🚀 go-pugleaf

Mr. or Miss Zhang

I don't know where did you find your MS-DOS reference, but my literature
say the opposite, look that:

Int    Purpose

1C       Com1
1B Com2

This is for PC-XT

I'm sure about int 1C, because, I work with com-interrupts.

I'm not sure, but I think com-interrupt in AT are inverse. That is,
com1 1B and Com2 1C, but look that:

You can know if your Pc is AT or XT, in this manner:

With basic,

10 def seg=&hf000
20 x=peek (&hffe)


If  x=FF       It's PC
    x=FE            XT
    x=FD            PCjr
    x=FC            AT

In assembly language

mov  ax,0f000h
mov  es,ax
mov  al,es:{0fffeh}

And al is equivalent to x

Some questions, refer to:
Juan Manuel Gonzalez Nava
Informatic Research Center
ITESM Monterrey Mexico
Bitnet:   PA163514@MTYTECVM.MTY.ITESM.MX

There is a new country. Mexico