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Path: utzoo!linus!philabs!cmcl2!seismo!mcvax!tnocsda!jaap
From: jaap@tnocsda.UUCP (Jaap van den Eersten)
Newsgroups: net.micro.pc
Subject: exec function, help wanted
Message-ID: <116@tnocsda.UUCP>
Date: Fri, 7-Sep-84 12:31:20 EDT
Article-I.D.: tnocsda.116
Posted: Fri Sep  7 12:31:20 1984
Date-Received: Sun, 16-Sep-84 12:01:17 EDT
Lines: 62


I cannot get the EXEC function working. In the example program I am trying
to execute the Personal Editor, editting the file 'test'. The EXEC function
results in executing PE, the filename is rubbish (should be test).
Exit from PE results in a hang up of the PC. Does anyone know a solution
to this problem? The DOS manual tells not much about the EXEC function.

Thanks in advance for any help
Jaap van den Eersten

EXAMPLE PROGRAM :

CMD	DB	5,' test',0DH           ; command line : edit file test
FILE	DB	'C:PE.EXE',0            ; ASCIIZ string with filename

; save locations

SAVE_SS DW	0			; save location for SS register
SAVE_SP DW	0			; save location for SP register

; parameter block

PARBLK	DW	0			; WORD segment address of environment string
	DW	OFFSET CMD		; displacement of command line
	DW	DSEG			; segment containing command line
	DW	4 DUP(0)		; no default fcb's



	PUSH	DS			; prepare return to DOS
	XOR	AX,AX
	PUSH	AX
	MOV	AX,DSEG 		; init DATA segment register
	MOV	DS,AX
	LEA	DX,FILE 		; (DS:DX) points to ASCIIZ string

	MOV	AL,0			; free memory
	MOV	AH,4AH
	MOV	BX,4
	INT	21H

	LEA	BX,PARBLK		; point (ES:BX) to parameter block
	MOV	AX,DS
	MOV	ES,AX
	MOV	AX,SS			; save SS register
	MOV	SAVE_SS,AX
	MOV	AX,SP			; save SP register
	MOV	SAVE_SP,AX

	MOV	AL,0			; call the execute function
	MOV	AH,4BH
	INT	21H

	MOV	AH,4DH			; call the wait function
	INT	21H

	MOV	AX,SAVE_SS		; restore SS register
	MOV	SS,AX
	MOV	AX,SAVE_SP		; restore SP register
	MOV	SP,AX

	RET