
INT 17 - PC Paint Plus 2.0 - PRINTER DRIVER - SET ??? FLAG
    AX = 2001h
    BL = printer number???
Return: AX = status (see AX=2000h)
--------P-172002-----------------------------
INT 17 - PC Paint Plus 2.0 - PRINTER DRIVER - GET INFORMATION
    AX = 2002h
    BL = printer number???
    CL = desired information
        00h printer type
        Return: ES:DI -> ASCIZ printer name
        01h paper size
        DX = size index
        Return: ES:DI -> ASCIZ paper size description
        02h ???
        Return: BX = ???
        03h printer information???
        DX = ???
        ES:BX -> buffer for ??? (min 134 bytes)
Return: AX = status (see AX=2000h)
SeeAlso: AX=2000h,AX=2004h
--------P-172003-----------------------------
INT 17 - PC Paint Plus 2.0 - PRINTER DRIVER - ???
    AX = 2003h
    ES:BX -> ???
Return: AX = status (see AX=2000h)
SeeAlso: AX=2000h,AX=2004h
--------P-172004-----------------------------
INT 17 - PC Paint Plus 2.0 - PRINTER DRIVER - GET ???
    AX = 2004h
    BL = printer number???
Return: AX = status (see AX=2000h)
    ES:DI -> ???
SeeAlso: AX=2000h,AX=2003h
--------P-172005-----------------------------
INT 17 - PC Paint Plus 2.0 - PRINTER DRIVER - ADVANCE PRINTER TO NEXT PAGE
    AX = 2005h
    BL = printer number???
Return: AX = status (see AX=2000h)
Note:    this function also clears the flag set by AX=2001h
SeeAlso: AX=2000h,AX=2001h,AX=2006h
--------P-172006-----------------------------
INT 17 - PC Paint Plus 2.0 - PRINTER DRIVER - ADVANCE TO NEXT PAGE & SHUT DOWN
    AX = 2006h
    BL = printer number???
Return: AX = status (see AX=2000h)
Note:    this function also clears the flag set by AX=2001h and disables
      functions other than AX=2000h
SeeAlso: AX=2000h,AX=2001h,AX=2005h
--------P-172007-----------------------------
INT 17 - PC Paint Plus 2.0 - PRINTER DRIVER - UNIMPLEMENTED
    AX = 2007h
Return: AX unchanged
SeeAlso: AX=2000h
--------N-172400-----------------------------
INT 17 - Shamrock Software NET.24 v3.11+ - ENABLE/DISABLE API FUNCTIONS
    AX = 2400h
    DL = new state
        00h disabled
        01h enabled
Return: DL = 24h if installed
    DH = minor version number
    CX = network address of this machine
    AL = status
        00h successful
        01h timeout
        02h header error
        03h data error
        04h busy
        05h invalid parameters
SeeAlso: AX=2403h,INT 16/AX=4500h
--------N-172401-----------------------------
INT 17 - Shamrock Software NET.24 v3.11+ - RECEIVE BLOCK, NO HANDSHAKE
    AX = 2401h
    BL = timeout in clock ticks
Return: AL = status (see AX=2400h)
    DX:BX -> receive buffer
SeeAlso: AX=2402h,AX=2404h,AX=2408h
--------N-172402-----------------------------
INT 17 - Shamrock Software NET.24 v3.11+ - TRANSMIT BLOCK, NO HANDSHAKE
    AX = 2402h
    transmit buffer filled (see AX=2403h)
Return: AL = status (see AX=2400h)
SeeAlso: AX=2401h,AX=2403h,AX=2404h,AX=2409h
--------N-172403-----------------------------
INT 17 - Shamrock Software NET.24 v3.11+ - GET STATUS AND TRANSMISSION BUFFER
    AX = 2403h
Return: AL = status (see AX=2400h)
    CX = number of characters in receive ring buffer
    DX:BX -> transmit buffer
SeeAlso: AX=2400h,AX=2402h
--------N-172404-----------------------------
INT 17 - Shamrock Software NET.24 v3.11+ - SEND ACK BLOCK
    AX = 2404h
    BX = target address
Return: AL = status (see AX=2400h)
SeeAlso: AX=2402h,AX=2405h
--------N-172405-----------------------------
INT 17 - Shamrock Software NET.24 v3.11+ - SEND NAK BLOCK
    AX = 2405h
    BX = target address
Return: AL = status (see AX=2400h)
SeeAlso: AX=2402h,AX=2404h
--------N-172406-----------------------------
INT 17 - Shamrock Software NET.24 v3.11+ - PREPARE CHARACTER-ORIENTED RECEIVE
    AX = 2406h
Return: AL = status (see AX=2400h)
SeeAlso: AX=2407h,AX=240Ah
--------N-172407-----------------------------
INT 17 - Shamrock Software NET.24 v3.11+ - RECEIVE CHARACTER FROM REMOTE
    AX = 2407h
Return: AL = status (see also AX=2400h)
        06h end of data
    DL = received character
SeeAlso: AX=2406h
--------N-172408-----------------------------
INT 17 - Shamrock Software NET.24 v3.11+ - RECEIVE BLOCK, WITH HANDSHAKE
    AX = 2408h
Return: AL = status (see also AX=2400h)
        06h end of data
    CX = number of bytes in receive buffer
    DX:SI -> receive buffer
SeeAlso: AX=2401h,AX=2405h,AX=2409h
--------N-172409-----------------------------
INT 17 - Shamrock Software NET.24 v3.11+ - TRANSMIT COMMAND, WITH HANDSHAKE
    AX = 2409h
    BX = target address
    CX = number of data bytes
    DL = command code to send
    DS:SI -> data bytes for command
Return: AL = status (see also AX=2400h)
        03h no response
        06h remote currently unable to perform command
SeeAlso: AX=2405h,AX=2408h
--------N-17240A-----------------------------
INT 17 - Shamrock Software NET.24 v3.11+ - PREPARE CHARACTER-ORIENTED TRANSMIT
    AX = 240Ah
Return: AL = status (see AX=2400h)
SeeAlso: AX=2406h,AX=240Bh,AX=240Ch
--------N-17240B-----------------------------
INT 17 - Shamrock Software NET.24 v3.11+ - TRANSMIT SINGLE CHARACTER TO REMOTE
    AX = 240Bh
    DL = character to send
Return: AL = status (see also AX=2400h)
        03h transmission error
        06h write error
SeeAlso: AX=2407h,AX=240Ah,AX=240Ch
--------N-17240C-----------------------------
INT 17 - Shamrock Software NET.24 v3.11+ - END CHARACTER-ORIENTED TRANSMIT
    AX = 240Ch
Return: AL = status (see also AX=2400h)
        03h transmission error
        06h remote breaks connection
SeeAlso: AX=240Ah,AX=240Bh
--------J-175000-----------------------------
INT 17 - AX (Japanese AT) PRINTER - SET PRINTER COUNTRY CODE
    AX = 5000h
    BX = country code
        0001h USA (English), 0051h Japan
Return: AL = status
        00h successful
        01h bad country code
        02h other error
SeeAlso: AX=5001h,AH=51h,INT 10/AX=5000h,INT 16/AX=5000h
--------J-175001-----------------------------
INT 17 - AX (Japanese AT) PRINTER - GET PRINTER COUNTRY CODE
    AX = 5001h
Return: AL = status
        00h successful
        BX = country code
        02h error
SeeAlso: AX=5000h,AH=51h,INT 10/AX=5001h,INT 16/AX=5001h
--------J-1751-------------------------------
INT 17 - AX (Japanese AT) PRINTER - JIS to Shift-JIS CONVERSION
    AH = 51h
    DX = 2-byte JIS code
Return: DX = shift-JIS value or 0000h on error
Note:    one of AH=51h and AH=52h converts from JIS (Japanese Industry Standard)
      characters to Shift-JIS characters, and the other performs the
      opposite conversion
SeeAlso: AX=5000h,AH=52h
--------J-1752-------------------------------
INT 17 - AX (Japanese AT) PRINTER - Shift-JIS to JIS CONVERSION
    AH = 52h
    DX = 2-byte shift-JIS code
Return: DX = JIS code or 0000h on error
Note:    one of AH=51h and AH=52h converts from JIS (Japanese Industry Standard)
      characters to Shift-JIS characters, and the other performs the
      opposite conversion
SeeAlso: AH=51h
--------V-1760-------------------------------
INT 17 - FLASHUP.COM - INSTALLATION CHECK
    AH = 60h
Return: AL = 60h
    DX = CS of resident code
Notes:    FLASHUP.COM is part of Flash-Up Windows by The Software Bottling Co.
    FLASHUP also hooks INT 10 and receives commands via INT 10/AH=09h,0Ah
      consisting of an 80h followed by the actual command
SeeAlso: INT 10/AH=09h,INT 10/AH=0Ah
--------V-1761-------------------------------
INT 17 - SPEEDSCR.COM - INSTALLATION CHECK
    AH = 61h
Return: AL = 61h
    DX = CS of resident code
Note:    SPEEDSCR.COM is by The Software Bottling Co.
--------P-1762-------------------------------
INT 17 U - T2PS v1.0 - UNINSTALL
    AH = 62h
Return: nothing
SeeAlso: AH=63h,AH=64h,INT 05/AX=554Eh
--------P-1763-------------------------------
INT 17 U - T2PS v1.0 - SET PARAMETERS
    AH = 63h
    ES:SI -> settings (see below)
Program: T2PS is a shareware ASCII-to-PostScript converter by A.N.D.
      Technologies
SeeAlso: AH=62h,AH=64h,INT 05/AX=4E57h

Format of settings:
Offset    Size    Description
 00h    WORD    LPT port number (0=LPT1, etc.)
 02h    WORD    page heigh in points
 04h    WORD    page width in points
 06h    WORD    top margin in points
 08h    WORD    bottom margin in points
 0Ah    WORD    left margin in points
 0Ch    WORD    right margin in points
 0Eh    WORD    font size in points
 10h    WORD    tab size
 12h    WORD    timeout in clock ticks
--------P-1764-------------------------------
INT 17 U - T2PS v1.0 - GET PARAMETERS
    AH = 64h
    ES:SI -> buffer for settings (see AH=63h)
Return: ES:SI buffer filled
SeeAlso: AH=62h,AH=63h,INT 05/AX=5053h
--------N-1781-------------------------------
INT 17 - Alloy NTNX, MW386 - CANCEL JOBS FOR CURRENT USER
    AH = 81h
    AL = 00h (NTNX compatibility mode)
    CL = number of jobs to cancel
Return: AL = status
        00h success
        01h..7Fh warning
        80h general failure
        81h host overloaded (NTNX only)
        82h module busy (NTNX only)
        83h host busy (NTNX only)
        84h re-entry flag set
        85h invalid request
        86h invalid printer
        87h invalid process ID
        89h access denied
        8Ah option not available for given port type
        8Bh option not available for given task type
        91h printer busy
        C2h file not found
        C3h path not found
        C4h file access failure
Note:    cancels the last CL printouts for the current task
SeeAlso: AH=82h
--------N-1782-------------------------------
INT 17 - Alloy NTNX, MW386 - CANCEL ALL JOBS FOR CURRENT USER
    AH = 82h
    AL = 00h (NTNX compatibility mode)
Return: AL = status (see AH=81h)
SeeAlso: AH=81h
--------N-1783-------------------------------
INT 17 - Alloy NTNX, MW386 - SET NUMBER OF COPIES
    AH = 83h
    AL = mode
        00h NTNX compatibility
        CL = number of copies (max 99, default 1)
        02h MW386 v2+
        BX = logical device number
            00h-03h = LPT1-LPT4
            04h-07h = COM1-COM4
        CX = number of copies
Return: AL = status (see AH=81h)
Note:    in NTNX compatibility mode, this function only affects LPT1
--------N-1784-------------------------------
INT 17 - Alloy NTNX, MW386 - GENERATE PRINT BREAK
    AH = 84h
    AL = mode
        00h NTNX compatibility
        02h MW386 v2+
        BX = logical device number
            00h-03h = LPT1-LPT4
            04h-07h = COM1-COM4
Note:    closes spool file and tells spooler to queue the print job (LPT1 only
      under MW386 in NTNX compatibility mode)
--------J-1784-------------------------------
INT 17 - AX (Japanese AT) PRINTER - OUTPUT CHARACTER WITHOUT CONVERSION
    AH = 84h
    AL = character
    DX = printer number
Return: AH = printer status (see AH=00h)
SeeAlso: AH=00h,AH=85h
--------J-1785-------------------------------
INT 17 - AX (Japanese AT) PRINTER - ENABLE/DISABLE CHARACTER CONVERSION
    AH = 85h
    AL = new state (00h enabled, 01h disabled)
SeeAlso: AH=84h"AX"
--------N-1787-------------------------------
INT 17 - Alloy NTNX - SET INDOS POINTER
    AH = 87h
    AL = 00h
    CX:BX -> buffer for user-written printer drivers
Return: BX,CX destroyed
Note:    must be executed before the printer is enabled
SeeAlso: AH=8Ah
--------N-1788-------------------------------
INT 17 - Alloy NTNX, MW386 - REMOVE PRINTER FROM SPOOLER
    AH = 88h
    AL = mode
        00h NTNX compatibility
        DX = NTNX printer number
            00h host LPT1
            01h host LPT2
            02h host LPT3
            03h host LPT4
            04h host COM1
            05h host COM2
            06h user's logical COM2
            07h user's terminal AUX port
            08h user's logical COM1 (MW386 only)
        01h MW386
        DX = MW386 printer number
Return: AH = status (see AH=81h)
Note:    removes specified printer from the spooler's list of printers
SeeAlso: AH=89h,AH=8Bh
--------N-1789-------------------------------
INT 17 - Alloy NTNX, MW386 - ADD PRINTER TO SPOOLER
    AH = 89h
    AL = mode
        00h NTNX compatibility
        DX = NTNX printer number (see AH=88h)
        01h MW386
        DX = MW386 printer number
Return: AL = status (see AH=81h)
Note:    the specified printer is added to the spooler's list of available
      printers
SeeAlso: AH=88h,AH=8Bh
--------N-178A-------------------------------
INT 17 - Alloy NTNX - ACTIVATE USER-WRITTEN PRINTER DRIVER
    AH = 8Ah
    ???
SeeAlso: AH=92h
--------N-178B-------------------------------
INT 17 - Alloy MW386 - GET PHYSICAL DEVICE NUMBER FROM NAME
    AH = 8Bh
    DS:DX -> ASCIZ printer name
Return: AL = status (see also AH=81h)
        00h successful
        DX = physical device number
SeeAlso: AH=89h,AH=8Ch,INT 14/AH=20h"Alloy"
--------N-178C-------------------------------
INT 17 - Alloy MW386 - GET DEVICE NAME FROM PHYSICAL DEVICE NUMBER
    AH = 8Ch
    DX = physical device number
    ES:DI -> 17-byte buffer for ASCIZ device name
Return: AL = status (see also AH=81h)
        00h successful
        ES:DI buffer filled
SeeAlso: AH=88h,AH=8Bh
--------N-178D-------------------------------
INT 17 - Alloy NTNX,MW386 - RESET SPOOLER
    AH = 8Dh
    AL = 00h
Notes:    clears all buffers and resets spooler to boot-up values
    MW386 supports this function for compatibility only; it is a NOP
Return: AL = status (see AH=81h)
--------N-178E-------------------------------
INT 17 - Alloy NTNX - GET INT 28 ENTRY POINT
    AH = 8Eh
    AL = 00h
Return: CX:BX -> INT 28 entry point
SeeAlso: AH=8Fh
--------N-178F-------------------------------
INT 17 - Alloy NTNX - GET DOS INTERCEPT ENTRY POINT
    AH = 8Fh
    AL = 00h
Return: CX:BX -> DOS intercept routine
SeeAlso: AH=8Eh
--------N-1790-------------------------------
INT 17 - Alloy NTNX, MW386 - SPOOL FILE BY NAME
    AH = 90h
    AL = mode
        00h NTNX compatibility
        DL = printer code (FFh=current) (NTNX, MW386 v1.x only)
        DH = number of copies (FFh=current) (NTNX, MW386 v1.x only)
        02h MW386 v2+
        BX = logical device number
            00h-03h = LPT1-LPT4
            04h-07h = COM1-COM4
    CX:SI -> ASCIZ pathname
Return: AL = status (see AH=81h)
Note:    in mode 00h, the file is always sent to logical LPT1
SeeAlso: AH=A0h
--------N-1791-------------------------------
INT 17 - Alloy NTNX, MW386 - GET USER NUMBER AND CURRENT PRINTER
    AH = 91h
    AL = mode
        00h NTNX compatibility
        Return: CX = user number (00h = host)
            DX = currently selected printer number (00h-08h)
        01h MW386
        Return: CX = user number
            DX = physical dev number of currently selected printer
        02h MW386 v2+
        BX = logical device number
            00h-03h = LPT1-LPT4
            04h-07h = COM1-COM4
        Return: CX = user number
            DX = physical device number
Return: AL = status (see AH=81h)
SeeAlso: AH=8Ch
--------N-1792-------------------------------
INT 17 - Alloy NTNX - CHECK PRINTER DRIVER
    AH = 92h
    AL = 00h
    CL = 00h
Return: CL = driver state
        01h initialized
        80h not initialized
    AX = status (see AH=81h)
SeeAlso: AH=8Ah
--------N-1794-------------------------------
INT 17 - Alloy NTNX, MW386 - SELECT PRINTER
    AH = 94h
    AL = mode
        00h NTNX compatibility
        DX = NTNX printer number (see AH=88h)
        01h MW386
        DX = MW386 printer number
        02h MW386 v2+
        BX = logical printer number
        DX = MW386 printer number
Return: AL = status (see AH=81h)
Note:    modes 00h and 01h affect only logical LPT1
SeeAlso: AH=8Bh,AH=95h
--------N-1795-------------------------------
INT 17 - Alloy NTNX, MW386 - GET CURRENT PRINTER
    AH = 95h
    AL = mode
        00h NTNX compatibility
        Return: DX = NTNX printer number (see AH=88h)
                (FFFFh if current printer not compatible with NTNX)
        01h MW386
        Return: DX = MW386 printer number
        02h MW386 v2+
        BX = logical device number
            00h-03h = LPT1-LPT4
            04h-07h = COM1-COM4
        Return: DX = MW386 printer number (FFFFh = none)
Return: AL = status (see AH=81h)
Note:    modes 00h and 01h return the printer number of logical LPT1 only
SeeAlso: AH=94h
--------N-1796-------------------------------
INT 17 - Alloy NTNX - SET SERIAL PORT PARAMETERS
    AH = 96h
    AL = 00h
Note:    documentation states that this is a NOP, doing only XOR AX,AX before
      returning
SeeAlso: INT 14/AH=24h
--------N-1797-------------------------------
INT 17 - Alloy NTNX, MW386 - SET DATA DRIVEN PRINT BREAK
    AH = 97h
    AL = mode
        00h NTNX compatibility
        02h MW386 v2+
        BX = logical device number
            00h-03h = LPT1-LPT4
            04h-07h = COM1-COM4
    CH,CL,DH = three character break sequence
    DL = subfunction
        00h set break string
        else reset break
Return: AL = status (see AH=81h)
Notes:    mode 00h affects only logical LPT1
    when the break string is encountered, the spool file will be closed and
      queued for printing automatically
    the break string is not permanently saved, and will be reset each time
      MW386 or the user is rebooted
SeeAlso: AH=9Bh
--------N-1798-------------------------------
INT 17 - Alloy NTNX,MW386 - RESTART PRINTER
    AH = 98h
    AL = 00h
    DL = printer number (FFh=current)
Return: AL = status
        00h successful
        01h incorrect printer
        02h task not found
Note:    MW386 supports this function for compatibility only; it is a NOP
--------N-1799-------------------------------
INT 17 - Alloy NTNX, MW386 - GET/SET PRINTER MODE
    AH = 99h
    AL = mode
        00h NTNX compatibility
        DL = NTNX printer number (see AH=88h)
            (FFh = task's current logical LPT1)
        DH = mode
            bit 0: get mode if 1, set mode if 0
            bit 1: private ("attached")
            bit 2: direct instead of spooled
            bits 3-7 reserved (0)
        01h MW386
        DX = MW386 printer number
        CL = mode (as for DH above)
Return: AL = status (see AH=81h)
    DH = mode (bits 1 and 2 set as above)
    DL = printer owner's user number if not spooled
--------N-179A-------------------------------
INT 17 - Alloy NTNX,MW386 - SET TAB EXPANSION
    AH = 9Ah
    AL = mode
        00h NTNX compatibility
        DX = NTNX printer number (see AH=88h)
            (FFFFh = current logical LPT1)
        01h MW386
        DX = MW386 printer number
    CL = tab length (00h = no expansion, 01h-63h = spaces per tab)
Return: AL = status (see AH=81h)
Note:    beginning with MW386 v2.0, tab expansion is set on a per-printer basis
      rather than a per-user basis; NTNX and MW386 v1.x ignore DX
SeeAlso: AH=A4h
--------N-179B-------------------------------
INT 17 - Alloy NTNX,MW386 - SET PRINT BREAK TIMEOUT
    AH = 9Bh
    AL = mode
        00h NTNX compatibility
        CX = timeout value in clock ticks (1/18 sec) (00h = never)
        01h MW386
        CX = timeout value in seconds (00h = never)
        02h MW386 v2+
        BX = logical device number
            00h-03h = LPT1-LPT4
            04h-07h = COM1-COM4
        CX = timeout value in seconds (00h = never)
Return: AL = status (see AH=81h)
Notes:    modes 00h and 01h affect only the current logical LPT1
    if no data is sent to a printer for the specified amount of time, the
      spool file will be closed and queued for printing automatically
SeeAlso: AH=97h
--------N-17A0-------------------------------
INT 17 - Alloy MW386 - SPOOL COPY OF FILE
    AH = A0h
    AL = mode
        00h NTNX compatibility
        DX = ??? (NTNX, MW386 v1.x only)
        02h MW386 v2+
        BX = logical device number
            00h-03h = LPT1-LPT4
            04h-07h = COM1-COM4
    CX:SI -> ASCIZ pathname
Return: AL = status (see AH=81h)
Notes:    makes a copy of the specified file in the spooler's directory, allowing
      the original file to be modified or deleted while the copy is printed
    in mode 00h, the file is printed on logical LPT1
SeeAlso: AH=90h
--------N-17A4-------------------------------
INT 17 - Alloy MW386 - ENABLE/DISABLE FORM FEED
    AH = A4h
    AL = new state
        00h form feed after end of print job disabled
        01h form feed enabled
Return: AL = status (see AH=81h)
Note:    only affects the current logical LPT1
SeeAlso: AH=9Ah,AH=A6h,INT 7F/AH=05h"NTNX (Host)"
--------N-17A6-------------------------------
INT 17 - Alloy MW386 - ENABLE/DISABLE BANNER PAGE
    AH = A6h
    AL = new state
        00h banner page before print job disabled
        01h banner page enabled
Return: AL = status (see AH=81h)
Note:    only affects the current logical LPT1
SeeAlso: AH=A4h
--------N-17A7-------------------------------
INT 17 - Alloy MW386 v2+ - GET/SET SPOOL FLAGS
    AH = A7h
    AL = spool flags
        bit 0: banner page enabled (see AH=A4h)
        bit 1: form feed enabled (see AH=A6h)
        bits 2-6: reserved (0)
        bit 7: set flags if 1, get flags if 0
    BX = logical device number
        00h-03h = LPT1-LPT4
        04h-07h = COM1-COM4
Return: AL = status (see AH=81h)
Note:    the documentation does not state which register contains the result of
      a GET
SeeAlso: AH=A4h,AH=A6h
--------N-17A8-------------------------------
INT 17 - Alloy MW386 - DEFINE TEMPORARY FILENAME
    AH = A8h
    CX:SI -> ASCIZ filename without extension (max 8 chars)
Return: AL = status (see AH=81h)
Note:    allows application to specify banner page filename for spool files
      collected from the application's printer output
SeeAlso: AH=A9h
--------N-17A9-------------------------------
INT 17 - Alloy MW386 - CHANGE TEMPORARY SPOOL DRIVE
    AH = A9h
    AL = new spool drive (2=C:,3=D:,etc)
Return: AL = status (see AH=81h)
Note:    does not remove previous spooling directory since jobs may be pending
SeeAlso: AH=A8h
--------N-17AA-------------------------------
INT 17 - Alloy MW386 v2+ - GET REAL-TIME PRINTER STATUS
    AH = AAh
    AL = mode
        00h NTNX
        DX = NTNX printer number (see AH=88h)
        01h MW386
        DX = MW386 printer number
Return: AH = instantaneous printer status
        00h printer ready
        01h not ready
        12h off line
        13h out of paper
        14h general device failure
        15h device timeout
        16h bad device number
--------N-17AF-------------------------------
INT 17 - Alloy MW386 - CHECK SPOOLER
    AH = AFh
Return: AX = 55AAh if spooler available
--------c-17C0-------------------------------
INT 17 - PC Magazine PCSpool - GET CONTROL BLOCK ADDRESS
    AH = C0h
    DX = printer port (0-3)
Return: ES:BX -> control block (see below)
SeeAlso: AH=C1h

Format of control block:
Offset    Size    Description
 00h    WORD    printer number
 02h    WORD    address of printer status port
 04h    WORD    number of first record in queue
 06h    WORD    number of last record in queue
 08h    DWORD    characters already printed
 0Ch    DWORD    number of characters remaining
 10h    DWORD    pointer to dequeue buffer
 14h    DWORD    previous count of characters printed
 18h    DWORD    number of clock ticks taken to print them
 1Ch    WORD    offset of next character to output
 1Eh    WORD    offset of next character to print
 20h    WORD    pointer to spooling queue record
 22h    BYTE    current spooling status
 23h    BYTE    current printer status:
        00h OK
        01h not ready
        02h paused with message
        03h paused
        04h initializing
        FEh non-existent port
        FFh not spooled
 24h    BYTE    current control record type
 25h    WORD    observed printer speed
 27h    WORD    characters to print per service
 29h    BYTE    01h if disk write needed
 2Ah    BYTE    01h if queued data should be flushed
 2Bh    BYTE    01h to update cps status
--------c-17C1--------------------------------
INT 17 - PC Magazine PCSpool - BUILD PAUSE CONTROL RECORD
    AH = C1h
    DX = printer port (0-3)
    DS:SI -> ASCIIZ string to save for display
Note:    flushes pending writes
SeeAlso: AH=C0h,AH=C2h
--------c-17C2-------------------------------
INT 17 - PC Magazine PCSpool - FLUSH PENDING WRITES
    AH = C2h
    DX = printer port (0-3)
SeeAlso: AH=C3h
--------c-17C3-------------------------------
INT 17 - PC Magazine PCSpool - CANCEL PRINTER QUEUE (FLUSH ALL QUEUED OUTPUT)
    AH = C3h
    DX = printer port (0-3)
SeeAlso: AH=C2h,AH=C7h
--------c-17C4-------------------------------
INT 17 - PC Magazine PCSpool - QUERY SPOOLER ACTIVE
    AH = C4h
Return: DI = B0BFh
    SI = segment
--------c-17C5-------------------------------
INT 17 - PC Magazine PCSpool - JOB SKIP PRINTER QUEUE
    AH = C5h
    DX = printer port (0-3)
Note:    cancels up to the pause record
--------c-17C6-------------------------------
INT 17 - PC Magazine PCSpool - CHECK PRINTER QUEUE STATUS
    AH = C6h
    DX = printer port (0-3)
Return: AX = 0 printer not active or at pause
       = 1 printer busy
--------c-17C7-------------------------------
INT 17 - PC Magazine PCSpool - CLOSE QUEUE
    AH = C7h
    DX = printer port (0-3)
SeeAlso: AH=C3h
--------P-17CD00-----------------------------
INT 17 - INSET - EXECUTE COMMAND STRING
    AX = CD00h
    DS:DX -> ASCIZ command string (max 80 bytes)
Return: CX = 07C2h (1986d)
Note:    user interface menus pop up after last command, unless that command
    exits INSET
--------P-17CD01-----------------------------
INT 17 - INSET - GET IMAGE SIZE
    AX = CD01h
    DS:DX -> ASCIZ name of image file
Return: AX = height in 1/720th inch
    BX = width in 1/720th inch
    CX = 07C2h (1986d)
--------P-17CD02-----------------------------
INT 17 - INSET - INITIALIZE
    AX = CD02h
Return: CX = 07C2h (1986d)
Note:    all open files are closed and the printer is reset
SeeAlso: AX=CD04h
--------P-17CD03-----------------------------
INT 17 - INSET - EXECUTE INSET MENU WITHIN OVERRIDE MODE
    AX = CD03h
Return: CX = 07C2h (1986d)
--------P-17CD04-----------------------------
INT 17 - INSET - INITIALIZE LINKED MODE
    AX = CD04h
    ES:SI -> FAR routine for linked mode
Return: CX = 07C2h
Note:    calling sequence for linked-mode routine
    AL = 00h send character in BL to printer
       = 01h send CX bytes from DS:DX to printer
       = 02h move print head to horizontal starting position of image
    return code for linked-mode routine:
    AX = 0000h success
       = 0001h failure
SeeAlso: AX=CD02h,AX=CD08h
--------P-17CD05-----------------------------
INT 17 - INSET - START MERGING IMAGE INTO TEXT
    AX = CD05h
    DS:DX -> ASCIZ name of PIX file
    CX = left margin of text in 1/720th inch
Return: AH = printer type
        00h page-oriented (multiple images may be placed side-by-side)
        01h line-oriented (use AX=CD06h for vertical paper movement)
    CX = 07C2h (1986d)
SeeAlso: AX=CD07h
--------P-17CD06-----------------------------
INT 17 - INSET - GRAPHICS LINE FEED
    AX = CD06h
Return: AH = completion status
        00h image complete
        01h image incomplete
    CX = 07C2h (1986d)
SeeAlso: AX=CD09h
--------P-17CD07-----------------------------
INT 17 - INSET - FLUSH GRAPHICS FROM MERGE BUFFER
    AX = CD07h
Return: CX = 07C2h
SeeAlso: AX=CD05h
--------P-17CD08-----------------------------
INT 17 - INSET - CANCEL LINK MODE
    AX = CD08h
Return: CX = 07C2h
SeeAlso: AX=CD04h
--------P-17CD09-----------------------------
INT 17 - INSET - ALTER TEXT LINE SPACING
    AX = CD09h
    CX = line spacing in 1/720th inch
Return: CX = 07C2h
Note:    not yet implemented, line spacing is currently fixed at 1/6 inch
SeeAlso: AX=CD06h
--------P-17CD0A-----------------------------
INT 17 - INSET - GET SETUP
    AX = CD0Ah
    DS:DX -> buffer for IN.SET data
Return: CX = 07C2h
--------P-17CD0B-----------------------------
INT 17 - INSET - START GETTING SCALED IMAGE
    AX = CD0Bh
    DS:SI -> ASCIZ pathname of .PIX file
    BX = number of bitplanes
    CX = number of rows in output bitmap
    DX = number of columns in output bitmap
Return: AX = status
        0000h OK
        FFFFh error
Note:    image is returned in strips by repeated calls to AX=CD0Ch
--------P-17CD0C-----------------------------
INT 17 - INSET - GET NEXT IMAGE STRIP
    AX = CD0Ch
Return: AX = status
        0000h OK but not complete
        0001h OK and image complete
        FFFFh error
    DS:SI -> buffer (max 4K) for bit map strip
    CX = start row
    DX = number of rows
    BX = offset in bytes between bit planes
Note:    buffer may be overwritten by subsequent calls
SeeAlso: AX=CD0Bh
--------P-17F0-------------------------------
INT 17 - NorthNet Jetstream API - INSTALLATION CHECK
    AH = F0h
    DX = printer port (0-3)
Return: AX = 0001h Jetstream present
         else  non-Jetstream port
Note:    NorthNet Jetstream is a high-performance DMA-driven parallel card able
      to drive printers at up to 80000 characters per second
--------P-17F1-------------------------------
INT 17 - NorthNet Jetstream API - PRINT DATA BUFFER
    AH = F1h
    CX = data buffer length
    DX = printer port (0-3)
    DS:SI -> data buffer
Return: AX = status
        0000h printer not ready (see also AH=02h)
        other printing started
SeeAlso: AH=00h,AH=F2h,AH=F3h,AH=F5h
--------P-17F2-------------------------------
INT 17 - NorthNet Jetstream API - GET PRINT PROGRESS STATUS
    AH = F2h
    DX = printer port (0-3)
Return: AX = status
        0000h prior print request finished
        other number of characters left to print
SeeAlso: AH=02h,AH=F1h,AH=F3h
--------P-17F3-------------------------------
INT 17 - NorthNet Jetstream API - ABORT PRINT OPERATION
    AH = F3h
    DX = printer port (0-3)
Return: AX = number of unprinted characters due to abort
SeeAlso: AH=F1h,AH=F4h
--------P-17F4-------------------------------
INT 17 - NorthNet Jetstream API - SET COMPLETION (POST) ADDRESS
    AH = F4h
    DX = printer port (0-3)
    DS:DS -> FAR post address (called with interrupts on)
SeeAlso: AH=F1h,AH=F3h
--------P-17F5-------------------------------
INT 17 - NorthNet Jetstream API - PRINT DATA BUFFER FROM EXTENDED MEMORY
    AH = F5h
    CX = data buffer length
    DX = printer port (0-3)
    DS:SI -> data buffer (32-bit physical address)
Return: AX = status
        0000h printer not ready (see also AH=02h)
        other printing started
SeeAlso: AH=F1h
----------17FF--BX0000-----------------------
INT 17 U - PC-MOS/386 v5.01 - PRINT SPOOLER - CLOSE SPOOL FILE
    AH = FFh
    BX = 0000h
    CX = 0000h
    DX = printer port number
Return: AH = printer status (see AH=00h)
Program: PC-MOS/386 v5.01 is a multitasking, multiuser MS-DOS 5.0-compatible
      operating system by The Software Link, Inc.
Desc:    close the spool file immediately instead of waiting for the close time
      to elapse
SeeAlso: AH=01h,AH=03h"PC-MOS"
--------B-18---------------------------------
INT 18 - DISKLESS BOOT HOOK (START CASSETTE BASIC)
Desc:    called when there is no bootable disk available to the system
Notes:    only PCs produced by IBM contain BASIC in ROM, so the action is
      unpredicatable on compatibles; this interrupt often reboots the
      system, and often has no effect at all
    network cards with their own BIOS can hook this interrupt to allow
      a diskless boot off the network (even when a hard disk is present
      if none of the partitions is marked as the boot partition)
SeeAlso: INT 86"NetBIOS"
--------J-1800-------------------------------
INT 18 - NEC PC-9800 series - KEYBOARD - GET KEYSTROKE
    AH = 00h
Return: AX = keystroke
SeeAlso: AH=01h,AH=02h,INT 16/AH=00h
--------J-1801-------------------------------
INT 18 - NEC PC-9800 series - KEYBOARD - CHECK FOR KEYSTROKE
    AH = 01h
Return: ZF set if no keystroke available
    ZF clear if keystroke available
        AX = keystroke
SeeAlso: AH=00h,AH=02h,INT 16/AH=01h
--------J-1802-------------------------------
INT 18 - NEC PC-9800 series - KEYBOARD - GET SHIFT STATUS
    AH = 02h
Return: AL = shift flags
SeeAlso: AH=00h,AH=02h,AH=03h,AH=04h,INT 16/AH=02h
--------J-1803-------------------------------
INT 18 - NEC PC-9800 series - KEYBOARD - INITIALIZE
    AH = 03h
    ???
Return: ???
SeeAlso: AH=00h,AH=04h
--------J-1804-------------------------------
INT 18 - NEC PC-9800 series - KEYBOARD - KEY PRESSED
    AH = 04h
    ???
Return: ???
Note:    details are not available at this time
SeeAlso: AH=00h,AH=02h,INT 16/AH=00h,INT 16/AH=01h,INT 16/AH=02h
--------J-18---------------------------------
INT 18 - NEC PC-9800 series - VIDEO
    AH = function
        0Ah set video mode
        0Bh get video mode
        0Ch start text screen display
        0Dh end text screen display
        0Eh set single display area
        0Fh set multiple display area
        10h set cursor shape
        11h display cursor
        12h terminate cursor
        13h set cursor position
        14h read font patter
        16h initialize text video RAM
        1Ah define user character
    ???
Return: ???
Notes:    details are not available at this time
    text video RAM is located at segments A000h (characters) and A200h
      (attributes)
--------B-19---------------------------------
INT 19 - SYSTEM - BOOTSTRAP LOADER
Desc:    This interrupt reboots the system without clearing memory or restoring
      interrupt vectors.  Because interrupt vectors are preserved, this
      interrupt usually causes a system hang if any TSRs have hooked
      vectors from 00h through 1Ch, particularly INT 08.
Notes:    Usually, the BIOS will try to read sector 1, head 0, track 0 from drive
      A: to 0000h:7C00h.  If this fails, and a hard disk is installed, the
      BIOS will read sector 1, head 0, track 0 of the first hard disk.
      This sector should contain a master bootstrap loader and a partition
      table.  After loading the master boot sector at 0000h:7C00h, the
      master bootstrap loader is given control.  It will scan the partition
      table for an active partition, and will then load the operating
      system's bootstrap loader (contained in the first sector of the
      active partition) and give it control.
    true IBM PCs and most clones issue an INT 18 if neither floppy nor hard
      disk have a valid boot sector
    to accomplish a warm boot equivalent to Ctrl-Alt-Del, store 1234h in
      0040h:0072h and jump to FFFFh:0000h.    For a cold boot equivalent to
      a reset, store 0000h at 0040h:0072h before jumping.
    VDISK.SYS hooks this interrupt to allow applications to find out how
      much extended memory has been used by VDISKs (see below).  DOS 3.3+
      PRINT hooks INT 19 but does not set up a correct VDISK header block
      at the beginning of its INT 19 handler segment, thus causing some
      programs to overwrite extended memory which is already in use.
    the default handler is at F000h:E6F2h for 100% compatible BIOSes
    MS-DOS 3.2+ hangs on booting (even from floppy) if the hard disk
      contains extended partitions which point at each other in a loop,
      since it will never find the end of the linked list of extended
      partitions
SeeAlso: INT 14/AH=17h,INT 18

Format of VDISK header block (at beginning of INT 19 handler's segment):
Offset    Size    Description
 00h 18 BYTEs    n/a (for VDISK.SYS, the device driver header)
 12h 11 BYTEs    signature string "VDISK     Vn.m" for VDISK.SYS version n.m
 1Dh 15 BYTEs    n/a
 2Ch  3 BYTEs    linear address of first byte of available extended memory

Format of hard disk master boot sector:
Offset    Size    Description
 00h 446 BYTEs    Master bootstrap loader code
1BEh 16 BYTEs    partition record for partition 1 (see below)
1CEh 16 BYTEs    partition record for partition 2
1DEh 16 BYTEs    partition record for partition 3
1EEh 16 BYTEs    partition record for partition 4
1FEh    WORD    signature, AA55h indicates valid boot block

Format of partition record:
Offset    Size    Description
 00h    BYTE    boot indicator (80h = active partition)
 01h    BYTE    partition start head
 02h    BYTE    partition start sector (bits 0-5)
 03h    BYTE    partition start track (bits 8,9 in bits 6,7 of sector)
 04h    BYTE    operating system indicator (see below)
 05h    BYTE    partition end head
 06h    BYTE    partition end sector (bits 0-5)
 07h    BYTE    partition end track (bits 8,9 in bits 6,7 of sector)
 08h    DWORD    sectors preceding partition
 0Ch    DWORD    length of partition in sectors

Values for operating system indicator:
 00h    empty
 01h    DOS 12-bit FAT
 02h    XENIX root file system
 03h    XENIX /usr file system (obsolete)
 04h    DOS 16-bit FAT
 05h    DOS 3.3+ extended partition
 06h    DOS 3.31+ Large File System
 07h    QNX
 07h    OS/2 HPFS
 07h    Advanced Unix
 08h    AIX bootable partition, SplitDrive
 09h    AIX data partition
 09h    Coherent filesystem
 0Ah    OS/2 Boot Manager
 0Ah    OPUS
 0Ah    Coherent swap partition
 10h    OPUS
 24h    NEC MS-DOS 3.x
 40h    VENIX 80286
 50h    Disk Manager, read-only partition
 51h    Disk Manager, read/write partition
 51h    Novell???
 52h    CP/M
 52h    Microport System V/386
 56h    GoldenBow VFeature
 61h    SpeedStor
 63h    Unix SysV/386, 386/ix
 63h    Mach, MtXinu BSD 4.3 on Mach
 63h    GNU HURD
 64h    Novell NetWare
 65h    Novell NetWare (3.11)
 75h    PC/IX
 80h    Minix v1.1 - 1.4a
 81h    Minix v1.4b+
 81h    Linux
 81h    Mitac Advanced Disk Manager
 82h    Linux Swap partition (planned)
 84h    OS/2-renumbered type 04h partition (related to hiding DOS C: drive)
 93h    Amoeba file system
 94h    Amoeba bad block table
 B7h    BSDI file system (secondarily swap)
 B8h    BSDI swap partition (secondarily file system)
 C1h    DR-DOS 6.0 LOGIN.EXE-secured 12-bit FAT partition
 C4h    DR-DOS 6.0 LOGIN.EXE-secured 16-bit FAT partition
 C6h    DR-DOS 6.0 LOGIN.EXE-secured Huge partition
 DBh    CP/M, Concurrent CP/M, Concurrent DOS
 DBh    CTOS (Convergent Technologies OS)
 E1h    SpeedStor 12-bit FAT extended partition
 E4h    SpeedStor 16-bit FAT extended partition
 F2h    DOS 3.3+ secondary
 FEh    LANstep
 FFh    Xenix bad block table
--------B-1A00-------------------------------
INT 1A - TIME - GET SYSTEM TIME
    AH = 00h
Return: CX:DX = number of clock ticks since midnight
    AL = midnight flag, nonzero if midnight passed since time last read
Notes:    there are approximately 18.2 clock ticks per second, 1800B0h per 24 hrs
    IBM and many clone BIOSes set the flag for AL rather than incrementing
      it, leading to loss of a day if two consecutive midnights pass
      without a request for the time (e.g. if the system is on but idle)
SeeAlso: AH=01h,AH=02h,INT 21/AH=2Ch,INT 62/AX=0099h
--------B-1A01-------------------------------
INT 1A - TIME - SET SYSTEM TIME
    AH = 01h
    CX:DX = number of clock ticks since midnight
SeeAlso: AH=00h,AH=03h,INT 21/AH=2Dh
--------B-1A02-------------------------------
INT 1A - TIME - GET REAL-TIME CLOCK TIME (AT,XT286,PS)
    AH = 02h
Return: CF clear if successful
        CH = hour (BCD)
        CL = minutes (BCD)
        DH = seconds (BCD)
        DL = daylight savings flag (00h standard time, 01h daylight time)
    CF set on error (i.e. clock not running or in middle of update)
SeeAlso: AH=00h
--------B-1A03-------------------------------
INT 1A - TIME - SET REAL-TIME CLOCK TIME (AT,XT286,PS)
    AH = 03h
    CH = hour (BCD)
    CL = minutes (BCD)
    DH = seconds (BCD)
    DL = daylight savings flag (00h standard time, 01h daylight time)
SeeAlso: AH=01h
--------B-1A04-------------------------------
INT 1A - TIME - GET REAL-TIME CLOCK DATE (AT,XT286,PS)
    AH = 04h
Return: CF clear if successful
        CH = century (BCD)
        CL = year (BCD)
        DH = month (BCD)
        DL = day (BCD)
    CF set on error
SeeAlso: AH=02h,AH=05h,INT 21/AH=2Ah
--------B-1A05-------------------------------
INT 1A - TIME - SET REAL-TIME CLOCK DATE (AT,XT286,PS)
    AH = 05h
    CH = century (BCD)
    CL = year (BCD)
    DH = month (BCD)
    DL = day (BCD)
SeeAlso: AH=04h,INT 21/AH=2Bh
--------B-1A06-------------------------------
INT 1A - TIME - SET ALARM (AT,XT286,PS)
    AH = 06h
    CH = hour (BCD)
    CL = minutes (BCD)
    DH = seconds (BCD)
Return: CF set on error (alarm already set or clock stopped for update)
    CF clear if successful
Note:    the alarm occurs every 24 hours until turned off, invoking INT 4A each
      time
SeeAlso: AH=07h,INT 4A
--------B-1A07-------------------------------
INT 1A - TIME - CANCEL ALARM (AT,XT286,PS)
    AH = 07h
Return: alarm disabled
Note:    does not disable the real-time clock's IRQ
SeeAlso: AH=06h,INT 70
--------B-1A08-------------------------------
INT 1A - TIME - SET RTC ACTIVATED POWER ON MODE (CONVERTIBLE)
    AH = 08h
    CH = hours in BCD
    CL = minutes in BCD
    DH = seconds in BCD
SeeAlso: AH=09h
--------B-1A09-------------------------------
INT 1A - TIME - READ RTC ALARM TIME AND STATUS (CONV,PS30)
    AH = 09h
Return: CH = hours in BCD
    CL = minutes in BCD
    DH = seconds in BCD
    DL = alarm status
        00h alarm not enabled
        01h alarm enabled but will not power up system
        02h alarm will power up system
SeeAlso: AH=08h
--------B-1A0A-------------------------------
INT 1A - TIME - READ SYSTEM-TIMER DAY COUNTER (XT2,PS)
    AH = 0Ah
Return: CF set on error
    CF clear if successful
        CX = count of days since Jan 1,1980
SeeAlso: AH=04h,AH=0Bh
--------B-1A0B-------------------------------
INT 1A - TIME - SET SYSTEM-TIMER DAY COUNTER (XT2,PS)
    AH = 0Bh
    CX = count of days since Jan 1,1980
Return: CF set on error
    CF clear if successful
SeeAlso: AH=05h,AH=0Ah
--------J-1A10-------------------------------
INT 1A - NEC PC-9800 series - PRINTER - INITIALIZE
    AH = 10h
    ???
Return: ???
SeeAlso: AH=11h,AH=12h,INT 17/AH=01h
--------J-1A11-------------------------------
INT 1A - NEC PC-9800 series - PRINTER - OUTPUT CHARACTER
    AH = 11h
    ???
Return: ???
SeeAlso: AH=10h,AH=12h,INT 17/AH=00h
--------J-1A12-------------------------------
INT 1A - NEC PC-9800 series - PRINTER - SENSE STATUS
    AH = 12h
    ???
Return: ???
SeeAlso: AH=10h,AH=11h,INT 17/AH=02h
--------A-1A3601-----------------------------
INT 1A - WORD PERFECT v5.0 Third Party Interface - INSTALLATION CHECK
    AX = 3601h
Return: DS:SI = routine to monitor keyboard input, immediately preceded by the
        ASCIZ string "WPCORP\0"
Notes:    WordPerfect 5.0 will call this interrupt at start up to determine if a
      third party product wants to interface with it.  The third party
      product must intercept this interrupt and return the address of a
      keyboard monitor routine.
    Before checking for keyboard input, and after every key entered by the
      user, Word Perfect will call the routine whose address was provided
      in DS:SI with the following parameters:
        Entry:    AX = key code or 0
            BX = WordPerfect state flag
        Exit:    AX = 0 or key code
            BX = 0 or segment address of buffer with key codes
    See the "WordPerfect 5.0 Developer's Toolkit" for further information.
SeeAlso: INT 16/AX=5500h
--------N-1A6108-----------------------------
INT 1A - SNAP.EXE 3.2+ - "SNAP_SENDWITHREPLY" - SEND MSG AND GET REPLY
    AX = 6108h
    STACK:    WORD    conversation ID (0000h-0009h)
        DWORD    pointer to message buffer
        WORD    length of message
        DWORD    pointer to reply buffer
        WORD    length of reply buffer
        WORD    0000h (use default "Cparams" structure)
Return: AX = status (see below)
    STACK unchanged
Program: SNAP.EXE is a TSR written by IBM and Carnegie Mellon University
      which implements the Simple Network Application Protocol
SeeAlso: AX=6205h

Values for status:
 0000h    successful
 F830h    "SNAP_ABORTED"
 FC04h    "SNAP_SERVERDIED"
 FC05h    "SNAP_RESEND"
 FC06h    "SNAP_SELECTFAILED"
 FC07h    "SNAP_WRONGVERSION"
 FC08h    "SNAP_INVALIDACK"
 FC09h    "SNAP_TIMEOUT"
 FC0Ah    "SNAP_SERVERREJECT"
 FC0Bh    "SNAP_NOREPLYDUE"
 FC0Ch    "SNAP_NOAUTHENTICATE"/"SNAP_GUARDIAN_ERROR"
 FC0Dh    "SNAP_NOINIT"
 FC0Eh    "SNAP_SOCKETERROR"
 FC0Fh    "SNAP_BUFFERLIMIT"
 FC10h    "SNAP_INVALIDCID"
 FC11h    "SNAP_INVALIDOP"
 FC12h    "SNAP_XMITFAIL"
 FC13h    "SNAP_NOMORERETRIES"
 FC14h    "SNAP_BADPARMS"
 FC15h    "SNAP_NOMEMORY"
 FC16h    "SNAP_NOMORECONVS"
 FFFFh    failed (invalid function/parameter)
--------N-1A6205-----------------------------
INT 1A - SNAP.EXE 3.2+ - "SNAP_SENDNOREPLY" - SEND MSG, DON'T AWAIT REPLY
    AX = 6205h
    STACK:    WORD    conversation ID (0000h-0009h)
        DWORD    pointer to message
        WORD    length of message
        WORD    0000h (use default "Cparms" structure)
Return: AX = status (see AX=6108h)
    STACK unchanged
SeeAlso: AX=6108h
--------N-1A6308-----------------------------
INT 1A - SNAP.EXE 3.2+ - "SNAP_BEGINCONV" - BEGIN CONVERSATION
    AX = 6308h
    STACK:    WORD    offset of ASCIZ "guardian"
        WORD    offset of ASCIZ hostname
        WORD    offset of ASCIZ server name
        WORD    offset of ASCIZ userid
        WORD    offset of ASCIZ password
        WORD    offset of password length
        WORD    offset of password type
        WORD    offset of "Cparms" structure (see below)
Return: ???
    STACK unchanged
Note:    all stacked offsets are within the SNAP data segment (use AX=6A01h
      to allocate a buffer)
SeeAlso: AX=6405h,AX=7202h

Format of Cparms structure:
Offset    Size    Description
 00h    WORD    retry delay in seconds
 02h    WORD    timeout delay in seconds
 04h    WORD    maximum buffer size
 06h    WORD    encryption level
--------N-1A6405-----------------------------
INT 1A - SNAP.EXE 3.2+ - "SNAP_ENDCONV" - END CONVERSATION
    AX = 6405h
    STACK:    WORD    conversation ID (0000h-0009h)
        DWORD    pointer to message buffer
        WORD    length of message
        WORD    0000h (use default "Cparms" structure)
Return: AX = status (see AX=6108h)
    STACK unchanged
Program: SNAP.EXE is a TSR written by IBM and Carnegie Mellon University
      which implements the Simple Network Application Protocol
SeeAlso: AX=6308h
--------N-1A6900-----------------------------
INT 1A - SNAP.EXE 3.2+ - "SNAP_DATASEG" - GET RESIDENT DATA SEGMENT
    AX = 6900h
Return: AX = value used for DS by resident code
SeeAlso: AX=6A01h,AX=6F01h
--------N-1A6A01-----------------------------
INT 1A - SNAP.EXE 3.2+ - "SNAP_ALLOC" - ALLOCATE BUFFER IN SNAP DATA SEGMENT
    AX = 6A01h
    STACK:    WORD    number of bytes to allocate
Return: AX = offset of allocated buffer or 0000h if out of memory
    STACK unchanged
Program: SNAP.EXE is a TSR written by IBM and Carnegie Mellon University
      which implements the Simple Network Application Protocol
SeeAlso: AX=6B01h
--------N-1A6B01-----------------------------
INT 1A - SNAP.EXE 3.2+ - "SNAP_FREE" - DEALLOCATE BUFFER IN SNAP DATA SEGMENT
    AX = 6B01h
    STACK:    WORD    offset within SNAP data segment of previously allocated
            buffer
Return: STACK unchanged
Note:    this call is a NOP if the specified offset is 0000h
SeeAlso: AX=6A01h
--------N-1A6C04-----------------------------
INT 1A - SNAP.EXE 3.2+ - "SNAP_COPYTO" - COPY DATA TO RESIDENT SNAP PACKAGE
    AX = 6C04h
    STACK:    WORD    offset within SNAP data segment of dest (nonzero)
        WORD    segment of source buffer
        WORD    offset of source buffer
        WORD    number of bytes to copy
Return: AX = offset of byte after last one copied to destination
    STACK unchanged
Program: SNAP.EXE is a TSR written by IBM and Carnegie Mellon University
      which implements the Simple Network Application Protocol
SeeAlso: AX=6D04h
--------N-1A6D04-----------------------------
INT 1A - SNAP.EXE 3.2+ - "SNAP_COPYFROM" - COPY DATA FROM RESIDENT SNAP PACKAGE
    AX = 6D04h
    STACK:    WORD    offset within SNAP data segment of source buffer
        WORD    segment of destination buffer
        WORD    offset of destination buffer
        WORD    number of bytes to copy
Return: AX = offset of byte after last one copied from source
    buffer filled
    STACK unchanged
SeeAlso: AX=6C04h
--------N-1A6E01-----------------------------
INT 1A - SNAP.EXE 3.2+ - "SNAP_SETDEBUG" - SET ???
    AX = 6E01h
    STACK:    WORD    new value for ???
Return: AX = old value of ???
    STACK unchanged
Program: SNAP.EXE is a TSR written by IBM and Carnegie Mellon University
      which implements the Simple Network Application Protocol
--------N-1A6F01-----------------------------
INT 1A - SNAP.EXE 3.2+ - "SNAP_CHKINSTALL" - INSTALLATION CHECK
    AX = 6F01h
    STACK: WORD 0000h
Return: AX = status
        0000h SNAP is resident
        other SNAP not present
    STACK unchanged
Program: SNAP.EXE is a TSR written by IBM and Carnegie Mellon University
      which implements the Simple Network Application Protocol, and is
      required by PCVENUS (a network shell).  The combination of SNAP and
      PCVENUS allows the use of the Andrew File System as one or more
      networked drives.
SeeAlso: AX=6900h,AX=7400h
--------N-1A7002-----------------------------
INT 1A - SNAP.EXE 3.2+ - "SNAP_SETANCHOR"
    AX = 7002h
    STACK:    WORD    anchor number (0000h-0009h)
        WORD    new value for the anchor
Return: AX = status
        0000h successful
        FFFFh failed (top word on stack not in range 00h-09h)
    STACK unchanged
SeeAlso: AX=7101h
--------N-1A7101-----------------------------
INT 1A - SNAP.EXE 3.2+ - "SNAP_GETANCHOR"
    AX = 7101h
    STACK:    WORD    anchor number (0000h-0009h)
Return: AX = anchor's value
    STACK unchanged
Program: SNAP.EXE is a TSR written by IBM and Carnegie Mellon University
      which implements the Simple Network Application Protocol
SeeAlso: AX=7002h
--------N-1A7202-----------------------------
INT 1A - SNAP.EXE 3.2+ - "SNAP_SETCONVPARMS" - SET CONVERSATION PARAMETERS
    AX = 7202h
    STACK:    WORD    conversation ID (0000h-0009h)
        WORD    offset within resident data segment of "Cparms"
            structure (see AX=6308h)
Return: AX = status???
    STACK unchanged
SeeAlso: AX=6308h
--------N-1A7302-----------------------------
INT 1A - SNAP.EXE 3.2+ - "SNAP_CLIENTVERSION" - ???
    AX = 7302h
    STACK:    WORD    conversation ID (0000h-0009h)
        WORD    offset within resident data segment of ???
Return: AX = ???
    ???
    STACK unchanged
SeeAlso: AX=7400h
--------N-1A7400-----------------------------
INT 1A - SNAP.EXE 3.2+ - "SNAP_VERSION" - GET VERSION
    AX = 7400h
Return: AX = version (AH=major, AL=minor)
Note:    this call is only valid if SNAP is installed
SeeAlso: AX=7302h,INT 1A/AX=6F01h
--------N-1A75-------------------------------
INT 1A - SNAP.EXE 3.2+ - "SNAP_NOP" - ???
    AH = 75h
    AL = ???
Return: AX = ??? (0000h)
Program: SNAP.EXE is a TSR written by IBM and Carnegie Mellon University
      which implements the Simple Network Application Protocol
--------N-1A76-------------------------------
INT 1A - SNAP.EXE 3.2+ - "SNAP_802_5" - ???
    AH = 76h
    AL = ???
Return: AX = ???
--------N-1A77-------------------------------
INT 1A - SNAP.EXE 3.4 - ???
    AH = 77h
    AL = ??? (at least 01h)
    STACK:    WORD    ???
        ???
Return: ???
    STACK unchanged
--------N-1A7802-----------------------------
INT 1A - SNAP.EXE 3.4 - ???
    AX = 7802h
    STACK:    WORD    ???
        WORD    ???
Return: ???
    STACK unchanged
Program: SNAP.EXE is a TSR written by IBM and Carnegie Mellon University
      which implements the Simple Network Application Protocol
--------s-1A7F-------------------------------
INT 1A - Tandy 2500, Tandy 1000L series - DIGITAL SOUND???
    AH = 7Fh
    ???
Return: ???
SeeAlso: AH=80h,AH=83h,AH=85h
--------s-1A80-------------------------------
INT 1A - PCjr - SET UP SOUND MULTIPLEXOR
    AH = 80h
    AL = 00h source is 8253 channel 2
         01h source is cassette input
         02h source is I/O channel "Audio IN"
         03h source is sound generator chip
SeeAlso: AH=7Fh,AH=83h
--------X-1A80-------------------------------
INT 1A - PCMCIA Socket Services - GET NUMBER OF ADAPTERS
    AH = 80h
    ???
Return: ???
SeeAlso: AH=83h"PCMCIA"
--------X-1A81-------------------------------
INT 1A - PCMCIA Socket Services - REGISTER STATUS CHANGE CALLBACK
    AH = 81h
    ???
Return: ???
SeeAlso: AH=80h"PCMCIA",AH=82h"PCMCIA"
--------s-1A8100-----------------------------
INT 1A - Tandy 2500, Tandy 1000L series - DIGITAL SOUND - INSTALLATION CHECK
    AX = 8100h
Return: AH > 80h if supported
--------X-1A82-------------------------------
INT 1A - PCMCIA Socket Services - REGISTER CARD TECHNOLOGY CALLBACK
    AH = 82h
    ???
Return: ???
SeeAlso: AH=81h"PCMCIA"
--------s-1A83-------------------------------
INT 1A - Tandy 2500, Tandy 1000L series - START PLAYING DIGITAL SOUND
    AH = 83h
    AL = volume (0=lowest, 7=highest)
    CX = number of bytes to play
    DX = time between sound samples (multiples of 273 nanoseconds)
    ES:BX -> sound data (array of 8-bit PCM samples)
Return: ???
Notes:    this call returns immediately while the sound plays in the
      background
    The sound data pointed to by ES:BX probably shouldn't cross a 64k
      boundary.  The BIOS appears to call INT 15/AX=91FBh when the sound
      device underflows to allow another INT 1A/AH=83h for seamless
      playing of long sounds.
SeeAlso: AH=84h,INT 15/AH=91h
--------X-1A83-------------------------------
INT 1A - PCMCIA Socket Services - GET SOCKET SERVICES VERSION NUMBER
    AH = 83h
    ???
Return: ???
SeeAlso: AH=80h"PCMCIA"
--------s-1A84-------------------------------
INT 1A - Tandy 2500, Tandy 1000L series - STOP PLAYING DIGITAL SOUND
    AH = 84h
Return: ???
SeeAlso: AH=83h,AH=85h
--------X-1A84-------------------------------
INT 1A - PCMCIA Socket Services - INQUIRE ADAPTER
    AH = 84h
    ???
Return: ???
SeeAlso: AH=80h"PCMCIA",AH=85h"PCMCIA",AH=87h
--------s-1A85-------------------------------
INT 1A - Tandy 2500, Tandy 1000L series - DIGITAL SOUND???
    AH = 85h
    ???
Return: ???
SeeAlso: AH=7Fh,AH=83h
--------X-1A85-------------------------------
INT 1A - PCMCIA Socket Services - GET ADAPTER
    AH = 85h
    ???
Return: ???
SeeAlso: AH=84h"PCMCIA",AH=86h
--------X-1A86-------------------------------
INT 1A - PCMCIA Socket Services - SET ADAPTER
    AH = 86h
    ???
Return: ???
SeeAlso: AH=84h"PCMCIA",AH=85h"PCMCIA"
--------X-1A87-------------------------------
INT 1A - PCMCIA Socket Services - INQUIRE WINDOW
    AH = 87h
    ???
Return: ???
SeeAlso: AH=84h"PCMCIA",AH=88h,AH=89h,AH=8Ch
--------X-1A88-------------------------------
INT 1A - PCMCIA Socket Services - GET WINDOW
    AH = 88h
    ???
Return: ???
SeeAlso: AH=87h,AH=89h,AH=8Ah
--------X-1A89-------------------------------
INT 1A - PCMCIA Socket Services - SET WINDOW
    AH = 89h
    ???
Return: ???
SeeAlso: AH=87h,AH=88h,AH=8Bh
--------X-1A8A-------------------------------
INT 1A - PCMCIA Socket Services - GET PAGE
    AH = 8Ah
    ???
Return: ???
SeeAlso: AH=88h,AH=8Bh
--------X-1A8B-------------------------------
INT 1A - PCMCIA Socket Services - SET PAGE
    AH = 8Bh
    ???
Return: ???
SeeAlso: AH=89h,AH=8Ah
--------X-1A8C-------------------------------
INT 1A - PCMCIA Socket Services - INQUIRE SOCKET
    AH = 8Ch
    ???
Return: ???
SeeAlso: AH=87h,AH=8Dh,AH=8Eh
--------X-1A8D-------------------------------
INT 1A - PCMCIA Socket Services - GET SOCKET
    AH = 8Dh
    ???
Return: ???
SeeAlso: AH=8Ch,AH=8Eh
--------X-1A8E-------------------------------
INT 1A - PCMCIA Socket Services - SET SOCKET
    AH = 8Eh
    ???
Return: ???
SeeAlso: AH=8Ch,AH=8Dh
--------X-1A8F-------------------------------
INT 1A - PCMCIA Socket Services - GET CARD
    AH = 8Fh
    ???
Return: ???
SeeAlso: AH=8Dh,AH=90h
--------X-1A90-------------------------------
INT 1A - PCMCIA Socket Services - RESET CARD
    AH = 90h
    ???
Return: ???
--------X-1A91-------------------------------
INT 1A - PCMCIA Socket Services - READ ONE
    AH = 91h
    ???
Return: ???
SeeAlso: AH=92h,AH=93h,INT 21/AX=440Dh"IOCTL"
--------X-1A92-------------------------------
INT 1A - PCMCIA Socket Services - WRITE ONE
    AH = 92h
    ???
Return: ???
SeeAlso: AH=91h,AH=94h,INT 21/AX=440Dh"IOCTL"
--------X-1A93-------------------------------
INT 1A - PCMCIA Socket Services - READ MULTIPLE
    AH = 93h
    ???
Return: ???
SeeAlso: AH=91h,AH=94h,INT 21/AX=440Dh"IOCTL"
--------X-1A94-------------------------------
INT 1A - PCMCIA Socket Services - WRITE MULTIPLE
    AH = 94h
    ???
Return: ???
SeeAlso: AH=92h,AH=93h,INT 21/AX=440Dh"IOCTL"
--------X-1A95-------------------------------
INT 1A - PCMCIA Socket Services - INQUIRE ERROR DETECTION CODE
    AH = 95h
    ???
Return: ???
SeeAlso: AH=96h,AH=9Ch
--------X-1A96-------------------------------
INT 1A - PCMCIA Socket Services - GET ERROR DETECTION CODE
    AH = 96h
    ???
Return: ???
SeeAlso: AH=95h,AH=97h,AH=9Ch
--------X-1A97-------------------------------
INT 1A - PCMCIA Socket Services - SET ERROR DETECTION CODE
    AH = 97h
    ???
Return: ???
SeeAlso: AH=96h,AH=9Ch
--------X-1A98-------------------------------
INT 1A - PCMCIA Socket Services - START ERROR DETECTION CODE
    AH = 98h
    ???
Return: ???
SeeAlso: AH=96h,AH=99h,AH=9Bh,AH=9Ch
--------X-1A99-------------------------------
INT 1A - PCMCIA Socket Services - PAUSE ERROR DETECTION CODE
    AH = 99h
    ???
Return: ???
SeeAlso: AH=9Ah
--------X-1A9A-------------------------------
INT 1A - PCMCIA Socket Services - RESUME ERROR DETECTION CODE
    AH = 9Ah
    ???
Return: ???
SeeAlso: AH=99h,AH=98h
--------X-1A9B-------------------------------
INT 1A - PCMCIA Socket Services - STOP ERROR DETECTION CODE
    AH = 9Bh
    ???
Return: ???
SeeAlso: AH=98h,AH=99h,AH=9Ch
--------X-1A9C-------------------------------
INT 1A - PCMCIA Socket Services - READ ERROR DETECTION CODE
    AH = 9Ch
    ???
Return: ???
SeeAlso: AH=95h,AH=96h,AH=98h,AH=99h,AH=9Bh
--------c-1AA0-------------------------------
INT 1A U - Disk Spool II v2.07+ - INSTALLATION CHECK
    AH = A0h
Return: AH = B0h if installed
        AL = pending INT 1A/AH=D0h subfunction if nonzero???
        ES = code segment
        ES:BX -> name of current spool file
        ES:SI -> current despool file
        CL = despooler state (00h disabled, 41h enabled)
        CH = spooler state (00h disabled, 41h enabled)
        DL = 00h despooler is currently active printing a file
           = 41h despooler is standing by
        DH = 00h ???
           = 41h ???
        DI = 0000h ???
         0001h ???
Program: Disk Spool II is a shareware disk-based print spooler by Budget
      Software Company
Note:    this function is also supported by Vertisoft's Emulaser utility ELSPL,
      as that is a licensed version of Disk Spool II
SeeAlso: AH=ABh,AH=C0h,AH=D0h,AH=E1h
--------c-1AAB-------------------------------
INT 1A U - Disk Spool II v1.83 - INSTALLATION CHECK
    AH = ABh
Return: AH = BAh if installed
        AL = pending INT 1A/AH=ADh subfunction if nonzero???
        ES = code segment
        ES:BX -> name of current spool file
        ES:SI -> current despool file
        CL = 00h despooler is disabled
           = 41h despooler is enabled
        CH = 00h spooler is disabled
           = 41h spooler is enabled
        DL = 00h despooler is currently active printing a file
           = 41h despooler is standing by
        DH = 00h ???
           = 41h ???
        DI = 0000h ???
         0001h ???
Program: Disk Spool II is a shareware disk-based print spooler by Budget
      Software Company
SeeAlso: AH=A0h,AH=ACh,AH=ADh,AH=E1h
--------c-1AAC-------------------------------
INT 1A U - Disk Spool II v1.83 - INSTALLATION CHECK
    AH = ACh
Return: (see AH=ABh)
Note:    this function is identical to AH=ABh
SeeAlso: AH=A0h,AH=ABh,AH=ADh
--------c-1AAD-------------------------------
INT 1A U - Disk Spool II v1.83 - FUNCTION CALLS
    AH = ADh
    AL = function code
        02h enable spooler only
        03h enable the despooler
        04h disable the despooler
        08h inhibit popup menu
        09h enable popup menu
        0Ah ???
        0Bh disable the spooler
        0Ch start despooler after last successfully printed document???
        0Dh start despooler at the exact point where it last left off???
        0Eh pop up the menu
        0Fh ???
        11h ???
        14h ???
        15h ???
        16h ???
        17h ???
        18h ???
        19h ???
        20h clear file pointed to by the despooler???
        21h ???
        22h ???
        23h ???
        30h ???
Return: AH = 00h if successful
SeeAlso: AH=ABh
--------d-1AB001CX4D52-----------------------
INT 1A - Microsoft Real-Time Compression Interface (MRCI) - ROM-BASED SERVER
    AX = B001h
    CX = 4D52h ("MR")
    DX = 4349h ("CI")
Return: CX = 4943h ("IC") if installed
    DX = 524Dh ("RM") if installed
        ES:DI -> MRCINFO structure (see below)
Note:    this call is functionally identical to INT 2F/AX=4A12h, which should
      be called first, as this call is used for the first, ROM-based
      MRCI server, while the other call is used for RAM-based servers
      which may be partially or entirely replacing a prior server
SeeAlso: INT 2F/AX=4A12h

Format of MRCINFO structure:
Offset    Size    Description
 00h  4 BYTEs    vendor signature
        "MSFT" Microsoft
 04h    WORD    server version (high=major)
 06h    WORD    MRCI specification version
 08h    DWORD    address of server entry point
 0Ch    WORD    bit flags: server capabilities (see below)
 0Eh    WORD    bit flags: hardware assisted capabilities (see below)
 10h    WORD    maximum block size supported by server (at least 8192 bytes)

Bitfields for capabilities:
 bit 0    standard compress
 bit 1    standard decompress
 bit 2    update compress
 bit 3    MaxCompress
 bit 4    reserved
 bit 5    incremental decompress
 bits 6-14 reserved
 bit 15 this structure is in ROM and can't be modified
    (server capabilities only)

Call MRCI entry point with:
    DS:SI -> MRCREQUEST structure (see below)
    CX = type of client (0000h application, 0001h file system)
    AX = operation
        0001h perform standard compression
        0002h perform standard decompression
        0004h perform update compression
        0008h perform MaxCompress
        0020h perform incremental decompression
    AX = FFFFh clear flags
        BX = bitmask of flags to clear (set bits in BX are flags to clear)
Return: AX = status
        0000h successful
        0001h invalid function
        0002h server busy, try again
        0003h destination buffer too small
        0004h incompressible data
        0005h bad compressed data format
Note:    MRCI driver may chain to a previous driver

Format of MRCREQUEST structure:
Offset    Size    Description
 00h    DWORD    pointer to source buffer
 04h    WORD    size of source buffer (0000h = 64K)
 06h    WORD    (UpdateCompress only)
        (call) offset in source buffer of beginning of changed data
        (return) offset in destination buffer of beginning of changed
            compressed data
 08h    DWORD    pointer to destination buffer
        must contain original compressed data for UpdateCompress
 0Ch    WORD    size of destination buffer (0000h = 64K)
        any compression: size of buffer for compressed data
        standard decompression: number of bytes to be decompressed
        incremental decompression: number of byte to decompress now
        (return) actual size of resulting data
 0Eh    WORD    client compressed data storage allocation size
 10h    DWORD    incremental decompression state data
        set to 00000000h before first incremental decompression call
Notes:    the source and destination buffers may not overlap
    the source and destination buffer sizes should normally be the same
    application should not update the contents of the MRCREQUEST structure
      between incremental decompression calls
--------X-1AB101-----------------------------
INT 1A - Intel PCI BIOS v2.0c - INSTALLATION CHECK
    AX = B101h
Return: AH = 00h if installed
        CF clear
        EDX = 20494350h (' ICP')
        EDI = physical address of protected-mode entry point (see below)
        AL = PCI hardware characteristics
        bit 0: configuration space access mechanism 1 supported
        bit 1: configuration space access mechanism 2 supported
        bits 2-3 reserved
        bit 4: Special Cycle generation mechanism 1 supported
        bit 5: Special Cycle generation mechanism 2 supported
        bits 6-7 reserved
        BH = PCI interface level major version (BCD)
        BL = PCI interface level minor version (BCD)
        CL = number of last PCI bus in system
    EAX, EBX, ECX, and EDX may be modified
    all other flags (except IF) may be modified
Note:    this function may require up to 1024 byte of stack; it will not enable
      interrupts if they were disabled before making the call
SeeAlso: AX=B181h

Call protected-mode entry point with:
    registers as for real/V86-mode INT call
    CS = ring 0 descriptor with access to full address space
Return: as for real/V86-mode call
--------X-1AB102-----------------------------
INT 1A - Intel PCI BIOS v2.0c - FIND PCI DEVICE
    AX = B102h
    CX = device ID
    DX = vendor ID
    SI = device index (0-n)
Return: CF clear if successful
    CF set on error
    AH = status
        00h successful
        BL = bus number
        BH = device/function number (bits 7-3 device, bits 2-0 func)
        83h bad vendor ID
        86h device not found
    EAX, EBX, ECX, and EDX may be modified
    all other flags (except IF) may be modified
Notes:    this function may require up to 1024 byte of stack; it will not enable
      interrupts if they were disabled before making the call
    device ID FFFFh may be reserved as a wildcard in future implementations
    the meanings of BL and BH on return may be exchanged in future
      implementations
    all devices sharing a single vendor ID and device ID may be enumerated
      by incrementing SI from 0 until error 86h is returned
SeeAlso: AX=B182h
--------X-1AB103-----------------------------
INT 1A - Intel PCI BIOS v2.0c - FIND PCI CLASS CODE
    AX = B103h
    ECX = class code (bits 23-0)
    SI = device index (0-n)
Return: CF clear if successful
    CF set on error
    AH = status
        00h successful
        BL = bus number
        BH = device/function number (bits 7-3 device, bits 2-0 func)
        86h device not found
    EAX, EBX, ECX, and EDX may be modified
    all other flags (except IF) may be modified
Notes:    this function may require up to 1024 byte of stack; it will not enable
      interrupts if they were disabled before making the call
    the meanings of BL and BH on return may be exchanged in future
      implementations
    all devices sharing the same Class Code may be enumerated by
      incrementing SI from 0 until error 86h is returned
SeeAlso: AX=B183h
--------X-1AB102-----------------------------
INT 1A - Intel PCI BIOS v2.0c - PCI BUS-SPECIFIC OPERATIONS
    AX = B106h
    BL = bus number
    EDX = Special Cycle data
Return: CF clear if successful
    CF set on error
    AH = status
        00h successful
        81h unsupported function
    EAX, EBX, ECX, and EDX may be modified
    all other flags (except IF) may be modified
Note:    this function may require up to 1024 byte of stack; it will not enable
      interrupts if they were disabled before making the call
SeeAlso: AX=B186h
--------X-1AB108-----------------------------
INT 1A - Intel PCI BIOS v2.0c - READ CONFIGURATION BYTE
    AX = B108h
    BL = bus number
    BH = device/function number (bits 7-3 device, bits 2-0 function)
    DI = register number (0000h-00FFh)
Return: CF clear if successful
        CL = byte read
    CF set on error
    AH = status
        00h successful
        87h bad register number
    EAX, EBX, ECX, and EDX may be modified
    all other flags (except IF) may be modified
Notes:    this function may require up to 1024 byte of stack; it will not enable
      interrupts if they were disabled before making the call
    the meanings of BL and BH on entry may be exchanged in future
      implementations
SeeAlso: AX=B188h
--------X-1AB109-----------------------------
INT 1A - Intel PCI BIOS v2.0c - READ CONFIGURATION WORD
    AX = B109h
    BL = bus number
    BH = device/function number (bits 7-3 device, bits 2-0 function)
    DI = register number (0000h-00FFh)
Return: CF clear if successful
        CX = word read
    CF set on error
    AH = status
        00h successful
        87h bad register number
    EAX, EBX, ECX, and EDX may be modified
    all other flags (except IF) may be modified
Notes:    this function may require up to 1024 byte of stack; it will not enable
      interrupts if they were disabled before making the call
    the meanings of BL and BH on entry may be exchanged in future
      implementations
SeeAlso: AX=B189h
--------X-1AB10A-----------------------------
INT 1A - Intel PCI BIOS v2.0c - READ CONFIGURATION DWORD
    AX = B10Ah
    BL = bus number
    BH = device/function number (bits 7-3 device, bits 2-0 function)
    DI = register number (0000h-00FFh)
Return: CF clear if successful
        ECX = dword read
    CF set on error
    AH = status
        00h successful
        87h bad register number
    EAX, EBX, ECX, and EDX may be modified
    all other flags (except IF) may be modified
Notes:    this function may require up to 1024 byte of stack; it will not enable
      interrupts if they were disabled before making the call
    the meanings of BL and BH on entry may be exchanged in future
      implementations
SeeAlso: AX=B18Ah
--------X-1AB10B-----------------------------
INT 1A - Intel PCI BIOS v2.0c - WRITE CONFIGURATION BYTE
    AX = B10Bh
    BL = bus number
    BH = device/function number (bits 7-3 device, bits 2-0 function)
    DI = register number (0000h-00FFh)
    CL = byte to write
Return: CF clear if successful
    CF set on error
    AH = status
        00h successful
        87h bad register number
    EAX, EBX, ECX, and EDX may be modified
    all other flags (except IF) may be modified
Notes:    this function may require up to 1024 byte of stack; it will not enable
      interrupts if they were disabled before making the call
    the meanings of BL and BH on entry may be exchanged in future
      implementations
SeeAlso: AX=B18Bh
--------X-1AB10C-----------------------------
INT 1A - Intel PCI BIOS v2.0c - WRITE CONFIGURATION WORD
    AX = B10Ch
    BL = bus number
    BH = device/function number (bits 7-3 device, bits 2-0 function)
    DI = register number (multiple of 2 less than 0100h)
    CX = word to write
Return: CF clear if successful
    CF set on error
    AH = status
        00h successful
        87h bad register number
    EAX, EBX, ECX, and EDX may be modified
    all other flags (except IF) may be modified
Notes:    this function may require up to 1024 byte of stack; it will not enable
      interrupts if they were disabled before making the call
    the meanings of BL and BH on entry may be exchanged in future
      implementations
SeeAlso: AX=B18Ch
--------X-1AB10D-----------------------------
INT 1A - Intel PCI BIOS v2.0c - WRITE CONFIGURATION DWORD
    AX = B10Dh
    BL = bus number
    BH = device/function number (bits 7-3 device, bits 2-0 function)
    DI = register number (multiple of 4 less than 0100h)
    ECX = dword to write
Return: CF clear if successful
    CF set on error
    AH = status
        00h successful
        87h bad register number
    EAX, EBX, ECX, and EDX may be modified
    all other flags (except IF) may be modified
Notes:    this function may require up to 1024 byte of stack; it will not enable
      interrupts if they were disabled before making the call
    the meanings of BL and BH on entry may be exchanged in future
      implementations
SeeAlso: AX=B18Dh
--------X-1AB181-----------------------------
INT 1A - Intel PCI BIOS v2.0c - INSTALLATION CHECK (32-bit)
    AX = B181h
Return: as for AX=B101h
SeeAlso: AX=B101h
--------X-1AB182-----------------------------
INT 1A - Intel PCI BIOS v2.0c - FIND PCI DEVICE (32-bit)
    AX = B182h
    CX = device ID
    DX = vendor ID
    SI = device index (0-n)
Return: as for AX=B102h
SeeAlso: AX=B102h
--------X-1AB183-----------------------------
INT 1A - Intel PCI BIOS v2.0c - FIND PCI CLASS CODE (32-bit)
    AX = B183h
    ECX = class code (bits 23-0)
    SI = device index (0-n)
Return: as for AX=B103h
SeeAlso: AX=B103h
--------X-1AB186-----------------------------
INT 1A - Intel PCI BIOS v2.0c - PCI BUS-SPECIFIC OPERATIONS (32-bit)
    AX = B186h
    BL = bus number
    EDX = Special Cycle data
Return: as for AX=B106h
SeeAlso: AX=B106h
--------X-1AB188-----------------------------
INT 1A - Intel PCI BIOS v2.0c - READ CONFIGURATION BYTE (32-bit)
    AX = B188h
    BL = bus number
    BH = device/function number (bits 7-3 device, bits 2-0 function)
    DI = register number (0000h-00FFh)
Return: as for AX=B108h
SeeAlso: AX=B108h
--------X-1AB189-----------------------------
INT 1A - Intel PCI BIOS v2.0c - READ CONFIGURATION WORD (32-bit)
    AX = B189h
    BL = bus number
    BH = device/function number (bits 7-3 device, bits 2-0 function)
    DI = register number (0000h-00FFh)
Return: as for AX=B109h
SeeAlso: AX=B109h
--------X-1AB18A-----------------------------
INT 1A - Intel PCI BIOS v2.0c - READ CONFIGURATION DWORD (32-bit)
    AX = B18Ah
    BL = bus number
    BH = device/function number (bits 7-3 device, bits 2-0 function)
    DI = register number (0000h-00FFh)
Return: as for AX=B10Ah
SeeAlso: AX=B10Ah
--------X-1AB18B-----------------------------
INT 1A - Intel PCI BIOS v2.0c - WRITE CONFIGURATION BYTE (32-bit)
    AX = B18Bh
    BL = bus number
    BH = device/function number (bits 7-3 device, bits 2-0 function)
    DI = register number (0000h-00FFh)
    CL = byte to write
Return: as for AX=B10Bh
SeeAlso: AX=B10Bh
--------X-1AB18C-----------------------------
INT 1A - Intel PCI BIOS v2.0c - WRITE CONFIGURATION WORD (32-bit)
    AX = B18Ch
    BL = bus number
    BH = device/function number (bits 7-3 device, bits 2-0 function)
    DI = register number (multiple of 2 less than 0100h)
    CX = word to write
Return: as for AX=B10Ch
SeeAlso: AX=B10Ch
--------X-1AB18D-----------------------------
INT 1A - Intel PCI BIOS v2.0c - WRITE CONFIGURATION DWORD (32-bit)
    AX = B18Dh
    BL = bus number
    BH = device/function number (bits 7-3 device, bits 2-0 function)
    DI = register number (multiple of 4 less than 0100h)
    ECX = dword to write
Return: as for AX=B10Dh
SeeAlso: AX=B10Dh
--------c-1AC0-------------------------------
INT 1A U - Disk Spool II v2.07+ - ALTERNATE INSTALLATION CHECK
    AH = C0h
Return: (see AH=A0h)
Notes:    this call is identical to AH=A0h
    this function is also supported by Vertisoft's Emulaser utility ELSPL,
      as that is a licensed version of Disk Spool II
SeeAlso: AH=A0h,AH=ABh,AH=D0h
----------1ACCCCBXCCCC-----------------------
INT 1A U - DATEFIX - INSTALLATION CHECK
    AX = CCCCh
    BX = CCCCh
    CX = 0000h
Return: CX = CCCCh if installed
        ES:BX -> original interrupt handler
Program: DATEFIX is a public-domain TSR to correct the date on AT&T 6300
      machines, where the realtime clock's calendar wraps after 1991
SeeAlso: AH=FEh,AH=FFh"AT&T"
--------c-1AD0-------------------------------
INT 1A U - Disk Spool II v2.07+ - FUNCTION CALLS
    AH = D0h
    AL = function code
        01h enable spooler and despooler
        02h enable spooler only
        03h enable despooler at beginning of file
        04h disable the despooler
        05h disable the despooler and spooler
        06h clear the spool file
        08h inhibit the popup menu
        09h enable the popup menu
        0Ah ??? (called by Disk Spool's INT 21 handler)
        0Bh disable the spooler
        0Ch start despooler after last successfully printed document
        0Dh start despooler at the exact point where it last left off
        0Eh pop up the menu
        0Fh ???
        11h start new spool file??? (called by Disk Spool's INT 21 handler
            when a program terminates)
        14h ???
        15h delete despool file and reset ???
        16h ??? (writes something to unknown file)
        17h ??? (writes something to despool file, then reads something
            else and ???)
        18h ??? (reads something from despool file, and then ???)
        19h ??? (creates/truncates spool file)
        20h clear file pointed to by the despooler
        21h ??? (writes something to unknown file)
        22h ??? (writes something to spool file if spooler/despooler using
            same file)
        23h ??? (opens/creates unknown file, then ???)
        30h ???
        31h ???
        32h beep
        33h append CRLF to spool file???
        34h ???
        35h ???
        36h ???
        37h append CRLF to spool file and start a new spool file???
        38h ???
        40h ??? (v4.05)
        41h ??? (v4.05)
        51h ??? (called by Disk Spool's INT 21 handler)
        52h ??? (called by Disk Spool's INT 21 handler)
        57h ???
        5Ah ??? (v4.05)
        5Bh ??? (v4.05)
        5Ch ??? (v4.05)
Note:    this function is also supported by Vertisoft's Emulaser utility ELSPL,
      as that is a licensed version of Disk Spool II
SeeAlso: AH=A0h,AH=ADh
--------c-1AE0-------------------------------
INT 1A - Disk Spool II v4.0x - ENABLE/DISABLE
    AH = E0h
    AL = subfunction
        01h enable spooler
        02h disable spooler
        03h enable despooler
        04h disable despooler
    CL = printer port (01h COM1, 02h COM2, 05h LPT1, 06h LPT2)
Return: AH = status
        00h successful
        F0h printer port not managed by Disk Spool II
        FFH failed
Note:    this function is also supported by Vertisoft's Emulaser utility ELSPL,
      as that is a licensed version of Disk Spool II
SeeAlso: AH=A0h,AH=E1h,AX=E301h,AX=E401h
--------c-1AE1-------------------------------
INT 1A - Disk Spool II v4.0x - GET STATUS
    AH = E1h
    CL = printer port (01h COM1, 02h COM2, 05h LPT1, 06h LPT2)
Return: AH = status
        00h successful
        CL = despooler state (00h disabled, 41h enabled)
        CH = spooler state (00h disabled, 41h enabled)
        DL = despooler activity (00h standing by, 41h printing)
        ES:BX -> ASCIZ name of current spool file (or next if AutoSpool
            or AutoDespool enabled)
        ES:SI -> ASCIZ name of current despool file
        ES:DI -> 3-byte file extension used by Disk Spool II
        F0h printer port not managed by Disk Spool II
Note:    this function is also supported by Vertisoft's Emulaser utility ELSPL,
      as that is a licensed version of Disk Spool II
SeeAlso: AH=A0h,AH=E0h,AH=E2h
--------c-1AE2-------------------------------
INT 1A - Disk Spool II v4.0x - GET SPOOL FILES
    AH = E2h
    AL = which
        01h first
        02h next (can only call after "first")
    CL = printer port (01h COM1, 02h COM2, 05h LPT1, 06h LPT2)
Return: AH = status
        00h successful
        ES:BX -> ASCIZ filename
        F0h no (more) spool files
        FFh failed
Note:    this function is also supported by Vertisoft's Emulaser utility ELSPL,
      as that is a licensed version of Disk Spool II
SeeAlso: AH=E0h,AH=E1h
--------c-1AE301-----------------------------
INT 1A - Disk Spool II v4.0x - GET SPOOL FILE STATUS
    AX = E301h
    ES:BX -> ASCIZ filename (max 32 chars)
Return: AH = status
        00h successful
        ES:SI -> spool file status record (see below)
        F0h not a spool file
        FFh failed
Note:    this function is also supported by Vertisoft's Emulaser utility ELSPL,
      as that is a licensed version of Disk Spool II
SeeAlso: AH=E0h,AX=E302h,AX=E401h

Format of spool file status record:
Offset    Size    Description
 00h    BYTE    hour of creation or last update
 01h    BYTE    minute of creation or last update
 02h    BYTE    year-1980 of creation or last update
 03h    BYTE    month of creation or last update
 04h    BYTE    day of creation or last update
 05h    BYTE    total number of copies to print
 06h    BYTE    number of copies already printed
 07h    BYTE    printer port (01h COM1, 02h COM2, 05h LPT1, 06h LPT2)
 08h    BYTE    save status (00h delete after printing, 01h save)
 09h    BYTE    file status
        01h done printing, but being saved
        02h on hold
        03h queued for printing
        04h being spooled
        05h being despooled (i.e. printed)
 0Ah 16 BYTEs    ASCIZ description
 1Ah  2 WORDs    file size in bytes (high,low)
 1Eh  2 WORDs    bytes left to print (high,low)
--------c-1AE302-----------------------------
INT 1A - Disk Spool II v4.0x - UPDATE SPOOL FILE
    AX = E302h
    ES:BX -> ASCIZ filename (max 32 chars)
    ES:SI -> spool file status record (see AX=E301h)
Return: AH = status
        00h successful
        F0h not a spool file
        FFh failed
Note:    this function is also supported by Vertisoft's Emulaser utility ELSPL,
      as that is a licensed version of Disk Spool II
SeeAlso: AH=E0h,AX=E301h,AX=E401h
--------c-1AE401-----------------------------
INT 1A - Disk Spool II v4.0x - SPOOL EXISTING FILE
    AX = E401h
    ES:BX -> ASCIZ filename (max 32 chars)
    CL = printer port (01h COM1, 02h COM2, 05h LPT1, 06h LPT2)
Return: AH = status
        00h successful
        FFh failed
Note:    this function is also supported by Vertisoft's Emulaser utility ELSPL,
      as that is a licensed version of Disk Spool II
SeeAlso: AH=E1h,AX=E302h,AX=E402h
--------c-1AE402-----------------------------
INT 1A U - Disk Spool II v4.0x - SPOOL EXISTING FILE???
    AX = E402h
    ES:BX -> ASCIZ filename (max 32 chars)
    CL = printer port (01h COM1, 02h COM2, 05h LPT1, 06h LPT2)
Return: AH = status
        00h successful
        FFh failed
Note:    this function is also supported by Vertisoft's Emulaser utility ELSPL,
      as that is a licensed version of Disk Spool II
SeeAlso: AH=E1h,AX=E302h,AX=E401h
--------c-1AE5-------------------------------
INT 1A U - Emulaser ELSPL.COM - ???
    AH = E5h
    ???
Return: ???
Program: ELSPL.COM is a licensed version of Disk Spool II which is distributed
      as part of Vertisoft's Emulaser PostScript emulator
SeeAlso: AH=A0h,INT 17/AH=03h
--------c-1AEE-------------------------------
INT 1A U - Disk Spool II v4.05 - ???
    AH = EEh
    AL = printer port???
    ???
Return: ???
Note:    this function is also supported by Vertisoft's Emulaser utility ELSPL,
      as that is a licensed version of Disk Spool II
SeeAlso: AH=E1h
--------U-1AF7-------------------------------
INT 1A - RighTime v1.1 - TEMPORARILY DISABLE
    AH = F7h
Program: RighTime is a TSR by G.T. Becker which continuously adjusts the system
      time to correct for clock drift
Note:    any AH value from F0h-F7h or F9h-FEh will perform this function in
      version 1.1, but F7h is the function called by transient portion
SeeAlso: AH=F8h,AH=FFh"RighTime"
--------U-1AF8-------------------------------
INT 1A - RighTime v1.1 - ENABLE
    AH = F8h
Program: RighTime is a TSR by G.T. Becker which continuously adjusts the system
      time to correct for clock drift
Note:    RighTime is TeSseRact-compatible (see INT 2F/AX=5453h) and modifies its
      TeSseRact program identifier based on its current state: "RighTime"
      when enabled, "RighTim"F7h when disabled.
SeeAlso: AH=F7h,AH=FFh"RighTime"
--------b-1AFE-------------------------------
INT 1A - AT&T 6300 - READ TIME AND DATE
    AH = FEh
Return: BX = day count (0 = Jan 1, 1984)
    CH = hour
    CL = minute
    DH = second
    DL = hundredths
SeeAlso: AX=CCCCh/BX=CCCCh,AH=FFh"AT&T",INT 21/AH=2Ah,INT 21/AH=2Ch
--------b-1AFF-------------------------------
INT 1A - AT&T 6300 - SET TIME AND DATE
    AH = FFh
    BX = day count (0 = Jan 1, 1984)
    CH = hour
    CL = minute
    DH = second
    DL = hundredths
Return: ???
SeeAlso: AX=CCCCh/BX=CCCCh,AH=FEh,INT 21/AH=2Bh,INT 21/AH=2Dh
--------U-1AFF-------------------------------
INT 1A - RighTime v1.1 - PERMANENTLY DISABLE
    AH = FFh
Program: RighTime is a TSR by G.T. Becker which continuously adjusts the system
      time to correct for clock drift
Note:    upon being permanently disabled, RighTime closes the file handle
      referencing its executable (which is updated with time correction
      information every two minutes while RighTime is enabled).
--------s-1AFF00-----------------------------
INT 1A - SND - INSTALLATION CHECK???
    AX = FF00h
Return: AL = version??? (02h)
    AH = busy flag (00h if not in a SND call, 01h if SND currently active)
Note:    the SND API is also supported by IC (Internal Commands) v2.0, a
      shareware TSR by Geoff Friesen which extends COMMAND.COM's internal
      command set
SeeAlso: AX=FF01h,AX=FF02h,AX=FF04h,AX=FF05h
--------s-1AFF01-----------------------------
INT 1A - SND - PAUSE
    AX = FF01h
    DX = number of clock ticks to delay
Return: AH = status
        00h successful
        01h SND busy
Notes:    if successful, execution returns to the caller after the delay expires;
      if SND is busy, execution returns immediately
    the IC v2.0 implementation of this API makes no special allowance for
      time rollover at midnight, which can cause the delay to be over one
      hour if this function is called just before the BIOS time count
      rolls over and the delay extends into the next day
SeeAlso: AX=FF00h,INT 15/AH=86h,INT 62/AX=0096h,INT 7F/AH=E8h,INT 80/BX=0009h
SeeAlso: INT E0/CL=BDh
--------s-1AFF02-----------------------------
INT 1A - SND - START SOUND
    AX = FF02h
    DX = frequency in Hertz (14h-FFFFh)
Return: AH = status
        00h successful
        01h SND busy
SeeAlso: AX=FF00h,AX=FF01h,AX=FF03h
--------s-1AFF03-----------------------------
INT 1A - SND - STOP SOUND
    AX = FF03h
Return: AH = status
        00h successful
        01h busy
Note:    turns off any sound currently being emitted by the PC's speaker unless
      SND is currently busy processing an API call (this includes
      background music).  Use AX=FF05h to stop the sound even if an API
      call is in progress.
SeeAlso: AX=FF00h,AX=FF02h,AX=FF05h
--------s-1AFF04-----------------------------
INT 1A - SND - PLAY MUSIC STRING IN BACKGROUND
    AX = FF04h
    DS:DX -> ASCIZ music string
Return: AH = status
        00h successful (music begins playing in background)
        01h busy
Note:    the music string accepted by SND is not the same as that accepted by
      BASIC and other programs which process music strings
SeeAlso: AX=FF00h,AX=FF05h,INT 80/BX=0006h
--------s-1AFF05-----------------------------
INT 1A - SND - UNCONDITIONALLY STOP SOUND
    AX = FF05h
Return: AH = 00h (successful)
Note:    this function is the same as AX=FF03h, but will stop the sound even if
      SND is currently busy, such as playing background music
SeeAlso: AX=FF00h,AX=FF03h,INT 80/BX=0007h
--------B-1B---------------------------------
INT 1B C - KEYBOARD - CONTROL-BREAK HANDLER
Desc:    this interrupt is automatically called when INT 09 determines that
      Control-Break has been pressed
Note:    normally points to a short routine in DOS which sets the Ctrl-C flag,
      thus invoking INT 23h the next time DOS checks for Ctrl-C.
SeeAlso: INT 23
--------B-1C---------------------------------
INT 1C - TIME - SYSTEM TIMER TICK
Desc:    this interrupt is automatically called on each clock tick by the INT 08
      handler
Notes:    this is the preferred interrupt to chain when a program needs to be
      invoked regularly
    not available on NEC 9800-series PCs
SeeAlso: INT 08
--------B-1D---------------------------------
INT 1D - SYSTEM DATA - VIDEO PARAMETER TABLES
Note:    default parameter table at F000h:F0A4h for 100% compatible BIOSes
SeeAlso: INT 10/AH=00h

Format of video parameters:
Offset    Size    Description
 00h 16 BYTEs    6845 register values for modes 00h and 01h
 10h 16 BYTEs    6845 register values for modes 02h and 03h
 20h 16 BYTEs    6845 register values for modes 04h and 05h
 30h 16 BYTEs    6845 register values for modes 06h and 07h
 40h    WORD    bytes in video buffer for modes 00h and 01h
 42h    WORD    bytes in video buffer for modes 02h and 03h
 44h    WORD    bytes in video buffer for modes 04h and 05h
 46h    WORD    bytes in video buffer for modes 06h and 07h
 48h  8 BYTEs    columns on screen for each of modes 00h through 07h
 50h  8 BYTEs    CRT controller mode bytes for each of modes 00h through 07h
--------B-1E---------------------------------
INT 1E - SYSTEM DATA - DISKETTE PARAMETERS
Note:    default parameter table at F000h:EFC7h for 100% compatible BIOSes
SeeAlso: INT 13/AH=0Fh,INT 41

Format of diskette parameter table:
Offset    Size    Description
 00h    BYTE    first specify byte
        bits 7-4: step rate
        bits 3-0: head unload time (0Fh = 240 ms)
 01h    BYTE    second specify byte
        bits 7-1: head load time (01h = 4 ms)
        bit    0: non-DMA mode (always 0)
 02h    BYTE    delay until motor turned off (in clock ticks)
 03h    BYTE    bytes per sector (00h = 128, 01h = 256, 02h = 512, 03h = 1024)
 04h    BYTE    sectors per track
 05h    BYTE    length of gap between sectors (2Ah for 5.25", 1Bh for 3.5")
 06h    BYTE    data length (ignored if bytes-per-sector field nonzero)
 07h    BYTE    gap length when formatting (50h for 5.25", 6Ch for 3.5")
 08h    BYTE    format filler byte (default F6h)
 09h    BYTE    head settle time in milliseconds
 0Ah    BYTE    motor start time in 1/8 seconds
--------B-1F---------------------------------
INT 1F - SYSTEM DATA - 8x8 GRAPHICS FONT
Desc:    this vector points at 1024 bytes of graphics data, 8 bytes for each
      character 80h-FFh
Note:    graphics data for characters 00h-7Fh stored at F000h:FA6Eh in 100%
      compatible BIOSes
SeeAlso: INT 10/AX=5000h,INT 43
--------O-20---------------------------------
INT 20 - Minix - SEND/RECEIVE MESSAGE
    AX = process ID of other process
    BX -> message
    CX = operation (1 send, 2 receive, 3 send&receive)
Program: Minix is a Version 7 Unix-compatible operating system by Andrew
      Tanenbaum
Note:    the message contains the system call number (numbered as in V7
      Unix(tm)) and the call parameters
--------D-20---------------------------------
INT 20 - DOS 1+ - TERMINATE PROGRAM
    CS = PSP segment
Return: never
Note:    (see INT 21/AH=00h)
SeeAlso: INT 21/AH=00h,INT 21/AH=4Ch
--------G-20---------------------------------
INT 20 - COMTROL HOSTESS i/ISA DEBUGGER - INVOKE FIRMWARE DEBUGGER
    ???
Return: ???
SeeAlso: INT 21"COMTROL"
--------G-21---------------------------------
INT 21 - COMTROL HOSTESS i/ISA DEBUGGER - GET SEGMENT FOR CONTROL PROGRAM USE
    ???
Return: AX = first segment available for control program use
SeeAlso: INT 20"COMTROL",INT 22"COMTROL"
--------D-2100-------------------------------
INT 21 - DOS 1+ - TERMINATE PROGRAM
    AH = 00h
    CS = PSP segment
Notes:    Microsoft recommends using INT 21/AH=4Ch for DOS 2+
    execution continues at the address stored in INT 22 after DOS performs
      whatever cleanup it needs to do
    if the PSP is its own parent, the process's memory is not freed; if
      INT 22 additionally points into the terminating program, the
      process is effectively NOT terminated
    not supported by MS Windows 3.0 DOSX.EXE DOS extender
SeeAlso: AH=26h,AH=31h,AH=4Ch,INT 20,INT 22
--------D-2101-------------------------------
INT 21 - DOS 1+ - READ CHARACTER FROM STANDARD INPUT, WITH ECHO
    AH = 01h
Return: AL = character read
Notes:    ^C/^Break are checked, and INT 23 executed if read
    character is echoed to standard output
    standard input is always the keyboard and standard output the screen
      under DOS 1.x, but they may be redirected under DOS 2+
SeeAlso: AH=06h,AH=07h,AH=08h,AH=0Ah
--------D-2102-------------------------------
INT 21 - DOS 1+ - WRITE CHARACTER TO STANDARD OUTPUT
    AH = 02h
    DL = character to write
Return: AL = last character output (despite the official docs which state
        nothing is returned) (at least DOS 3.3-5.0)
Notes:    ^C/^Break are checked, and INT 23 executed if pressed
    standard output is always the screen under DOS 1.x, but may be
      redirected under DOS 2+
    the last character output will be the character in DL unless DL=09h
      on entry, in which case AL=20h as tabs are expanded to blanks
SeeAlso: AH=06h,AH=09h
--------D-2103-------------------------------
INT 21 - DOS 1+ - READ CHARACTER FROM STDAUX
    AH = 03h
Return: AL = character read
Notes:    keyboard checked for ^C/^Break, and INT 23 executed if detected
    STDAUX is usually the first serial port
SeeAlso: AH=04h,INT 14/AH=02h,INT E0/CL=03h
--------D-2104-------------------------------
INT 21 - DOS 1+ - WRITE CHARACTER TO STDAUX
    AH = 04h
    DL = character to write
Notes:    keyboard checked for ^C/^Break, and INT 23 executed if detected
    STDAUX is usually the first serial port
    if STDAUX is busy, this function will wait until it becomes free
SeeAlso: AH=03h,INT 14/AH=01h,INT E0/CL=04h
--------D-2105-------------------------------
INT 21 - DOS 1+ - WRITE CHARACTER TO PRINTER
    AH = 05h
    DL = character to print
Notes:    keyboard checked for ^C/^Break, and INT 23 executed if detected
    STDPRN is usually the first parallel port, but may be redirected under
      DOS 2+
    if the printer is busy, this function will wait
SeeAlso: INT 17/AH=00h
--------D-2106-------------------------------
INT 21 - DOS 1+ - DIRECT CONSOLE OUTPUT
    AH = 06h
    DL = character (except FFh)
Return: AL = character output (despite official docs which state nothing is
        returned) (at least DOS 3.3-5.0)
Notes:    does not check ^C/^Break
    writes to standard output, which is always the screen under DOS 1.x,
      but may be redirected under DOS 2+
SeeAlso: AH=02h,AH=09h
--------D-2106--DLFF-------------------------
INT 21 - DOS 1+ - DIRECT CONSOLE INPUT
    AH = 06h
    DL = FFh
Return: ZF set if no character available
    ZF clear if character available
        AL = character read
Notes:    ^C/^Break are NOT checked
    if the returned character is 00h, the user pressed a key with an
      extended keycode, which will be returned by the next call of this
      function
    reads from standard input, which is always the keyboard under DOS 1.x,
      but may be redirected under DOS 2+
SeeAlso: AH=0Bh
--------D-2107-------------------------------
INT 21 - DOS 1+ - DIRECT CHARACTER INPUT, WITHOUT ECHO
    AH = 07h
Return: AL = character read from standard input
Notes:    does not check ^C/^Break
    standard input is always the keyboard under DOS 1.x, but may be
      redirected under DOS 2+
    if the interim console flag is set (see AX=6301h), partially-formed
      double-byte characters may be returned
SeeAlso: AH=01h,AH=06h,AH=08h,AH=0Ah
--------D-2108-------------------------------
INT 21 - DOS 1+ - CHARACTER INPUT WITHOUT ECHO
    AH = 08h
Return: AL = character read from standard input
Notes:    ^C/^Break are checked, and INT 23 executed if detected
    standard input is always the keyboard under DOS 1.x, but may be
      redirected under DOS 2+
    if the interim console flag is set (see AX=6301h), partially-formed
      double-byte characters may be returned
SeeAlso: AH=01h,AH=06h,AH=07h,AH=0Ah,AH=64h
--------D-2109-------------------------------
INT 21 - DOS 1+ - WRITE STRING TO STANDARD OUTPUT
    AH = 09h
    DS:DX -> '$'-terminated string
Return: AL = 24h (the '$' terminating the string, despite official docs which
        state that nothing is returned) (at least DOS 3.3-5.0)
Notes:    ^C/^Break are checked, and INT 23 is called if either pressed
    standard output is always the screen under DOS 1.x, but may be
      redirected under DOS 2+
    under the FlashTek X-32 DOS extender, the pointer is in DS:EDX
SeeAlso: AH=02h,AH=06h"OUTPUT"
--------D-210A-------------------------------
INT 21 - DOS 1+ - BUFFERED INPUT
    AH = 0Ah
    DS:DX -> buffer (see below)
Return: buffer filled with user input
Notes:    ^C/^Break are checked, and INT 23 is called if either detected
    reads from standard input, which may be redirected under DOS 2+
    if the maximum buffer size (see below) is set to 00h, this call returns
      immediately without reading any input
SeeAlso: AH=0Ch,INT 2F/AX=4810h

Format of input buffer:
Offset    Size    Description
 00h    BYTE    maximum characters buffer can hold
 01h    BYTE    (input) number of chars from last input which may be recalled
        (return) number of characters actually read, excluding CR
 02h  N BYTEs    actual characters read, including the final carriage return
--------K-210A00-----------------------------
INT 21 - WCED v1.6+ - INSTALLATION CHECK
    AX = 0A00h
    DS:DX -> 6-byte buffer whose first two bytes must be 00h
Return: buffer offset 02h-05h filled with "Wced" if installed
Program: WCED is a free command-line editor and history utility by Stuart
      Russell
SeeAlso: AH=FFh"CED"
--------D-210B-------------------------------
INT 21 - DOS 1+ - GET STDIN STATUS
    AH = 0Bh
Return: AL = 00h if no character available
       = FFh if character is available
Notes:    ^C/^Break are checked, and INT 23 is called if either pressed
    standard input is always the keyboard under DOS 1.x, but may be
      redirected under DOS 2+
    if the interim console flag is set (see AX=6301h), this function
      returns AL=FFh if a partially-formed double-byte character is
      available
SeeAlso: AH=06h"INPUT",AX=4406h
--------v-210B56-----------------------------
INT 21 - VIRUS - "Perfume" - INSTALLATION CHECK
    AX = 0B56h
Return: AX = 4952h if resident
SeeAlso: AX=0D20h
--------D-210C-------------------------------
INT 21 - DOS 1+ - FLUSH BUFFER AND READ STANDARD INPUT
    AH = 0Ch
    AL = STDIN input function to execute after flushing buffer
    other registers as appropriate for the input function
Return: as appropriate for the specified input function
Note:    if AL is not one of 01h,06h,07h,08h, or 0Ah, the buffer is flushed but
      no input is attempted
SeeAlso: AH=01h,AH=06h"INPUT",AH=07h,AH=08h,AH=0Ah
--------D-210D-------------------------------
INT 21 - DOS 1+ - DISK RESET
    AH = 0Dh
Notes:    writes all modified disk buffers to disk, but does not update directory
      information (that is only done when files are closed or a SYNC call
      is issued)
SeeAlso: AX=5D01h,INT 13/AH=00h,INT 2F/AX=1120h
--------v-210D20-----------------------------
INT 21 - VIRUS - "Crazy Imp" - INSTALLATION CHECK
    AX = 0D20h
Return: AX = 1971h if resident
SeeAlso: AX=0B56h,AH=30h/DX=ABCDh
--------D-210E-------------------------------
INT 21 - DOS 1+ - SELECT DEFAULT DRIVE
    AH = 0Eh
    DL = new default drive (00h = A:, 01h = B:, etc)
Return: AL = number of potentially valid drive letters
Notes:    under Novell NetWare, the return value is always 32, the number of
      drives that NetWare supports
    under DOS 3+, the return value is the greatest of 5, the value of
      LASTDRIVE= in CONFIG.SYS, and the number of drives actually present
    on a DOS 1.x/2.x single-floppy system, AL returns 2 since the floppy
      may be accessed as either A: or B:
    otherwise, the return value is the highest drive actually present
    DOS 1.x supports a maximum of 16 drives, 2.x a maximum of 63 drives,
      and 3+ a maximum of 26 drives
SeeAlso: AH=19h,AH=3Bh,AH=DBh
--------D-210F-------------------------------
INT 21 - DOS 1+ - OPEN FILE USING FCB
    AH = 0Fh
    DS:DX -> unopened File Control Block (see below)
Return: AL = status
        00h successful
        FFh file not found or access denied
Notes:    (DOS 3.1+) file opened for read/write in compatibility mode
    an unopened FCB has the drive, filename, and extension fields filled
      in and all other bytes cleared
    not supported by MS Windows 3.0 DOSX.EXE DOS extender
    DR-DOS checks password attached with AX=4303h
SeeAlso: AH=10h,AH=16h,AH=3Dh,4303h

Format of File Control Block:
Offset    Size    Description
 -7    BYTE    extended FCB if FFh
 -6   5 BYTEs    reserved
 -1    BYTE    file attribute if extended FCB
 00h    BYTE    drive number (0 = default, 1 = A, etc)
 01h  8 BYTEs    blank-padded file name
 09h  3 BYTEs    blank-padded file extension
 0Ch    WORD    current block number
 0Eh    WORD    logical record size
 10h    DWORD    file size
 14h    WORD    date of last write (see AX=5700h)
 16h    WORD    time of last write (see AX=5700h) (DOS 1.1+)
 18h  8 BYTEs    reserved (see below)
 20h    BYTE    record within current block
 21h    DWORD    random access record number (if record size is > 64 bytes, high
        byte is omitted)
Note:    to use an extended FCB, you must specify the address of the FFh flag at
      offset -7, rather than the address of the drive number field

Format of reserved field for DOS 1.0:
Offset    Size    Description
 16h    WORD    location in directory (if high byte = FFh, low byte is device
        ID)
 18h    WORD    number of first cluster in file
 1Ah    WORD    current absolute cluster number on disk
 1Ch    WORD    current relative cluster number within file
        (0 = first cluster of file, 1 = second cluster, etc.)
 1Eh    BYTE    dirty flag (00h = not dirty)
 1Fh    BYTE    unused

Format of reserved field for DOS 1.10-1.25:
Offset    Size    Description
 18h    BYTE    bit 7: set if logical device
        bit 6: not dirty
        bits 5-0: disk number or logical device ID
 19h    WORD    starting cluster number on disk
 1Bh    WORD    current absolute cluster number on disk
 1Dh    WORD    current relative cluster number within file
 1Fh    BYTE    unused

Format of reserved field for DOS 2.x:
Offset    Size    Description
 18h    BYTE    bit 7: set if logical device
        bit 6: set if open???
        bits 5-0: ???
 19h    WORD    starting cluster number on disk
 1Bh    WORD    ???
 1Dh    BYTE    ???
 1Eh    BYTE    ???
 1Fh    BYTE    ???

Format of reserved field for DOS 3.x:
Offset    Size    Description
 18h    BYTE    number of system file table entry for file
 19h    BYTE    attributes
        bits 7,6: 00 = SHARE.EXE not loaded, disk file
              01 = SHARE.EXE not loaded, character device
              10 = SHARE.EXE loaded, remote file
              11 = SHARE.EXE loaded, local file or device
        bits 5-0: low six bits of device attribute word
---SHARE.EXE loaded, local file---
 1Ah    WORD    starting cluster of file on disk
 1Ch    WORD    (DOS 3.x) offset within SHARE of sharing record (see AH=52h)
 1Eh    BYTE    file attribute
 1Fh    BYTE    ???
---SHARE.EXE loaded, remote file---
 1Ah    WORD    number of sector containing directory entry
 1Ch    WORD    relative cluster within file of last cluster accessed
 1Eh    BYTE    absolute cluster number of last cluster accessed
 1Fh    BYTE    ???
---SHARE.EXE not loaded---
 1Ah    BYTE    (low byte of device attribute word AND 0Ch) OR open mode
 1Bh    WORD    starting cluster of file
 1Dh    WORD    number of sector containing directory entry
 1Fh    BYTE    number of directory entry within sector
Note:    if FCB opened on character device, DWORD at 1Ah is set to the address
      of the device driver header, then the BYTE at 1Ah is overwritten.

Format of reserved field for DOS 5.0:
Offset    Size    Description
 18h    BYTE    number of system file table entry for file
 19h    BYTE    attributes
        bits 7,6: 00 = SHARE.EXE not loaded, disk file
              01 = SHARE.EXE not loaded, character device
              10 = SHARE.EXE loaded, remote file
              11 = SHARE.EXE loaded, local file or device
        bits 5-0: low six bits of device attribute word
---SHARE.EXE loaded, local file---
 1Ah    WORD    starting cluster of file on disk
 1Ch    WORD    unique sequence number of sharing record
 1Eh    BYTE    file attributes
 1Fh    BYTE    unused???
---SHARE.EXE loaded, remote file---
 1Ah    WORD    network handle
 1Ch    DWORD    network ID
---SHARE not loaded, local device---
 1Ah    DWORD    pointer to device driver header
 1Eh  2 BYTEs    unused???
---SHARE not loaded, local file---
 1Ah    BYTE    extra info
        bit 7: read-only attribute from SFT
        bit 6: archive attribute from SFT
        bits 5-0: high bits of sector number
 1Bh    WORD    starting cluster of file
 1Dh    WORD    low word of sector number containing directory entry
 1Fh    BYTE    number of directory entry within sector
--------D-2110-------------------------------
INT 21 - DOS 1+ - CLOSE FILE USING FCB
    AH = 10h
    DS:DX -> File Control Block (see AH=0Fh)
Return: AL = status
        00h successful
        FFh failed
Notes:    a successful close forces all disk buffers used by the file to be
      written and the directory entry to be updated
    not supported by MS Windows 3.0 DOSX.EXE DOS extender
SeeAlso: AH=0Fh,AH=16h,AH=3Eh
--------D-2111-------------------------------
INT 21 - DOS 1+ - FIND FIRST MATCHING FILE USING FCB
    AH = 11h
    DS:DX -> unopened FCB (see AH=0Fh), may contain '?' wildcards
Return: AL = status
        00h successful
        [DTA] unopened FCB for first matching file
        FFh no matching filename, or bad FCB
Notes:    the type of the returned FCB depends on whether the input FCB was a
      normal or an extended FCB
    the data returned in the DTA is actually the drive number (or extended
      FCB header and drive number) followed by the file's directory entry
      (see below); this format happens to be compatible with an unopened
      FCB
    for extended FCBs with search attribute 08h, the volume label (if any)
      will be returned even if the current directory is not the root dir.
    DOS 3+ also allows the '*' wildcard
    the search FCB must not be modified if AH=12h will be used to continue
      searching; DOS 3.3 has set the following parts of the FCB:
         0Ch    BYTE    ???
         0Dh    WORD    directory entry number of matching file
         0Fh    WORD    cluster number of current directory
         11h  4 BYTEs    ???
         15h    BYTE    drive number (1=A:)
    this function is used by many copy protection schemes to obtain the
      starting cluster of a file
SeeAlso: AH=12h,AH=1Ah,AH=4Eh,INT 2F/AX=111Bh

Format of directory entry:
Offset    Size    Description
 00h  8 BYTEs    blank-padded filename
 08h  3 BYTEs    blank-padded file extension
 0Bh    BYTE    attributes
 0Ch 10 BYTEs    reserved
        used by DR-DOS to store file password
 16h    WORD    time of creation or last update (see AX=5700h)
 18h    WORD    date of creation or last update (see AX=5700h)
 1Ah    WORD    starting cluster number
 1Ch    DWORD    file size
--------D-2112-------------------------------
INT 21 - DOS 1+ - FIND NEXT MATCHING FILE USING FCB
    AH = 12h
    DS:DX -> unopened FCB (see AH=0Fh)
Return: AL = status
        00h successful
        [DTA] = unopened FCB
        FFh no more matching filenames
Note:    (see AH=11h)
    assumes that successful FindFirst executed on search FCB before call
SeeAlso: AH=1Ah,AH=4Fh,INT 2F/AX=111Ch
--------D-2113-------------------------------
INT 21 - DOS 1+ - DELETE FILE USING FCB
    AH = 13h
    DS:DX -> unopened FCB (see AH=0Fh), filename filled with template for
        deletion ('?' wildcards allowed)
Return: AL = status
        00h one or more files successfully deleted
        FFh no matching files or all were read-only or locked
Notes:    DOS 1.25+ deletes everything in the current directory (including
      subdirectories) and sets the first byte of the name to 00h (entry
      never used) instead of E5h if called on an extended FCB with
      filename '???????????' and bits 0-4 of the attribute set (bits 1 and
      2 for DOS 1.x).  This may have originally been an optimization to
      minimize directory searching after a mass deletion (DOS 1.25+ stop
      the directory search upon encountering a never-used entry), but can
      corrupt the filesystem under DOS 2+ because subdirectories are
      removed without deleting the files they contain.
    currently-open files should not be deleted
    MS-DOS allows deletion of read-only files with an extended FCB, whereas
      Novell NetWare does not
SeeAlso: AH=41h,INT 2F/AX=1113h
--------D-2114-------------------------------
INT 21 - DOS 1+ - SEQUENTIAL READ FROM FCB FILE
    AH = 14h
    DS:DX -> opened FCB (see AH=0Fh)
Return: AL = status
        00h successful
        01h end of file (no data)
        02h segment wrap in DTA
        03h end of file, partial record read
    [DTA] = record read from file
Notes:    reads a record of the size specified in the FCB beginning at the
      current file position, then updates the current block and current
      record fields in the FCB
    if a partial record was read, it is zero-padded to the full size
    not supported by MS Windows 3.0 DOSX.EXE DOS extender
SeeAlso: AH=0Fh,AH=15h,AH=1Ah,AH=3Fh,INT 2F/AX=1108h
--------D-2115-------------------------------
INT 21 - DOS 1+ - SEQUENTIAL WRITE TO FCB FILE
    AH = 15h
    DS:DX -> opened FCB (see AH=0Fh)
    [DTA] = record to write
Return: AL = status
        00h successful
        01h disk full
        02h segment wrap in DTA
Notes:    writes a record of the size specified in the FCB beginning at the
      current file position, then updates the current block and current
      record fields in the FCB
    if less than a full sector is written, the data is placed in a DOS
      buffer to be written out at a later time
    not supported by MS Windows 3.0 DOSX.EXE DOS extender
SeeAlso: AH=0Fh,AH=14h,AH=1Ah,AH=40h,INT 2F/AX=1109h
--------D-2116-------------------------------
INT 21 - DOS 1+ - CREATE OR TRUNCATE FILE USING FCB
    AH = 16h
    DS:DX -> unopened FCB (see AH=0Fh), wildcards not allowed
Return: AL = status
        00h successful
        FFh directory full or file exists and is read-only or locked
Notes:    if file already exists, it is truncated to zero length
    if an extended FCB is used, the file is given the attribute in the
      FCB; this is how to create a volume label in the disk's root dir
    not supported by MS Windows 3.0 DOSX.EXE DOS extender
SeeAlso: AH=0Fh,AH=10h,AH=3Ch
--------D-2117-------------------------------
INT 21 - DOS 1+ - RENAME FILE USING FCB
    AH = 17h
    DS:DX -> modified FCB (see also AH=0Fh)
        the old filename ('?' wildcards OK) is in the standard location
        while the new filename ('?' wildcards OK) is stored in the 11
        bytes beginning at offset 11h
Return: AL = status
        00h successfully renamed
        FFh no matching files,file is read-only, or new name already exists
Notes:    subdirectories may be renamed using an extended FCB with the
      appropriate attribute, as may volume labels
    DR-DOS checks password attached with AX=4303h before permitting rename
SeeAlso: AH=0Fh,AH=13h,AX=4303h,AH=56h,INT 2F/AX=1111h
--------D-2118-------------------------------
INT 21 - DOS 1+ - NULL FUNCTION FOR CP/M COMPATIBILITY
    AH = 18h
Return: AL = 00h
Note:    corresponds to the CP/M BDOS function "get bit map of logged drives",
      which is meaningless under MS-DOS
SeeAlso: AH=1Dh,AH=1Eh,AH=20h,AX=4459h
--------D-2119-------------------------------
INT 21 - DOS 1+ - GET CURRENT DEFAULT DRIVE
    AH = 19h
Return: AL = drive (00h = A:, 01h = B:, etc)
Note:    Novell NetWare uses the fact that DOS 2.x COMMAND.COM issues this call
      from a particular location every time it starts a command to
      determine when to issue an automatic EOJ
SeeAlso: AH=0Eh,AH=47h,AH=BBh
--------D-211A-------------------------------
INT 21 - DOS 1+ - SET DISK TRANSFER AREA ADDRESS
    AH = 1Ah
    DS:DX -> Disk Transfer Area (DTA)
Notes:    the DTA is set to PSP:0080h when a program is started
    under the FlashTek X-32 DOS extender, the pointer is in DS:EDX
SeeAlso: AH=11h,AH=12h,AH=2Fh,AH=4Eh,AH=4Fh
--------D-211B-------------------------------
INT 21 - DOS 1+ - GET ALLOCATION INFORMATION FOR DEFAULT DRIVE
    AH = 1Bh
Return: AL = sectors per cluster (allocation unit)
    CX = bytes per sector
    DX = total number of clusters
    DS:BX -> media ID byte (see below)
Note:    under DOS 1.x, DS:BX points at an actual copy of the FAT; later
      versions return a pointer to a copy of the FAT's ID byte
SeeAlso: AH=1Ch,AH=36h

Values for media ID byte:
 FFh    floppy, double-sided, 8 sectors per track (320K)
 FEh    floppy, single-sided, 8 sectors per track (160K)
 FDh    floppy, double-sided, 9 sectors per track (360K)
 FCh    floppy, single-sided, 9 sectors per track (180K)
 F9h    floppy, double-sided, 15 sectors per track (1.2M)
 F8h    hard disk
 F0h    other
--------D-211C-------------------------------
INT 21 - DOS 1+ - GET ALLOCATION INFORMATION FOR SPECIFIC DRIVE
    AH = 1Ch
    DL = drive (00h = default, 01h = A:, etc)
Return: AL = sectors per cluster (allocation unit), or FFh if invalid drive
    CX = bytes per sector
    DX = total number of clusters
    DS:BX -> media ID byte (see AH=1Bh)
Notes:    under DOS 1.x, DS:BX points at an actual copy of the FAT; later
      versions return a pointer to a copy of the FAT's ID byte
    on a DBLSPACE drive, the total number of clusters is based on the
      estimated compression ratio
SeeAlso: AH=1Bh,AH=36h
--------D-211D-------------------------------
INT 21 - DOS 1+ - NULL FUNCTION FOR CP/M COMPATIBILITY
    AH = 1Dh
Return: AL = 00h
Note:    corresponds to the CP/M BDOS function "get bit map of read-only
      drives", which is meaningless under MS-DOS
SeeAlso: AH=18h,AH=1Eh,AH=20h,AX=4459h
--------D-211E-------------------------------
INT 21 - DOS 1+ - NULL FUNCTION FOR CP/M COMPATIBILITY
    AH = 1Eh
Return: AL = 00h
Note:    corresponds to the CP/M BDOS function "set file attributes" which was
     meaningless under MS-DOS 1.x
SeeAlso: AH=18h,AH=1Dh,AH=20h
--------D-211F-------------------------------
INT 21 - DOS 1+ - GET DRIVE PARAMETER BLOCK FOR DEFAULT DRIVE
    AH = 1Fh
Return: AL = status
        00h successful
        DS:BX -> Drive Parameter Block (DPB) (see below for DOS 1.x,
            AH=32h for DOS 2+)
        FFh invalid drive
Note:    this call was undocumented prior to the release of DOS 5.0; however,
      only the DOS 4+ version of the DPB has been documented
SeeAlso: AH=32h

Format of DOS 1.1 and MS-DOS 1.25 drive parameter block:
Offset    Size    Description
 00h    BYTE    sequential device ID
 01h    BYTE    logical drive number (0=A:)
 02h    WORD    bytes per sector
 04h    BYTE    highest sector number within a cluster
 05h    BYTE    shift count to convert clusters into sectors
 06h    WORD    starting sector number of first FAT
 08h    BYTE    number of copies of FAT
 09h    WORD    number of directory entries
 0Bh    WORD    number of first data sector
 0Dh    WORD    highest cluster number (number of data clusters + 1)
 0Fh    BYTE    sectors per FAT
 10h    WORD    starting sector of directory
 12h    WORD    address of allocation table
Note:    the DOS 1.0 table is the same except that the first and last fields
      are missing; see INT 21/AH=32h for the DOS 2+ version
--------D-2120-------------------------------
INT 21 - DOS 1+ - NULL FUNCTION FOR CP/M COMPATIBILITY
    AH = 20h
Return: AL = 00h
Note:    corresponds to the CP/M BDOS function "get/set default user
      (sublibrary) number", which is meaningless under MS-DOS
SeeAlso: AH=18h,AH=1Dh,AH=1Eh,AX=4459h
--------D-2121-------------------------------
INT 21 - DOS 1+ - READ RANDOM RECORD FROM FCB FILE
    AH = 21h
    DS:DX -> opened FCB (see AH=0Fh)
Return: AL = status
        00h successful
        01h end of file, no data read
        02h segment wrap in DTA, no data read
        03h end of file, partial record read
    [DTA] = record read from file
Notes:    the record is read from the current file position as specified by the
      random record and record size fields of the FCB
    the file position is not updated after reading the record
    if a partial record is read, it is zero-padded to the full size
    not supported by MS Windows 3.0 DOSX.EXE DOS extender
SeeAlso: AH=14h,AH=22h,AH=27h,AH=3Fh
--------D-2122-------------------------------
INT 21 - DOS 1+ - WRITE RANDOM RECORD TO FCB FILE
    AH = 22h
    DS:DX -> opened FCB (see AH=0Fh)
    [DTA] = record to write
Return: AL = status
        00h successful
        01h disk full
        02h segment wrap in DTA
Notes:    the record is written to the current file position as specified by the
      random record and record size fields of the FCB
    the file position is not updated after writing the record
    if the record is located beyond the end of the file, the file is
      extended but the intervening data remains uninitialized
    if the record only partially fills a disk sector, it is copied to a
      DOS disk buffer to be written out to disk at a later time
    not supported by MS Windows 3.0 DOSX.EXE DOS extender
SeeAlso: AH=15h,AH=21h,AH=28h,AH=40h
--------D-2123-------------------------------
INT 21 - DOS 1+ - GET FILE SIZE FOR FCB
    AH = 23h
    DS:DX -> unopened FCB (see AH=0Fh), wildcards not allowed
Return: AL = status
        00h successful (matching file found)
        FCB random record field filled with size in records, rounded up
        to next full record
        FFh failed (no matching file found)
Notes:    not supported by MS Windows 3.0 DOSX.EXE DOS extender
    MS-DOS returns nonsense is the FCB record number field is set to a very
      large positive number, and status FFh if negative; DR-DOS returns the
      correct file size in both cases
SeeAlso: AH=42h
--------D-2124-------------------------------
INT 21 - DOS 1+ - SET RANDOM RECORD NUMBER FOR FCB
    AH = 24h
    DS:DX -> opened FCB (see AH=0Fh)
Notes:    computes the random record number corresponding to the current record
      number and record size, then stores the result in the FCB
    normally used when switching from sequential to random access
    not supported by MS Windows 3.0 DOSX.EXE DOS extender
SeeAlso: AH=21h,AH=27h,AH=42h
--------D-2125-------------------------------
INT 21 - DOS 1+ - SET INTERRUPT VECTOR
    AH = 25h
    AL = interrupt number
    DS:DX -> new interrupt handler
Notes:    this function is preferred over direct modification of the interrupt
      vector table
    some DOS extenders place an API on this function, as it is not
      directly meaningful in protected mode
    under DR-DOS 5.0+, this function does not use any of the DOS-internal
      stacks and may thus be called at any time
    Novell NetWare (except the new DOS Requester) monitors the offset of
      any INT 24 set, and if equal to the value at startup, substitutes
      its own handler to allow handling of network errors; this introduces
      the potential bug that any program whose INT 24 handler offset
      happens to be the same as COMMAND.COM's will not have its INT 24
      handler installed
SeeAlso: AX=2501h,AH=35h
--------E-212501-----------------------------
INT 21 P - Phar Lap 386/DOS-Extender - RESET DOS EXTENDER DATA STRUCTURES
    AX = 2501h
    SS = application's original SS or DS (FlashTek X-32VM)
Return: CF clear if successful
    CF set on error
        caller is operating on X-32 stack (FlashTek X-32VM)
Notes:    Phar Lap uses INT 21/AH=25h as the entry point for all 386/DOS-Extender
      system calls.     Only available when directly using 386/DOS-Extender or
      a compatible DOS extender, or when using a product that was created
      using 386-DOS/Extender or a compatible
    this function is also supported by FlashTek X-32VM
SeeAlso: AH=30h"Phar Lap"
--------E-212502-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - GET PROTECTED-MODE INTERRUPT VECTOR
    AX = 2502h
    CL = interrupt number
Return: CF clear
    ES:EBX = CS:EIP of protected-mode interrupt handler
Note:    this function is also supported by FlashTek X-32VM
SeeAlso: AX=2503h,AX=2504h,INT 31/AX=0204h
--------E-212503-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - GET REAL-MODE INTERRUPT VECTOR
    AX = 2503h
    CL = interrupt number
Return: CF clear
    EBX = CS:IP of real-mode interrupt handler
Note:    this function is also supported by FlashTek X-32VM
SeeAlso: AX=2502h,AX=2504h,AH=35h,INT 31/AX=0200h
--------E-212504-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - SET PROTECTED-MODE INTERRUPT VECTOR
    AX = 2504h
    CL = interrupt number
    DS:EDX = CS:EIP of protected-mode interrupt handler
Return: CF clear
Note:    this function is also supported by FlashTek X-32VM
SeeAlso: AX=2502h,AX=2505h,INT 31/AX=0205h
--------E-212505-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - SET REAL-MODE INTERRUPT VECTOR
    AX = 2505h
    CL = interrupt number
    EBX = CS:IP of real-mode interrupt handler
Return: CF clear
Note:    this function is also supported by FlashTek X-32VM
SeeAlso: AX=2503h,AX=2504h,INT 31/AX=0201h
--------E-212506-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - SET INT TO ALWAYS GAIN CONTRL IN PROT MODE
    AX = 2506h
    CL = interrupt number
    DS:EDX = CS:EIP of protected-mode interrupt handler
Return: CF clear
Notes:    this function modifies both the real-mode low-memory interrupt
      vector table and the protected-mode Interrupt Descriptor Table (IDT)
    interrupts occurring in real mode are resignaled in protected mode
    this function is also supported by FlashTek X-32VM
--------E-212507-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - SET REAL- & PROTECTED-MODE INT VECTORS
    AX = 2507h
    CL = interrupt numbern
    DS:EDX = CS:EIP of protected-mode interrupt handler
    EBX = CS:IP of real-mode interrupt handler
Return: CF clear
Notes:    interrupts are disabled until both vectors have been modified
    this function is also supported by FlashTek X-32VM
SeeAlso: AX=2504h,AX=2505h
--------E-212508-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - GET SEGMENT LINEAR BASE ADDRESS
    AX = 2508h
    BX = segment selector
Return: CF clear if successful
        ECX = linear base address of segment
    CF set if invalid segment selector
Note:    this function is also supported by FlashTek X-32VM
SeeAlso: AX=2509h
--------E-212509-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - CONVERT LINEAR TO PHYSICAL ADDRESS
    AX = 2509h
    EBX = linear address to convert
Return: CF clear if successful
        ECX = physical address (carry flag clear)
    CF set if linear address not mapped in page tables
SeeAlso: AX=2508h
--------E-212509-----------------------------
INT 21 - FlashTek X-32VM - GET SYSTEM SEGMENTS AND SELECTORS
    AX = 2509h
Return: CF clear
    EAX high word = default DS
    AX = alias for 16-bit data segment
    BX = real mode code segment
    EDX high word = selector covering full 4GB address space
    DX = default SS
    ESI high word = PSP selector
    SI = environment selector
--------E-21250A-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - MAP PHYSICAL MEMORY AT END OF SEGMENT
    AX = 250Ah
    ES = segment selector in the Local Descriptor Table (LDT) of segment
         to modify
    EBX = physical base address of memory to map (multiple of 4K)
    ECX = number of physical 4K pages to map
Return: CF clear if successful
        EAX = 32-bit offset in segment of mapped memory
    CF set on error
        EAX = error code
        08h insufficient memory to create page tables
        09h invalid segment selector
SeeAlso: INT 31/AX=0800h
--------E-21250C-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - GET HARDWARE INTERRUPT VECTORS
    AX = 250Ch
Return: CF clear
    AL = base interrupt vector for IRQ0-IRQ7
    AH = base interrupt vector for IRQ8-IRQ15
    BL = interrupt vector for BIOS print screen function (Phar Lap only)
Note:    this function is also supported by FlashTek X-32VM
SeeAlso: INT 31/AX=0400h,INT 67/AX=DE0Ah
--------E-21250D-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - GET REAL-MODE LINK INFORMATION
    AX = 250Dh
Return: CF clear
    EAX = CS:IP of real-mode callback procedure that will call through
        from real mode to a protected-mode routine
    EBX = 32-bit real-mode address of intermode call data buffer
    ECX = size in bytes of intermode call data buffer
    ES:EDX = protected-mode address of intermode call data buffer
Notes:    this function is also supported by FlashTek X-32VM
    X-32VM guarantees the intermode buffer to be at least 4 KB
SeeAlso: AX=250Eh

Call real-mode callback with:
    STACK:    DWORD    offset to protected-mode code
        WORD    placeholder for protected-mode CS
        DWORD    pointer to selector structure (see below)
            or 0000h:0000h for defaults
        var    parameters for protected-mode procedure
Return: via FAR return

Format of selector structure:
Offset    Size    Description
 00h    WORD    protected-mode GS selector
 02h    WORD    protected-mode FS selector
 04h    WORD    protected-mode ES selector
 06h    WORD    protected-mode DS selector
--------E-21250E-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - CALL REAL-MODE PROCEDURE
    AX = 250Eh
    EBX = CS:IP of real-mode procedure to call
    ECX = number of two-byte words to copy from protected-mode stack
          to real-mode stack
Return: CF clear if successful
        all segment registers unchanged
        all general registers contain values set by real-mode procedure
        all other flags set as they were left by real-mode procedure
        stack unchanged
    CF set on error
        EAX = error code
        01h not enough real-mode stack space
Note:    this function is also supported by FlashTek X-32VM; under X-32VM, the
      call will fail if ECX > 0000003Fh
SeeAlso: AX=250Dh,AX=2510h,AH=E1h"OS/286",INT 31/AX=0301h
--------E-21250F-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - CONVERT PROTECTED-MODE ADDRESS TO MS-DOS
    AX = 250Fh
    ES:EBX = 48-bit protected-mode address to convert
Return: CF clear if successful (address < 1MB)
        ECX = 32-bit real-mode MS-DOS address
    CF set on error (address >= 1MB)
        ECX = linear address
Note:    this function is also supported by FlashTek X-32VM
SeeAlso: AX=2510h
--------E-212510-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - CALL REAL-MODE PROCEDURE, REGISTERS
    AX = 2510h
    EBX = CS:IP of real-mode procedure to call
    ECX = number of two-byte words to copy to protected-mode stack to
          real-mode stack
    DS:EDX -> pointer to parameter block (see below)
Return: CF clear if successful
        all segment registers unchanged,
        EDX unchanged
        all other general registers contain values set by real-mode proc
        all other flags are set as they were left by real-mode procedure
        real-mode register values are returned in the parameter block
    CF set on error
        EAX = error code
        01h not enough real-mode stack space
Note:    unlike most of the preceding 25xxh functions, this one is not
      supported by FlashTek X-32VM
SeeAlso: AX=250Eh,AX=250Fh

Format of parameter block:
Offset    Size    Description
 00h    WORD    real-mode DS value
 02h    WORD    real-mode ES value
 04h    WORD    real-mode FS value
 06h    WORD    real-mode GS value
 08h    DWORD    real-mode EAX value
 0Ch    DWORD    real-mode EBX value
 10h    DWORD    real-mode ECX value
 14h    DWORD    real-mode EDX value
--------E-212511-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - ISSUE REAL-MODE INTERRUPT
    AX = 2511h
    DS:EDX -> parameter block (see below)
Return: all segment registers unchanged
    EDX unchanged
    all other registers contain values set by the real-mode int handler
    the flags are set as they were left by the real-mode interrupt handler
    real-mode register values are returned in the parameter block
Note:    this function is also supported by FlashTek X-32VM
SeeAlso: AX=2503h,AX=2505h,AX=250Eh,AH=E3h"OS/286",INT 31/AX=0300h

Format of parameter block:
Offset    Size    Description
 00h    WORD    interrupt number
 02h    WORD    real-mode DS value
 04h    WORD    real-mode ES value
 06h    WORD    real-mode FS value
 08h    WORD    real-mode GS value
 0Ah    DWORD    real-mode EAX value
 0Eh    DWORD    real-mode EDX value
Note: all other real-mode values set from protected-mode registers
--------E-212512-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - LOAD PROGRAM FOR DEBUGGING
    AX = 2512h
    DS:EDX -> pointer to ASCIIZ program name
    ES:EBX -> pointer to parameter block (see below)
    ECX = size in bytes of LDT buffer
Return: CF clear if successful
        EAX = number of segment descriptors in LDT
    CF set on error
        EAX = error code
        02h file not found or path invalid
        05h access denied
        08h insufficient memory
        0Ah environment invalid
        0Bh invalid file format
        80h LDT too small

Format of parameter block:
Offset    Size    Description
Input:
 00h    DWORD    32-bit offset of environment string
 04h    WORD    segment of environment string
 06h    DWORD    32-bit offset of command-tail string
 0Ah    WORD    segment of command-tail string
 0Ch    DWORD    32-bit offset of LDT buffer (size in ECX)
 10h    WORD    segment of LDT buffer
Output:
 12h    WORD    real-mode paragraph address of PSP (see also AH=26h)
 14h    WORD    real/protected mode flag
        0000h  real mode
        0001h  protected mode
 16h    DWORD    initial EIP value
 1Ah    WORD    initial CS value
 1Ch    DWORD    initial ESP value
 20h    WORD    initial SS value
 22h    WORD    initial DS value
 24h    WORD    initial ES value
 26h    WORD    initial FS value
 28h    WORD    initial GS value
--------E-212513-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - ALIAS SEGMENT DESCRIPTOR
    AX = 2513h
    BX = segment selector of descriptor in GDT or LDT
    CL = access-rights byte for alias descriptor
    CH = use-type bit (USE16 or USE32) for alias descriptor
Return: CF clear if successful
        AX = segment selector for created alias
    CF set on error
        EAX = error code
        08h insufficient memory (can't grow LDT)
        09h invalid segment selector in BX
--------E-212514-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - CHANGE SEGMENT ATTRIBUTES
    AX = 2514h
    BX = segment selector of descriptor in GDT or LDT
    CL = new access-rights byte
    CH = new use-type bit (USE16 or USE32)
Return: CF clear if successful
    CF set on error
        EAX = error code
        09h invalid selector in BX
SeeAlso: AX=2515h,INT 31/AX=0009h
--------E-212515-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - GET SEGMENT ATTRIBUTES
    AX = 2515h
    BX = segment selector of descriptor in GDT or LDT
Return: CF clear if successful
        CL = access-rights byte for segment
        CH = use-type bit (USE16 or USE32)
    ECX<16-31> destroyed
    CF set on error
        EAX = error code
        09h invalid segment selector in BX
SeeAlso: AX=2514h
--------E-212516-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - FREE ALL MEMORY OWNED BY LDT
    AX = 2516h
    ???
Return: ???
--------E-212517-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - GET INFO ON DOS DATA BUFFER
    AX = 2517h
    ???
Return: ???
--------E-212518-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - SPECIFY HANDLER FOR MOVED SEGMENTS
    AX = 2518h
    ???
Return: ???
--------E-212519-----------------------------
INT 21 - Phar Lap 386/DOS-Extender VMM - GET ADDITIONAL MEMORY ERROR INFO
    AX = 2519h
Return: CF clear
    EAX = error code
        0000h  no error
        0001h  out of physical memory
        0002h  out of swap space (unable to grow swap file)
        0003h  out of LDT entries and unable to grow LDT
        0004h  unable to change extended memory allocation mark
        FFFFFFFFh    paging disabled
Note:    VMM is the Virtual Memory Manager option
--------E-21251A-----------------------------
INT 21 - Phar Lap 386/DOS-Extender VMM - LOCK PAGES IN MEMORY
    AX = 251Ah
    EDX = number of 4k pages to lock
    if BL = 00h
        ECX = linear address of first page to lock
    if BL = 01h
        ES:ECX -> pointer to first page to lock
Return: CF clear if successful
    CF set on error
        EAX = error code
        08h insufficient memory
        09h invalid address range
SeeAlso: AX=251Bh,AX=EB06h,INT 31/AX=0600h
--------E-21251B-----------------------------
INT 21 - Phar Lap 386/DOS-Extender VMM - UNLOCK PAGES
    AX = 251Bh
    EDX = number of pages to unlock
    if BL = 00h
        ECX = linear address of first page to unlock
    if BL = 01h
        ES:ECX -> pointer to first page to unlock
Return: CF clear if successful
    CF set on error
        EAX = error code
        09h invalid address range
SeeAlso: AX=251Ah,AX=EB07h,INT 31/AX=0601h
--------E-21251D-----------------------------
INT 21 - Phar Lap 386/DOS-Extender VMM - READ PAGE-TABLE ENTRY
    AX = 251Dh
    ???
Return: ???
SeeAlso: AX=251Eh,AX=EB00h,INT 31/AX=0506h
--------E-21251E-----------------------------
INT 21 - Phar Lap 386/DOS-Extender VMM - WRITE PAGE-TABLE ENTRY
    AX = 251Eh
    ???
Return: ???
SeeAlso: AX=251Dh,INT 31/AX=0507h
--------E-21251F-----------------------------
INT 21 - Phar Lap 386/DOS-Extender VMM - EXHANGE TWO PAGE-TABLE ENTRIES
    AX = 251Fh
    ???
Return: ???
SeeAlso: AX=251Dh,AX=251Eh
--------E-212520-----------------------------
INT 21 - Phar Lap 386/DOS-Extender VMM - GET MEMORY STATISTICS
    AX = 2520h
    DS:EDX -> pointer to buffer at least 100 bytes in size (see below)
    BL = 0 (don't reset VM stats), 1 (reset VM stats)
Return: carry flag clear

Format of VM stats buffer:
Offset    Size    Description
 00h    DWORD    VM status
        0001h VM subsystem is present
        0000h VM not present
 04h    DWORD    "nconvpg" number of conventional memory pages available
 08h    DWORD    "nbimpg" number of Compaq built-in memory pages available
 0Ch    DWORD    "nextpg" total number of extended memory pages
 10h    DWORD    "extlim" extender memory pages limit
 14h    DWORD    "aphyspg" number of physical memory pages allocated to appl
 18h    DWORD    "alockpg" number of locked pages owned by application
 1Ch    DWORD    "sysphyspg" number physical memory pages allocated to system
 20h    DWORD    "nfreepg" number of free physical pages; approx if EMS VCPI
 24h    DWORD    linear address of beginning of application address space
 28h    DWORD    linear address of end of application address space
 2Ch    DWORD    number of seconds since last time VM stats were reset
 30h    DWORD    number of page faults since last time
 34h    DWORD    number of pages written to swap file since last time
 38h    DWORD    number of reclaimed pages (page faults on swapped pages)
 3Ch    DWORD    number of virtual pages allocated to the application
 40h    DWORD    size in pages of swap file
 44h    DWORD    number of system pages allocated with EMS calls
 48h    DWORD    minimum number of conventional memory pages
 4Ch    DWORD    maximum size in bytes to which swap file can be increased
 50h    DWORD    "vmflags" bit 0 = 1 if page fault in progress
---v4.0+ ---
 54h  8 BYTEs    ???
 5Ch    DWORD    size in pages of largest free block of memory (including disk
        swap space)
 60h  4 BYTEs    ???
--------E-212521-----------------------------
INT 21 - Phar Lap 386/DOS-Extender VMM - LIMIT PROGRAM'S EXTENDED MEMORY USAGE
    AX = 2521h
    EBX = max 4k pages of physical extended memory which program may use
Return: CF clear if successful
       EBX = maximum limit in pages
       ECX = minimum limit in pages
    CF set on error
        EAX = error code
        08h insufficient memory or -nopage switch used
SeeAlso: AX=2522h
--------E-212522-----------------------------
INT 21 - Phar Lap 386/DOS-Extender VMM - SPECIFY ALTERNATE PAGE-FAULT HANDLER
    AX = 2522h
    ???
Return: ???
SeeAlso: AX=2523h
--------E-212523-----------------------------
INT 21 - Phar Lap 386/DOS-Extender VMM - SPECIFY OUT-OF-SWAP-SPACE HANDLER
    AX = 2523h
    ???
Return: ???
SeeAlso: AX=2522h
--------E-212524-----------------------------
INT 21 - Phar Lap 386/DOS-Extender VMM - INSTALL PAGE-REPLACEMENT HANDLERS
    AX = 2524h
    ???
Return: ???
--------E-212525-----------------------------
INT 21 - Phar Lap 386/DOS-Extender VMM - LIMIT PROGRAM'S CONVENTIONAL MEM USAGE
    AX = 2525h
    EBX = limit in 4k pages of physical conventional memory which program
          may use
Return: CF clear if successful
        EBX = maximum limit in pages
        ECX = minimum limit in pages
    CF set on error
        EAX = error code
        08h insufficient memory or -nopage switch used
SeeAlso: AX=2521h
--------E-212526-----------------------------C33!
INT 21 - Phar Lap 386/DOS-Extender - GET CONFIGURATION INFORMATION
    AX = 2526h
    ???
Return: ???
Note:    details not available at this time

Format of configuration buffer:
Offset    Size    Description
 00h    DWORD    flags 1
        bit 24: set if -NESTDPMI specified
        bit 25: set if -NONESTDPMI specified
        bit 26: set if -NODPMI specified
        bit 27: set if -NOPCDWEITEK specified
--------E-212529-----------------------------C33!
INT 21 - Phar Lap 386/DOS-Extender - LOAD FLAT MODEL .EXP or .REX FILE
    AX = 2529h
    ???
Return: ES:EBX -> parameter block
    ???
Note:    details not available at this time

Format of parameter block:
Offset    Size    Description
 00h 28 BYTEs    ???
 1Ch    DWORD    flags
        bit 0: child linked with -UNPRIVILEGED
        bits 1-31 reserved
--------E-21252B-----------------------------
INT 21 - FlashTek X-32VM - VIRTUAL MEMORY MANAGEMENT - PAGE LOCKING
    AX = 252Bh
    BH = function
        05h lock pages
        06h unlock pages
    BL = address type
        00h linear address
        ECX = linear start address of memory region
        01h segmented address
        ES:ECX -> start of memory region
    EDX = size of memory region in bytes
Return: CF clear if successful
    CF set on error
Note:    if X-32 is not using virtual memory, this function always succeeds
--------E-21252BBH09-------------------------C33!
INT 21 - Phar Lap 386/DOS-Extender v4.1 - GET PAGE TABLE ENTRY/PAGE TABLE INFO
    AX = 252Bh
    BH = 09h
    BL = subfunction
        00h get page table entry by linear address
        ECX = linear address for which to get page table entry
        01h get page table entry by logical address
        ES:ECX = address for which to get page table entry
Return: CF clear if successful
        EAX = page table entry
        EBX = additional page table information
    CF set on error
        EAX = error code
        0009h invalid address
        0082h running under DPMI
SeeAlso: AX=252Bh/BH=0Ah
--------E-21252BBH0A-------------------------C33!
INT 21 - Phar Lap 386/DOS-Extender v4.1 - SET PAGE TABLE ENTRY/PAGE TABLE INFO
    AX = 252Bh
    BH = 0Ah
    BL = subfunction
        00h set page table entry for linear address
        ECX = linear address for which to get page table entry
        01h set page table entry for logical address
        ES:ECX = address for which to get page table entry
    ESI = page table entry
    EDI = additional page table information
Return: CF clear if successful
    CF set on error
        EAX = error code
        0009h invalid address
        0082h running under DPMI
SeeAlso: AX=252Bh/BH=09h
--------E-21252BBH0B-------------------------C33!
INT 21 - Phar Lap 386/DOS-Extender v4.1 - MAP DATA FILE AT FILE OFFSET
    AX = 252Bh
    BH = 0Bh
    BL = subfunction
        00h by linear address
        ECX = linear address at which to map data file
        01h by logical address
        ES:ECX = logical address at which to map data file
    EDX = number of bytes to map
    DS:ESI -> mapping structure (see below)
    DS:EDI -> ASCIZ filename
Return: CF clear if successful
    CF set on error
        EAX = error code
        0002h file error
            ECX = phase (01h opening file, 02h seeking, 03h reading)
            EDX = error code returned by DOS
        0009h invalid address
        0081h invalid parameters or 386|VMM not present
        0086h all 386|VMM file handles already in use
SeeAlso: AX=252Bh/BH=09h

Format of mapping structure:
Offset    Size    Description
 00h    DWORD    starting file offset to be mapped
 04h    DWORD    DOS file access and sharing modes (see INT 21/AH=3Dh)
--------E-212532-----------------------------
INT 21 - FlashTek X-32VM - GET EXCEPTION HANDLER VECTOR
    AX = 2532h
    CL = exception number (00h-0Fh)
Return: CF clear if successful
        ES:EBX = CS:EIP of current exception handler
    CF set on error (CL > 0Fh)
SeeAlso: AX=2533h
--------E-212533-----------------------------
INT 21 - FlashTek X-32VM - SET EXCEPTION HANDLER VECTOR
    AX = 2533h
    CL = exception number (00h-0Fh)
    DS:EDX = CS:EIP of new exception handler
Return: CF clear if successful
    CF set on error (CL > 0Fh)
SeeAlso: AX=2532h
--------E-212534-----------------------------C33!
INT 21 - Phar Lap 386/DOS-Extender v4.0+ - GET INTERRUPT FLAG
    AX = 2534h
    ???
Return: ???
Note:    details not available at this time
--------E-212535-----------------------------C33!
INT 21 - Phar Lap 386/DOS-Extender v4.0+ - READ/WRITE SYSTEM REGISTERS
    AX = 2535h
    ???
Return: ???
Notes:    only available under MS Windows if PHARLAP.386 VDD is installed
    details not available at this time
--------E-21253C-----------------------------C33!
INT 21 - Phar Lap 386/DOS-Extender v4.0+ - SHRINK 386|VMM SWAP FILE
    AX = 253Ch
    ???
Return: ???
Note:    details not available at this time
--------E-2F253D-----------------------------C33!
INT 2F - Phar Lap 386/DOS-Extender v4.0+ - READ/WRITE IDT DESCRIPTOR
    AX = 253Dh
    BL = interrupt number
    ECX = direction (0 = read, 1 = write)
    DS:EDX -> 8-byte buffer for descriptor
Return: CF clear if successful
        DS:EDX filled if reading
    CF set on error
        EAX = error code (0082h if running under DPMI)
Desc:    access hardware-level IDT rather than the internal 386/DOS-Extender
      shadow IDT
Notes:    this call will always fail under DPMI because it is not possible to
      access the IDT
    the descriptor is not checked when writing
    this call can normally be used only by programs running in ring 0
      because the processor does not allow an interrupt to be vectored to
      a less privileged ring
--------E-2125C0-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - ALLOCATE MS-DOS MEMORY BLOCK
    AX = 25C0h
    BX = number of 16-byte paragraphs of MS-DOS memory requested
Return: CF clear if successful
        AX = real-mode paragraph address of memory
    CF set on error
        AX = error code
        07h MS-DOS memory control blocks destroyed
        08h insufficient memory
        BX = size in paragraphs of largest available memory block
SeeAlso: AX=25C1h,AX=25C2h
--------E-2125C1-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - RELEASE MS-DOS MEMORY BLOCK
    AX = 25C1h
    CX = real-mode paragraph address of memory block to free
Return: CF clear if successful
        EAX destroyed
    CF set on error
        AX = error code
        07h MS-DOS memory control blocks destroyed
        09h invalid memory block address in CX
SeeAlso: AX=25C0h,AX=25C2h
--------E-2125C2-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - MODIFY MS-DOS MEMORY BLOCK
    AX = 25C2h
    BX = new requested block size in paragraphs
    CX = real-mode paragraph address of memory block to modify
Return: CF clear if successful
        EAX destroyed
    CF set on error
        AX = error code
        07h MS-DOS memory control blocks destroyed
        08h insufficient memory
        09h invalid memory block address in CX
        BX = size in paragraphs of largest available memory block
SeeAlso: AX=25C0h,AX=25C1h
--------E-2125C3-----------------------------
INT 21 - Phar Lap 386/DOS-Extender - EXECUTE PROGRAM
    AX = 25C3h
    ES:EBX -> pointer to parameter block (see below)
    DS:EDX -> pointer to ASCIIZ program filename
Return: CF clear if successful
        all registers unchanged
    CF set on error
        EAX = error code
        01h function code in AL is invalid ???
        02h file not found or path invalid
        05h access denied
        08h insufficient memory to load program
        0Ah environment invalid
        0Bh invalid file format

Format of parameter block:
Offset    Size    Description
 00h    DWORD    32-bit offset of environment string
 04h    WORD    segment selector of environment string
 06h    DWORD    32-bit offset of command-tail string
 0Ah    WORD    segment selector of command-tail string
--------D-2126-------------------------------
INT 21 - DOS 1+ - CREATE NEW PROGRAM SEGMENT PREFIX
    AH = 26h
    DX = segment at which to create PSP (see below)
Notes:    new PSP is updated with memory size information; INTs 22h, 23h, 24h
      taken from interrupt vector table
    (DOS 2+) DOS assumes that the caller's CS is the segment of the PSP to
      copy
SeeAlso: AH=4Bh,AH=50h,AH=51h,AH=55h,AH=62h,AH=67h

Format of PSP:
Offset    Size    Description
 00h  2 BYTEs    INT 20 instruction for CP/M CALL 0 program termination
        the CDh 20h here is often used as a signature for a valid PSP
 02h    WORD    segment of first byte beyond memory allocated to program
 04h    BYTE    unused filler
 05h    BYTE    CP/M CALL 5 service request (FAR JMP to 000C0h)
        BUG: (DOS 2+) PSPs created by INT 21/AH=4Bh point at 000BEh
 06h    WORD    CP/M compatibility--size of first segment for .COM files
 08h  2 BYTEs    remainder of FAR JMP at 05h
 0Ah    DWORD    stored INT 22 termination address
 0Eh    DWORD    stored INT 23 control-Break handler address
 12h    DWORD    DOS 1.1+ stored INT 24 critical error handler address
 16h    WORD    segment of parent PSP
 18h 20 BYTEs    DOS 2+ Job File Table, one byte per file handle, FFh = closed
 2Ch    WORD    DOS 2+ segment of environment for process
 2Eh    DWORD    DOS 2+ process's SS:SP on entry to last INT 21 call
 32h    WORD    DOS 3+ number of entries in JFT (default 20)
 34h    DWORD    DOS 3+ pointer to JFT (default PSP:0018h)
 38h    DWORD    DOS 3+ pointer to previous PSP (default FFFFFFFFh in 3.x)
        used by SHARE in DOS 3.3
 3Ch    BYTE    apparently unused by DOS versions <= 6.00
 3Dh    BYTE    apparently used by some versions of APPEND
 3Eh    BYTE    (Novell NetWare) flag: next byte initialized if CEh
 3Fh    BYTE    (Novell Netware) Novell task number if previous byte is CEh
 40h  2 BYTEs    DOS 5+ version to return on INT 21/AH=30h
 42h    WORD    (MSWin3) selector of next PSP (PDB) in linked list
        Windows keeps a linked list of Windows programs only
 44h  4 BYTEs    unused by DOS versions <= 6.00
 48h    BYTE    (MSWindows3) bit 0 set if non-Windows application (WINOLDAP)
 49h  7 BYTEs    unused by DOS versions <= 6.00
 50h  3 BYTEs    DOS 2+ service request (INT 21/RETF instructions)
 53h  2 BYTEs    unused in DOS versions <= 6.00
 55h  7 BYTEs    unused in DOS versions <= 6.00; can be used to make first FCB
        into an extended FCB
 5Ch 16 BYTEs    first default FCB, filled in from first commandline argument
        overwrites second FCB if opened
 6Ch 16 BYTEs    second default FCB, filled in from second commandline argument
        overwrites beginning of commandline if opened
 7Ch  4 BYTEs    unused
 80h 128 BYTEs    commandline / default DTA
        command tail is BYTE for length of tail, N BYTEs for the tail,
        followed by a BYTE containing 0Dh
Notes:    in DOS v3+, the limit on simultaneously open files may be increased by
      allocating memory for a new open file table, filling it with FFh,
      copying the first 20 bytes from the default table, and adjusting the
      pointer and count at 34h and 32h.  However, DOS will only copy the
      first 20 file handles into a child PSP (including the one created on
      EXEC).
    network redirectors based on the original MS-Net implementation use
      values of 80h-FEh in the open file table to indicate remote files;
      Novell NetWare reportedly also uses values of 80h-FEh
    MS-DOS 5.00 incorrectly fills the FCB fields when loading a program
      high; the first FCB is empty and the second contains the first
      parameter
    some DOS extenders place protected-mode values in various PSP fields
      such as the "parent" field, which can confuse PSP walkers.  Always
      check either for the CDh 20h signature or that the suspected PSP is
      at the beginning of a memory block which owns itself (the preceding
      paragraph should be a valid MCB with "owner" the same as the
      suspected PSP).
    Novell NetWare updates the fields at offsets 3Eh and 3Fh without
      checking that a legal PSP segment is current; see AH=50h for further
      discussion

Format of environment block:
Offset    Size    Description
 00h  N BYTEs    first environment variable, ASCIZ string of form "var=value"
      N BYTEs    second environment variable, ASCIZ string
    ...
      N BYTEs    last environment variable, ASCIZ string of form "var=value"
    BYTE    00h
---DOS 3+---
    WORD    number of strings following environment (normally 1)
      N BYTEs    ASCIZ full pathname of program owning this environment
        other strings may follow
--------D-2127-------------------------------
INT 21 - DOS 1+ - RANDOM BLOCK READ FROM FCB FILE
    AH = 27h
    CX = number of records to read
    DS:DX -> opened FCB (see AH=0Fh)
Return: AL = status
        00h successful, all records read
        01h end of file, no data read
        02h segment wrap in DTA, no data read
        03h end of file, partial read
    [DTA] = records read from file
    CX = number of records read (return AL = 00h or 03h)
Notes:    read begins at current file position as specified in FCB; the file
      position is updated after reading
    not supported by MS Windows 3.0 DOSX.EXE DOS extender
SeeAlso: AH=21h,AH=28h,AH=3Fh
--------D-2128-------------------------------
INT 21 - DOS 1+ - RANDOM BLOCK WRITE TO FCB FILE
    AH = 28h
    CX = number of records to write
    DS:DX -> opened FCB (see AH=0Fh)
    [DTA] = records to write
Return: AL = status
        00h successful
        01h disk full or file read-only
        02h segment wrap in DTA
    CX = number of records written
Notes:    write begins at current file position as specified in FCB; the file
      position is updated after writing
    if CX = 0000h on entry, no data is written; instead the file size is
      adjusted to be the same as the file position specified by the random
      record and record size fields of the FCB
    if the data to be written is less than a disk sector, it is copied into
      a DOS disk buffer, to be written out to disk at a later time
    not supported by MS Windows 3.0 DOSX.EXE DOS extender
SeeAlso: AH=22h,AH=27h,AH=40h,AH=59h
--------D-2129-------------------------------
INT 21 - DOS 1+ - PARSE FILENAME INTO FCB
    AH = 29h
    AL = parsing options (see below)
    DS:SI -> filename string (both '*' and '?' wildcards OK)
    ES:DI -> buffer for unopened FCB
Return: AL = result code
        00h successful parse, no wildcards encountered
        01h successful parse, wildcards present
        FFh failed (invalid drive specifier)
    DS:SI -> first unparsed character
    ES:DI buffer filled with unopened FCB (see AH=0Fh)
Notes:    asterisks expanded to question marks in the FCB
    all processing stops when a filename terminator is encountered
    cannot be used with filespecs which include a path (DOS 2+)
    Novell NetWare monitors the result code since an 'invalid drive' may
      signal an attempt to reconnect a network drive; if there are no
      connections to the specified drive, NetWare attempts to build a
      connection and map the drive to the SYS:LOGIN directory
SeeAlso: AH=0Fh,AH=16h,AH=26h

Bitfields for parsing options:
 bit 0    skip leading separators
 bit 1    use existing drive number in FCB if no drive is specified, instead of
        setting field to zero
 bit 2    use existing filename in FCB if no base name is specified, instead of
        filling field with blanks
 bit 3    use existing extension in FCB if no extension is specified, instead of
        filling field with blanks
 bits 4-7 reserved (0)
--------D-212A-------------------------------
INT 21 - DOS 1+ - GET SYSTEM DATE
    AH = 2Ah
Return: CX = year (1980-2099)
    DH = month
    DL = day
---DOS 1.10+---
    AL = day of week (00h=Sunday)
SeeAlso: AH=2Bh"DOS",AH=2Ch,AH=E7h,INT 1A/AH=04h,INT 2F/AX=120Dh
--------D-212B-------------------------------
INT 21 - DOS 1+ - SET SYSTEM DATE
    AH = 2Bh
    CX = year (1980-2099)
    DH = month
    DL = day
Return: AL = status
        00h successful
        FFh invalid date, system date unchanged
Note:    DOS 3.3+ also sets CMOS clock
SeeAlso: AH=2Ah,AH=2Dh,INT 1A/AH=05h
--------E-212B--CX4149-----------------------
INT 21 - AI Architects - ??? - INSTALLATION CHECK
    AH = 2Bh
    CX = 4149h ('AI')
    DX = 413Fh ('A?')
Return: AL <> FFh if installed
Note:    Borland's TKERNEL makes this call
--------c-212B--CX4358-----------------------
INT 21 - Super PC-Kwik v3.20+ - INSTALLATION CHECK
    AH = 2Bh
    CX = 4358h ('CX')
Return: AL = FFh if PC-Kwik/PC-Cache not installed
    AL = 00h if installed
        CF clear
        CX = 6378h ('cx')
        BX = ???
        DX = version (DH = major version, DL = binary minor version)
Note:    PC Tools PC-Cache v5.x and Qualitas Qcache v4.00 are OEM versions of
      Super PC-Kwik, and thus support this call (PC-Cache 5.1 corresponds
      to PC-Kwik v3.20)
SeeAlso: INT 13/AH=A0h,INT 13/AH=B0h,INT 16/AX=FFA5h/CX=1111h
Index:    PC-Cache;installation check|Qualitas Qcache;installation check
Index:    installation check;PC-Cache 5.x|installation check;Qualitas Qcache
--------Q-212B--CX4445-----------------------
INT 21 - DESQview - INSTALLATION CHECK
    AH = 2Bh
    CX = 4445h ('DE')
    DX = 5351h ('SQ')
    AL = subfunction (DV v2.00+)
        01h get version
        Return: BX = version (BH = major, BL = minor)
        Note: early copies of v2.00 return 0002h
        02h get shadow buffer info, and start shadowing
        Return: BH = rows in shadow buffer
            BL = columns in shadow buffer
            DX = segment of shadow buffer
        04h get shadow buffer info
        Return: BH = rows in shadow buffer
            BL = columns in shadow buffer
            DX = segment of shadow buffer
        05h stop shadowing
Return: AL = FFh if DESQview not installed
Notes:    in DESQview v1.x, there were no subfunctions; this call only identified
      whether or not DESQview was loaded.  DESQview v2.52 performs function
      01h for all subfunction requests 0Ch and higher and appears to ignore
      all lower-numbered functions not listed here.
    DESQview versions 2.5x are part of DESQview/X v1.0x.
BUG:    subfunction 05h does not appear to work correctly in DESQview 2.52
SeeAlso: INT 10/AH=FEh,INT 10/AH=FFh,INT 15/AX=1024h,INT 15/AX=DE30h
--------U-212B--CX454C-----------------------
INT 21 - ELRES v1.1 - INSTALLATION CHECK
    AH = 2Bh
    CX = 454Ch ('EL')
    DX = 5253h ('RS')
Return: ES:BX -> ELRES history structure (see below)
    DX = DABEh (signature, DAve BEnnett)
Program: ELRES is an MS-DOS return code (errorlevel) recorder by David H.
      Bennett which stores recent errorlevel values, allows them to be
      retrieved for use in batch files, and can place them in an
      environment variable
SeeAlso: AH=4Bh"ELRES",AH=4Dh

Format of ELRES history structure:
Offset    Size    Description
 00h    WORD    number of return codes which can be stored by following buffer
 02h    WORD    current position in buffer (treated as a ring)
 04h  N BYTEs    ELRES buffer
--------T-212B01CX5441-----------------------
INT 21 - TAME v2.10+ - INSTALLATION CHECK
    AX = 2B01h
    CX = 5441h ('TA')
    DX = 4D45h ('ME')
---v2.60---
    BH = ???
        00h skip ???, else do
Return: AL = 02h if installed
    ES:DX -> data area in TAME-RES (see below)
Program: TAME is a shareware program by David G. Thomas which gives up CPU time
      to other partitions under a multitasker when the current partition's
      program incessantly polls the keyboard or system time

Format of TAME 2.10-2.20 data area:
Offset    Size    Description
 00h    BYTE    data structure minor version number (01h in TAME 2.20)
 01h    BYTE    data structure major version number (07h in TAME 2.20)
 02h    DWORD    number of task switches
 06h    DWORD    number of keyboard polls
 0Ah    DWORD    number of time polls
 0Eh    DWORD    number of times DESQview told program runs only in foreground
 12h    DWORD    original INT 10h
 16h    DWORD    original INT 14h
 1Ah    DWORD    original INT 15h
 1Eh    DWORD    original INT 16h
 22h    DWORD    original INT 17h
 26h    DWORD    original INT 21h
 2Ah    DWORD    original INT 28h
 2Eh    WORD    offset of TAME INT 10h handler
 30h    WORD    offset of TAME INT 14h handler
 32h    WORD    offset of TAME INT 15h handler
 34h    WORD    offset of TAME INT 16h handler
 36h    WORD    offset of TAME INT 17h handler
 38h    WORD    offset of TAME INT 21h handler
 3Ah    WORD    offset of TAME INT 28h handler
 3Ch    WORD    X in /max:X,Y or /freq:X,Y
 3Eh    WORD    Y in /max:X,Y or /freq:X,Y
 40h    WORD    number of polls remaining before next task switch
 42h    WORD    /KEYIDLE value
 44h    BYTE    interrupts already grabbed by TAME (see below)
 45h    BYTE    flags for interrupts which may be acted on (same bits as above)
 46h    BYTE    TAME enabled (01h) or disabled (00h)
 47h    BYTE    /TIMEPOLL (01h) or /NOTIMEPOLL (00h)
 48h    BYTE    /NOTIMER (01h) or /TIMER (00h)
 49h    BYTE    window or task number for this task
 4Ah    BYTE    multitasker type (see below)
 4Bh    BYTE    type of task switching selected
        bit 0: DESQview???
        bit 1: DoubleDOS???
        bit 2: TopView???
        bit 3: KeySwitch
        bit 4: HLT instruction
 4Ch    BYTE    ???
 4Dh    BYTE    flags
        bit 1: /FREQ instead of /MAX
 4Eh    BYTE    /FG: value
 4Fh    BYTE    task switches left until next FGONLY DESQview API call
 50h    BYTE    ???

Bitfields for interrupts already grabbed by TAME:
 bit 0    INT 10h
 bit 1    INT 14h
 bit 2    INT 15h
 bit 3    INT 16h
 bit 4    INT 17h
 bit 5    INT 21h
 bit 6    INT 28h

Values for multitasker type:
 01h    DESQview
 02h    DoubleDOS
 03h    TopView
 04h    OmniView
 05h    VM/386

Bitfields for type of task switching selected:
 bit 0    DESQview
 bit 1    DoubleDOS
 bit 2    TopView
 bit 3    OmniView
 bit 4    KeySwitch
 bit 5    HLT instruction

Format of TAME 2.30 data area:
Offset    Size    Description
 00h    BYTE    data structure minor version number (02h in TAME 2.30)
 01h    BYTE    data structure major version number (0Ah in TAME 2.30)
 02h    DWORD    number of task switches
 06h    DWORD    number of keyboard polls
 0Ah    DWORD    number of time polls
 0Eh    DWORD    number of times DESQview told program runs only in foreground
 12h    DWORD    time of last /CLEAR or TAME-RES load
 16h    DWORD    time yielded
 1Ah    DWORD    time spent polling
 1Eh    DWORD    time spent waiting on key input with INT 16/AH=01h,11h
 22h    DWORD    original INT 10h
 26h    DWORD    original INT 14h
 2Ah    DWORD    original INT 15h
 2Eh    DWORD    original INT 16h
 32h    DWORD    original INT 17h
 36h    DWORD    original INT 21h
 3Ah    DWORD    original INT 28h
 3Eh    WORD    offset of TAME INT 10h handler
 40h    WORD    offset of TAME INT 14h handler
 42h    WORD    offset of TAME INT 15h handler
 44h    WORD    offset of TAME INT 16h handler
 46h    WORD    offset of TAME INT 17h handler
 48h    WORD    offset of TAME INT 21h handler
 4Ah    WORD    offset of TAME INT 28h handler
 4Ch    WORD    X in /max:X,Y or /freq:X,Y
 4Eh    WORD    Y in /max:X,Y or /freq:X,Y
 50h    WORD    number of polls remaining before next task switch
 52h    WORD    /KEYIDLE value
 54h    WORD    /FG: value
 56h    WORD    task switches left until next FGONLY DESQview API call
 58h    WORD    multitasker version
 5Ah    WORD    virtual screen segment
 5Ch    BYTE    interrupts already grabbed by TAME (see above)
 5Dh    BYTE    flags for interrupts which may be acted on (same bits as above)
 5Eh    BYTE    window or task number for this task
 5Fh    BYTE    multitasker type (see above)
 60h    BYTE    type of task switching selected (bit flags) (see above)
 61h    BYTE    watch_DOS
 62h    BYTE    bit flags
        bit 0: TAME enabled
        bit 1: /FREQ instead of /MAX (counts in 3Ch and 3Eh per tick)
        bit 2: /TIMEPOLL
        bit 3: /KEYPOLL
        bit 4: inhibit timer
        bit 5: enable status monitoring
 63h    BYTE    old status
 64h    WORD    signature DA34h

Format of TAME 2.60 data area:
Offset    Size    Description
 00h    BYTE    data structure minor version number (02h in TAME 2.60)
 01h    BYTE    data structure major version number (0Bh in TAME 2.60)
 02h    DWORD    number of task switches
 06h    DWORD    number of keyboard polls
 0Ah    DWORD    number of time polls
 0Eh    DWORD    number of times DESQview told program runs only in foreground
 12h    DWORD    time of last /CLEAR or TAME-RES load
 16h    DWORD    time yielded
 1Ah    DWORD    time spent polling
 1Eh    DWORD    time spent waiting on key input with INT 16/AH=01h,11h
 22h  4 BYTEs    ???
 26h    DWORD    original INT 10h
 2Ah    DWORD    original INT 14h
 2Eh    DWORD    original INT 15h
 32h    DWORD    original INT 16h
 36h    DWORD    original INT 17h
 3Ah    DWORD    original INT 21h
 3Eh    DWORD    original INT 28h
 42h    WORD    offset of TAME INT 10h handler
 44h    WORD    offset of TAME INT 14h handler
 46h    WORD    offset of TAME INT 15h handler
 48h    WORD    offset of TAME INT 16h handler
 4Ah    WORD    offset of TAME INT 17h handler
 4Ch    WORD    offset of TAME INT 21h handler
 4Eh    WORD    offset of TAME INT 28h handler
 50h    WORD    X in /max:X,Y or /freq:X,Y
 52h    WORD    Y in /max:X,Y or /freq:X,Y
 54h    WORD    number of polls remaining before next task switch
 56h    WORD    /KEYIDLE value
 58h  4 BYTEs    ???
 5Ch    WORD    X in /boost:X,Y
 5Eh    WORD    Y in /boost:X,Y
 60h    WORD    /FG: value
 62h    WORD    task switches remaining until next FGONLY DESQview API call
 64h    WORD    multitasker version ???
 66h    WORD    virtual screen segment
 68h    BYTE    interrupts already grabbed by TAME (see above)
 69h    BYTE    flags for interrupts which may be acted on (same bits as above)
 6Ah    BYTE    window or task number for this task
 6Bh    BYTE    multitasker type (see above)
 6Ch    BYTE    type of task switching selected (bit flags) (see above)
 6Dh    BYTE    watch_DOS
 6Eh    BYTE    bit flags
        bit 0: TAME enabled
        bit 1: /FREQ instead of /MAX (counts in 50h and 52h per tick)
        bit 2: /TIMEPOLL
        bit 3: /KEYPOLL
        bit 4: inhibit timer
        bit 5: enable status monitoring
 6Fh    BYTE    old status
 70h    WORD    signature DA34h
--------R-212B44BX4D41-----------------------
INT 21 - pcANYWHERE IV/LAN - INSTALLATION CHECK
    AX = 2B44h ('D')
    BX = 4D41h ('MA')
    CX = 7063h ('pc')
    DX = 4157h ('AW')
Return: AX = 4F4Bh ('OK') if large host resident
       = 6F6Bh ('ok') if small host resident
    CX:DX -> API entry point
SeeAlso: INT 16/AH=79h

Call API entry point with:
    AX = 0000h get pcANYWHERE IV version
        DS:SI -> BYTE buffer for host type code
        Return: AH = version number
            AL = revision number
            DS:DI buffer byte filled with
            00h full-featured host
            01h limited-feature LAN host
            other API may not be supported
    AX = 0001h initialize operation
        DS:SI -> initialization request structure (see below)
        Return: AX = function status (see below)
    AX = 0002h get status
        Return: AH = current operating mode (see init req structure below)
            AL = current connection status
            bit 0: a physical connection is active
            bit 1: remove screen updating is active
            bit 2: connection checking is active
            bit 3: hot key detection is active
            bit 4: background file transfer is active
    AX = 0003h suspend remote screen updates
        Return: AX = function status (see below)
    AX = 0004h resume screen updates
        Return: AX = function status (see below)
    AX = 0005h end current remote access session
        DS:SI -> termination request structure (see below)
        Return: AX = function status (see below)
    AX = 0006h remove pcANYWHERE IV from memory
        Return: AX = status
            0000h successful
            FFD2h unable to release allocated memory
            FFD1h unable to release interrupt vectors
    AX = 8000h read data from communications channel
        DS:BX -> buffer
        CX = buffer size
        Return: AX >= number of characters read/available
            AX < 0 on error
    AX = 8001h write data to communications channel
        DS:BX -> buffer
        CX = buffer size
        Return: AX >= number of characters written
            AX < 0 on error
    AX = 8002h get connection status
        Return: AX = status
            > 0000h if connection active
            = 0000h if connection lost
            < 0000h on error

Format of initialization request structure:
Offset    Size    Description
 00h    BYTE    operating mode
        00h wait for a call
        01h hot key activates
        02h incoming call activates
        03h initiate a call
 01h  3 BYTEs    user ID to append to config file names
 04h    WORD    DS-relative pointer to path for config files
 06h    WORD    DS-relative pointer to path for program files

Format of termination request structure:
Offset    Size    Description
 00h    BYTE    operating mode after termination
        00h wait for a call
        01h hot key activates
        02h incoming call activates
        80h use current mode
        FFh remove from memory

Values for function status:
 0000h    function completed successfully
 FFF2h    unable to establish a connection when operating mode is
    "Initiate a call"
 FFF3h    modem configuration is invalid (corrupt config)
 FFF4h    modem initialization failed (no modem response)
 FFF5h    the communications device could not be initialized
 FFF6h    the host operator aborted the function
 FFF7h    the communications driver type specified in the configuration file is
    different than the one loaded when pcANYWHERE IV was initially started
 FFF9h    the configuration file is invalid
 FFFAh    the configuration file could not be found
 FFFBh    no session is active
 FFFCh    a remote access session is active
 FFFDh    the specified operating mode is invalid
--------D-212C-------------------------------
INT 21 - DOS 1+ - GET SYSTEM TIME
    AH = 2Ch
Return: CH = hour
    CL = minute
    DH = second
    DL = 1/100 seconds
Note:    on most systems, the resolution of the system clock is about 5/100sec,
      so returned times generally do not increment by 1
    on some systems, DL may always return 00h
SeeAlso: AH=2Ah,AH=2Dh,AH=E7h,INT 1A/AH=00h,INT 1A/AH=02h,INT 1A/AH=FEh
SeeAlso: INT 2F/AX=120Dh
--------D-212D-------------------------------
INT 21 - DOS 1+ - SET SYSTEM TIME
    AH = 2Dh
    CH = hour
    CL = minute
    DH = second
    DL = 1/100 seconds
Return: AL = result
        00h successful
        FFh invalid time, system time unchanged
Note:    DOS 3.3+ also sets CMOS clock
SeeAlso: AH=2Bh"DOS",AH=2Ch,INT 1A/AH=01h,INT 1A/AH=03h,INT 1A/AH=FFh"AT&T"
--------T-212D01CX7820-----------------------
INT 21 - PC-Mix - INSTALLATION CHECK
    AX = 2D01h
    CX = 7820h ('X ')
    DX = 6D69h ('MI')
Return: AL = 00h if installed
--------D-212E--DL00-------------------------
INT 21 - DOS 1+ - SET VERIFY FLAG
    AH = 2Eh
    DL = 00h (DOS 1.x/2.x only)
    AL = new state of verify flag
        00h off
        01h on
Notes:    default state at system boot is OFF
    when ON, all disk writes are verified provided the device driver
      supports read-after-write verification
SeeAlso: AH=54h
--------D-212F-------------------------------
INT 21 - DOS 2+ - GET DISK TRANSFER AREA ADDRESS
    AH = 2Fh
Return: ES:BX -> current DTA
Note:    under the FlashTek X-32 DOS extender, the pointer is in ES:EBX
SeeAlso: AH=1Ah
--------D-2130-------------------------------
INT 21 - DOS 2+ - GET DOS VERSION
    AH = 30h
---DOS 5+ ---
    AL = what to return in BH
        00h OEM number (as for DOS 2.0-4.0x)
        01h version flag
Return: AL = major version number (00h if DOS 1.x)
    AH = minor version number
    BL:CX = 24-bit user serial number (most versions do not use this)
---if DOS <5 or AL=00h---
    BH = MS-DOS OEM number (see below)
---if DOS 5+ and AL=01h---
    BH = version flag
        bit 3: DOS is in ROM
        other: reserved (0)
Notes:    the OS/2 v1.x Compatibility Box returns major version 0Ah (10)
    the OS/2 v2.x Compatibility Box returns major version 14h (20)
    the Windows/NT DOS box returns version 5.00, subject to SETVER
    DOS 4.01 and 4.02 identify themselves as version 4.00; use
      INT 21/AH=87h to distinguish between the original European MS-DOS 4.0
      and the later PC-DOS 4.0x and MS-DOS 4.0x
    generic MS-DOS 3.30, Compaq MS-DOS 3.31, and others identify themselves
      as PC-DOS by returning OEM number 00h
    the version returned under DOS 4.0x may be modified by entries in
      the special program list (see AH=52h)
    the version returned under DOS 5+ may be modified by SETVER; use
      AX=3306h to get the true version number
SeeAlso: AX=3000h/BX=3000h,AX=3306h,AX=4452h,AH=87h,INT 15/AX=4900h
SeeAlso: INT 2F/AX=122Fh,INT 2F/AX=E002h

Values for MS-DOS OEM number:
 00h    IBM
 01h    Compaq
 02h    MS Packaged Product
 04h    AT&T
 05h    Zenith
 06h    Hewlett-Packard
 0Dh    Packard-Bell
 16h    DEC
 23h    Olivetti
 29h    Toshiba
 33h    Novell (Windows/386 device IDs only)
 34h    MS Multimedia Systems (Windows/386 device IDs only)
 35h    MS Multimedia Systems (Windows/386 device IDs only)
 4Dh    Hewlett-Packard
 66h    PhysTechSoft (PTS-DOS)
 99h    General Software's Embedded DOS
 FFh    Microsoft, Phoenix
--------E-2130-------------------------------
INT 21 - Phar Lap 386/DOS-Extender, Intel Code Builder - INSTALLATION CHECK
    AH = 30h
    EAX = 00003000h
    EBX = 50484152h ("PHAR")
Return: AL = major DOS version
    AH = minor DOS version
    EAX bits 31-16 = 4458h ('DX') if 386/DOS-extender installed
        BL = ASCII major version number
    EAX bits 31-16 = 4243h ('BC') if Intel Code Builder installed
        EDX = address of GDA
SeeAlso: AX=2501h,AX=FF00h,INT 2F/AX=F100h
--------v-2130--DXABCD-----------------------
INT 21 - VIRUS - "Possessed" - INSTALLATION CHECK
    AH = 30h
    DX = ABCDh
Return: DX = DCBAh if installed
SeeAlso: AX=0D20h,AX=30F1h
--------T-213000BX1234-----------------------
INT 21 - CTask 2.0+ - INSTALLATION CHECK
    AX = 3000h
    BX = 1234h
    DS:DX -> 8-byte version string (DX < FFF0h) "CTask21",00h for v2.1-2.2
Return: AL = DOS major version
    AH = DOS minor version
    CX:BX -> Ctask global data block
Program: CTask is a multitasking kernel for C written by Thomas Wagner
Note:    if first eight bytes of returned data block equal eight bytes passed
      in, CTask is resident
--------O-213000BX3000-----------------------
INT 21 - PC-MOS/386 v3.0 - INSTALLATION CHECK/GET VERSION
    AX = 3000h
    BX = 3000h
    CX = DX = 3000h
Return: AX = PC-MOS version
Program: PC-MOS/386 is a multitasking/multiuser MS-DOS-compatible operating
      system by The Software Link, Inc.
SeeAlso: AH=30h,INT 38/AH=02h,INT 38/AH=10h
----------213022-----------------------------
INT 21 - StopPrg v2.0 - INSTALLATION CHECK
    AX = 3022h
Return: AX = DOS version (see AH=30h)
    CX = 1112h if StopPrg installed
        BX = segment of resident code
Program: StopPrg is a resident program aborter by MAK-TRAXON's Prophet
Note:    StopPrg may be temporarily disabled by storing 9090h in the word at
      0000h:04FEh
--------v-2130F1-----------------------------
INT 21 - VIRUS - "Dutch-555"/"Quit 1992" - INSTALLATION CHECK
    AX = 30F1h
Return: AL = 00h if resident
SeeAlso: AH=30h/DX=ABCDh,AX=330Fh
----------2130FFCX4445-----------------------
INT 21 - DESQ??? - INSTALLATION CHECK
    AX = 30FFh
    CX = 4445h ("DE")
    DX = 5351h ("SQ")
Return: BH = 05h if installed
    ???
Note:    called by DUBLDISK.COM v2.6; this function is not supported by
      DESQview, so it may be for DESQview's precursor DESQ.
SeeAlso: AX=4404h"DUBLDISK"
--------D-2131-------------------------------
INT 21 - DOS 2+ - TERMINATE AND STAY RESIDENT
    AH = 31h
    AL = return code
    DX = number of paragraphs to keep resident
Return: never
Notes:    the value in DX only affects the memory block containing the PSP;
      additional memory allocated via AH=48h is not affected
    the minimum number of paragraphs which will remain resident is 11h
      for DOS 2.x and 06h for DOS 3+
    most TSRs can save some memory by releasing their environment block
      before terminating (see AH=26h,AH=49h)
SeeAlso: AH=00h,AH=4Ch,AH=4Dh,INT 20,INT 22,INT 27
--------D-2132-------------------------------
INT 21 - DOS 2+ - GET DOS DRIVE PARAMETER BLOCK FOR SPECIFIC DRIVE
    AH = 32h
    DL = drive number (00h = default, 01h = A:, etc)
Return: AL = status
        00h successful
        DS:BX -> Drive Parameter Block (DPB) for specified drive
        FFh invalid or network drive
Notes:    the OS/2 compatibility box supports the DOS 3.3 version of this call
      except for the DWORD at offset 12h
    this call updates the DPB by reading the disk; the DPB may be accessed
      via the DOS list of lists (see AH=52h) if disk access is not
      desirable.
    undocumented prior to the release of DOS 5.0; only the DOS 4+ version
      of the DPB has been documented, however
    supported by DR-DOS 3.41+; DR-DOS 3.41-6.0 return the same data as
      MS-DOS 3.31
SeeAlso: AH=1Fh,AH=52h

Format of DOS Drive Parameter Block:
Offset    Size    Description
 00h    BYTE    drive number (00h = A:, 01h = B:, etc)
 01h    BYTE    unit number within device driver
 02h    WORD    bytes per sector
 04h    BYTE    highest sector number within a cluster
 05h    BYTE    shift count to convert clusters into sectors
 06h    WORD    number of reserved sectors at beginning of drive
 08h    BYTE    number of FATs
 09h    WORD    number of root directory entries
 0Bh    WORD    number of first sector containing user data
 0Dh    WORD    highest cluster number (number of data clusters + 1)
        16-bit FAT if greater than 0FF6h, else 12-bit FAT
 0Fh    BYTE    number of sectors per FAT
 10h    WORD    sector number of first directory sector
 12h    DWORD    address of device driver header
 16h    BYTE    media ID byte
 17h    BYTE    00h if disk accessed, FFh if not
 18h    DWORD    pointer to next DPB
---DOS 2.x---
 1Ch    WORD    cluster containing start of current directory, 0000h=root,
        FFFFh = unknown
 1Eh 64 BYTEs    ASCIZ pathname of current directory for drive
---DOS 3.x---
 1Ch    WORD    cluster at which to start search for free space when writing
 1Eh    WORD    number of free clusters on drive, FFFFh = unknown
---DOS 4.0-6.0---
 0Fh    WORD    number of sectors per FAT
 11h    WORD    sector number of first directory sector
 13h    DWORD    address of device driver header
 17h    BYTE    media ID byte
 18h    BYTE    00h if disk accessed, FFh if not
 19h    DWORD    pointer to next DPB
 1Dh    WORD    cluster at which to start search for free space when writing,
        usually the last cluster allocated
 1Fh    WORD    number of free clusters on drive, FFFFh = unknown
--------D-2133-------------------------------
INT 21 - DOS 2+ - EXTENDED BREAK CHECKING
    AH = 33h
    AL = subfunction
        00h get current extended break state
        Return: DL = current state, 00h = off, 01h = on
        01h set state of extended ^C/^Break checking
        DL = 00h off, check only on character I/O functions
             01h on, check on all DOS functions
Note:    under DOS 3.1+ and DR-DOS, this function does not use any of the
      DOS-internal and may thus be called at any time
SeeAlso: AX=3302h
--------D-213302-----------------------------
INT 21 - DOS 3.x+ internal - GET AND SET EXTENDED CONTROL-BREAK CHECKING STATE
    AX = 3302h
    DL = new state
         00h for OFF or 01h for ON
Return: DL = old state of extended BREAK checking
Notes:    this function does not use any of the DOS-internal stacks and may thus
      be called at any time; one possible use is modifying Control-Break
      checking from within an interrupt handler or TSR
    not supported by DR-DOS through at least version 6.0
SeeAlso: AH=33h
--------D-213305-----------------------------
INT 21 - DOS 4+ - GET BOOT DRIVE
    AX = 3305h
Return: DL = boot drive (1=A:,...)
Notes:    fully reentrant
    NEC 9800-series PCs always call the boot drive A: and assign the other
      drive letters sequentially to the other drives in the system
--------D-213306-----------------------------
INT 21 - DOS 5+ - GET TRUE VERSION NUMBER
    AX = 3306h
Return: BL = major version
    BH = minor version
    DL = revision (bits 2-0, all others 0)
    DH = version flags
        bit 3: DOS is in ROM
        bit 4: DOS in in HMA
    AL = FFh if true DOS version < 5.0
Notes:    this function always returns the true version number, unlike AH=30h,
      whose return value may be changed with SETVER
    because of the conflict from the CBIS PowerLAN redirector (see next
      entry), programs should check whether BH is less than 100 (64h)
      and BL is at least 5 before accepting the returned BX as the true
      version number; however, even this is not entirely reliable when
      that redirector is loaded
    fully reentrant
    OS/2 v2.1 will return BX=0A14h (version 20.10)
    the Windows NT DOS box returns BX=3205h (version 5.50)
BUG:    DR-DOS 5.0 and 6.0 return CF set/AX=0001h for INT 21/AH=33h
      subfunctions other than 00h-02h and 05h, while MS-DOS returns AL=FFh
      for invalid subfunctions
SeeAlso: AH=30h,INT 2F/AX=122Fh
--------N-213306-----------------------------
INT 21 - CBIS POWERLAN - NETWORK REDIRECTOR - ???
    AX = 3306h
Return: AX = 3306h
    BL = ??? (usually 00h)
    BH = ??? (usually 00h or FFh)
Note:    unknown function, is in conflict with DOS 5+ version call
SeeAlso: AX=3306h"DOS"
--------v-21330F-----------------------------
INT 21 - VIRUS - "Burghofer" - INSTALLATION CHECK
    AX = 330Fh
Return: AL = 0Fh if resident (DOS returns AL=FFh)
SeeAlso: AX=30F1h,AX=33E0h
--------k-213341-----------------------------
INT 21 - Diet Disk v1.0 - INSTALLATION CHECK
    AX = 3341h
Return: DX = 1234h if installed
        CX = resident code segment
Program: Diet Disk is a public domain transparent data file compressor by
      Barry Nance
--------v-2133E0-----------------------------
INT 21 - VIRUS - "Oropax" - INSTALLATION CHECK
    AX = 33E0h
Return: AL = E0h if resident (DOS returns AL=FFh)
SeeAlso: AX=330Fh,AX=357Fh
--------D-2134-------------------------------
INT 21 - DOS 2+ - GET ADDRESS OF INDOS FLAG
    AH = 34h
Return: ES:BX -> one-byte InDOS flag
Notes:    the value of InDOS is incremented whenever an INT 21 function begins
      and decremented whenever one completes
    during an INT 28 call, it is safe to call some INT 21 functions even
      though InDOS may be 01h instead of zero
    InDOS alone is not sufficient for determining when it is safe to
      enter DOS, as the critical error handling decrements InDOS and
      increments the critical error flag for the duration of the critical
      error.  Thus, it is possible for InDOS to be zero even if DOS is
      busy.
    SMARTDRV 4.0 sets the InDOS flag while flushing its buffers to disk,
      then zeros it on completion
    the critical error flag is the byte immediately following InDOS in
      DOS 2.x, and the byte BEFORE the InDOS flag in DOS 3+ and
      DR-DOS 3.41+ (except COMPAQ DOS 3.0, where the critical error flag
      is located 1AAh bytes BEFORE the critical section flag)
    for DOS 3.1+, an undocumented call exists to get the address of the
      critical error flag (see AX=5D06h)
    this function was undocumented prior to the release of DOS 5.0.
SeeAlso: AX=5D06h,AX=5D0Bh,INT 15/AX=DE1Fh,INT 28
--------D-2135-------------------------------
INT 21 - DOS 2+ - GET INTERRUPT VECTOR
    AH = 35h
    AL = interrupt number
Return: ES:BX -> current interrupt handler
Note:    under DR-DOS 5.0+, this function does not use any of the DOS-internal
      stacks and may thus be called at any time
SeeAlso: AH=25h,AX=2503h
--------E-213501-----------------------------
INT 21 P - FlashTek X-32VM - ALLOCATE PROTECTED-MODE SELECTOR
    AX = 3501h
Return: CF clear if successful
        BX = new selector
    CF set on error (no more selectors available)
Note:    the new selector will be an expand-up read/write data selector with
      undefined base and limit
SeeAlso: AX=3502h,INT 31/AX=0000h
--------E-213502-----------------------------
INT 21 P - FlashTek X-32VM - DEALLOCATE PROTECTED-MODE SELECTOR
    AX = 3502h
    BX = selector
Return: CF clear if successful
    CF set on error (invalid selector)
Note:    only selectors allocated via AX=3501h should be deallocated
SeeAlso: AX=3501h,INT 31/AX=0001h
--------E-213503-----------------------------
INT 21 P - FlashTek X-32VM - SET SELECTOR BASE ADDRESS
    AX = 3503h
    BX = selector
    ECX = base address
Return: CF clear if successful
    CF set on error (invalid selector)
SeeAlso: AX=3504h,AX=3505h,INT 31/AX=0007h
--------E-213504-----------------------------
INT 21 P - FlashTek X-32VM - GET SELECTOR BASE ADDRESS
    AX = 3504h
    BX = selector
Return: CF clear if successful
        ECX = absolute base address of selector
    CF set on error (invalid selector)
SeeAlso: AX=3503h,INT 31/AX=0006h
--------E-213505-----------------------------
INT 21 P - FlashTek X-32VM - SET SELECTOR LIMIT
    AX = 3505h
    BX = selector
    ECX = desired limit
Return: CF clear if successful
        ECX = actual limit set
    CF set on error (no more selectors available)
Note:    the limit will be rounded down to nearest 4K boundary if the requested
      limit is greater than 1MB
SeeAlso: AX=3503h,INT 31/AX=0008h
--------E-21350A-----------------------------
INT 21 P - FlashTek X-32VM - PHYSICAL ADDRESS MAPPING
    AX = 350Ah
    EBX = absolute physical address
    ECX = size in bytes of area to map
Return: CF clear if successful
    CF set on error (insufficient memory or service refused by DPMI host)
Notes:    should not make repeated calls for the same physical address
    there is no provision for unmapping memory
--------E-21350B-----------------------------
INT 21 P - FlashTek X-32VM - UPDATE AND RETURN AVAILABLE FREE MEMORY
    AX = 350Bh
    DS = default selector for DS
Return: CF clear
    EAX = maximum amount of memory which can be allocated via AX=350Ch
SeeAlso: AX=350Ch
--------E-21350C-----------------------------
INT 21 P - FlashTek X-32VM - ALLOCATE A BLOCK OF MEMORY
    AX = 350Ch
    ECX = size of block in bytes
    DS = default DS
Return: CF clear if successful
        EAX = near pointer to new block
        EDX = new lowest legal value for stack
    CF set on error (requested size not multiple of 4K)
SeeAlso: AX=350Bh,AX=350Dh
--------E-21350D-----------------------------
INT 21 P - FlashTek X-32VM - RESERVE BLOCK OF MEMORY FOR 32-BIT STACK
    AX = 350Dh
    EBX = current ESP value
    ECX = size of block in bytes
    DS = default DS
Return: CF clear if successful
        EBX = new value for ESP
        EDX = suggested new limit for SS
    CF set on error
Note:    this function should only be called once during initialization
SeeAlso: AX=350Bh,AX=350Ch
--------v-21357F-----------------------------
INT 21 - VIRUS - "Agiplan"/"Month 4-6" - INSTALLATION CHECK
    AX = 357Fh
Return: DX = FFFFh if installed
SeeAlso: AX=33E0h,AX=3DFFh
--------D-2136-------------------------------
INT 21 - DOS 2+ - GET FREE DISK SPACE
    AH = 36h
    DL = drive number (00h = default, 01h = A:, etc)
Return: AX = FFFFh if invalid drive
    else
        AX = sectors per cluster
        BX = number of free clusters
        CX = bytes per sector
        DX = total clusters on drive
Notes:    free space on drive in bytes is AX * BX * CX
    total space on drive in bytes is AX * CX * DX
    "lost clusters" are considered to be in use
    according to Dave Williams' MS-DOS reference, the value in DX is
      incorrect for non-default drives after ASSIGN is run
SeeAlso: AH=1Bh,AH=1Ch
--------D-213700-----------------------------
INT 21 - DOS 2+ - "SWITCHAR" - GET SWITCH CHARACTER
    AX = 3700h
Return: AL = status
        00h successful
        DL = current switch character
        FFh unsupported subfunction
Desc:    Determine the character which is used to introduce command switches.
      This setting is ignored by DOS commands in version 4.0 and higher,
      but is honored by many third-party programs.
Notes:    documented in some OEM versions of some releases of DOS
    supported by OS/2 compatibility box
    always returns AL=00h/DL=2Fh for MS-DOS 5+ and DR-DOS 3.41+
SeeAlso: AX=3701h
--------D-213701-----------------------------
INT 21 - DOS 2+ - "SWITCHAR" - SET SWITCH CHARACTER
    AX = 3701h
    DL = new switch character
Return: AL = status
        00h successful
        FFh unsupported subfunction
Notes:    documented in some OEM versions of some releases of DOS
    supported by OS/2 compatibility box
    ignored by MS-DOS 5+ and DR-DOS 3.41+; DR-DOS 6.0 leaves AX unchanged
SeeAlso: AX=3700h
--------D-2137-------------------------------
INT 21 - DOS 2.x and 3.3+ only - "AVAILDEV" - SPECIFY \DEV\ PREFIX USE
    AH = 37h
    AL = subfunction
        02h get availdev flag
        Return: DL = 00h \DEV\ must precede character device names
               = nonzero \DEV\ is optional
        03h set availdev flag
        DL = 00h    \DEV\ is mandatory
           = nonzero    \DEV\ is optional
Return: AL = status
        00h successful
        FFh unsupported subfunction
Notes:    all versions of DOS from 2.00 allow \DEV\ to be prepended to device
      names without generating an error even if the directory \DEV does
      not actually exist (other paths generate an error if they do not
      exist).
    although MS-DOS 3.3+ and DR-DOS 3.41+ accept these calls, they have no
      effect, and AL=02h always returns DL=FFh
--------k-2137D0BX899D-----------------------
INT 21 - DIET v1.43e - TSR INSTALLATION CHECK
    AX = 37D0h
    BX = 899Dh ('DI' + 'ET')
Return: AL = FFh if not present as TSR (default return value from DOS)
    AX = 0000h if installed as a TSR
        CX = 899Dh
        DX = version ID
Program: DIET is a transparent file copressor/decompressor by Teddy Matsumoto
SeeAlso: AX=37D1h,AX=37D2h,AX=37D4h,AX=37D6h,AX=37DFh,AX=4BF0h,AX=4BF1h
--------k-2137D1BX899D-----------------------
INT 21 - DIET v1.43e - GET DIET.EXE RESIDENT SEGMENT
    AX = 37D1h
    BX = 899Dh ('DI' + 'ET')
Return: AX = 0000h
    CX = code segment of TSR part of DIET.EXE
    DX = memory block segment of TSR DIET.EXE
        (0000h if installed as device driver)
SeeAlso: AX=37D0h,AX=37DFh
--------k-2137D2BX899D-----------------------
INT 21 - DIET v1.43e - GET TSR CONTROL FLAGS
    AX = 37D2h
    BX = 899Dh ('DI' + 'ET')
Return: AX = 0000h
    DL = control flag (00h active, else disabled)
    DH = skip flag (nonzero while TSR active)
SeeAlso: AX=37D0h,AX=37D3h,AX=37D4h
--------k-2137D3BX899D-----------------------
INT 21 - DIET v1.43e - SET TSR CONTROL FLAGS
    AX = 37D3h
    BX = 899Dh ('DI' + 'ET')
    DL = control flag (00h active, else disabled)
    DH = skip flag (00h)
Return: AX = 0000h
SeeAlso: AX=37D0h,AX=37D2h,AX=37D5h
--------k-2137D4BX899D-----------------------
INT 21 - DIET v1.43e - GET TSR OPTIONS
    AX = 37D4h
    BX = 899Dh ('DI' + 'ET')
Return: AX = 0000h
    DX = TSR options (see below)
SeeAlso: AX=37D0h,AX=37D2h,AX=37D5h

Bitfields for TSR options:
 bit 0    automated compression of DIETed file
 bit 1    automated compression of newly-created file
 bit 2    suppress DIET message
 bit 3    display original file size
 bits 4-15 reserved (0)
--------k-2137D5BX899D-----------------------
INT 21 - DIET v1.43e - SET TSR OPTIONS
    AX = 37D5h
    BX = 899Dh ('DI' + 'ET')
    DX = TSR options (see AX=37D4h)
Return: AX = 0000h
Program: DIET is a transparent file copressor/decompressor by Teddy Matsumoto
SeeAlso: AX=37D0h,AX=37D3h,AX=37D4h
--------k-2137D6BX899D-----------------------
INT 21 - DIET v1.43e - GET TEMPORARY DIRECTORY NAMES
    AX = 37D6h
    BX = 899Dh ('DI' + 'ET')
Return: AX = 0000h
    DS:DX -> name of temporary directory or 0000h:0000h for current dir
SeeAlso: AX=37D0h,AX=37D7h
--------k-2137D7BX899D-----------------------
INT 21 - DIET v1.43e - SET TEMPORARY DIRECTORY NAMES
    AX = 37D7h
    BX = 899Dh ('DI' + 'ET')
    DS:DX -> ASCIZ name of temporary directory (max 61 chars)
        0000h:0000h for current directory
Return: AX = 0000h
Note:    the specified directory name must include a drive letter and end with
      a backslash
SeeAlso: AX=37D0h,AX=37D6h
--------k-2137DCBX899D-----------------------
INT 21 - DIET v1.43e - SET ADDRESS OF EXTERNAL PROCEDURE
    AX = 37DCh
    BX = 899Dh ('DI' + 'ET')
    DS:DX -> external procedure
Return: AX = 0000h
Note:    the resident code will call the specified external procedure at the
      beginning of decompression and when compression is exited on failure
SeeAlso: AX=37DDh

External procedure called with:
    STACK:    WORD    class
            FFFDh creation failed for unknown reasons
            FFFEh creation failed due to lack of space
            FFFFh file creation error
            else file handle of DIETed file to be decompressed
        DWORD    -> compressed filename
        DWORD    -> decompressed or temporary filename
Return: SI,DI,BP,DS,ES must be preserved by external procedure
--------k-2137DDBX899D-----------------------
INT 21 - DIET v1.43e - RELEASE EXTERNAL PROCEDURE
    AX = 37DDh
    BX = 899Dh ('DI' + 'ET')
Program: DIET is a transparent file copressor/decompressor by Teddy Matsumoto
Note:    unlinks the external procedure specified by AX=37DCh
SeeAlso: AX=37DCh
--------k-2137DEBX899D-----------------------
INT 21 - DIET v1.43e - READ EMS STATUS
    AX = 37DEh
    BX = 899Dh ('DI' + 'ET')
Return: AX = 0000h
    CX = EMS status
        0000h not used
        0001h used as work area
        0002h used for code and as work area
    DX = EMM handle when EMS is in use
--------k-2137DFBX899D-----------------------
INT 21 - DIET v1.43e - UNLOAD TSR
    AX = 37DFh
    BX = 899Dh ('DI' + 'ET')
Return: AX = status
        0000h successful
        00FFh failed
Program: DIET is a transparent file copressor/decompressor by Teddy Matsumoto
SeeAlso: AX=37D0h
Index:    uninstall;DIET
--------D-2138-------------------------------
INT 21 - DOS 2+ - GET COUNTRY-SPECIFIC INFORMATION
    AH = 38h
--DOS 2.x--
    AL = 00h get current-country info
    DS:DX -> buffer for returned info (see below)
Return: CF set on error
        AX = error code (02h)
    CF clear if successful
        AX = country code (MS-DOS 2.11 only)
        buffer at DS:DX filled
--DOS 3+--
    AL = 00h for current country
    AL = 01h thru 0FEh for specific country with code <255
    AL = 0FFh for specific country with code >= 255
       BX = 16-bit country code
    DS:DX -> buffer for returned info (see below)
Return: CF set on error
        AX = error code (02h)
    CF clear if successful
        BX = country code
        DS:DX buffer filled
Note:    this function is not supported by the Borland DPMI host, but no error
      is returned; as a workaround, one should allocate a buffer in
      conventional memory with INT 31/AX=0100h and simulate an INT 21 with
      INT 31/AX=0300h
SeeAlso: AH=65h,INT 10/AX=5001h,INT 2F/AX=110Ch,INT 2F/AX=1404h

Format of PC-DOS 2.x country info:
Offset    Size    Description
 00h    WORD    date format  0 = USA    mm dd yy
                 1 = Europe dd mm yy
                 2 = Japan    yy mm dd
 02h    BYTE    currency symbol
 03h    BYTE    00h
 04h    BYTE    thousands separator char
 05h    BYTE    00h
 06h    BYTE    decimal separator char
 07h    BYTE    00h
 08h 24 BYTEs    reserved

Format of MS-DOS 2.x,DOS 3+ country info:
Offset    Size    Description
 00h    WORD    date format (see above)
 02h  5 BYTEs    ASCIZ currency symbol string
 07h  2 BYTEs    ASCIZ thousands separator
 09h  2 BYTEs    ASCIZ decimal separator
 0Bh  2 BYTEs    ASCIZ date separator
 0Dh  2 BYTEs    ASCIZ time separator
 0Fh    BYTE    currency format
        bit 2 = set if currency symbol replaces decimal point
        bit 1 = number of spaces between value and currency symbol
        bit 0 = 0 if currency symbol precedes value
            1 if currency symbol follows value
 10h    BYTE    number of digits after decimal in currency
 11h    BYTE    time format
        bit 0 = 0 if 12-hour clock
            1 if 24-hour clock
 12h    DWORD    address of case map routine
        (FAR CALL, AL = character to map to upper case [>= 80h])
 16h  2 BYTEs    ASCIZ data-list separator
 18h 10 BYTEs    reserved

Values for country code:
 001h    United States
 002h    Canadian-French
 003h    Latin America
 01Fh    Netherlands
 020h    Belgium
 021h    France
 022h    Spain
 024h    Hungary (not supported by DR-DOS 5.0)
 026h    Yugoslavia (not supported by DR-DOS 5.0)
 027h    Italy
 029h    Switzerland
 02Ah    Czechoslovakia/Tjekia (not supported by DR-DOS 5.0)
 02Bh    Austria (DR-DOS 5.0)
 02Ch    United Kingdom
 02Dh    Denmark
 02Eh    Sweden
 02Fh    Norway
 030h    Poland (not supported by DR-DOS 5.0)
 031h    Germany
 037h    Brazil (not supported by DR-DOS 5.0)
 03Dh    International English [Australia in DR-DOS 5.0]
 051h    Japan (DR-DOS 5.0, MS-DOS 5.0+)
 052h    Korea (DR-DOS 5.0)
 056h    China (MS-DOS 5.0+)
 058h    Taiwan (MS-DOS 5.0+)
 05Ah    Turkey (MS-DOS 5.0+)
 15Fh    Portugal
 162h    Iceland
 166h    Finland
 311h    Middle East/Saudi Arabia (DR-DOS 5.0,MS-DOS 5.0+)
 3CCh    Israel (DR-DOS 5.0,MS-DOS 5.0+)
--------D-2138--DXFFFF-----------------------
INT 21 - DOS 3+ - SET COUNTRY CODE
    AH = 38h
    DX = FFFFh
    AL = 01h thru FEh for specific country with code <255
    AL = FFh for specific country with code >= 255
       BX = 16-bit country code (see AH=38h)
Return: CF set on error
        AX = error code (see AH=59h)
    CF clear if successful
Note:    not supported by OS/2
SeeAlso: INT 2F/AX=1403h
--------D-2139-------------------------------
INT 21 - DOS 2+ - "MKDIR" - CREATE SUBDIRECTORY
    AH = 39h
    DS:DX -> ASCIZ pathname
Return: CF clear if successful
        AX destroyed
    CF set on error
        AX = error code (03h,05h) (see AH=59h)
Notes:    all directories in the given path except the last must exist
    fails if the parent directory is the root and is full
    DOS 2.x-3.3 allow the creation of a directory sufficiently deep that
      it is not possible to make that directory the current directory
      because the path would exceed 64 characters
    under the FlashTek X-32 DOS extender, the pointer is in DS:EDX
SeeAlso: AH=3Ah,AH=3Bh,AH=6Dh,AH=E2h/SF=0Ah,INT 2F/AX=1103h
--------D-213A-------------------------------
INT 21 - DOS 2+ - "RMDIR" - REMOVE SUBDIRECTORY
    AH = 3Ah
    DS:DX -> ASCIZ pathname of directory to be removed
Return: CF clear if successful
        AX destroyed
    CF set on error
        AX = error code (03h,05h,06h,10h) (see AH=59h)
Notes:    directory must be empty (contain only '.' and '..' entries)
    under the FlashTek X-32 DOS extender, the pointer is in DS:EDX
SeeAlso: AH=39h,AH=3Bh,AH=E2h/SF=0Bh,INT 2F/AX=1101h
--------D-213B-------------------------------
INT 21 - DOS 2+ - "CHDIR" - SET CURRENT DIRECTORY
    AH = 3Bh
    DS:DX -> ASCIZ pathname to become current directory (max 64 bytes)
Return: CF clear if successful
        AX destroyed
    CF set on error
        AX = error code (03h) (see AH=59h)
Notes:    if new directory name includes a drive letter, the default drive is
      not changed, only the current directory on that drive
    changing the current directory also changes the directory in which
      FCB file calls operate
    under the FlashTek X-32 DOS extender, the pointer is in DS:EDX
SeeAlso: AH=47h,INT 2F/AX=1105h
--------D-213C-------------------------------
INT 21 - DOS 2+ - "CREAT" - CREATE OR TRUNCATE FILE
    AH = 3CH
    CX = file attributes (see below)
    DS:DX -> ASCIZ filename
Return: CF clear if successful
        AX = file handle
    CF set on error
        AX = error code (03h,04h,05h) (see AH=59h)
Notes:    if a file with the given name exists, it is truncated to zero length
    under the FlashTek X-32 DOS extender, the pointer is in DS:EDX
    DR-DOS checks the system password or explicitly supplied password at
      the end of the filename against the reserved field in the directory
      entry before allowing access
SeeAlso: AH=16h,AH=3Dh,AH=5Ah,AH=5Bh,AH=93h,INT 2F/AX=1117h

Bitfields for file attributes:
 bit 0    read-only
 bit 1    hidden
 bit 2    system
 bit 3    volume label (ignored)
 bit 4    reserved, must be zero (directory)
 bit 5    archive bit
 bit 7    if set, file is shareable under Novell NetWare
--------D-213D-------------------------------
INT 21 - DOS 2+ - "OPEN" - OPEN EXISTING FILE
    AH = 3Dh
    AL = access and sharing modes (see below)
    DS:DX -> ASCIZ filename
    CL = attribute mask of files to look for (server call only)
Return: CF clear if successful
        AX = file handle
    CF set on error
        AX = error code (01h,02h,03h,04h,05h,0Ch,56h) (see AH=59h)
Notes:    file pointer is set to start of file
    file handles which are inherited from a parent also inherit sharing
      and access restrictions
    files may be opened even if given the hidden or system attributes
    under the FlashTek X-32 DOS extender, the pointer is in DS:EDX
    DR-DOS checks the system password or explicitly supplied password at
      the end of the filename against the reserved field in the directory
      entry before allowing access
    sharing modes are only effective on local drives if SHARE is loaded
SeeAlso: AH=0Fh,AH=3Ch,AX=4301h,AX=5D00h,INT 2F/AX=1116h,INT 2F/AX=1226h

Bitfields for access and sharing modes:
 bits 2-0 access mode
    000 read only
    001 write only
    010 read/write
    011 (DOS 5+ internal) passed to redirector on EXEC to allow
        case-sensitive filenames
 bit 3    reserved (0)
 bits 6-4 sharing mode (DOS 3+)
    000 compatibility mode
    001 "DENYALL" prohibit both read and write access by others
    010 "DENYWRITE" prohibit write access by others
    011 "DENYREAD" prohibit read access by others
    100 "DENYNONE" allow full access by others
    111 network FCB (only available during server call)
 bit 7    inheritance
    if set, file is private to current process and will not be inherited
      by child processes

File sharing behavior:
      |    Second and subsequent Opens
 First      |Compat  Deny      Deny     Deny    Deny
 Open      |       All      Write     Read    None
      |R W RW R W RW R W RW R W RW R W RW
 - - - - -| - - - - - - - - - - - - - - - - -
 Compat R |Y Y Y  N N N     1 N N    N N N  1 N N
    W |Y Y Y  N N N     N N N    N N N  N N N
    RW|Y Y Y  N N N     N N N    N N N  N N N
 - - - - -|
 Deny    R |C C C  N N N     N N N    N N N  N N N
 All    W |C C C  N N N     N N N    N N N  N N N
    RW|C C C  N N N     N N N    N N N  N N N
 - - - - -|
 Deny    R |2 C C  N N N     Y N N    N N N  Y N N
 Write    W |C C C  N N N     N N N    Y N N  Y N N
    RW|C C C  N N N     N N N    N N N  Y N N
 - - - - -|
 Deny    R |C C C  N N N     N Y N    N N N  N Y N
 Read    W |C C C  N N N     N N N    N Y N  N Y N
    RW|C C C  N N N     N N N    N N N  N Y N
 - - - - -|
 Deny    R |2 C C  N N N     Y Y Y    N N N  Y Y Y
 None    W |C C C  N N N     N N N    Y Y Y  Y Y Y
    RW|C C C  N N N     N N N    N N N  Y Y Y
Legend: Y = open succeeds, N = open fails with error code 05h
    C = open fails, INT 24 generated
    1 = open succeeds if file read-only, else fails with error code
    2 = open succeeds if file read-only, else fails with INT 24
--------v-213DFF-----------------------------
INT 21 - VIRUS - "JD-448" - INSTALLATION CHECK
    AX = 3DFFh
Return: AX = 4A44h if resident
SeeAlso: AX=357Fh,AX=4203h
--------D-213E-------------------------------
INT 21 - DOS 2+ - "CLOSE" - CLOSE FILE
    AH = 3Eh
    BX = file handle
Return: CF clear if successful
        AX destroyed
    CF set on error
        AX = error code (06h) (see AH=59h)
Note:    if the file was written to, any pending disk writes are performed, the
      time and date stamps are set to the current time, and the directory
      entry is updated
SeeAlso: AH=10h,AH=3Ch,AH=3Dh,INT 2F/AX=1106h,INT 2F/AX=1227h
--------D-213F-------------------------------
INT 21 - DOS 2+ - "READ" - READ FROM FILE OR DEVICE
    AH = 3Fh
    BX = file handle
    CX = number of bytes to read
    DS:DX -> buffer for data
Return: CF clear if successful
        AX = number of bytes actually read (0 if at EOF before call)
    CF set on error
        AX = error code (05h,06h) (see AH=59h)
Notes:    data is read beginning at current file position, and the file position
      is updated after a successful read
    the returned AX may be smaller than the request in CX if a partial
      read occurred
    if reading from CON, read stops at first CR
    under the FlashTek X-32 DOS extender, the pointer is in DS:EDX
SeeAlso: AH=27h,AH=40h,AH=93h,INT 2F/AX=1108h,INT 2F/AX=1229h
--------G-213F-------------------------------
INT 21 - Turbo Debug HARDWARE BREAKPOINTS - READ STATUS BLOCK
    AH = 3Fh
    BX = handle for character device "TDHDEBUG"
    CX = number of bytes to read
    DS:DX -> buffer for status block (see below)
Return: CF clear if successful
        AX = number of bytes actually read
    CF set on error
        AX = error code (05h,06h) (see AH=59h)
SeeAlso: AH=40h"Turbo Debug"

Values for status of command:
 00h    successful
 01h    invalid handle
 02h    no more breakpoints available
 03h    hardware does not support specified breakpoint type
 04h    previous command prevents execution
 05h    debugger hardware not found
 06h    hardware failure
 07h    invalid command
 08h    driver not initialized yet
 FEh    recursive entry (hardware breakpoint inside hw bp handler)

Format of status block:
Offset    Size    Description
 00h    BYTE    status of command (see above)
---status for command 01h---
 01h    WORD    device driver interface version number (currently 1)
 03h    WORD    device driver software version
 05h    BYTE    maximum simultaneous hardware breakpoints
 06h    BYTE    configuration bits (see below)
 07h    BYTE    supported breakpoint types (see below)
 08h    WORD    supported addressing match modes (see below)
 0Ah    WORD    supported data matches (see below)
 0Ch    BYTE    maximum data match length (01h, 02h, or 04h)
 0Dh    WORD    size of onboard memory (in KB)
 0Fh    WORD    maximum number of trace-back events
 11h    WORD    hardware breakpoint enable byte address segment (0000h if not
        supported)
---status for command 04h---
 01h    BYTE    handle to use when referring to the just-set breakpoint

Bitfields for configuration bits:
 bit 0    CPU and DMA accesses are distinct
 bit 1    can detect DMA transfers
 bit 2    supports data mask
 bit 3    hardware pass counter on breakpoints
 bit 4    can match on data as well as addresses

Bitfields for supported breakpoint types:
 bit 0    memory read
 bit 1    memory write
 bit 2    memory read/write
 bit 3    I/O read
 bit 4    I/O write
 bit 5    I/O read/write
 bit 6    instruction fetch

Bitfields for supported addressing match modes:
 bit 0    any address
 bit 1    equal to test value
 bit 2    not equal
 bit 3    above test value
 bit 4    below test value
 bit 5    below or equal
 bit 6    above or equal
 bit 7    within range
 bit 8    outside range

Bitfields for supported data matches:
 bit 0    any data
 bit 1    equal to test value
 bit 2    not equal
 bit 3    above test value
 bit 4    below test value
 bit 5    below or equal
 bit 6    above or equal
 bit 7    within range
 bit 8    outside range
--------N-213F-------------------------------
INT 21 - PC/TCP IPCUST.SYS - READ CONFIGURATION DATA
    AH = 3Fh
    BX = handle for character device "$IPCUST"
    CX = number of bytes to read
    DS:DX -> buffer for configuration data (see below)
Return: CF clear if successful
        AX = number of bytes actually read
    CF set on error
        AX = error code (05h,06h) (see AH=59h)
Notes:    if less than the entire data is read or written, the next read/write
      continues where the previous one ended; IOCTL calls AX=4402h and
      AX=4403h both reset the location at which the next operation starts
      to zero
    the data pointer is also reset to zero if the previous read or write
      reached or exceeded the end of the data, when the current function
      is read and the previous was write, or vice versa
    v2.1+ uses a new configuration method, but allows the installation
      of IPCUST.SYS for backward compatibility with other software which
      must read the PC/TCP configuration
SeeAlso: AH=40h"IPCUST",AX=4402h"IPCUST",AX=4402h"FTPSOFT"

Format of configuration data:
Offset    Size    Description
 00h 12 BYTEs    IPCUST.SYS device driver header
 12h    BYTE    ???
 13h    BYTE    ???
 14h    WORD    ???
 16h    BYTE    bit flags
        bit 0: send BS rather than DEL for BackSpace key
        bit 1: wrap long lines
 17h    BYTE    ???
 18h 64 BYTEs    ASCIZ hostname
 58h 64 BYTEs    ASCIZ domain name
        (fully qualified domain name is hostname.domain-name)
 98h 16 BYTEs    ASCIZ username
 A8h 64 BYTEs    ASCIZ full name
 E8h 64 BYTEs    ASCIZ office address
128h 32 BYTEs    ASCIZ phone number
148h    WORD    offset from GMT in minutes
14Ah  4 BYTEs    ASCIZ timezone name
14Eh    WORD    number of time servers
150h  ? DWORDs    (big-endian) IP addresses for time servers
    ???
164h    WORD    number of old-style name servers
166h  3 DWORDs    (big-endian) IP addresses for name servers
172h    WORD    number of domain name servers
174h  3 DWORDs    (big-endian) IP addresses for domain name servers
180h    DWORD    (big-endian) IP address of default gateway
184h    DWORD    (big-endian) IP address of log server
188h    DWORD    (big-endian) IP address of cookie server
18Ch    DWORD    (big-endian) IP address of lpr server
190h    DWORD    (big-endian) IP address of imagen print server
194h 54 BYTEs    ???
1E8h    WORD    TCP default window size in bytes
1EAh    WORD    TCP low window size
1ECh 64 BYTEs    ASCIZ host tabel filename
22Ch  2 BYTEs    ???
22Eh 80 BYTEs    ASCIZ mail relay host name
27Eh    BYTE    ???
27Fh    BYTE    ??? bit flags
280h 44 BYTEs    ???
2ACh    WORD    ???
2AEh 202 BYTEs    ???
--------N-213F-------------------------------
INT 21 - WORKGRP.SYS - GET ENTRY POINT
    AH = 3Fh
    BX = file handle for device "NET$HLP$"
    CX = 0008h
    DS:DX -> buffer for entry point record (see AX=4402h"WORKGRP.SYS")
Return: CF clear if successful
        AX = number of bytes actually read (0 if at EOF before call)
    CF set on error
        AX = error code (05h,06h) (see AH=59h)
Program: WORKGRP.SYS is distributed with MS-DOS 6.0 to permit communication
      with PCs running Windows for Workgroups or LAN Manager
SeeAlso: AX=4402h"WORKGRP.SYS",INT 2F/AX=9400h
--------N-213F-------------------------------
INT 21 - BW-TCP - GET DRIVER INFO
    AH = 3Fh
    BX = file handle for device "ETHDEV27"
    CX = 002Bh
    DS:DX -> buffer for driver info (see below)
Return: CF clear if successful
        AX = number of bytes actually read (0 if at EOF before call)
    CF set on error
        AX = error code (05h,06h) (see AH=59h)
Program: BW-TCP is a TCP/IP protocol stack by Beame & Whiteside Software
Notes:    the B&W socket library performs an INT 21/AX=4401h with DX=0060h before
      making this call to retrieve the driver information; one should also
      call the private API interrupt with AH=15h
    the installation check for the TCP/IP stack is to test for the
      existence of the character device UDP-IP10
Index:    installation check;BW-TCP hardware driver
Index:    installation check;BW-TCP TCPIP.SYS

Format of driver info:
Offset    Size    Description
 00h    WORD    I/O base address
 02h    BYTE    shared memory page (01h = segment 0100h, etc.)
 03h    BYTE    interrupt vector for private API
 04h    BYTE    IRQ used by board
 05h    WORD    size of data buffer
 07h    WORD    maximum transfer window
 09h    WORD    time zone
 0Bh    BYTE    address type (01h user, 04h RARP, 05h BOOTP)
 0Ch    DWORD    internet address
 10h    WORD    "value" ???
 12h    BYTE    subnet mask
 13h    WORD    "ether_pointer" ???
 15h    WORD    offset in device driver of log server records
 17h    WORD    offset in device driver of name server records
 19h    WORD    offset in device driver of print server records
 1Bh    WORD    offset in device driver of time server records
 1Dh    WORD    offset in device driver of gateway records
 1Fh    WORD    segment address of device driver
 21h    BYTE    transfer size
 22h  9 BYTEs    network adapter board name
---11/21/91+ ---
 23h    BYTE    ETHDEV version (major in high nybble, minor in low nybble)
 24h    BYTE    ETHDEV revision
 25h    BYTE    TCPIP version (major in high nybble, minor in low nybble)
 26h    BYTE    TCPIP revision
 27h    BYTE    BWRPC version (major in high nybble, minor in low nybble)
 28h    BYTE    BWRPC revision
 29h    BYTE    BWNFS version (major in high nybble, minor in low nybble)
 2Ah    BYTE    BWNFS revision
 2Bh    BYTE    Telnet version (major in high nybble, minor in low nybble)
 2Ch    BYTE    Telnet revision
 2Dh    BYTE    NETBIOS version (major in high nybble, minor in low nybble)
 2Eh    BYTE    NETBIOS revision
Note:    for each driver, if version=0, the driver is not installed or does
      not support the version check

Format of server records:
Offset    Size    Description
 00h    BYTE    number of server records following
 01h  N DWORDs    internet addresses of servers
--------y-213F-------------------------------
INT 21 - Trusted Access - NB.SYS - GET STATE
    AH = 3Fh
    BX = file handle for device "$$NB$$NB"
    CX = 0002h (size of state)
    DS:DX -> buffer for state record
Return: CF clear if successful
        AX = number of bytes actually read (0 if at EOF before call)
    CF set on error
        AX = error code (05h,06h) (see AH=59h)
Program: Trusted Access is a security and access-control package by Lassen
      Software, Inc.; NB.SYS is a device driver to prevent the user from
      terminating CONFIG.SYS or AUTOEXEC.BAT with Ctrl-Break
SeeAlso: AH=40h"NB.SYS",AX=4101h

Format of state record:
Offset    Size    Description
 00h    BYTE    00h off, 01h on
 01h    BYTE    keys being disabled
        bit 0: Ctrl-Break
        bit 1: SysRq
        bit 2: Ctrl and Alt
        bit 3: Ctrl-Alt-Del
        bit 7: all keys (overrides other bits)
--------D-2140-------------------------------
INT 21 - DOS 2+ - "WRITE" - WRITE TO FILE OR DEVICE
    AH = 40h
    BX = file handle
    CX = number of bytes to write
    DS:DX -> data to write
Return: CF clear if successful
        AX = number of bytes actually written
    CF set on error
        AX = error code (05h,06h) (see AH=59h)
Notes:    if CX is zero, no data is written, and the file is truncated or
      extended to the current position
    data is written beginning at the current file position, and the file
      position is updated after a successful write
    the usual cause for AX < CX on return is a full disk
BUG:    a write of zero bytes will appear to succeed when it actually failed
      if the write is extending the file and there is not enough disk
      space for the expanded file (DOS 5.0-6.0); one should therefore check
      whether the file was in fact extended by seeking to 0 bytes from
      the end of the file (INT 21/AX=4202h/CX=0/DX=0)
    under the FlashTek X-32 DOS extender, the pointer is in DS:EDX
SeeAlso: AH=28h,AH=3Fh,AH=93h,INT 2F/AX=1109h
--------G-2140-------------------------------
INT 21 - Turbo Debug HARDWARE BREAKPOINTS - SEND CMD TO HARDWARE BRKPNT DRIVER
    AH = 40h
    BX = handle for character device "TDHDEBUG"
    CX = number of bytes to write
    DS:DX -> hardware breakpoint command (see below)
Return: CF clear if successful
        AX = number of bytes actually written
    CF set on error
        AX = error code (05h,06h) (see AH=59h)
Note:    results are retrieved by reading from the device
SeeAlso: AH=3Fh"Turbo Debug"

Format of hardware breakpoint commands:
Offset    Size    Description
 00h    BYTE    command code
        00h install interrupt vectors
        01h get hardware capabilities
        02h enable hardware breakpoints
        03h disable hardware breakpoints
        04h set hardware breakpoint
        05h clear hardware breakpoint
        06h set I/O base address and reset hardware
        07h restore interrupt vectors
---command code 00h---
 01h    DWORD    pointer to Turbo Debugger entry point to be jumped to on
        hardware breakpoint; call with CPU state the same as on
        the breakpoint except for pushing AX and placing an entry
        code (FFh if breakout button or breakpoint handle) in AH
---command code 04h---
 01h    BYTE    breakpoint type
        00h memory read
        01h memory write
        02h memory read/write
        03h I/O read
        04h I/O write
        05h I/O read/write
        06h instruction fetch
 02h    BYTE    address matching mode
        00h any address
        01h equal to test value
        02h different from test value
        03h above test value
        04h below test value
        05h below or equal to test value
        06h above or equal to test value
        07h within inclusive range
        08h outside specified range
 03h    DWORD    32-bit linear low address
 07h    DWORD    32-bit linear high address
 0Bh    WORD    pass count
 0Dh    BYTE    data size (01h, 02h, or 04h)
 0Eh    BYTE    source of matched bus cycle
        01h CPU
        02h DMA
        03h either
 0Fh    BYTE    data-matching mode
        00h match any
        01h equal to test value
        02h different from test value
        03h above test value
        04h below test value
        05h below or equal to test value
        06h above or equal to test value
        07h within specified range
        08h outside specified range
 10h    DWORD    low data value
 14h    DWORD    high data value
 18h    DWORD    data mask specifying which bits of the data are tested
---command code 05h---
 01h    BYTE    handle of breakpoint to clear (breakpoint returned from command
        04h)
---command code 06h---
 01h    WORD    base address of hardware debugger board
--------N-2140-------------------------------
INT 21 - PC/TCP IPCUST.SYS - WRITE CONFIGURATION DATA
    AH = 40h
    BX = handle for character device "$IPCUST"
    CX = number of bytes to write
    DS:DX -> buffer for configuration data (AH=3Fh"IPCUST")
Return: CF clear if successful
        AX = number of bytes actually written
    CF set on error
        AX = error code (05h,06h) (see AH=59h)
Notes:    if less than the entire data is read or written, the next read/write
      continues where the previous one ended; IOCTL calls AX=4402h and
      AX=4403h both reset the location at which the next operation starts
      to zero
    the data pointer is also reset to zero if the previous read or write
      reached or exceeded the end of the data, when the current function
      is read and the previous was write, or vice versa
    v2.1+ uses a new configuration method, but allows the installation
      of IPCUST.SYS for backward compatibility with other software which
      must read the PC/TCP configuration
SeeAlso: AH=3Fh"IPCUST",AX=4402h"IPCUST"
--------y-2140-------------------------------
INT 21 U - Trusted Access - NB.SYS - SET STATE
    AH = 40h
    BX = handle for character device "$$NB$$NB"
    DS:DX -> state record (see AH=3Fh"NB.SYS")
    CX ignored
Return: CF clear if successful
        AX = number of bytes actually written
    CF set on error
        AX = error code (05h,06h) (see AH=59h)
Program: Trusted Access is a security and access-control package by Lassen
      Software, Inc.; NB.SYS is a device driver to prevent the user from
      terminating CONFIG.SYS or AUTOEXEC.BAT with Ctrl-Break
SeeAlso: AH=3Fh"NB.SYS"
--------j-214000BX0002-----------------------
INT 21 - FARTBELL.EXE - INSTALLATION CHECK
    AX = 4000h
    BX = 0002h
    CX = 0000h
    DS:DX = 0000h:0000h
Return: CF clear if installed
        AX = CS of resident code
Program: FARTBELL is a joke program by Guenther Thiele which makes various
      noises when programs output a bell
SeeAlso: AX=4001h
--------j-214001BX0002-----------------------
INT 21 - FARTBELL.EXE - FORCE NOISE
    AX = 4001h
    BX = 0002h
    CX = 0000h
    DS:DX = 0000h:0000h
Program: FARTBELL is a joke program by Guenther Thiele which makes various
      noises when programs output a bell
SeeAlso: AX=4000h
--------D-2141-------------------------------
INT 21 - DOS 2+ - "UNLINK" - DELETE FILE
    AH = 41h
    DS:DX -> ASCIZ filename (no wildcards, but see below)
    CL = attribute mask for deletion (server call only, see below)
Return: CF clear if successful
        AX destroyed (DOS 3.3) AL seems to be drive of deleted file
    CF set on error
        AX = error code (02h,03h,05h) (see AH=59h)
Notes:    (DOS 3.1+) wildcards are allowed if invoked via AX=5D00h, in which case
      the filespec must be canonical (as returned by AH=60h), and only
      files matching the attribute mask in CL are deleted
    DR-DOS 5.0-6.0 returns error code 03h if invoked via AX=5D00h
    DOS does not erase the file's data; it merely becomes inaccessible
      because the FAT chain for the file is cleared
    deleting a file which is currently open may lead to filesystem
      corruption.  Unless SHARE is loaded, DOS does not close the handles
      referencing the deleted file, thus allowing writes to a nonexistant
      file.
    under DRDOS and DR Multiuser DOS, this function will fail if the file
      is currently open
    under the FlashTek X-32 DOS extender, the pointer is in DS:EDX
BUG:    DR-DOS 3.41 crashes if called via AX=5D00h
SeeAlso: AH=13h,AX=4301h,AX=4380h,AX=5D00h,AH=60h,AX=F244h,INT 2F/AX=1113h
--------y-214101DXFFFE-----------------------
INT 21 - SoftLogic Data Guardian - ???
    AX = 4101h
    DX = FFFEh
Return: AX = 0000h if installed
Note:    resident code sets several internal variables on this call
SeeAlso: AH=3Fh"NB.SYS",INT 16/AX=FFA3h/BX=0000h
--------!------------------------------------