80x86 Assembly Trouble.

[DigitalKnight]

I trying to write a simple assmebly program for a lab class and I can't seem to get it to work right. It'll store the string entered but it will not print it back you. The trouble maybe something simple that I just can't see right now, but I would like any help anyone can give. I'm going to bed, maybe after a nights sleep I can see what I am missing.

Thanks.

Code is as follows:

;PROGRAM 3 OF LAB 1
;FILENAME: INTRO3.ASM
;FILE FORMAT: EXE
PAGE 55,132
.386

STACK_SEG SEGMENT STACK USE16
DB 255 DUP(0)
STACK_SEG ENDS

DATA_SEG SEGMENT 'DATA' USE16
MESSAGE DB 'ECE4210/ECE7210 LAB1 PART 3',0DH,0AH
DB 'ENTER A STRING FROM KEYBORD: $'
OUTMSG DB 0DH,0AH,'THE STRING YOU JUST ENTERED IS: $'
INCHAR DB 255,255 DUP(0)
NEWLINE DB 0DH,0AH,'$'
DATA_SEG ENDS

CODE_SEG SEGMENT PARA 'CODE' PUBLIC USE16
ASSUME CS:CODE_SEG, DSATA_SEG, SS:STACK_SEG

MAIN PROC FAR
PUSH DS ;INITIATE THE PROGRAM
XOR AX,AX
PUSH AX
MOV AX,DATA_SEG
MOV DS,AX

LEA DX,MESSAGE ;PRINT MESSAGE
MOV AH,9
INT 21H

LEA DX,INCHAR
MOV AH,0AH ;READ A STRING
INT 21H

LEA DX,OUTMSG ;PRINT A MESSAGE
MOV AH,09H
INT 21H

LEA DX,INCHAR ;OUTPUT THE CHARACTER TO THE SCREEN
MOV AH,09H
INT 21H

MOV DX,OFFSET NEWLINE
MOV AH,9 ;MOVE CURSOR TO NEXT LINE
INT 21H

RET
MAIN ENDP
CODE_SEG ENDS
END MAIN

[robbie]

It's been about 9 years since I've done assembly, sorry I can't be more help. I'm sure one of our guru's will chime in soon enough.
Rob

[Gizmo]

I believe your problem is that you are trying to print the string pointed at by MESSAGE, but that string is not terminated by the '$' symbol. As a consequence, your subsequent calls to int 21 don't do anything useful. But that is just a guess. It's been quite some time since I messed with x86 assembly.

[Kaitain]

On a barely related matter, is there an x86 chip simulator or similar? The only assembly I've ever done is for a teeny 8 bit controller that can be modelled entirely in software.

[DimViesel]

I can see the problem...
You seem to have overlooked a smilie in the listing on the line which begins:
ASSUME CS:CODE_SEG, DSATA_SEG, SS:STACK_SEG
(Line 18 from the top of the listing)
The compiler will attempt to take this code & will give erratic output due to the smilie...

(yes I know... I'll get me coat...)
On a serious note - if you are working on a self developed algorithm after working on it for considerable amounts of time you being to see not what it actually is... I used to pass my listings to someone else who had a nack for seeing the 'obvious mistake' that was just not eviendent to myself... I believe it is because when you are concerning yourself with bringing to existance the machanics of the algorithm you cannot read it literally - which is the mode of reading that will bring to your attention the 'typos' or logical errors to you.

[Kaitain]

Originally Posted by gizmo

I believe your problem is that you are trying to print the string pointed at by MESSAGE, but that string is not terminated by the '$' symbol. As a consequence, your subsequent calls to int 21 don't do anything useful. But that is just a guess. It's been quite some time since I messed with x86 assembly.

Ya you're right. x86 assembly keeps me sane while Excel is updating cells (yes, really, it is that bad). At least in NASM, losing the $ from the end of the "MESSAGE DB 'ECE4210/ECE7210 LAB1 PART 3',0DH,0AH" line causes it to stall there.

[Gizmo]

Originally Posted by Kaitain

Ya you're right. x86 assembly keeps me sane while Excel is updating cells (yes, really, it is that bad). At least in NASM, losing the $ from the end of the "MESSAGE DB 'ECE4210/ECE7210 LAB1 PART 3',0DH,0AH" line causes it to stall there.

Dude, now that is truly sad.

Try assembly on a sane architecture, like the 68k, or even Z80.

[DimViesel]

Yeah 68k - that is the way to go, or Zilogs are pretty neat too
I don't even have to go with an emulator if I do not wish to - my grandmother has a brand new unopened Z80 based machine & I have 4 Amiga machines:
68000, 68020 & 68030 CPUs respectively.
All OC'd of course

(Not.)

[Kaitain]

Yeah well unfortunately I don't have a monitor capable of handling the range of screen modes my '030 accelerated A1200 can produce. I think I left it last using the VGA screenmode so that a normal PC monitor can handle it. Since the most reliable machines I have are x86-based (sad but true) and the limits of my prior knowledge are Intel 8bit controllers, the x86 is the easiest logical progression.

Unless I want to learn the pseudo-assembly required for a Core War

[DimViesel]

Heh I'm sure you will miss the raw power of your 25MHz '030 A1200.

What really brought home how obsolete the hardware performance of these machines is, was when I looked at my £20 cable router & saw that it ran @ 40MHz (Amiga 68040 anyone?) & had 4MB of RAM (double that of the std. A1200).

If we want to exorcise any remainingCBM nostalgia I propose it should have a thread of its own.

[barneygumble742]

Originally Posted by gizmo

Try assembly on a sane architecture, like the 68k, or even Z80.

Ditto!