Path: utzoo!attcan!uunet!samsung!zaphod.mps.ohio-state.edu!ncar!ames!vsi1!octopus!stever
From: stever@Octopus.COM (Steve Resnick )
Newsgroups: comp.os.msdos.programmer
Subject: Need info on 286/386 exceptions and int handling under DOS
Message-ID: <1990Oct10.163006.8081@Octopus.COM>
Date: 10 Oct 90 16:30:06 GMT
Reply-To: stever@octopus.COM (Steve Resnick )
Organization: Octopus Enterprises, Cupertino CA
Lines: 24

Hello peoples!

Heres's a good question for you PC guru types ...

On 80286 and 80386 processors, int 12 is designated as a stack fault exception.
So far so good. Also on PC's in general, IRQ4 is designated as the default
interrupt for COM1. Since IRQ int numbers are IRQ += 8, IRQ4 becomes int 12
also. My question is, how does the system determine what interrupt to vector
where and how are "separate" interrupt vectors defined? I have some serial
code which needs to tweek int vectors from time to time. The code is all
there to handle the serial interrupts, but there is no vector chaining
being done. I can force an int 12 by mov'ing 0 into SP and pushing AX onto
the stack, and I get my default "stack fault exception" message. What magic
is being done here?

Thanx, in advance....

Steve

-- 
----------------------------------------------------------------------------
steve.resnick@f105.n143.z1.FIDONET.ORG - or - apple!camphq!105!steve.resnick
Flames, grammar errors, spelling errrors >/dev/nul
----------------------------------------------------------------------------