INT E0 - CP/M-86, Concurrent CP/M, DR Multiuser DOS - FUNCTION CALLS
        CL = function number
        DS,DX = parameters
Return: as appropriate for function
Notes:  several functions are covered in more detail in following entries
        most of these calls are also supported by Digital Research's DOS Plus
          v2.1; the unsupported functions are 26h,29h-2Bh,3Ah,3Dh-62h,71h-8Ch,
          90h-92h,94h-97h,9Bh-ABh, and AEh-FFh
SeeAlso: INT 21/AH=E0h"DOS Plus"

Values for function number:
 00h    terminate calling process (see also INT 21/AH=00h)
 01h    read a character
 02h    write character to default console (see also INT 21/AH=02h)
 03h    read character from default AUX (see also INT 21/AH=03h)
 04h    write character to default AUX (see also INT 21/AH=04h)
 05h    write character to default list device (see also INT 21/AH=05h)
 06h    perform raw I/O on default console (see also INT 21/AH=06h)
 07h    return default AUX input status
 08h    return default AUX output status
 09h    write string to default console (see also INT 21/AH=09h)
 0Ah    read string from default console (see also INT 21/AH=0Ah)
 0Bh    return default console input status (see also INT 21/AH=0Bh)
 0Ch    get BDOS release ID
 0Dh    reset all disk drives (see also INT 21/AH=0Dh)
 0Eh    set default drive (see also INT 21/AH=0Eh)
 0Fh    open file via FCB (see also INT 21/AH=0Fh)
 10h    close file via FCB (see also INT 21/AH=10h)
 11h    search for first matching file with FCB (see also INT 21/AH=11h)
 12h    search for next matching file with FCB (see also INT 21/AH=12h)
 13h    delete file via FCB (see also INT 21/AH=13h)
 14h    sequential read via FCB (see also INT 21/AH=14h)
 15h    sequential write via FCB (see also INT 21/AH=15h)
 16h    create file via FCB (see also INT 21/AH=16h)
 17h    rename file via FCB (see also INT 21/AH=17h)
 18h    get bit map of logged drives
 19h    get default drive (see also INT 21/AH=19h)
 1Ah    set DMA address offset
 1Bh    get default disk allocation vector (see also INT 21/AH=1Bh)
 1Ch    set default drive to read-only
 1Dh    get bit map of read-only drives
 1Eh    set file attributes via FCB (see also INT 21/AX=4301h)
 1Fh    get address of disk parameter block (see also INT 21/AH=1Fh)
 20h    get/set default user number
 21h    read random record via FCB (see also INT 21/AH=21h)
 22h    write random record via FCB (see also INT 21/AH=22h)
 23h    compute file size with FCB (see also INT 21/AH=23h)
 24h    get FCB random record number (see also INT 21/AH=24h)
 25h    reset specified drives
 26h    access specified drives (not in DR DOS Plus v2.1)
 27h    free specified drives
 28h    write random with FCB, zero fill (see also also INT 21/AH=28h)
 2Ah    lock records in FCB file (see also INT 21/AH=5Ch)
 2Bh    unlock records in FCB file (see also INT 21/AH=5Ch)
 2Ch    set BDOS multisector count
 2Dh    set BDOS error mode
 2Eh    get free space on disk
 2Fh    load, initialize, and jump to process (see also INT 21/AH=4Bh)
 30h    flush write-deferred buffers
 31h    get/set system variable (DOS Plus v2.1)
 32h    call BIOS (XIOS) character routine (see below)
 33h    set DMA address segment
 34h    get DMA buffer address
 35h    CP/M-86 allocate maximum memory
 36h    allocate maximum memory at specified segment
 37h    CP/M-86 allocate memory segment (see also INT 21/AH=48h)
 38h    allocate memory at specified segment
 39h    CP/M-86 free specified memory segment (see also INT 21/AH=49h)
 3Ah    CP/M-86 free all memory (not in DOS Plus v2.1)
 3Bh    load .CMD file into memory
 3Ch    (DOS Plus v2.1) call RSX program
 40h    (DR-NET) log on a server
 41h    (DR-NET) log off a server
 42h    (DR-NET) send a message
 43h    (DR-NET) receive a message
 44h    (DR-NET) get network status
 45h    (DR-NET) get requestor configuration table
 46h    (DR-NET) set compatibility attributes
 47h    (DR-NET) get server configuration table
 48h    (DR-NET) set network error mode
 49h    (DR-NET) attach network
 4Ah    (DR-NET) detach network
 4Bh    (DR-NET) set default password
 4Ch    (DR-NET) get-set long timeout
 4Dh    (DR-NET) get parameter table
 50h    (DR-NET) get network information
 53h    get current time (see also INT 21/AH=2Ch)
 54h    set current time (see also INT 21/AH=2Dh)
 55h    get binary system date (see also INT 21/AH=2Ah)
 56h    set system date (see also INT 21/AH=2Bh)
 57h    allocate system flag
 58h    deallocate system flag
 59h    reserve memory in global area
 5Ah    lock physical drive
 5Bh    unlock physical drive
 5Ch    search path for executable file
 5Dh    load and execute command (see also INT 21/AH=4Bh)
 5Eh    get/set process exit code
 5Fh    set country information
 60h    get country information
 63h    truncate FCB file (see also INT 21/AH=28h)
 64h    create/update directory label
 65h    get directory label
 66h    get FCB date stamp and password mode
 67h    write extended FCB
 68h    set system date and time
 69h    get system date and time in binary
 6Ah    establish password for file access
 6Bh    get OS serial number
 6Ch    (DOS Plus v2.1) get/set program return code
 6Dh    get/set console mode
 6Eh    get/set string delimiter
 6Fh    write block to default console
 70h    write block to default list device
 71h    execute DOS-compatible function
 74h    set FCB time and date stamps
 80h    allocate memory
 82h    deallocate memory
 83h    poll I/O device
 84h    wait on system flag
 85h    set system flag
 86h    create message queue
 87h    open message queue
 88h    delete message queue
 89h    read from message queue
 8Ah    conditionally read from message queue
 8Bh    write to message queue
 8Ch    conditionally write to message queue
 8Dh    delay calling process
 8Eh    call process dispatcher (yield CPU)
 8Fh    terminate calling process (same as function 00h)
 90h    create a process
 91h    set calling process' priority
 92h    attach to default console
 93h    detach from default console
 95h    assign default console to process
 96h    interpret and execute commandline
 97h    resident procedure library
 98h    parse ASCII string into FCB (see also INT 21/AH=29h)
 99h    return default console
 9Ah    get address of system data (SYSDAT)
 9Bh    get system time and date
 9Ch    return calling process' descriptor
 9Dh    terminate process by name or PD address
 9Eh    attach to default list device
 9Fh    detach from default list device
 A0h    select default list device
 A1h    conditionally attach to default list device
 A2h    conditionally attach to default console
 A3h    get OS version number
 A4h    get default list device
 A5h    attach to default AUX
 A6h    detach from default AUX
 A7h    conditionally attach to default AUX
 A8h    set default AUX
 A9h    return default AUX
 ACh    read block from default AUX
 ADh    (DOS Plus v2.1) write block to default AUX
 B0h    configure default AUX
 B1h    get/set device control parameters
 B2h    send Break through default AUX
 B3h    allocate physical memory
 B4h    free physical memory
 B5h    map physical memory
 B6h    nondestructive message queue read
 B7h    timed wait on system flag
 B8h    get/set I/O port mapping
 B9h    set list device timeout
 BAh    set AUX timeout value
 BBh    execute XIOS service
 BDh    (DR Multiuser DOS) delay
 FFh    return 80386 to native mode

Values for DOS Plus v2.1 XIOS functions:
 00h    terminate program
 01h    ???
 02h    check for console input status
 03h    read character from console
 04h    write character to console
 05h    write character to list device
 06h    write character to auxiliary device
 07h    read cahracter from auxiliary device
 0Fh    get list device status
 10h-14h reserved
 15h    device initialization
 16h    check console output status
 17h-7Fh reserved
---BBC Acorn---
 80h    get XIOS version
 81h    get Tube semaphore
 82h    release Tube semaphore
 83h    select text/graphics
 84h    update B&W graphics rectangle
 85h    update color graphics rectangle
 86h    get/release/update mouse
 87h    get system error info
 88h    entry in CLOCK called by WatchDog RSP
 89h    BBC OSBYTE function
 8Ah    BBC OSWORD function

DR Multiuser DOS Error Return Codes:
 00h no error
 01h system call not implmented
 02h illegal system call number
 03h cannot find memory
 04h illegal flag number
 05h flag overrun
 06h flag underrun
 07h no unused Queue Descriptors
 08h no free queue buffer
 09h cannot find queue
 0Ah queue in use
 0Ch no free Process Descriptors
 0Dh no queue access
 0Eh empty queue
 0Fh full queue
 10h CLI queue missing
 11h no 8087 in system
 12h no unused Memory Descriptors
 13h illegal console number
 14h no Process Descriptor match
 15h no console match
 16h no CLI process
 17h illegal disk number
 18h illegal filename
 19h illegal filetype
 1Ah character not ready
 1Bh illegal Memory Descriptor
 1Ch bad return from BDOS load
 1Dh bad return from BDOS read
 1Eh bad return from BDOS open
 1Fh null command
 20h not owner of resource
 21h no CSEG in load file
 22h process Descriptor exists on Thread Root
 23h could not terminate process
 24h cannot attach to process
 25h illegal list device number
 26h illegal password
 28h external termination occurred
 29h fixup error upon load
 2Ah flag set ignored
 2Bh illegal auxilliary device number