Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!purdue!bu-cs!tasos
From: tasos@bu-cs.BU.EDU (Anastasios Kotsikonas)
Newsgroups: comp.lang.pascal
Subject: TSR in Turbo Pascal
Summary: Interrupt $1C
Keywords: TSR, TIMER INTERRUPT
Message-ID: <38490@bu-cs.BU.EDU>
Date: 20 Sep 89 03:31:12 GMT
Distribution: usa
Organization: Boston U. Comp. Sci.
Lines: 18

I am trying to write a TSR in Turbo Pascal, and I capture the $1C timer
interrupt. Once inside the interrupt routine, I switch stacks and look
for the hot key. The problem is that I cannot chain the interrupt before 
exiting. If I try:
   { code to switch stacks }
   GetIntVec ($1C, old_intr);
   SetIntVec ($1C, prev_intr); { the vector before my TSR came to life }
   Intr ($1C, Regs);
   SetIntVec ($1C, old_intr);
   { code to restore original stack configuration }
the system freezes. This technique works for the $28 interrupt, but it
is impossible to do it this way for the timer interrupt.

If anyone knows anything about it I would appreciate any comments.

Tasos

tasos@cs.bu.edu