Path: utzoo!attcan!uunet!tektronix!tekgen!tekigm2!alanr
From: alanr@tekigm2.MEN.TEK.COM (Alan Rovner)
Newsgroups: comp.sys.ibm.pc
Subject: Question 2 of 3 for assembly language programmers
Keywords: How do you call existing interrupt handlers in ass'y?
Message-ID: <4497@tekigm2.MEN.TEK.COM>
Date: 17 Apr 89 16:07:35 GMT
Distribution: na
Organization: Tektronix Inc., Beaverton, Or.
Lines: 14


If I wanted to hook onto the keyboard interrupt handler to write my own
TSR in assembly language how would I call the original handler(s) that
were already in use?  I understand that when grabbing onto an existing
interrupt vector you should call however many functions have already been
in use there.  This is easy in C, one could call the function via a
pointer, like (*orig_name)().  But I'm unclear how to do this in assembly
language.  I'm sure if there's a way to screw up the segment registers
I'll find it.  Again, any examples would be helpful.

Thanks,
Al Rovner
Tektronix Inc.
Vancouver, Wash.