Article View: comp.os.msdos.programmer
Article #2613Need info on 286/386 exceptions and int handling under DOS
From: Steve Resnick
Date: Wed, 10 Oct 1990 16:30
Date: Wed, 10 Oct 1990 16:30
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1534 bytes
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 ----------------------------------------------------------------------------
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Path: arc1-ca.pugleaf.net!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