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MEMORY.LST
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1996-07-28
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MEMORY MAP Release 51 Last change 7/28/96
Copyright (c) 1989,1990,1991,1992,1993,1994,1995,1996 Ralf Brown
--------H-M00000000--------------------------
MEM 0000h:0000h R - INTERRUPT VECTOR TABLE
Size: 1024 BYTEs
Note: see also the main interrupt list
--------b-M0000031D--------------------------
MEM 0000h:031Dh - 1989 AMI 386sx BIOS - USER-DEFINABLE TYPE 47 HARD DISK PARMS
Size: 16 BYTEs
Note: these fields are used if the AMI BIOS setup is set to use the top of
the interrupt table for the extended BIOS data area
SeeAlso: MEM 0000h:032Dh,INT 41
--------b-M0000032D--------------------------
MEM 0000h:032Dh - 1989 AMI 386sx BIOS - USER-DEFINABLE TYPE 48 HARD DISK PARMS
Size: 16 BYTEs
Note: these fields are used if the AMI BIOS setup is set to use the top of
the interrupt table for the extended BIOS data area
SeeAlso: MEM 0000h:031Dh,INT 46
--------B-M00000400--------------------------
MEM 0000h:0400h - BIOS DATA AREA
Size: 256 BYTEs
Note: see also the MEM 0040h:xxxxh entries
----------M00000500--------------------------
MEM 0000h:0500h - DATA AREA
Size: 256 BYTEs
----------M00000600--------------------------
MEM 0000h:0600h - MS-DOS 1.x LOAD ADDRESS
----------M00000700--------------------------
MEM 0000h:0700h - MS-DOS 2+ LOAD ADDRESS
----------M00400000--------------------------
MEM 0040h:0000h - BASE I/O ADDRESS OF FIRST SERIAL I/O PORT
Size: WORD
Notes: the BIOS sets this word to zero if is unable to find any serial ports
at the addresses it is programmed to check at boot
DOS and BIOS serial device numbers may be redefined by re-assigning
these values of the base I/O addresses stored here
SeeAlso: MEM 0040h:0002h,MEM 0040h:0004h,MEM 0040h:0006h,MEM 0040h:0008h
SeeAlso: MEM 0040h:007Ch
----------M00400002--------------------------
MEM 0040h:0002h - BASE I/O ADDRESS OF SECOND SERIAL I/O PORT
Size: WORD
Note: the BIOS sets this word to zero if is unable to find more than one
serial port at the addresses it is programmed to check at boot
SeeAlso: MEM 0040h:0000h,MEM 0040h:0004h,MEM 0040h:0006h,MEM 0040h:000Ah
SeeAlso: MEM 0040h:007Dh
----------M00400004--------------------------
MEM 0040h:0004h - BASE I/O ADDRESS OF THIRD SERIAL I/O PORT
Size: WORD
Note: the BIOS sets this word to zero if is unable to find more than two
serial ports at the addresses it is programmed to check at boot
SeeAlso: MEM 0040h:0000h,MEM 0040h:0002h,MEM 0040h:0006h,MEM 0040h:000Ch
SeeAlso: MEM 0040h:007Eh
----------M00400006--------------------------
MEM 0040h:0006h - BASE I/O ADDRESS OF FOURTH SERIAL I/O PORT
Size: WORD
Note: the BIOS sets this word to zero if is unable to find more than three
serial ports at the addresses it is programmed to check at boot
SeeAlso: MEM 0040h:0000h,MEM 0040h:0002h,MEM 0040h:0004h,MEM 0040h:0008h
SeeAlso: MEM 0040h:007Fh
----------M00400008--------------------------
MEM 0040h:0008h - BASE I/O ADDRESS OF FIRST PARALLEL I/O PORT
Size: WORD
Notes: the BIOS POST routine fills in the parallel port address fields in
turn as it finds parallel ports. All fields beyond the last one
for which a valid parallel port was found are set to zero.
the BIOS INT 17 handler uses these fields to address the parallel
ports
SeeAlso: MEM 0040h:0000h,MEM 0040h:000Ah,MEM 0040h:000Ch
----------M0040000A--------------------------
MEM 0040h:000Ah - BASE I/O ADDRESS OF SECOND PARALLEL I/O PORT
Size: WORD
Note: zero if fewer than two parallel ports installed
SeeAlso: MEM 0040h:0002h,MEM 0040h:0008h,MEM 0040h:000Ch
----------M0040000C--------------------------
MEM 0040h:000Ch - BASE I/O ADDRESS OF THIRD PARALLEL I/O PORT
Size: WORD
Note: zero if fewer than three parallel ports installed
SeeAlso: MEM 0040h:0004h,MEM 0040h:0008h,MEM 0040h:000Ah,MEM 0040h:000Eh
----------M0040000E--------------------------
MEM 0040h:000Eh - BASE I/O ADDRESS OF FOURTH PARALLEL I/O PORT (pre-PS/2)
Size: WORD
Note: zero if fewer than four parallel ports installed
SeeAlso: MEM 0040h:0008h,MEM 0040h:000Ah,MEM 0040h:000Eh"BIOS DATA"
----------M0040000E--------------------------
MEM 0040h:000Eh - SEGMENT OF EXTENDED BIOS DATA SEGMENT (PS/2, newer BIOSes)
Size: WORD
SeeAlso: MEM 0040h:000Eh"PARALLEL"
Format of Extended BIOS Data Area (IBM):
Offset Size Description (Table M001)
00h BYTE length of EBDA in kilobytes
01h 15 BYTEs reserved
17h BYTE number of entries in POST error log (0-5)
18h 5 WORDs POST error log (each word is a POST error number)
22h DWORD Pointing Device Driver entry point
26h BYTE Pointing Device Flags 1 (see #M002)
27h BYTE Pointing Device Flags 2 (see #M003)
28h 8 BYTEs Pointing Device Auxiliary Device Data
30h DWORD Vector for INT 07h stored here during 80387 interrupt
34h DWORD Vector for INT 01h stored here during INT 07h emulation
38h BYTE Scratchpad for 80287/80387 interrupt code
39h WORD Timer3: Watchdog timer initial count
3Bh BYTE ??? seen non-zero on Model 30
3Ch BYTE ???
3Dh 16 BYTEs Fixed Disk parameter table for drive 0 (for older machines
which don't directly support the installed drive)
4Dh 16 BYTEs Fixed Disk parameter table for drive 1 (for older machines
which don't directly support the installed drive)
5Dh-67h ???
68h BYTE cache control
bits 7-2 unused (0)
bit 1: CPU cache failed test
bit 0: CPU cache disabled
69h-6Bh ???
6Ch BYTE Fixed disk: (=FFh on ESDI systems)
bits 7-4: Channel number 00-0Fh
bits 3-0: DMA arbitration level 00-0Eh
6Dh BYTE ???
6Eh WORD current typematic setting (see INT 16/AH=03h)
70h BYTE number of attached hard drives
71h BYTE hard disk 16-bit DMA channel
72h BYTE interrupt status for hard disk controller (1Fh on timeout)
73h BYTE hard disk operation flags
bit 7: controller issued operation-complete INT 76h
bit 6: controller has been reset
bits 5-0: unused (0)
74h DWORD old INT 76h vector
78h BYTE hard disk DMA type
typically 44h for reads and 4Ch for writes
79h BYTE status of last hard disk operation
7Ah BYTE hard disk timeout counter
7Bh-7Dh
7Eh 8 WORDs storage for hard disk controller status
8Eh-E6h
E7h BYTE floppy drive type
bit 7: drive(s) present
bits 6-2: unused (0)
bit 1: drive 1 is 5.25" instead of 3.5"
bit 0: drive 0 is 5.25"
E8h 4 BYTEs ???
ECh BYTE hard disk parameters flag
bit 7: parameters loaded into EBDA
bits 6-0: unused (0)
EDh BYTE ???
EEh BYTE CPU family ID (03h = 386, 04h = 486, etc.) (see INT 15/AH=C9h)
EFh BYTE CPU stepping (see INT 15/AH=C9h)
F0h 39 BYTEs ???
117h WORD keyboard ID (see INT 16/AH=0Ah)
(most commonly 41ABh)
119h BYTE ???
11Ah BYTE non-BIOS INT 18h flag
bits 7-1: unused (0)
bit 0: set by BIOS before calling user INT 18h at offset 11Dh
11Bh 2 BYTE ???
11Dh DWORD user INT 18h vector if BIOS has re-hooked INT 18h
121h and up: ??? seen non-zero on Model 60
3F0h BYTE Fixed disk buffer (???)
SeeAlso: #M004
Bitfields for Pointing Device Flags 1:
Bit(s) Description (Table M002)
7 command in progress
6 resend byte (FAh) received
5 acknowledge byte (FEh) received
4 error byte (FCh) received
3 unexpected value received
2-0 index count for auxiliary device data at 28h
SeeAlso: #M001,#M003
Bitfields for Pointing Device Flags 2:
Bit(s) Description (Table M003)
7 device driver far call flag
6-3 reserved
2-0 package size (number of bytes received) - 1
SeeAlso: #M001,#M002
Format of Extended BIOS Data Area (AMI v1.00.12.AX1T):
Offset Size Description (Table M004)
00h BYTE length of XBDA in kilobytes
01h 15 BYTEs reserved
17h BYTE number of entries in POST error log (0-10)
18h 10 BYTEs unused???
22h DWORD Pointing Device Driver entry point
26h BYTE Pointing Device Flags 1 (see #M002)
27h BYTE Pointing Device Flags 2 (see #M003)
28h 8 BYTEs Pointing Device Auxiliary Device Data
30h 13 BYTEs ???
3Dh 16 BYTEs Fixed Disk parameter table for drive 0
4Dh 16 BYTEs Fixed Disk parameter table for drive 1
5Dh 16 BYTEs parameter table for drive 2???
6Dh 16 BYTEs parameter table for drive 3???
80h 56 BYTEs? IDE drive 0 manufacturer/model string
B8h 41 BYTEs AMIBIOS copyright string
E1h unused???
102h WORD ??? flags
bit 15: ???
108h WORD offset of IntelIDECfgTbl (IDE configuration settings) within
segment F000h
10Ah 2 BYTEs ???
10Ch DWORD pointer to routine to call for language-specific error messages
110h WORD offset in segment F000h of end of currently-loaded optional
BIOS subsystems (language, APM, etc.)
112h WORD offset in segment F000h of end of area avaiable for loading
optional BIOS subsystems
1F0h BYTE APM status flags
1F1h 8 BYTEs APM power-state data for device classes 01h-06h
bits 0-3: current power state for devices 00h-03h in class
bits 7-4: current engaged state for devices 00h-03h in class
1F9h 4 BYTEs APM power-state data for device classes 01h-08h (four devices
per class)
1FDh 3 BYTEs ???
200h 10 WORDs POST error log
214h ???
SeeAlso: #M001
----------M00400010--------------------------
MEM 0040h:0010h - INSTALLED HARDWARE
Size: WORD
Bitfields for BIOS-detected installed hardware:
Bit(s) Description (Table M005)
15-14 number of parallel devices
00 or 11 sometimes used to indicate four LPT ports
13 (Convertible, PS/2-55LS) internal modem
12 game port installed
11-9 number of serial devices
000 or 111 sometimes used to indicate eight COM ports
8 reserved
7-6 number of floppy disk drives (minus 1)
5-4 initial video mode
00 EGA,VGA,PGA, or other with on-board video BIOS
01 40x25 CGA color
10 80x25 CGA color
11 80x25 mono text
3-2 (PC only) RAM on motherboard
00 = 16K, 01 = 32K, 10 = 48K, 11 = 64K
2 (pre-PS/2 except PC) reserved
(PS/2, newer BIOSes) pointing device installed
1 math coprocessor installed
0 floppy disk drives are installed
booted from floppy
----------M00400012--------------------------
MEM 0040h:0012h - Convertible - POST STATUS
Size: BYTE
----------M00400012--------------------------
MEM 0040h:0012h U - AT - MANUFACTURING TEST INITIALIZATION FLAGS
Size: BYTE
Bitfields for AT manufacturing test initialization flags:
Bit(s) Description (Table M006)
0 start in manufacturing test mode rather than normal operation
1-7 unused
----------M00400012--------------------------
MEM 0040h:0012h - MCA - MANUFACTURING TEST
Size: BYTE
Bitfields for MCA manufacturing test flags :
Bit(s) Description (Table M007)
7 POST flag, ???
6-5 unused
4 POST flag, slot 4 has adapter identifier EDAFh
3 POST flag, 80x25 color video
2 POST flag, ???
1 unused
0 manufacturing test mode rather than normal operation
----------M00400012--------------------------
MEM 0040h:0012h - PS/2 Model 25 - POST SYSTEM FLAG
Size: BYTE
Bitfields for PS/2 Model 25 POST sytem flag :
Bit(s) Description (Table M008)
0 optional memory failed; memory remapped
1 real-time clock installed
----------M00400013--------------------------
MEM 0040h:0013h - BASE MEMORY SIZE IN KBYTES
Size: WORD
----------M00400015--------------------------
MEM 0040h:0015h - PC, XT - ADAPTER MEMORY SIZE IN KBYTES
Size: WORD
----------M00400015--------------------------
MEM 0040h:0015h U - AT - MANUFACTURING TEST SCRATCH PAD
Size: BYTE
----------M00400015--------------------------
MEM 0040h:0015h - Compaq Deskpro 386 - PREVIOUS SCAN CODE
Size: BYTE
----------M00400016--------------------------
MEM 0040h:0016h U - AT - MANUFACTURING TEST SCRATCH PAD
Size: BYTE
----------M00400016--------------------------
MEM 0040h:0016h U - PS/2 Model 30 - BIOS CONTROL FLAGS
Size: BYTE
----------M00400016--------------------------
MEM 0040h:0016h - Compaq Deskpro 386 - KEYCLICK VOLUME
Size: BYTE
Range: 00h-7Fh
--------K-M00400017--------------------------
MEM 0040h:0017h - KEYBOARD - STATUS FLAGS 1
Size: BYTE
SeeAlso: MEM 0040h:0018h,INT 16/AH=01h
Bitfields for keyboard status flags 1:
Bit(s) Description (Table M009)
7 INSert active
6 Caps Lock active
5 Num Lock active
4 Scroll Lock active
3 either Alt pressed
2 either Ctrl pressed
1 Left Shift pressed
0 Right Shift pressed
SeeAlso: #M010
--------K-M00400018--------------------------
MEM 0040h:0018h - KEYBOARD - STATUS FLAGS 2
Size: BYTE
SeeAlso: MEM 0040h:0017h,INT 16/AH=01h
Bitfields for keyboard status flags 2 :
Bit(s) Description (Table M010)
7 INSert pressed
6 Caps Lock pressed
5 Num Lock pressed
4 Scroll Lock pressed
3 Pause state active
2 Sys Req pressed
1 Left Alt pressed
0 Left Ctrl pressed
SeeAlso: #M009
--------K-M00400019--------------------------
MEM 0040h:0019h - KEYBOARD - ALT-nnn KEYPAD WORKSPACE
Size: BYTE
Desc: holds the current value of an Alt-NNN keypad sequence; when Alt is
released and this byte is non-zero, the appropriate character is
placed in the keyboard buffer
SeeAlso: INT 16/AH=00h
--------K-M0040001A--------------------------
MEM 0040h:001Ah - KEYBOARD - POINTER TO NEXT CHARACTER IN KEYBOARD BUFFER
Size: WORD
SeeAlso: MEM 0040h:001Ch,MEM 0040h:0080h,MEM 0040h:0082h,INT 16/AH=00h
--------K-M0040001C--------------------------
MEM 0040h:001Ch - KEYBOARD - POINTER TO FIRST FREE SLOT IN KEYBOARD BUFFER
Size: WORD
SeeAlso: MEM 0040h:001Ah,MEM 0040h:0080h,MEM 0040h:0082h,INT 16/AH=00h
--------K-M0040001E--------------------------
MEM 0040h:001Eh - KEYBOARD - DEFAULT KEYBOARD CIRCULAR BUFFER
Size: 16 WORDs
SeeAlso: MEM 0040h:001Ah,MEM 0040h:001Ch,MEM 0040h:0080h,MEM 0040h:0082h
SeeAlso: INT 16/AH=00h
----------M0040003E--------------------------
MEM 0040h:003Eh - DISKETTE - RECALIBRATE STATUS
Size: BYTE
SeeAlso: MEM 0040h:003Fh,MEM 0040h:0040h
Bitfields for diskette recalibrate status:
Bit(s) Description (Table M011)
7 diskette hardware interrupt occurred
6-4 reserved
3 recalibrate diskette 3 (PC,XT only)
2 recalibrate diskette 2 (PC,XT only)
1 recalibrate diskette 1
0 recalibrate diskette 0
----------M0040003F--------------------------
MEM 0040h:003Fh - DISKETTE - MOTOR STATUS
Size: BYTE
SeeAlso: MEM 0040h:003Eh,MEM 0040h:0040h
Bitfields for diskette motor status:
Bit(s) Description (Table M012)
7 current operation is write or format, rather than read or verify
6 reserved (DMA enabled on 82077)
5-4 diskette drive number selected (0-3)
3 diskette 3 motor on (PC,XT only)
2 diskette 2 motor on (PC,XT only)
1 diskette 1 motor on
0 diskette 0 motor on
----------M00400040--------------------------
MEM 0040h:0040h - DISKETTE - MOTOR TURN-OFF TIMEOUT COUNT
Size: BYTE
Desc: number of clock ticks until diskette motor is turned off
Note: the typical implementation of the timeout is to have the INT 08
handler decrement this byte on every clock tick, and force the
diskette motor off if the result is equal to zero
SeeAlso: MEM 0040h:003Eh,MEM 0040h:003Fh,MEM 0040h:0041h
----------M00400041--------------------------
MEM 0040h:0041h - DISKETTE - LAST OPERATION STATUS
Size: BYTE
SeeAlso: MEM 0040h:003Eh
Bitfields for diskette last operation status:
Bit(s) Description (Table M013)
7 drive not ready
6 seek error
5 general controller failure
4-0 error reason
00h no error
01h invalid request/parameter
02h address mark not found
03h write-protect error
04h sector not found
06h diskette change line active
08h DMA overrun
09h DMA across 64k boundary
0Ch media type unknown
10h CRC error on read
Note: the following values for this byte differ somewhat from the
bitfield definition above:
30h drive does not support media sense
31h no media in drive
32h drive does not support media type
AAh diskette drive not ready
----------M00400042--------------------------
MEM 0040h:0042h - DISK - FLOPPY/HARD DRIVE STATUS/COMMAND BYTES
Size: 7 BYTEs
42h BYTE XT: command byte to hard disk controller
AT: write precompensation cylinder number / 4
43h BYTE XT: bit 5 = drive number, bits 3-0=head number
AT: sector count
44h BYTE XT: bits 6,7 = high bits of track, bits 5-0 = start sector-1
AT: starting sector
45h BYTE low byte of track number
46h BYTE XT: sector count
AT: high bits of track number
47h BYTE XT: controlbyte from HD parameters (step rate,...)
AT: 101DHHHH, D=drive number, HHHH=head number
48h BYTE XT: INT 13h subfunction number
AT: comand byte to hard disk controller
----------M00400042--------------------------
MEM 0040h:0042h - DISK CONTROLLER STATUS REGISTER 0
Size: BYTE
Bitfields for diskette controller status register 0:
Bit(s) Description (Table M014)
7-6 interrupt code
00 normal completion
01 abnormal termination during execution
10 invalid command
11 abnormal termination: ready line on/diskette change
5 requested seek complete
4 drive fault
3 drive not ready
2 head state at time of interrupt
1-0 selected drive (drives 2&3 on PC,XT only)
----------M00400043--------------------------
MEM 0040h:0043h - DISK CONTROLLER STATUS REGISTER 1
Size: BYTE
Bitfields for diskette controller status register 0:
Bit(s) Description (Table M015)
7 attempted access beyon last cylinder
6 unused
5 CRC error on read
4 DMA overrun
3 unused
2 data error
1 disk write protected
0 missing address mark
----------M00400044--------------------------
MEM 0040h:0044h - DISK CONTROLLER STATUS REGISTER 2
Size: BYTE
Bitfields for diskette controller status register 0:
Bit(s) Description (Table M016)
7 unused
6 found deleted data address mark
5 CRC error in data field
4 wrong cylinder number read
3 verify equal
2 can't find sector matching verify condition
1 bad cylinder
0 unable to find address mark
----------M00400049--------------------------
MEM 0040h:0049h - VIDEO - CURRENT VIDEO MODE
Size: BYTE
SeeAlso: MEM 0040h:004Ah,INT 10/AH=00h
----------M0040004A--------------------------
MEM 0040h:004Ah - VIDEO - COLUMNS ON SCREEN
Size: WORD
SeeAlso: MEM 0040h:0049h,MEM 0040h:004Ch,MEM 0040h:004Eh
----------M0040004C--------------------------
MEM 0040h:004Ch - VIDEO - PAGE (REGEN BUFFER) SIZE IN BYTES
Size: WORD
SeeAlso: MEM 0040h:004Ah,MEM 0040h:004Eh,MEM 0040h:0050h
----------M0040004E--------------------------
MEM 0040h:004Eh - VIDEO - CURRENT PAGE START ADDRESS IN REGEN BUFFER
Size: WORD
SeeAlso: MEM 0040h:004Ch,MEM 0040h:0050h,MEM 0040h:0062h
----------M00400050--------------------------
MEM 0040h:0050h - VIDEO - CURSOR POSITIONS
Size: 8 WORDs
Desc: contains row and column position for the cursors on each of eight
video pages
SeeAlso: MEM 0040h:004Eh,MEM 0040h:0060h
----------M00400060--------------------------
MEM 0040h:0060h - VIDEO - CURSOR TYPE
Size: WORD (big-endian)
Desc: contains cursor start scan line and cursor end scan line
SeeAlso: MEM 0040h:0050h,MEM 0040h:0062h,INT 10/AH=03h
----------M00400062--------------------------
MEM 0040h:0062h - VIDEO - CURRENT PAGE NUMBER
Size: BYTE
SeeAlso: MEM 0040h:004Eh,MEM 0040h:0063h
----------M00400063--------------------------
MEM 0040h:0063h - VIDEO - CRT CONTROLLER BASE I/O PORT ADDRESS
Size: WORD
Note: normally 03B4h for mono and 03D4h for color video boards
SeeAlso: MEM 0040h:0065h,MEM 0040h:0066h
----------M00400065--------------------------
MEM 0040h:0065h - VIDEO - CURRENT MODE SELECT REGISTER
Size: BYTE
Desc: contains last value written to I/O port 03B8h / 03D8h
SeeAlso: MEM 0040h:0063h,MEM 0040h:0066h
Bitfields for current video mode select register:
Bit(s) Description (Table M017)
7-6 unused
5 attribute bit 7 controls blinking instead of background
4 mode 6 graphics in monochrome
3 video signal enabled
2 monochrome
1 graphics
0 80x25 text
----------M00400066--------------------------
MEM 0040h:0066h - VIDEO - CURRENT SETTING OF CGA PALETTE REGISTER
Size: BYTE
Desc: contains the last value written to I/O port 03D9h
SeeAlso: MEM 0040h:0063h,MEM 0040h:0065h,INT 10h/AH=0Bh/BH=01h
Bitfields for CGA palette register:
Bit(s) Description (Table M018)
7-6 unused
5 palette (0/1)
4 intense background colors in text mode
3 intense border color (40x25) / background color (mode 5)
2 red
1 green
0 blue
----------M00400067--------------------------
MEM 0040h:0067h - PC only - CASSETTE TIME COUNT
Size: WORD
SeeAlso: INT 15/AH=00h
----------M00400067--------------------------
MEM 0040h:0067h - RESET RESTART ADDRESS
Size: DWORD
Desc: this address stores the address at which to resume execution after a
CPU reset (or jump to F000h:FFF0h) when certain magic values are
stored at 0040h:0072h or in CMOS RAM location 0Fh
SeeAlso: MEM 0040h:0072h,MEM F000h:FFF0h,CMOS 0Fh,INT 19
----------M00400069--------------------------
MEM 0040h:0069h - CASSETTE (PC only) - CASSETTE CRC REGISTER
Size: WORD
SeeAlso: MEM 0040h:006Bh"CASSETTE"
----------M00400069--------------------------
MEM 0040h:0069h - V20-XT-BIOS - KEY REPEAT
Size: BYTE
Bitfields for V20-XT-BIOS key repeat flags:
Bit(s) Description (Table M019)
7 key repeat disabled
6 Ctrl-Alt pressed instead of just Alt
----------M0040006B--------------------------
MEM 0040h:006Bh - CASSETTE (PC only) - LAST VALUE READ FROM CASSETTE
Size: BYTE
SeeAlso: MEM 0040h:0069h"CASSETTE"
----------M0040006B--------------------------
MEM 0040h:006Bh - POST LAST UNEXPECTED INTERRUPT (XT and later)
Size: BYTE
Desc: this is a bitmask of IRQs which have occurred while the corresponding
interrupt vector points at the default system BIOS handler
(bit 0 = IRQ0 to bit 7 = IRQ7)
----------M0040006C--------------------------
MEM 0040h:006Ch - TIMER TICKS SINCE MIDNIGHT
Size: DWORD
SeeAlso: MEM 0040h:0070h,INT 1A/AH=00h
----------M00400070--------------------------
MEM 0040h:0070h - TIMER OVERFLOW
Size: BYTE
Desc: non-zero if timer has counted past midnight since last call to
INT 1A/AH=00h
Note: the original IBM BIOS, and thus most other BIOSes, sets this byte to
01h at midnight; a few (such as the Eagle PC-2) increment it each
time midnight is passed. The former behavior results in lost days
if multiple midnights pass between "get-time" calls while the machine
is powered up.
SeeAlso: MEM 0040h:006Ch
----------M00400071--------------------------
MEM 0040h:0071h - Ctrl-Break FLAG
Size: BYTE
Desc: bit 7 is set when Ctrl-Break has been pressed
----------M00400072--------------------------
MEM 0040h:0072h - POST RESET FLAG
Size: WORD
Desc: specify the action the BIOS should take at the beginning of the
power-on self-test when the machine is reset
(Table M020)
Values for POST reset flag:
0000h cold boot
0064h Burn-in mode
1234h to bypass memory test (warm boot)
4321h [PS/2 except Mod 25,30] to preserve memory
5678h [Conv] system suspended
9ABCh [Conv] manufacturing test mode
ABCDh [Conv] POST loop mode
----------M00400074--------------------------
MEM 0040h:0074h - FIXED DISK LAST OPERATION STATUS (except ESDI drives)
Size: BYTE
SeeAlso: INT 13/AH=01h
(Table M021)
Values for fixed disk last operation status:
00h no error
01h invalid function request
02h address mark not found
03h write protect error
04h sector not found
05h reset failed
06h diskette removed
07h drive parameter activity failed
08h DMA overrun
09h DMA data boundary error
0Ah bad sector flag detected
0Bh bad track detected
0Ch requested diskette media type not found
(PS/2 or extended BIOS only) unsupported track
0Dh invalid number of sectors for Format
0Eh control data address mark detected
0Fh DMA arbitration level out of range
10h uncorrectable ECC or CRC error
11h ECC corrected data error
20h general controller failed
40h seek failed
80h time out
AAh drive not ready
BBh undefined error
CCh write fault on selected drive
E0h status error/error register is zero
FFh sense failed
----------M00400074--------------------------
MEM 0040h:0074h - WD1002-27X SuperBIOS - TOTAL DRIVES, FIRST CONTROLLER ONLY
Size: BYTE
SeeAlso: MEM 0040h:0075h"SuperBIOS",MEM 0040h:0076h"SuperBIOS"
----------M00400075--------------------------
MEM 0040h:0075h - FIXED DISK - NUMBER OF FIXED DISK DRIVES
Size: BYTE
SeeAlso: MEM 0040h:0076h"FIXED DISK",MEM 0040h:0077h"FIXED DISK"
----------M00400075--------------------------
MEM 0040h:0075h - WD1002-27X SuperBIOS - TOTAL FIXED DRIVES, BOTH CONTROLLERS
Size: BYTE
SeeAlso: MEM 0040h:0074h"SuperBIOS",MEM 0040h:0076h"SuperBIOS"
----------M00400076--------------------------
MEM 0040h:0076h - FIXED DISK - CONTROL BYTE {IBM document only for XT}
Size: BYTE
SeeAlso: MEM 0040h:0075h"FIXED DISK",MEM 0040h:0077h"FIXED DISK"
----------M00400076--------------------------
MEM 0040h:0076h - XT: hard disk controller's I/O address (Western Digital)
Size: BYTE
----------M00400076--------------------------
MEM 0040h:0076h - WD1002-27X SuperBIOS - USED IN TRACK RECALCULATION
Size: BYTE
SeeAlso: MEM 0040h:0074h"SuperBIOS",MEM 0040h:0075h"SuperBIOS"
SeeAlso: MEM 0040h:0077h"SuperBIOS"
----------M00400077--------------------------
MEM 0040h:0077h - FIXED DISK - I/O port offset {IBM document only for XT}
Size: BYTE
SeeAlso: MEM 0040h:0075h"FIXED DISK",MEM 0040h:0076h"FIXED DISK"
----------M00400077--------------------------
MEM 0040h:0077h - WD1002-27X SuperBIOS - USED IN TRACK RECALCULATION
Size: BYTE
SeeAlso: MEM 0040h:0076h"SuperBIOS"
----------M00400078--------------------------
MEM 0040h:0078h - PARALLEL DEVICE 1 TIME-OUT COUNTER
Size: BYTE
SeeAlso: MEM 0040h:0079h,MEM 0040h:007Ah
----------M00400079--------------------------
MEM 0040h:0079h - PARALLEL DEVICE 2 TIME-OUT COUNTER
Size: BYTE
SeeAlso: MEM 0040h:0078h,MEM 0040h:007Ah
----------M0040007A--------------------------
MEM 0040h:007Ah - PARALLEL DEVICE 3 TIME-OUT COUNTER
Size: BYTE
SeeAlso: MEM 0040h:0078h,MEM 0040h:0079h,MEM 0040h:007Bh"PARALLEL"
----------M0040007B--------------------------
MEM 0040h:007Bh - PARALLEL DEVICE 4 TIME-OUT COUNTER (pre-PS, PS Models 25,30)
Size: BYTE
SeeAlso: MEM 0040h:0078h,MEM 0040h:007Ah,MEM 0040h:007Bh"INT 4Bh"
----------M0040007B--------------------------
MEM 0040h:007Bh - INT 4Bh FLAGS (PS2 and newer)
Size: BYTE
Bitfields for INT 4Bh flags:
Bit(s) Description (Table M022)
7-6 reserved
5 set if Virtual DMA Spec supported [PS] (see INT 4B)
4 reserved
3 set if INT 4Bh intercepted and must be chained
2 reserved
1 set if Generic SCSI CBIOS services available on INT 4Bh
0 reserved
----------M0040007C--------------------------
MEM 0040h:007Ch - SERIAL DEVICE 1 TIMEOUT COUNTER
Size: BYTE
SeeAlso: MEM 0040h:0000h,MEM 0040h:007Dh,MEM 0040h:007Eh,MEM 0040h:007Fh
----------M0040007D--------------------------
MEM 0040h:007Dh - SERIAL DEVICE 2 TIMEOUT COUNTER
Size: BYTE
SeeAlso: MEM 0040h:0002h,MEM 0040h:007Ch,MEM 0040h:007Eh,MEM 0040h:007Fh
----------M0040007E--------------------------
MEM 0040h:007Eh - SERIAL DEVICE 3 TIMEOUT COUNTER
Size: BYTE
SeeAlso: MEM 0040h:0004h,MEM 0040h:007Ch,MEM 0040h:007Dh,MEM 0040h:007Fh
----------M0040007F--------------------------
MEM 0040h:007Fh - SERIAL DEVICE 4 TIMEOUT COUNTER
Size: BYTE
SeeAlso: MEM 0040h:0006h,MEM 0040h:007Ch,MEM 0040h:007Dh,MEM 0040h:007Eh
----------M00400080--------------------------
MEM 0040h:0080h - KEYBOARD BUFFER START OFFSET FROM SEGMENT 40h (normally 1Eh)
Size: WORD
SeeAlso: MEM 0040h:001Ah,MEM 0040h:001Eh,MEM 0040h:0082h
----------M00400082--------------------------
MEM 0040h:0082h - KEYBOARD BUFFER END+1 OFFSET FROM SEGMENT 40h (normally 3Eh)
Size: WORD
Note: XT BIOS dated 11/08/82 ends here
SeeAlso: MEM 0040h:001Ch,MEM 0040h:003Eh,MEM 0040h:0080h
----------M00400084--------------------------
MEM 0040h:0084h - VIDEO (EGA/MCGA/VGA) - ROWS ON SCREEN MINUS ONE
Size: BYTE
----------M00400085--------------------------
MEM 0040h:0085h - VIDEO (EGA/MCGA/VGA) - CHARACTER HEIGHT IN SCAN-LINES
Size: WORD
----------M00400087--------------------------
MEM 0040h:0087h - VIDEO (EGA/VGA) CONTROL: [MCGA: =00h]
Size: BYTE
Bitfields for EGA/VGA Video control flags:
Bit(s) Description (Table M023)
7 do not to clear RAM on mode set (see INT 10h, AH=00h)
6-5 RAM on adapter = (this field + 1) * 64K
4 reserved
3 EGA/VGA video system INactive
2 wait for display enable
1 mono monitor
0 alphanumeric cursor emulation DISabled
When enabled, text mode cursor size (INT 10,AH=01h) settings looking
like CGA ones are translated to equivalent EGA/VGA ones.
----------M00400088--------------------------
MEM 0040h:0088h - VIDEO (EGA/VGA) SWITCHES: [MCGA: reserved]
Size: BYTE
SeeAlso: MEM 0040h:0087h,MEM 0040h:0088h
Bitfields for EGA/VGA Video switches:
Bit(s) Description (Table M024)
7-4 power-on state of feature connector bits 3-0
3-0 configuration switches 4-1 (=0 on, =1 off) (see #M025)
Note: when bit 4 of 0040h:0089h is 0, VGA emulates 350-line EGA if this
byte is x3h or x9h, otherwise emulates 200-line CGA in 400-line
double scan. VGA resets this byte to x9h after the mode set.
See also note for 0040h:0089h.
(Table M025)
Values for EGA/VGA configuration switches:
00h Pri MDA, Sec EGA+old color display 40 x 25
01h Pri MDA, Sec EGA+old color display 80 x 25
02h Pri MDA, Sec EGA+ECD normal mode (CGA emul)
03h Pri MDA, Sec EGA+ECD enhanced mode
04h Pri CGA 40 x 25, Sec EGA mono display
05h Pri CGA 80 x 25, Sec EGA mono display
06h Pri EGA+old color display 40 x 25, Sec MDA
07h Pri EGA+old color display 80 x 25, Sec MDA
08h Pri EGA+ECD normal mode (CGA emul), Sec MDA
09h Pri EGA+ECD enhanced mode, Sec MDA
0Ah Pri EGA mono display, Sec CGA 40 x 25
0Bh Pri EGA mono display, Sec CGA 80 x 25
SeeAlso: #M024
----------M00400089--------------------------
MEM 0040h:0089h U - VIDEO (MCGA/VGA) - MODE-SET OPTION CONTROL
Size: BYTE
Bitfields for Video mode-set option control:
Bit(s) Description (Table M026)
7,4 requested scan lines
0 0 350-line mode requested
0 1 400-line mode at next mode set
1 0 200-line mode requested
1 1 reserved
Note: Apparently VGA BIOS mode set disregards bit 7 and uses
byte 40h:88h to determine 200/350 selection when bit 4
is zero. Presumably bit 7 is a convenience for other
purposes. Bit 7 is reset to zero after the mode set.
6 display switching enabled
5 reserved
4 if set: use 400-line mode at next mode set
if clear: [VGA] emulate EGA at next mode set
[MCGA] emulate CGA, digital monitor, 200 lines, 8x8 text
Note: this bit is set by the video mode set on VGA, unchanged on MCGA
3 default palette loading DISabled at mode set
2 mono display
1 gray scale summing enabled
0 [VGA] =1 if VGA active, =0 if not
[MCGA] reserved, zero
Note: the Tseng ET4000 BIOS v3.00 uses bits 6-4 of 88h and bits 6-5 of 89h
to specify graphics-mode refresh rates as follows
88h/6 640x480: 1 for 72Hz,0 for 60Hz
88h/5+89h/6 800x600: 00 60Hz
01 56Hz
11 72Hz
88h/4+89h/5 1024x768: 00 interlaced
01 60Hz
10 72Hz???
11 70Hz
----------M0040008A--------------------------
MEM 0040h:008Ah U - VIDEO (MCGA/VGA) - INDEX INTO DISPLAY COMBINATION CODE TBL
Size: BYTE
----------M0040008B--------------------------
MEM 0040h:008Bh - PC, PCjr, PC/XT 11/8/82, Convertible - RESERVED
Size: 11 BYTEs
----------M0040008B--------------------------
MEM 0040h:008Bh - DISKETTE MEDIA CONTROL
Size: BYTE
Bitfields for diskette media control:
Bit(s) Description (Table M027)
7-6 last data rate set by controller
00=500kbps, 01=300kbps, 10=250kbps, 11=1Mbps
5-4 last diskette drive step rate selected
00=0Ch, 01=0Dh, 10=0Eh, 11=0Ah
3-2 {data rate at start of operation}
1-0 reserved
Note: EHD BIOS sets this byte to 01h and never reads it back
----------M0040008C--------------------------
MEM 0040h:008Ch - FIXED DISK - CONTROLLER STATUS [not XT]
Size: BYTE
SeeAlso: MEM 0040h:008Dh,MEM 0040h:008Eh
----------M0040008D--------------------------
MEM 0040h:008Dh - FIXED DISK - CONTROLLER ERROR STATUS [not XT]
Size: BYTE
SeeAlso: MEM 0040h:008Ch,MEM 0040h:008Eh
----------M0040008E--------------------------
MEM 0040h:008Eh - FIXED DISK - INTERRUPT CONTROL [not XT]
Size: BYTE
Note: cleared to 00h at start of disk operation, set to FFh by IRQ14
handler when hard disk controller completes command
SeeAlso: MEM 0040h:008Ch,MEM 0040h:008Dh,MEM 0040h:008Fh
----------M0040008F--------------------------
MEM 0040h:008Fh U - DISKETTE CONTROLLER INFORMATION [not XT]
Size: BYTE
SeeAlso: MEM 0040h:008Ch,MEM 0040h:008Dh,MEM 0040h:008Eh
Bitfields for diskette controller information:
Bit(s) Description (Table M028)
7 reserved
6 =1 drive 1 determined
5 =1 drive 1 is multi-rate, valid if drive determined
4 =1 drive 1 supports 80 tracks, always valid
3 reserved
2 =1 drive 0 determined
1 =1 drive 0 is multi-rate, valid if drive determined
0 =1 drive 0 supports 80 tracks, always valid
Note: EHD BIOS sets this byte to 01h and never alters it again
----------M00400090--------------------------
MEM 0040h:0090h - DISKETTE DRIVE 0 MEDIA STATE
Size: BYTE
SeeAlso: MEM 0040h:0091h
Bitfields for diskette drive media state:
Bit(s) Description (Table M029)
7-6 data rate
00=500kbps, 01=300kbps, 10=250kbps, 11=1Mbps
5 double stepping required (e.g. 360kB in 1.2MB)
4 media type established
3 drive capable of supporting 4MB media
2-0 on exit from BIOS, contains
000 trying 360kB in 360kB
001 trying 360kB in 1.2MB
010 trying 1.2MB in 1.2MB
011 360kB in 360kB established
100 360kB in 1.2MB established
101 1.2MB in 1.2MB established
110 reserved
111 all other formats/drives
SeeAlso: #M030,#M031
----------M00400091--------------------------
MEM 0040h:0091h - DISKETTE DRIVE 1 MEDIA STATE
Size: BYTE
SeeAlso: MEM 0040h:0090h,#M029
----------M00400092--------------------------
MEM 0040h:0092h U - DISKETTE DRIVE 0 MEDIA STATE AT START OF OPERATION
Size: BYTE
Note: officially "Drive 2 media state"
SeeAlso: MEM 0040h:0093h"DRIVE 1"
Bitfields for diskette drive 0 media state at start of operation:
Bit(s) Description (Table M030)
7-3 (see #M029)
2 multiple data rate capability determined
1 multiple data rate capability
0 =1 if drive has 80 tracks, =0 if 40 tracks
SeeAlso: #M029,#M031
----------M00400092--------------------------
MEM 0040h:0092h - Olivetti Quaderno - HARD DISK POWERDOWN COUNTDOWN CLOCK TICKS
Size: BYTE
Note: hard disk is turned off when counter reaches zero
----------M00400093--------------------------
MEM 0040h:0093h U - DISKETTE DRIVE 1 MEDIA STATE AT START OF OPERATION
Size: BYTE
Note: officially "Drive 3 media state"
SeeAlso: MEM 0040h:0092h"DRIVE 0"
Bitfields for diskette drive 1 media state at start of operation:
Bit(s) Description (Table M031)
7-3 (see #M029)
2 multiple data rate capability determined
1 multiple data rate capability
0 =1 if drive has 80 tracks, =0 if 40 tracks
--HP 100LX/200LX--
display control status
0 =1 if DISPCTL -K
1 =1 if DISPCTL -C
----------M00400094--------------------------
MEM 0040h:0094h - DISKETTE DRIVE 0 CURRENT TRACK NUMBER
Size: BYTE
SeeAlso: MEM 0040h:0095h
----------M00400095--------------------------
MEM 0040h:0095h - DISKETTE DRIVE 1 CURRENT TRACK NUMBER
Size: BYTE
SeeAlso: MEM 0040h:0094h
----------M00400096--------------------------
MEM 0040h:0096h - KEYBOARD STATUS BYTE 1
Size: BYTE
Bitfields for keyboard status byte 1:
Bit(s) Description (Table M032)
7 =1 read-ID in progress
6 =1 last code read was first of two ID codes
5 =1 force Num Lock if read-ID and enhanced keyboard
4 =1 enhanced keyboard installed
3 =1 Right Alt pressed
2 =1 Right Ctrl pressed
1 =1 last code read was E0h
0 =1 last code read was E1h
SeeAlso: #M033
----------M00400097--------------------------
MEM 0040h:0097h - KEYBOARD STATUS BYTE 2
Size: BYTE
Bitfields for keyboard status byte 2:
Bit(s) Description (Table M033)
7 =1 keyboard transmit error flag
6 =1 LED update in progress
5 =1 RESEND received from keyboard
4 =1 ACK received from keyboard
3 reserved, must be zero
2 Caps Lock LED
1 Num Lock LED
0 Scroll Lock LED
SeeAlso: #M032
----------M00400098--------------------------
MEM 0040h:0098h - TIMER2 (AT, PS exc Mod 30) - PTR TO USER WAIT-COMPLETE FLAG
Size: DWORD
Note: (see INT 15/AX=8300h)
----------M0040009C--------------------------
MEM 0040h:009Ch - TIMER2 (AT, PS exc Mod 30) - USER WAIT COUNT IN MICROSECONDS
Size: DWORD
----------M0040009F--------------------------
MEM 0040h:009Fh - HP 100LX/200LX - VIDEO ZOOM MODE
Size: BYTE
(Table M034)
Values for HP 100LX/200LX video zoom mode:
02h 80x25 mono
03h 80x25 color
80h 64x18 mono
81h 64x18 color
82h 40x25 mono
83h 40x25 color
84h 40x16 mono
85h 40x16 color
SeeAlso: INT 10/AH=D0h
----------M004000A0--------------------------
MEM 0040h:00A0h - TIMER2 (AT, PS exc Mod 30) - WAIT ACTIVE FLAG
Size: BYTE
Bitfields for Timer2 wait active flag:
Bit(s) Description (Table M035)
7 wait time elapsed
6-1 reserved
0 INT 15/AH=86h has occurred
----------M004000A1--------------------------
MEM 0040h:00A1h - BIT 5 SET IF LAN SUPPORT PROGRAM INTERRUPT ARBITRATOR PRESENT
Size: BYTE
Note: DEVICE=DXMA0MOD.SYS
----------M004000A2--------------------------
MEM 0040h:00A2h - RESERVED FOR NETWORK ADAPTERS
Size: 6 BYTEs
----------M004000A4--------------------------
MEM 0040h:00A4h - PS/2 Mod 30 - SAVED FIXED DISK INTERRUPT VECTOR
Size: DWORD
----------M004000A8--------------------------
MEM 0040h:00A8h - VIDEO (EGA/MCGA/VGA) - POINTER TO VIDEO SAVE POINTER TABLE
Size: DWORD
Format of Video Save Pointer Table [EGA/VGA/MCGA only]:
Offset Size Description (Table M036)
00h DWORD ptr to Video Parameter Table
04h DWORD ptr to Parameter Dynamic Save Area, else 0 [EGA/VGA only]
08h DWORD ptr to Alphanumeric Character Set Override, else 0
0Ch DWORD ptr to Graphics Character Set Override, else 0
10h DWORD [VGA only] ptr to Secondary Save Pointer Table, must be valid
14h DWORD reserved, zero
18h DWORD reserved, zero
Note: table initially in ROM, copy to RAM to alter, then update 40h:A8h.
Format of Secondary Video Save Pointer Table [VGA only]:
Offset Size Description (Table M037)
00h WORD Length of this table in bytes, including this word (1Ah)
02h DWORD ptr to Display Combination Code Table, must be valid
06h DWORD ptr to second Alphanumeric Character Set Override, else 0
0Ah DWORD ptr to User Palette Profile Table, else 0
0Eh DWORD reserved, zero
12h DWORD reserved, zero
16h DWORD reserved, zero
Note: table initially in ROM, copy to RAM to alter, then alter Save Ptr Table.
Format of Display Combination Code Table [VGA only]:
Offset Size Description (Table M038)
00h BYTE Number of entries in the DCC table at offset 04h
01h BYTE Version number
02h BYTE Maximum display type code that can appear in DCC table
03h BYTE reserved
04h 2N BYTEs Each pair of bytes gives a valid display combination
Meaning of each byte:
00h no display
01h MDA with mono display
02h CGA with color display
03h reserved
04h EGA with color display
05h EGA with mono display
06h Professional Graphics Controller
07h VGA with mono display
08h VGA with color display
09h reserved
0Ah MCGA with digital color display
0Bh MCGA with analog mono display
0Ch MCGA with analog color display
FFh unrecognised video system
Format of Video Parameter Table [EGA, VGA only]:
Offset Size Description (Table M039)
00h-03h Modes 00h-03h in 200-line CGA emulation mode
04h-0Eh Modes 04h-0Eh
0Fh-10h Modes 0Fh-10h when only 64kB RAM on adapter
11h-12h Modes 0Fh-10h when >64kB RAM on adapter
13h-16h Modes 00h-03h in 350-line mode
17h VGA Modes 00h or 01h in 400-line mode
18h VGA Modes 02h or 03h in 400-line mode
19h VGA Mode 07h in 400-line mode
1Ah-1Ch VGA Modes 11h-13h
Note: An array of 23 [EGA] or 29 [VGA] elements, each element being 64
bytes long. Elements appear in the above order.
Format of Video Parameter Table element [EGA, VGA only]:
Offset Size Description (Table M040)
00h BYTE Columns on screen (see 40h:4Ah)
01h BYTE Rows on screen minus one (see 40h:84h)
02h BYTE Height of character in scan lines (see 40h:85h)
03h WORD Size of video buffer (see 40h:4Ch)
05h 4 BYTEs Values for Sequencer Registers 1-4
09h BYTE Value for Miscellaneous Output Register
0Ah 25 BYTEs Values for CRTC Registers 00h-18h
23h 20 BYTEs Values for Attribute Controller Registers 00h-13h
37h 9 BYTEs Values for Graphics Controller Registers 00h-08h
Format of Video Parameter Table [MCGA only] {guesswork from inspection}:
Offset Size Description (Table M041)
- 16 triplet BYTEs of R,G,B DAC info for 16 colors;
- An array of 11 elements, each element being 32 bytes long.
Elements appear in the order:
Modes 00h,01h in 200-line mode for digital displays
Modes 00h,01h in 400-line mode for analog displays
Modes 02h,03h in 200-line mode for digital displays
Modes 02h,03h in 400-line mode for analog displays
Modes 04h,05h in 200-line mode for digital displays
Modes 04h,05h in 400-line mode for analog displays
Mode 06h in 200-line mode for digital displays
Mode 06h in 400-line mode for analog displays
Mode 11h
Mode 13h in 200-line mode for digital displays
Mode 13h in 400-line mode for analog displays
Format of Video Parameter Table element [MCGA only]:
Offset Size Description (Table M042)
00h BYTE Columns on screen (see 40h:4Ah)
01h BYTE Rows on screen minus one (see 40h:84h)
02h BYTE Height of character in scan lines (see 40h:85h)
03h WORD Size of video buffer (see 40h:4Ch)
05h WORD ??? always zero
07h 21 BYTEs Video data registers 00h-14h to port 3D5h indexed by 3D4h
1Ch BYTE PEL Mask to port 3C6h
1Dh BYTE CGA Mode Control to port 3D8h
1Eh BYTE CGA Border Control to port 3D9h
1Fh BYTE Extended Mode Control to port 3DDh
Format of Video Parameter Dynamic Save Area [EGA, VGA only]:
Offset Size Description (Table M043)
00h 16 BYTEs Last data written to Attribute Contr. Palette Registers 0-15
10h BYTE Last data written to Attribute Controller Overscan Register
11h-FFh Reserved
Note: Need for table was that EGA registers were write-only.
Note: If default values (from the Video Parameter Table) are
over-ridden at a mode set by the VGA User Palette Profile
Table, then the Dynamic Save Area is updated with the
default values, not the User Profile ones.
Format of Alphanumeric Character Set Override:
Offset Size Description (Table M044)
00h BYTE Length in bytes of each character in font table
01h BYTE Character generator RAM bank to load, 0=normal
02h WORD Number of characters in font table, normally 256
04h WORD Code of first character in font table, normally 0
06h DWORD ptr to font table
0Ah BYTE Displayable rows (FFh=use maximum calculated value)
0Bh BYTEs Array of mode values to which this font is to pertain
BYTE FFh end of array
Format of Second Alphanumeric Character Set Override:
Offset Size Description (Table M045)
00h BYTE Length in bytes of each character in font table
01h BYTE Character generator RAM bank to load, normally non-zero
02h BYTE reserved
03h DWORD ptr to font table
07h BYTEs Array of mode values to which this font is to pertain
BYTE FFh end of array
Note: Authorities differ, some say same as first override above, but IBM
says it is as shown above
Format of Graphics Character Set Override:
Offset Size Description (Table M046)
00h BYTE Number of displayable character rows
01h WORD Length in bytes of each character in font table
03h DWORD ptr to font table
07h BYTEs Array of mode values to which this font is to pertain
BYTE FFh end of array
Format of User Palette Profile Table [VGA only]:
Offset Size Description (Table M047)
00h BYTE Underlining: 01h=enable in all alphanumeric modes
00h=enable in monochrome alphanumeric modes only
FFh=disable in all alphanumeric modes
01h BYTE reserved
02h WORD reserved
04h WORD Number (0-17) of Attribute Controller registers in table
06h WORD Index (0-16) of first Attribute Controller register in table
08h DWORD ptr to table of Attribute Controller registers to override
Table is an array of BYTEs.
0Ch WORD Number (0-256) of video DAC Color registers in table
0Eh WORD Index (0-255) of first video DAC Color register in table
10h DWORD ptr to table of video DAC Color registers to override
Table is ??? triplets ??? of BYTEs???
14h BYTEs array of mode values to which this profile is to pertain
BYTE FFh end of array
----------M004000AC--------------------------
MEM 0040h:00ACh - RESERVED
Size: 4 BYTEs
----------M004000B0--------------------------
MEM 0040h:00B0h - Phoenix 386 BIOS 1.10 10a - LOOP COUNT FOR HARD DISK TIMEOUT
Size: BYTE
Desc: number of times a tight software delay loop should be executed to
generate the sub-55ms delays used internally by the BIOS
Note: also used for delaying when beeping due to full keyboard buffer
----------M004000B0--------------------------
MEM 0040h:00B0h - PTR TO 3363 OPTICAL DISK DRIVER OR BIOS ENTRY POINT
Size: DWORD
Notes: When 3363 BIOS present, the ASCIZ signature "OPTIC "occurs 3 bytes
beyond this entry point
When 3363 BIOS and 3363 File System Driver present, the ASCIZ signature
"FILE SYSTEM DRIVER" occurs 3 bytes beyond this entry point
----------M004000B0--------------------------
MEM 0040h:00B0h - 1988 Phoenix 386 BIOS 1.10 03 - PARAMS FOR TYPE 48 HARD DISK
Size: 16 BYTEs
SeeAlso: INT 41,INT 46
----------M004000B4--------------------------
MEM 0040h:00B4h - RESERVED
Size: WORD
----------M004000B5--------------------------
MEM 0040h:00B5h - Dell 4xxDE
Size: BYTE
Bitfields for Dell 4xxDE flags:
Bit(s) Description (Table M048)
2 ??? (related to disk drives)
5 page tables set to allow Weitek addressing in real mode
6 Weitek math coprocessor present
----------M004000B6--------------------------
MEM 0040h:00B6h - RESERVED FOR POST???
Size: 3 BYTEs
----------M004000B9--------------------------
MEM 0040h:00B9h - ???
Size: 7 BYTEs
----------M004000C0--------------------------
MEM 0040h:00C0h - 1988 Phoenix 386 BIOS 1.10 03 - PARAMS FOR TYPE 49 HARD DISK
Size: 16 BYTEs
SeeAlso: INT 41,INT 46
----------M004000C0--------------------------
MEM 0040h:00C0h - RESERVED
Size: 14 BYTEs
----------M004000CE--------------------------
MEM 0040h:00CEh - COUNT OF DAYS SINCE LAST BOOT
Size: WORD
----------M004000D0--------------------------
MEM 0040h:00D0h - RESERVED
Size: 32 BYTEs
----------M004000D0--------------------------
MEM 0040h:00D0h - Digiboard MV/4 - LENGTH OF DATA TABLE
Size: BYTE
----------M004000D0--------------------------
MEM 0040h:00D0h EHD floppy - INSTALLATION FLAGS
Size: BYTE
Bitfields for EHD floppy installation flags:
Bit(s) Description (Table M049)
4 installation completed
3-0 drives 0-3
----------M004000D0--------------------------
MEM 0040h:00D0h - AMI BIOS v1.00.12.AX1T - EPP - SCRATCH SPACE
Size: WORD
Desc: this word holds the value of BX during an EPP BIOS call
SeeAlso: MEM 0040h:00D2h"AMI",MEM 0040h:00D5h"AMI",MEM 0040h:00D6h"AMI"
SeeAlso: MEM 0040h:00DDh"AMI"
----------M004000D1--------------------------
MEM 0040h:00D1h - Digiboard MV/4 - PRODUCT ID
Size: BYTE
----------M004000D2--------------------------
MEM 0040h:00D2h - Digiboard MV/4 - BASE ADDRESS FOUND
Size: WORD
----------M004000D2--------------------------
MEM 0040h:00D2h - AMI BIOS v1.00.12.AX1T - EPP BASE I/O PORT
Size: WORD
----------M004000D4--------------------------
MEM 0040h:00D4h - Digiboard MV/4 - PORTS
Size: BYTE
----------M004000D5--------------------------
MEM 0040h:00D5h - Digiboard MV/4 - IRQ
Size: BYTE
----------M004000D5--------------------------
MEM 0040h:00D5h - EHD floppy - NUMBER OF FLOPPY DISK CONTROLLERS IN SYSTEM
Size: BYTE
----------M004000D5--------------------------
MEM 0040h:00D5h - AMI BIOS v1.00.12.AX1T - EPP - PARALLEL PORT 0 CAPABILITIES
Size: BYTE
SeeAlso: MEM 0040h:00D2h"AMI",MEM 0040h:00D6h"AMI",MEM 0040h:00D7h"AMI"
SeeAlso: MEM 0040h:00DCh"AMI"
----------M004000D6--------------------------
MEM 0040h:00D6h - EHD floppy - AND-BITS TO ADJUST PORT ADDRESS
Size: BYTE
Note: this byte contains FFh if controller at 03Fxh and 7Fh if at 037xh; the
value is ANDed with DL prior to using IN A?,DX or OUT DX,A?
instructions
----------M004000D6--------------------------
MEM 0040h:00D6h - Digiboard MV/4 - NUMBER OF KEYBOARDS FOUND
Size: WORD
SeeAlso: MEM 0040h:00D8h"Digiboard"
----------M004000D6--------------------------
MEM 0040h:00D6h - AMI BIOS v1.00.12.AX1T - EPP - PARALLEL PORT 0 IRQ
Size: BYTE
SeeAlso: MEM 0040h:00D2h"AMI",MEM 0040h:00D5h"AMI",MEM 0040h:00D8h"AMI"
SeeAlso: MEM 0040h:00DDh"AMI"
----------M004000D7--------------------------
MEM 0040h:00D7h - EHD floppy - DRIVE 0 DISKETTE MEDIA STATE
Size: BYTE
Note: the value in this byte is copied into 0040h:0090h (diskette 0 status)
SeeAlso: MEM 0040h:00D8h"EHD",MEM 0040h:00D9h"EHD",MEM 0040h:00DAh"EHD"
Bitfields for EHD diskette media state:
Bit(s) Description (Table M050)
7-6 data rate: 00=500kbps,01=300kbps,10=250k,11=1M/S
5 double stepping required (e.g. 360kB in 1.2MB)
4 media type established
3 reserved
2-0 on exit from BIOS, contains:
000 trying 360kB in 360kB
001 trying 360kB in 1.2MB
010 trying 1.2MB in 1.2MB
011 360kB in 360kB established
100 360kB in 1.2MB established
101 1.2MB in 1.2MB established
110 reserved (2M8?)
111 all other formats/drives
----------M004000D7--------------------------
MEM 0040h:00D7h - AMI BIOS v1.00.12.AX1T - EPP - PARALLEL PORT 1 CAPABILITIES
Size: BYTE
SeeAlso: MEM 0040h:00D2h"AMI",MEM 0040h:00D5h"AMI",MEM 0040h:00D6h"AMI"
SeeAlso: MEM 0040h:00DDh"AMI"
----------M004000D8--------------------------
MEM 0040h:00D8h - Digiboard MV/4 - NUMBER OF MICE FOUND
Size: WORD
SeeAlso: MEM 0040h:00D6h"Digiboard",MEM 0040h:00DAh"Digiboard"
----------M004000D8--------------------------
MEM 0040h:00D8h - EHD floppy - DRIVE 1 DISKETTE MEDIA STATE
Size: BYTE
SeeAlso: MEM 0040h:00D7h"EHD",MEM 0040h:00D9h"EHD",MEM 0040h:00DAh"EHD"
----------M004000D8--------------------------
MEM 0040h:00D8h - AMI BIOS v1.00.12.AX1T - EPP - PARALLEL PORT 1 IRQ
Size: BYTE
SeeAlso: MEM 0040h:00D2h"AMI",MEM 0040h:00D6h"AMI",MEM 0040h:00D7h"AMI"
SeeAlso: MEM 0040h:00DDh"AMI"
----------M004000D9--------------------------
MEM 0040h:00D9h - EHD floppy - DRIVE 2 DISKETTE MEDIA STATE
Size: BYTE
SeeAlso: MEM 0040h:00D7h"EHD",MEM 0040h:00D8h"EHD",MEM 0040h:00DAh"EHD"
----------M004000DA--------------------------
MEM 0040h:00DAh - Digiboard MV/4 - CURRENT PORT (used by VGA initializatn only)
Size: BYTE
SeeAlso: MEM 0040h:00D8h"Digiboard"
----------M004000DA--------------------------
MEM 0040h:00DAh - EHD floppy - DRIVE 3 DISKETTE MEDIA STATE
Size: BYTE
SeeAlso: MEM 0040h:00D7h"EHD",MEM 0040h:00D8h"EHD",MEM 0040h:00D9h"EHD"
----------M004000DB--------------------------
MEM 0040h:00DBh - Digiboard MV/4 - MASTER 8259 MASK (used by VGA init only)
Size: BYTE
SeeAlso: MEM 0040h:00DCh"Digiboard"
----------M004000DB--------------------------
MEM 0040h:00DBh - EHD floppy - DRIVE 0 NEEDS RECALIBARATION
Size: BYTE
SeeAlso: MEM 0040h:00DCh"EHD",MEM 0040h:00DDh"EHD",MEM 0040h:00DEh"EHD"
----------M004000DC--------------------------
MEM 0040h:00DCh - Digiboard MV/4 - SLAVE 8259 MASK (used by VGA init only)
Size: BYTE
SeeAlso: MEM 0040h:00DBh"Digiboard"
----------M004000DC--------------------------
MEM 0040h:00DCh - AMI BIOS v1.00.12.AX1T - EPP - PARALLEL PORT 0 MODE
Size: BYTE
SeeAlso: MEM 0040h:00D2h"AMI",MEM 0040h:00D5h"AMI",MEM 0040h:00DDh"AMI"
(Table M051)
Values for AMI Enhanced Parallel Port mode:
01h compatibility mode
02h bi-directional mode
04h EPP mode
SeeAlso: #0530
----------M004000DC--------------------------
MEM 0040h:00DCh - EHD floppy - DRIVE 1 NEEDS RECALIBARATION
Size: BYTE
SeeAlso: MEM 0040h:00DBh"EHD",MEM 0040h:00DDh"EHD",MEM 0040h:00DEh"EHD"
----------M004000DC--------------------------
MEM 0040h:00DCh - AMI BIOS v1.00.12.AX1T - EPP - PARALLEL PORT 1 MODE
Size: BYTE
SeeAlso: MEM 0040h:00D2h"AMI",MEM 0040h:00DCh"AMI",#M051
----------M004000DD--------------------------
MEM 0040h:00DDh - EHD floppy - DRIVE 2 NEEDS RECALIBARATION
Size: BYTE
SeeAlso: MEM 0040h:00DBh"EHD",MEM 0040h:00DCh"EHD",MEM 0040h:00DEh"EHD"
----------M004000DE--------------------------
MEM 0040h:00DEh - EHD floppy - DRIVE 3 NEEDS RECALIBARATION
Size: BYTE
SeeAlso: MEM 0040h:00DBh"EHD",MEM 0040h:00DCh"EHD",MEM 0040h:00DDh"EHD"
----------M004000DF--------------------------
MEM 0040h:00DFh - AMI BIOS v1.00.12.AX1T - EPP - PARALLEL PORT LOCK STATE
Size: BYTE
Note: set to 01h if last request was to lock a port, 00h if last request was
to unlock a port
SeeAlso: MEM 0040h:00D2h"AMI",MEM 0040h:00DCh"AMI"
----------M004000E0--------------------------
MEM 0040h:00E0h - AMI BIOS v1.00.12.AX1T - EPP - REAL-TIME DEVICE COUNT
Size: BYTE
Desc: contains the number of advertised real-time devices as set by EPP
function 12h (see #0525)
SeeAlso: MEM 0040h:00D2h"AMI",MEM 0040h:00DFh"AMI"
----------M004000E0--------------------------
MEM 0040h:00E0h - Phoenix 386 BIOS - DRIVE PARAMETER TABLE FOR FIRST HARD DISK
Size: 16 BYTEs
Note: this area is used to store the driver parameter table for the first
hard disk if it has been setup as the user-configurable "type 47"
----------M004000E3--------------------------
MEM 0040h:00E3h - EHD floppy - DRIVE 0 DISKETTE TYPE (from jumpers)
Size: BYTE
SeeAlso: MEM 0040h:00E4h,MEM 0040h:00E5h"EHD",MEM 0040h:00E6h"EHD"
(Table M052)
Values for EHD floppy diskette type:
01h undefined by diskette change (360K)
02h 1.2M
03h 720K
04h 1.44M
05h 2.88M
----------M004000E4--------------------------
MEM 0040h:00E4h - EHD floppy - DRIVE 1 DISKETTE TYPE (from jumpers)
Size: BYTE
SeeAlso: MEM 0040h:00E3h,MEM 0040h:00E5h"EHD",MEM 0040h:00E6h"EHD"
----------M004000E5--------------------------
MEM 0040h:00E5h - EHD floppy - DRIVE 2 DISKETTE TYPE (from jumpers)
Size: BYTE
SeeAlso: MEM 0040h:00E3h,MEM 0040h:00E4h"EHD",MEM 0040h:00E6h"EHD"
----------M004000E6--------------------------
MEM 0040h:00E6h - EHD floppy - DRIVE 3 DISKETTE TYPE (from jumpers)
Size: BYTE
SeeAlso: MEM 0040h:00E3h,MEM 0040h:00E4h"EHD",MEM 0040h:00E5h"EHD"
----------M004000EA--------------------------
MEM 0040h:00EAh - Omti controller - SEGMENT OF EXTENDED BIOS DATA AREA???
Size: WORD
Note: drive parameter tables stored in specified segment
----------M004000EC--------------------------
MEM 0040h:00ECh - Dell 4xxDE BIOS A11 - LOOP COUNT FOR DELAYS
Size: WORD
----------M004000F0--------------------------
MEM 0040h:00F0h - INTRA-APPLICATION COMMUNICATION AREA
Size: 16 BYTEs
----------M00500000--------------------------
MEM 0050h:0000h - PRINT-SCREEN STATUS
Size: BYTE
--------J-M00500001--------------------------
MEM 0050h:0001h - NEC PC-9800 series - SCREEN MODE
Size: BYTE
Note: if bit 3 set, the screen is in high-resolution mode (start memory at
segment E000h instead of A000h)
----------M00500004--------------------------
MEM 0050h:0004h - MS-DOS - LOGICAL DRIVE FOR SINGLE-FLOPPY SYSTEM (A: / B:)
Size: BYTE
----------M0050000E--------------------------
MEM 0050h:000Eh - STATE OF BREAK CHECKING AT START OF BASICA.COM EXECUTION
Size: BYTE
----------M0050000F--------------------------
MEM 0050h:000Fh - BASICA VERSION FLAG
Size: BYTE
Note: this byte contains the value 02h if BASICA v2.10 is running
----------M00500010--------------------------
MEM 0050h:0010h - POINTER TO BASIC DATA SEGMENT
Size: WORD
----------M00500012--------------------------
MEM 0050h:0012h - INT 08 VECTOR AT START OF BASICA.COM EXECUTION
Size: DWORD
----------M00500016--------------------------
MEM 0050h:0016h - INT 1B VECTOR AT START OF BASICA.COM EXECUTION
Size: DWORD
----------M0050001A--------------------------
MEM 0050h:001Ah - INT 24 VECTOR AT START OF BASICA.COM EXECUTION
Size: DWORD
----------M00600000--------------------------
MEM 0060h:0000h - DOS SCRATCH SPACE
Size: 256 BYTEs
Note: used during DOS 2+ boot process
----------M00700000--------------------------
MEM 0070h:0000h - DOS 2+ IO.SYS LOAD ADDRESS
----------m80C00000--------------------------
MEM 80C00000h - Compaq Deskpro 386 system memory board register
Size: BYTE
80C00000 R Diagnostics register (see #M053)
80C00000 W RAM relocation register (see #M054)
Bitfields for Compaq Deskpro 386 diagnostics register:
Bit(s) Description (Table M053)
7 =0 memory expansion board is installed
6 =0 second 1 MB of system memory board is installed
5-4 base memory
00 set to 640 KB
01 invalid
10 set to 512 KB
11 set to 256 KB
3 parity correct in byte 3
2 parity correct in byte 2
1 parity correct in byte 1
0 parity correct in byte 0 (in 32-bit double word)
SeeAlso: #M054
Bitfields for Compaq Deskpro 386 RAM relocation register:
Bit(s) Description (Table M054)
7-2 reserved, always write 1's.
1 =0 Write-protect 128-Kbyte RAM at FE0000.
=1 Do not write-protect RAM at FE0000.
0 =0 Relocate 128-Kbyte block at FE0000 to address 0E0000
=1 128-Kbyte RAM is addressed only at FE0000.
SeeAlso: #M053
----------MA0000000--------------------------
MEM A000h:0000h - EGA+ GRAPHICS BUFFER
Size: 65536 BYTEs
----------MB0000000--------------------------
MEM B000h:0000h - MDA TEXT BUFFER
Size: 4096 BYTEs
----------MB0000000--------------------------
MEM B000h:0000h - HGC+ RAMFont-MODE TEXT BUFFER
Size: 16384 BYTEs
Note: in RAMFont Mode 1, the memory is filled with the usual
character/attribute pairs; in RAMFont Mode 2, four bits of each
'attribute' byte is used to provide 12 bits for specifying the
character
----------MB0000000--------------------------
MEM B000h:0000h - HGC GRAPHICS BUFFER (PAGE 0)
Size: 32768 BYTEs
----------MB4000000--------------------------
MEM B400h:0000h - HGC+ RAMFont BUFFER
Size: 4096 BYTEs
Notes: apparently write-only
RAMFont Mode 1: 256 characters (8 bits each for char and attribute)
RAMFont Mode 2: 3072 characters (12 bits for char, 4 bits for attrib)
each character definition is 8 pixels wide (with 9th-column duplication
if appropriate) by 8-16 pixels high
----------MB8000000--------------------------
MEM B800h:0000h - CGA TEXT/GRAPHICS BUFFER
Size: 16384 BYTEs
--------V-MB8000000--------------------------
MEM B800h:0000h - EGA/VGA+ TEXT BUFFER
Size: 32768 BYTEs
--------V-MB8000000--------------------------
MEM B800h:0000h - HGC GRAPHICS BUFFER (PAGE 1)
Size: 32768 BYTEs
----------MBFF00000--------------------------
MEM BFF0h:0000h - ET4000/W32 ACL accelerator
Size: 169 BYTES
Format of ET4000/W32 memory-mapped registers:
Offset Size Description (Table M055)
00h DWORD MMU Registers: memory base pointer register 0 (see #M056)
04h DWORD MMU Registers: memory base pointer register 1 (see #M056)
08h DWORD MMU Registers: memory base pointer register 2 (see #M056)
0Ch 7 BYTEs ???
13h BYTE MMU Registers: MMU control register (see #M057)
14h 28 BYTEs ???
30h BYTE Non-Queued Registers: suspend/terminate
31h BYTE Non-Queued Registers: operation state (see #M058) (write-only)
32h BYTE Non-Queued Registers: sync enable
33h BYTE ???
34h BYTE Non-Queued Registers: interrupt mask
35h BYTE Non-Queued Registers: interrupt status
36h BYTE Non-Queued Registers: ACL status (read-only)
bit 1: read status (RDST) 1=ACL active, queue not empty
bit 0: write status (WRST) 1=queue full
37h 73 BYTEs ???
80h DWORD Queued Registers: pattern address (see #M059)
84h DWORD Queued Registers: source address (see #M059)
88h WORD Queued Registers: pattern Y offset (see #M060)
8Ah WORD Queued Registers: source Y offset (see #M060)
8Ch WORD Queued Registers: destination y offset (see #M060)
8Eh BYTE Queued Registers: virtual bus size
8Fh BYTE Queued Registers: X/Y direction (see #M061)
90h BYTE Queued Registers: pattern wrap (see #M062)
91h BYTE ???
92h BYTE Queued Registers: source wrap (see #M062)
93h BYTE ???
94h WORD Queued Registers: X position
96h WORD Queued Registers: Y position
98h WORD Queued Registers: X count (see #M063)
9Ah WORD Queued Registers: Y count (see #M063)
9Ch BYTE Queued Registers: routine control (see #M064)
9Dh BYTE Queued Registers: reload control
9Eh BYTE Queued Registers: background ROP for mixing
9Fh BYTE Queued Registers: foreground ROP for mixing
A0h DWORD Queued Registers: destination address
A4h DWORD Queued Registers: internal pattern address
A8h DWORD Queued Registers: internal source address
Bitfields for ET4000/W32 memory base pointer register:
Bit(s) Description (Table M056)
31-22 reserved
21-0 memory base pointer
SeeAlso: #M055
Bitfields for ET4000/W32 MMU control register:
Bit(s) Description (Table M057)
7 reserved
6-4 linear address control (LAC)
bit 6: MMU aperture 2
bit 5: MMU aperture 1
bit 4: MMU aperture 0
3 reserved
t2-0 aperture type (APT)
bit 2: MMU aperture 2
bit 1: MMU aperture 1
bit 0: MMU aperture 0
SeeAlso: #M055
Bitfields for ET4000/W32 operation state register:
Bit(s) Description (Table M058)
7-4 reserved
3 restart operation after ACL-interruption
2-1 reserved
0 restore status before ACL-interruption
SeeAlso: #M055
Bitfields for ET4000/W32 memory address register:
Bit(s) Description (Table M059)
31-22 reserved
21-0 memory base pointer
SeeAlso: #M055
Bitfields for ET4000/W32 offset register:
Bit(s) Description (Table M060)
15-12 reserved
11-0 Y offset
SeeAlso: #M055
Bitfields for ET4000/W32 X/Y direction register:
Bit(s) Description (Table M061)
7-2 reserved
1 X direction
0 Y direction
SeeAlso: #M055
Bitfields for ET4000/W32 wrap register:
Bit(s) Description (Table M062)
7 reserved
6-4 pattern Y wrap
000 = 1 line
001 = 2 lines
010 = 4 lines
011 = 8 lines
100 = reserved
101 = reserved
110 = reserved
111 = no wrap
3 reserved
2-0 pattern X wrap
000 = reserved
001 = reserved
010 = 4 byte
011 = 8 byte
100 = 16 byte
101 = 32 byte
110 = 64 byte
111 = no wrap
SeeAlso: #M055
Bitfields for ET4000/W32 count register:
Bit(s) Description (Table M063)
15-12 reserved
11-0 pixel count
SeeAlso: #M055
Bitfields for ET4000/W32 routine control register:
Bit(s) Description (Table M064)
7-6 reserved
5-4 routing of CPU address (ADRO)
00 don't use CPU address
01 CPU address is destination
10 reserved
11 reserved
3 reserved
2-0 routing of CPU data (DARQ)
000 don't use CPU data
001 CPU data is source data
010 CPU data is mixed data
011 reserved
100 CPU data is x-count
101 CPU data is y-count
10x reserved
SeeAlso: #M055
----------MC0000000--------------------------
MEM C000h:0000h - VIDEO BIOS (EGA and newer)
Size: varies (usually 16K-24K for EGA, 24K-32K for VGA)
----------mC0000000--------------------------
MEM C0000000h - Weitek "Abacus" math coprocessor
Size: 4096 BYTEs
----------MC8000000--------------------------
MEM C800h:0000h - HARD DISK BIOS
Size: varies (usually 8K or 16K)
----------MC8001C00--------------------------
MEM C800h:1C00h - IBM XGA, XGA/A - MEMORY-MAPPED REGISTERS
Range: any 8K boundary within segments C000h to DFFFh
Notes: The XGA memory mapped registers can be assigned to the last 1K block in
in each 8K block in the range of C0000h-DFFFFh; the base offset of
the 128 memory mapped lcoation for a particular XGA instance is
Segment:(1C00h+instance*80h) for each XGA installed in a system
(default instance is 6). The instance number may be read from the
XGA's Programmable Option Select registers
The XGA/A (PS/2 adapter) uses the 7KB area below the memory-mapped
register area for ROM data; the XGA (PS/2 onboard) has included
this area in it's video BIOS ROM.
Most of the memory mapped registers are from the graphics coprocessor,
while the I/O-registers are for the display controller.
----------MF0006000--------------------------
MEM F000h:6000h - IBM PC ROM BASIC
Size: 32768 BYTEs
--------B-MF000E000--------------------------
MEM F000h:E000h - ORIGINAL IBM PC ROM BIOS
Size: 8192 BYTEs
--------H-MF000FFF0--------------------------
MEM F000h:FFF0h - RESET JUMP
Size: 5 BYTEs
--------B-MF000FFF5--------------------------
MEM F000h:FFF5h - ASCII BIOS DATE
Size: 8 BYTEs
----------MF000FFFD--------------------------
MEM F000h:FFFDh - OFTEN USED TO ENSURE CORRECT BIOS CHECKSUM
Size: BYTE
--------B-MF000FFFE--------------------------
MEM F000h:FFFEh - MACHINE TYPE CODE
Size: BYTE
SeeAlso: INT 15/AH=C0h
--------B-MF000xxxx--------------------------
MEM F000h:xxxxh - AWARD Flash Hook
Format of AWARD Flash BIOS interface:
Offset Size Description (Table M065)
00h 8 BYTEs signature "AWDFLASH"
08h WORD offset in F000h of FAR function: Get ???
Return: BL = ??? (00h)
0Ah WORD offset in F000h of FAR function: ???
0Ch WORD offset in F000h of FAR function: ???
0Eh WORD offset in F000h of FAR function: ???
10h WORD offset in F000h of FAR function: ???
12h WORD offset in F000h of FAR function: Disable Shadowing
14h WORD offset in F000h of FAR function: Enable Shadowing
16h WORD offset in F000h of FAR function: Get ???
Return: DS:SI -> ??? (30 bytes?)
18h WORD offset in F000h of FAR function: Set ???
DS:SI -> ??? (appears to be same as previous function)
Note: the AWDFLASH utility copies the ROM from F000h and uses the copy
instead of the original F000h:xxxxh addresses
--------B-MF000xxxx--------------------------
MEM F000h:xxxxh - Asustek Flash Hook
Format of Asustek Flash interface:
Offset Size Description (Table M066)
00h 10 BYTEs signature "ASUS_FLASH"
0Ah 6 BYTEs blanks (padding)
10h WORD interface version??? (current PFLASH.EXE requires 0101h)
12h DWORD -> position-independent code to enable shadowing
16h WORD size of code pointed at by previous field (<= 0400h)
18h DWORD -> position-independent code to disable shadowing
1Ch WORD size of code pointed at by previous field (<= 0400h)
----------Mxxxxxxx0--------------------------
MEM xxxxh:xxx0h - Multiprocessor Specification - FLOATING POINTER STRUCTURE
Range: any paragraph boundary in the first kilobyte of the XBDA, the last
kilobyte of conventional memory, or from F000h:0000h to F000h:FFE0h
Note: scan paragraph boundaries for the signature string "_MP_", followed
by a valid floating pointer structure (see #M067)
SeeAlso: MEM FEE00000h
Format of Multiprocessor Specification Floating Pointer structure:
Offset Size Description (Table M067)
00h 4 BYTEs signature "_MP_"
04h DWORD physical address of MP configuration table (see #M068)
00000000h if no configuration table
08h BYTE length of this structure in paragraphs (currently 01h)
09h BYTE revision of MP specification supported
01h = v1.1
04h = v1.4
0Ah BYTE checksum (8-bit sum of entire structure, including this
byte, must equal 00h)
0Bh BYTE MP feature byte 1: system configuration type
00h: MP configuration table present
nonzero: default configuration implemented by system
0Ch BYTE MP feature byte 2
bit 7: IMCR present
bits 6-0: reserved (0)
0Dh 3 BYTEs MP feature bytes 3-5 (reserved, must be 00h)
Format of Multiprocessor Specification configuration table header:
Offset Size Description (Table M068)
00h 4 BYTEs signature "PCMP"
04h WORD length of base configuration table in bytes, including
this header
06h BYTE revision of MP specification supported
01h = v1.1
04h = v1.4
07h BYTE checksum of entire base configuration table
08h 8 BYTEs OEM identifier
10h 12 BYTEs product ID
1Ch DWORD physical address to OEM-defined configuration table
00000000h if not present
20h WORD size of base OEM table in bytes (0000h if not present)
22h WORD number of entries in variable portion of base table
24h DWORD address of local APIC (see also MEM FEE0h:0020h)
28h WORD length of extended entries following end of base table
(in bytes)
2Ah BYTE checksum for extended table entries (includes only
extended entries following base table)
2Ch var configuration table entries (see #M069)
SeeAlso: #M067
Format of Multiprocessor Specification configuration table entries:
Offset Size Description (Table M069)
00h BYTE entry type code
00h processor
01h bus
02h I/O APIC
03h I/IO interrupt assignment
04h local interrupt assignment
80h system address space mapping
81h bus hierarchy descriptor
82h compatibility bus address space modifier
---processor---
01h BYTE local APIC identifier
02h BYTE local APIC version
03h BYTE CPU flags
bit 0: processor usable
bit 1: bootstrap processor
04h WORD CPU type
bits 11-8: CPU family
bits 7-4: CPU model
bits 3-0: stepping
(bits 11-0 all set indicate non-Intel-compatible CPU)
06h 2 BYTEs unused
08h DWORD feature flags (as returned by Pentium CPUID instruction)
0Ch 8 BYTEs reserved
---bus---
01h BYTE bus ID (assigned sequentially from 00h by BIOS)
02h 6 BYTEs bus type (blank-padded ASCII string) (see #M070)
---I/O APIC---
01h BYTE APIC identifier
02h BYTE APIC version
03h BYTE I/O APIC flags
bit 0: enabled
bits 7-1: reserved
04h DWORD base address for APIC
---I/O,local interrupt assignment---
01h BYTE interrupt type
00h vectored interrupt (from APIC)
01h NMI
02h system management interrupt
03h vectored interrupt (from external PIC)
02h BYTE APIC control (see #M071)
03h BYTE unused
04h BYTE source bus identifier
05h BYTE source bus IRQ
06h BYTE destination I/O APIC identifier
07h BYTE destination I/O APIC interrupt pin number
---system address space mapping---
01h BYTE entry length (14h)
02h BYTE bus ID
03h BYTE address type (00h I/O, 01h memory, 02h prefetch)
04h QWORD starting address of region visible to bus
0Ch QWORD length of region visible to bus
---bus hierarchy descriptor---
01h BYTE entry length (08h)
02h BYTE bus ID
03h BYTE bus information
bit 0: subtractive decoding
04h BYTE ID of parent bus
05h 3 BYTEs reserved
---compatibility bus address space modifier---
01h BYTE entry length (08h)
02h BYTE bus ID
03h BYTE address modifier
bit 0: remove address ranges in predefined range list from
bus's address space
04h DWORD number indicating predefined address space range to be removed
00h ISA-compatible I/O range (x100h-x3FFh and aliases)
01h VGA-compatible I/O range (x3B0h-x3BBh,x3C0h-x3DFh,aliases)
SeeAlso: #M068
(Table M070)
Values for Multiprocessor Specification bus name:
"CBUS" Corollary CBus
"CBUSII" Corollary CBus II
"EISA"
"FUTURE" IEEE FutureBus
"INTERN" internal bus
"ISA"
"MBI" Multibus I
"MBII" Multibus II
"MCA" Microchannel
"MPI"
"MPSA"
"NUBUS" Apple Macintosh NuBus
"PCI"
"PCMCIA"
"TC" DEC TurboChannel
"VL" VESA Local Bus
"VME" VMEbus
"XPRESS" Express System Bus
SeeAlso: #M069
Bitfields for Multiprocessor Specification APIC control:
Bit(s) Description (Table M071)
1-0 input signal polarity
00 conforms to bus specification
01 active high
10 reserved
11 active low
3-2 trigger mode
00 conforms to bus specification
01 edge-triggered
10 reserved
11 level-triggered
SeeAlso: #M069
----------mFEC00000--------------------------
MEM FEC00000h - Pentium - I/O APIC
Size: 4096 BYTEs
Range: the Multiprocessor Specification calls for I/O APICs to be memory-
mapped on 4K boundaries between FEC00000h and FEDFC000h
SeeAlso: MEM FEE00000h,MEM xxxxh:xxx0h"Multiprocessor"
----------mFEE00000--------------------------
MEM FEE00000h - Pentium - LOCAL APIC
Size: 4096 BYTEs
Notes: the Advanced Programmable Interrupt Controller built into
multiprocessor-capable Pentiums (P54C, etc. -- basically 75MHz and
faster Pentiums) maps its registers into the top of the physical
address space on data reads and writes, but not on code reads;
data accesses to the APIC registers do not cause external bus
cycles
the APIC's registers are only visible when the APIC is enabled (which
occurs at CPU reset when external data lines contain proper signals)
SeeAlso: MEM FEC00000h,MEM FEE00020h,MEM xxxxh:xxx0h"Multiprocessor"
----------mFEE00020--------------------------
MEM FEE00020h - Pentium - LOCAL APIC - LOCAL APIC ID REGISTER
SeeAlso: MEM FEE00030h
----------mFEE00030--------------------------
MEM FEE00030h - Pentium - LOCAL APIC - LOCAL APIC VERSION REGISTER
Note: read-only
SeeAlso: MEM FEE00020h
----------mFEE00040--------------------------
MEM FEE00040h - Pentium - LOCAL APIC - RESERVED
SeeAlso: MEM FEE00000h
----------mFEE00050--------------------------
MEM FEE00050h - Pentium - LOCAL APIC - RESERVED
SeeAlso: MEM FEE00000h
----------mFEE00060--------------------------
MEM FEE00060h - Pentium - LOCAL APIC - RESERVED
SeeAlso: MEM FEE00000h
----------mFEE00070--------------------------
MEM FEE00070h - Pentium - LOCAL APIC - RESERVED
SeeAlso: MEM FEE00000h
----------mFEE00080--------------------------
MEM FEE00080h - Pentium - LOCAL APIC - TASK PRIORITY REGISTER (TPR)
----------mFEE00090--------------------------
MEM FEE00090h - Pentium - LOCAL APIC - ARBITRATION PRIORITY REGISTER (APR)
Note: read-only
----------mFEE000A0--------------------------
MEM FEE000A0h - Pentium - LOCAL APIC - END OF INTERRUPT REGISTER (EOI)
Note: write-only
----------mFEE000A0--------------------------
MEM FEE000A0h - Pentium - LOCAL APIC - PROCESSOR PRIORITY REGISTER (PPR)
Note: read-only
SeeAlso: MEM FEE00000h
----------mFEE000B0--------------------------
MEM FEE000B0h - Pentium - LOCAL APIC - RESERVED
SeeAlso: MEM FEE00000h
----------mFEE000C0--------------------------
MEM FEE000C0h - Pentium - LOCAL APIC - REMOTE READ REGISTER
Note: read-only
----------mFEE000D0--------------------------
MEM FEE000D0h - Pentium - LOCAL APIC - LOGICAL DURATION REGISTER (LDR)
SeeAlso: MEM FEE00000h
----------mFEE000E0--------------------------
MEM FEE000E0h - Pentium - LOCAL APIC - DESTINATION FORMAT REGISTER (DFR)
bits 27-0: read-only
bits 31-28: read-write
----------mFEE000F0--------------------------
MEM FEE000F0h - Pentium - LOCAL APIC - SPURIOUS INTERRUPT VECTOR REGISTER
bits 3-0, read-only
bits 9-4, read/write
----------mFEE00100--------------------------
MEM FEE00100h - Pentium - LOCAL APIC - IN-SERVICE REGISTER (ISR)
Size: 128 BYTEs
Note: read-only
SeeAlso: MEM FEE00200h
----------mFEE00180--------------------------
MEM FEE00180h - Pentium - LOCAL APIC - TRIGGER MODE REGISTER (TMR)
Size: 128 BYTEs
Note: read-only
SeeAlso: MEM FEE00000h
----------mFEE00200--------------------------
MEM FEE00200h - Pentium - LOCAL APIC - INTERRUPT REQUEST REGISTER (IRR)
Size: 128 BYTEs
Note: read-only
SeeAlso: MEM FEE00100h
----------mFEE00280--------------------------
MEM FEE00280h - Pentium - LOCAL APIC - ERROR STATUS REGISTER
Size: 4 BYTEs
Note: read-only
Bitfields for Pentium APIC error status register:
Bit(s) Description (Table M072)
0 send checksum error
1 receive checksum error
2 send accept error
3 receive accept error
4 reserved
5 send illegal vector
6 receive illegal vector
7 illegal register address
31-8 reserved
----------mFEE00300--------------------------
MEM FEE00300h - Pentium - LOCAL APIC - INTERRUPT COMMAND REGISTER (ICR)
Size: 4 BYTEs
Note: this is the low half of the 64-bit ICR
SeeAlso: MEM FEE00310h,#M073
Bitfields for Pentium APIC Interrupt Command Register:
Bit(s) Description (Table M073)
7-0 interrupt vector number
10-8 delivery mode (see #M074)
11 destination mode
12 delivery status (read-only)
1 = transfer pending
13 reserved
14 level (0 = INIT Level Deassert message, 1 = anything else)
15 trigger mode (1)
17-16 remote read status (read-only)
19-18 destination shorthand
00 as specified by destination field
01 self
10 all including self
11 all except self
55-20 reserved
63-56 destination for interrupt request or message
SeeAlso: #M076
(Table M074)
Values for Pentium APIC delivery mode:
000b fixed
001b lowest-priority
010b SMI
011b remote read
100b NMI
101b INIT
110b start up
111b reserved
SeeAlso: #M073
----------mFEE00310--------------------------
MEM FEE00310h - Pentium - LOCAL APIC - INTERRUPT COMMAND REGISTER (ICR)
Size: 4 BYTEs
Note: this is the high half of the 64-bit ICR
SeeAlso: MEM FEE00300h,#M073
----------mFEE00320--------------------------
MEM FEE00320h - Pentium - LOCAL APIC - LOCAL VECTOR TABLE ENTRY 0 (TIMER)
Size: 4 BYTEs
SeeAlso: MEM FEE00350h,MEM FEE00370h,MEM FEE003E0h,INT 70h
Bitfields for Pentium APIC timer local vector entry:
Bit(s) Description (Table M075)
7-0 interrupt vector number
11-8 reserved
12 delivery status (read-only)
1 = interrupt being sent to APIC
15-13 reserved
16 interrupt delivery disabled
17 timer mode (0=one-shot, 1=periodic)
31-18 reserved
SeeAlso: #M077,#M076
----------mFEE00330--------------------------
MEM FEE00330h - Pentium - LOCAL APIC - RESERVED
SeeAlso: MEM FEE00000h
----------mFEE00340--------------------------
MEM FEE00340h - Pentium - LOCAL APIC - RESERVED
SeeAlso: MEM FEE00000h
----------mFEE00350--------------------------
MEM FEE00350h - Pentium - LOCAL APIC - LOCAL VECTOR TABLE ENTRY 1 (LINT0)
Size: 4 BYTEs
SeeAlso: MEM FEE00320h,MEM FEE00360h
Bitfields for Pentium APIC LINTx local vector entry:
Bit(s) Description (Table M076)
7-0 interrupt vector number
10-8 delivery mode
000 fixed
100 NMI
111 external interrupt (8259A-compatibility)
11 reserved
12 delivery status (read-only)
1 = interrupt being sent to APIC
13 interrupt pin is active low
14 remote IRR
15 trigger mode
0 edge-sensitive
1 level-sensitive
16 interrupt delivery disabled
31-17 reserved
SeeAlso: #M075
----------mFEE00360--------------------------
MEM FEE00360h - Pentium - LOCAL APIC - LOCAL VECTOR TABLE ENTRY 2 (LINT1)
Size: 4 BYTEs
SeeAlso: MEM FEE00350h,MEM FEE00370h,#M076
----------mFEE00370--------------------------
MEM FEE00370h - Pentium - LOCAL APIC - LOCAL VECTOR TABLE ENTRY 3 (Error)
Size: 4 BYTEs
SeeAlso: MEM FEE00320h,MEM FEE00370h
----------mFEE00380--------------------------
MEM FEE00380h - Pentium - LOCAL APIC - INITIAL COUNT REGISTER (ICR) TIMER
Desc: timer start value, which together with the Divide Configuration
Register also determines its period when periodic mode has been
selected
SeeAlso: MEM FEE00000h,MEM FEE00390h
----------mFEE00390--------------------------
MEM FEE00390h - Pentium - LOCAL APIC - CURRENT COUNT REGISTER (CCR) TIMER
Desc: current timer count; when this value reaches zero, an interrupt is
generated
Note: read-only
SeeAlso: MEM FEE00380h
----------mFEE003A0--------------------------
MEM FEE003A0h - Pentium - LOCAL APIC - RESERVED
SeeAlso: MEM FEE00000h
----------mFEE003B0--------------------------
MEM FEE003B0h - Pentium - LOCAL APIC - RESERVED
SeeAlso: MEM FEE00000h
----------mFEE003C0--------------------------
MEM FEE003C0h - Pentium - LOCAL APIC - RESERVED
SeeAlso: MEM FEE00000h
----------mFEE003D0--------------------------
MEM FEE003D0h - Pentium - LOCAL APIC - RESERVED
SeeAlso: MEM FEE00000h
----------mFEE003E0--------------------------
MEM FEE003E0h - Pentium - LOCAL APIC - TIMER DIVIDE CONFIGURATION REGISTER
SeeAlso: MEM FEE00000h,MEM FEE00320h
Bitfields for Pentium APIC timer divide configuration:
Bit(s) Description (Table M077)
3,1,0 divisor
000 divide by 2
001 by 4
010 by 8
...
110 by 128
111 by 1
2 zero (0)
31-4 reserved
Note: the divisor determines the timer's time base relative to the processor
clock
SeeAlso: #M075
----------MFFFF0010--------------------------
MEM FFFFh:0010h - HIGH MEMORY AREA
Size: 65520 BYTEs
---------------------------------------------
--------!---CONTRIBUTORS---------------------
Robin Walker <rdhw@cus.cam.ac.uk> ORIGINAL FILE
Wim Osterholt <wim@djo.wtm.tudelft.nl> or Wim Osterholt 2:512/56
EHD floppy = 'KEGAN 4.0M Floppy Drive Controller.',
'ACME FX4-K7tb2 v:2.5 11/5/91'
Stanley Appel <appel@stack.urc.tue.nl>
Matthias Paul <mpaul@ibh.rwth-aachen.de>
--------!---Admin----------------------------
Highest Table Number = M077
--------!---FILELIST-------------------------
Please redistribute all of the files comprising the interrupt list (listed at
the beginning of the list and in INTERRUP.1ST) unmodified as a group, in a
quartet of archives named INTER50A through INTER50D (preferably the original
authenticated PKZIP archives), and the utility programs in a two additional
archives called INTER50E.ZIP and INTER50F.ZIP
Copyright (c) 1989,1990,1991,1992,1993,1994,1995 Ralf Brown
--------!---CONTACT_INFO---------------------
Internet: ralf@pobox.com (currently forwards to ralf@telerama.lm.com)
UUCP: {uunet,harvard}!pobox.com!ralf
FIDO: Ralf Brown 1:129/26.1
or post a message to me in the DR_DEBUG echo (I probably won't see it
unless you address it to me)
CIS: >INTERNET:ralf@pobox.com
