Modify old soft to run on XP

[remcous]

Hello,

I have an old software who write a caracter on serial port. The soft is write in ASM, compiled with MASM 5.1 and normally writed for DOS.

Under XP, this soft work normally, except for write the caracter on serial port.

I think this can't work :

Code Select Expand


        mov     dx,3F8h
        mov     al,cl ' caracter to write
        out     dx,al


I have just a small quantity (5/10 lines ) to modify I think...

What is the better solution ? with INT14h ? like :

Code Select Expand


mov ah,00h ' init comm port
mov dx,0 'serial port com1
int 14h
mov ah,01h 'write caracter
mov al,cl 'caracter to be write
int 14h


Or with INT21h ? or another solution ?

It's just a challenge for me  ::)

Thank you !

rémy

[japheth]

IIRC there is a built-in emulation for the COM ports in NTVDM. So I doubt that Int 14h will work better than direct port access.

[Mark Jones]

Hi remcous, also see this and this and finally, this thread.