Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!munnari.oz.au!csource!david
From: david@csource.oz.au (david nugent)
Newsgroups: comp.os.msdos.programmer
Subject: Re: Backgroup processing (Was Re: DOS idle interrupt (INT28))
Message-ID: <773@csource.oz.au>
Date: 5 Jan 91 11:49:12 GMT
References: <5094@trantor.harris-atd.com> <1537@netmbx.UUCP> <1990Dec19.050307.16450@engin.umich.edu> <1991Jan5.043055.17637@bronze.ucs.indiana.edu>
Distribution: comp
Organization: Unique Computing Pty Ltd, Melb, Aust.
Lines: 21

In <1991Jan5.043055.17637@bronze.ucs.indiana.edu> yawei@bronze.ucs.indiana.edu (mr. yawei) writes:

> If you must use the timer interrupts, appending to int 8 is preferrable 
> than attaching to int 1Ch.

How so?

Using the timer (hardware) interrupt is guaranteed to cause problems where
some previously installed TSR or device driver speeds up the timer rate.
Normally such programs filter those to make any "higher level" timer
handler receive control at the correct rate.

Also, the PIC is rearmed by the time INT 1cH gets control, so you don't
have to fiddle around with EOI's at all.  It's an "ideal" place to pop-up.
I've been using INT 1cH for a looong time without problems, so I just
can't see why it's "preferrable", especially in a multitasking-under-DOS
environment, like DESQview.

I liked your suggestions re INT 16H though - they certainly have merrit.

  david