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Simtel MSDOS 1995 May
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Simtel-MSDOS-May1995-CD2.iso
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disc2
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sysutil
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exectest.asm
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Assembly Source File
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1984-09-19
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2KB
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83 lines
TITLE Exec call test
PAGE 60,132
; This program demonstrates shelling to DOS command processor
; using the EXEC funtion.
; Assemble, link and convert to a .COM file.
; Program written by Brian M. Markey
code SEGMENT 'codesg'
ASSUME CS:code,DS:code,ES:code
ORG 0100H ; Program entry point
exectest: ; ..
MOV SP,OFFSET stack ; Set up local stack
MOV AH,09H ; Print "Before shell"
MOV DX,OFFSET mess1 ; .
INT 21H ; ..
MOV BX,OFFSET lastloc+15 ; BX := program size in
MOV CX,4 ; paragraphs
SHR BX,CL ; ..
MOV AX,4A00H ; Deallocate unused memory
INT 21H ; ..
MOV SI,2CH ; Get environment address
MOV AX,CS:[SI] ; from PSP+2CH
MOV WORD PTR parmblk,AX ; ..
MOV AX,CS ; Set segment registers
MOV WORD PTR parmblk+4,AX ; in paramater block
MOV WORD PTR parmblk+8,AX ; .
MOV WORD PTR parmblk+12,AX ; ..
MOV DX,OFFSET filenam ; Set up exec call
MOV BX,OFFSET parmblk ; .
MOV AX,4B00H ; ..
PUSH DS ; Save machine state
PUSH ES ; .
MOV CS:savess,SS ; .
MOV CS:savesp,SP ; ..
INT 21H ; Shell to DOS
MOV SP,CS:savesp ; Restore machine state
MOV SS,CS:savess ; .
POP ES ; .
POP DS ; ..
MOV AH,09H ; Print "After shell"
MOV DX,OFFSET mess2 ; .
INT 21H ; ..
INT 20H ; Terminate program
savess DW ? ; Holders for SS:SP
savesp DW ? ; ..
mess1 DB 'Before shell',0DH,0AH,'$'
mess2 DB 'After shell',0DH,0AH,'$'
filenam DB 'A:\COMMAND.COM',0 ; Assume COMMAND.COM on A:
parmblk DW 00 ; Parameter block
DW OFFSET comline,00 ; .
DW 5CH,00 ; .
DW 6CH,00 ; ..
comline DB 09H,'/C dir A:',0DH ; Command line
PAGE
DB 128 DUP (?) ; Stack
stack LABEL BYTE ; ..
lastloc LABEL BYTE ; End of program
code ENDS
END exectest