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2180

Category: DOS kernel

INT 21 - 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
SeeAlso: AH=4Bh,AH=87h,INT 2F/AX=1400h"POPUP"

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