Int 21/AH=80h

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European MS-DOS 4.0 - AEXEC - EXECUTE PROGRAM IN BACKGROUND

AH = 80h
CX = mode
0000h place child in zombie mode on exit to preserve exit code
0001h discard child process and exit code on termination
DS:DX -> ASCIZ full program name
ES:BX -> parameter block (as for AX=4B00h)

Return:
CF clear if successful AX = Command Subgroup ID (CSID) CF set on error AX = error code (see #01680 at AH=59h/BX=0000h)

Program: European MS-DOS 4.0 was written for Siemens in Germany and then used by several other European OEMs; its release falls between mainstream versions 3.2 and 3.3

Desc: Asynchronously execute a program, creating a new process for it

Notes: This function is called by the DETACH command. There is a system-wide limit of 32 processes. The CSID is used to identify all processes that have been spawned by a given process, whether directly or indirectly. Programs to be run in the background must use the new executable format (see #01596 at AH=4Bh). Background processes may only perform asynchronous (background) EXECs, either this function or AX=4B04h. Background processes may execute INT 11, INT 12, INT 21, INT 2A, and INT 2F at any time; they may execute INT 10 and INT 16 only while they have opened a popup screen via INT 2F/AX=1401h; no other interrupts may be executed from the background.

Background processes may not use drive B:
Or overlay their code segments. See AX=8700h for an installation check. The "NE" new executable format made its first appearance in European MS-DOS 4.0

See Also: AH=4Bh - AH=87h - INT 2F/AX=1400h"POPUP"

Category: DOS Kernel - Int 21h - E

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