Coder's Guild Mailing List

.com programming

Posted by Ali Bhai on 1999-04-19

>That's because of the way a com program is made: The very first byte of the
>file has to be the first code byte.

I know that and the book tells me to start a com program according to the
following prototype:

TITLE name
ORG 100h

START: jmp main
; data definitions go here

main proc
; code goes here
main endp
end main


>This error message tells you that
>you're trying to make a com file with data at the beginning.
>What exactly is the situation?

Actually I once saw a tsr that displayed time in the upper right corner of
the screen. I wanted to reinvent the wheel. I have tired to put all my code
in a single file (following the above mentioned prototype) but that does not
help.


>PS, have you yet tried to make an .exe file? .exe files may have their
>entry point anywhere in the file

Yeah, I have worked on that. But tsrs should be written as com programs. Can
anyone help me in implementing a time display tsr. I have the following idea
in my mind:

The clock calls interrupt, 1Ch 18 times per second. If we write an interrupt
routine that gets time (function 2Ch; int 21h) and put the address of this
routine in 1Ch, the routine will automatically display time after every
clock tick. I have implemented the part till that (in an EXE result).

Now I want to make a tsr for this one. That is, I want my program to exit
and continue displaying time while the user works in dos. I had ideas for
that too but the assembler given error messages while assembling a com
program. Can anyone help me in that?



Thank you and thanks to Ryan too.

Ali Bhai
BCS III - FAST Institute of Computer Science, Karachi
email: mashah@xxxxx.xxx.xx
web page: www.pak.org/mufta
<----------------------------------------->
[To err is human but to really mess up the things you need a computer.]