Ad:

Assembly Discussion Thread
Marked Solved
Views: 1050

Sep 26th, 2009

-1

int 21 causes an access violation

Expand Post »

Hello guys. I am having a problem with the following code. When I try to run the program the instruction int 21 causes an access violation. Can someone tell me how to fix this problem?

Assembly Syntax (Toggle Plain Text)
.386
.model flat
 
.stack 100h
 
.data
 
message db 'Hello World', 13, 10, '$'
 
.code
 
_start: 
 
lea dx, message 
 
mov ah, 9h ; string output
 
int 21h ; display string
 
mov ax, 4c00h
 
int 21h
 
mov ah, 1h 
 
int 21h ; read character into al
 
mov dl, al 
 
mov ah, 2h 
 
int 21h ; display character in dl
 
mov ax, 4c00h 
 
int 21h
 
end _start
.386
.model flat

.stack 100h

.data

message db 'Hello World', 13, 10, '$'

.code

_start: 

lea dx, message 

mov ah, 9h ; string output

int 21h ; display string

mov ax, 4c00h

int 21h

mov ah, 1h 

int 21h ; read character into al

mov dl, al 

mov ah, 2h 

int 21h ; display character in dl

mov ax, 4c00h 

int 21h

end _start

Similar Threads

C++ "Access violation reading location 0x00000021." in C++
Access violation reading location 0xcccccc00 in C++
Memory Access Violation in C++
Need an easy way around an access violation in C++
access violation(segmentational fault) gah in C

blerina12

Reputation Points: 10

Solved Threads: 0

Newbie Poster

Offline

22 posts
since Jan 2007

Permalink

Sep 26th, 2009

Re: int 21 causes an access violation

Access violation is caused when a program attempts to
access memory reserved for the operating system.
I thought this could only happen in a windows program?

I assume your using MASM:

Assembly Syntax (Toggle Plain Text)
mov ax, seg message ; initialize the DS register so
mov ds, ax                  ; you can access variable 'message'
lea dx, message
mov ax, seg message ; initialize the DS register so
mov ds, ax                  ; you can access variable 'message'
lea dx, message

Program flow stops before line 23, because you terminated
with 21/4C.

NotNull

Reputation Points: 36

Solved Threads: 19

Junior Poster

Offline

198 posts
since Oct 2008

Permalink

Sep 27th, 2009

Re: int 21 causes an access violation

Click to Expand / Collapse Quote originally posted by NotNull ...

Access violation is caused when a program attempts to
access memory reserved for the operating system.
I thought this could only happen in a windows program?

I assume your using MASM:
Assembly Syntax (Toggle Plain Text)
mov ax, seg message ; initialize the DS register so
mov ds, ax                  ; you can access variable 'message'
lea dx, message
mov ax, seg message ; initialize the DS register so mov ds, ax ; you can access variable 'message' lea dx, message
Program flow stops before line 23, because you terminated
with 21/4C.

Thanks a lot

blerina12

Reputation Points: 10

Solved Threads: 0

Newbie Poster

Offline

22 posts
since Jan 2007

This thread is solved

Either the thread starter or a moderator has marked this thread as solved. You can most likely trust the responses and answers given. There is most likely no reason for any further responses to be posted here. If you have a related question, please start a new thread in this forum instead.

This thread is more than three months old

No one has posted to this discussion for at least three months. Please let old threads die and do not reply to them unless you feel you have something new and valuable to contribute that absolutely must be added to make the discussion complete. Otherwise, please start a new thread in this forum instead.

Previous Thread in Assembly Forum Timeline: need coding assembly ic 8051

Next Thread in Assembly Forum Timeline: Who Here Uses MASM

DaniWeb Message

Cancel Changes

User Name
Password