Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!cica!ctrsol!ginosko!uunet!nuchat!moray!siswat!buck
From: buck@siswat.UUCP (A. Lester Buck)
Newsgroups: comp.graphics
Subject: Re: IBM CGA, Using Stack Pushes to Screen Memory.
Summary: summary
Message-ID: <430@siswat.UUCP>
Date: 17 Jul 89 17:21:36 GMT
References: <313@edstip.EDS.COM> <2820@blake.acs.washington.edu>
Distribution: comp
Organization: Photon Graphics,  Houston
Lines: 24

In article <2820@blake.acs.washington.edu>, wiml@blake.acs.washington.edu (William Lewis) writes:
>
>     I've seen this question several times just recently. It makes me
> wonder how well people read manuals. There are two ways around this problem
> that just spring to mind.
>
>     The second way is what you should have done in the first place. Use
> a REP MOVSB (or REP MOVSW or...) instruction. Not only is this instruction
> uninterruptible (on mostm processors), but it is also faster.

You obviously don't read the manual yourself.

From iAPX86/88, 186/188 User's Manual, Hardware Reference, p 3-31:

"Repeated string sequences are interruptable; the processor recognizes
the interrupt before processing the next string element.  System interrupt
processing is not affected in any way.  Upon return from the interrupt,
the repeated operation is resumed from the point of interruption."

An interrupt is not recognized between the REP prefix and the MOVSB,
of course.

-- 
A. Lester Buck		...!texbell!moray!siswat!buck