How to turn num lock off in FASM?

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barneygumble742

Joined: 11 Jul 2004
Posts: 3

barneygumble742 11 Jul 2004, 19:11

hello,

this is a file i'm trying to assemble using fasm153 for dos:

---
;NUMOFF.ASM: Turn NUM-LOCK indicator off.

Code:

   .MODEL SMALL
        .STACK
      .CODE
       .STARTUP
    MOV     AX,40H                         ;set AX to 0040H
     MOV     DS,AX                           ;load data segment with 0040H
       MOV     SI,17H                          ;load SI with 0017H
 AND     BYTE PTR [SI],0DFH        ;clear NUMLOCK bit
        .EXIT
       END

---

this is the output i get when i try to assemble:
---
C:\fasm153>fasm numoff.asm numoff.com
flat assembler version 1.53
numoff.asm [3]:
.MODEL SMALL
error: illegal instruction.
---

this is my very first program i'm trying to make for the x86. i haven't changed anything. i took it directly from a floppy disk that came with the book. i think there's something wrong with this statement:
AND BYTE PTR [SI],0DFH ;clear NUMLOCK bit

thank you,
barneygumble742

11 Jul 2004, 19:11

crc

Joined: 21 Jun 2003
Posts: 637
Location: Penndel, PA [USA]

crc 11 Jul 2004, 19:25

Fasm doesn't need all of the red tape included in the code you provided. Here's the FASM version of your code:

Code:

org 100h             ; Start a DOS program
MOV AX,40H           ;set AX to 0040H
MOV DS,AX            ;load data segment with 0040H
MOV SI,17H           ;load SI with 0017H
AND BYTE [SI],0DFH   ;clear NUMLOCK bit
int 20h              ; exit

11 Jul 2004, 19:25

barneygumble742

Joined: 11 Jul 2004
Posts: 3

barneygumble742 11 Jul 2004, 19:48

wow. amazing. thanks. i'm on a xp machine now and it didn't work. so i got sceptical and booted up my win98se box. i compiled on there and it worked. is there a reason why that is?

11 Jul 2004, 19:48

crc

Joined: 21 Jun 2003
Posts: 637
Location: Penndel, PA [USA]

crc 11 Jul 2004, 19:58

NT/2000/XP lock various memory regions and I/O ports. It's for stability, but is a pain in the neck for those of us who know what we're doing Smile

11 Jul 2004, 19:58

barneygumble742

Joined: 11 Jul 2004
Posts: 3

barneygumble742 11 Jul 2004, 20:18

yeah that's what i figured. thank you very much.

barneygumble742

11 Jul 2004, 20:18

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