Assembly Program For Transmitting And Receiving A Message Using Ms-dos Debug

Thread Starter


Joined Jun 16, 2007
Hi guys ...
I need your help for the following
I need an assembly program for transmitting and receiving a message using a ms-dos debug.

I do not nothing about assembly programming.
I have started to read some assembly tutorial

question 1.- do you know about a good manual which contains examples to program?
question 2.- do you have the code for transmitting and reciving a message ussing ms-dos debug?

I started to use the following commands:
-a 300
1552:0300 mov ah,01
1552:0302 int 21
1552:0304 mov dx,378
-a 304
1552:0304 cmp ah,21
1552:0307 mov dx,378
1552:030A cmp ah,24
1552:030D jne 300
here i think that i'm getting an input from keyboard and when it is a "!" sign i'm receiving chaarcters until it has entered "$" sign ..

how can i transmitt the information for going viewing in other monitor the information transfered .

please let us know !!! :)

Thread Starter


Joined Jun 16, 2007
i want to transmit a line where starts "!" sign and finish the transmission when appears "$" sign as follows
the message for being transmitted must be: thisisanexample

please, let us know.

Thread Starter


Joined Jun 16, 2007
I need to transmit a string like "hola" using assembler language coded into debug of ms-dos
when i am writting on keyboard, in that moment I have to see that message in other monitor connected thourh a port ...

Thanks a lot. :rolleyes:


Joined Oct 14, 2005
Transmitting through what? What port? Different computer? Dual monitor system?

Please provide as much details as possible. It is just not possible for us to help you if you do not help us with the details.


Joined Feb 24, 2006
For starters 0x378 is the address of the printer port. Just moving the address 0x378 into the DX register won't do very much for you. It might do something if you had an out al,dx instruction that would write the contents of the al register the I/O port contained in DX.

Of more interest is the int 21 with the argument ah = 0x01. This would be a read keyboard with echo. Presumeably the echo already goes to the monitor. The return value is in the AL register. My information is valid through DOS 5.0

You need to take a deep breath and try very hard to construct a coherent paragraph which describes what you want to do. We understand you want to read characters from the keyboard. What has us puzzled is the loading of 0x378 into DX which does...nothing!