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From: pashler@sdics.ucsd.EDU (Hal Pashler)
Newsgroups: comp.sys.ibm.pc
Subject: NEC GB1 vertical retrace - which port to read?
Message-ID: <352@sdics.ucsd.EDU>
Date: Sun, 3-May-87 17:55:52 EDT
Article-I.D.: sdics.352
Posted: Sun May  3 17:55:52 1987
Date-Received: Tue, 5-May-87 00:37:10 EDT
Organization: Institute for Cognitive Science, UC San Diego
Lines: 32
Summary: NEC GB1 + Multisync Monitors


I just got some IBM PC's equipped with NEC GB1 display cards
and NEC MultiSync Monitors.

For various reasons,
I need to read the memory location or port that will
tell me whether the
monitor is in vertical retrace or not.  
On my other PC equipment (Princeton Graphics SR-12 monitors +
Sigma Designs Color-400 boards), I simply look at a
particular port [$2da], and it with 16,
 and that value is 0 or 16 depending upon whether the
monitor is in retrace mode. 
(I do this in turbo pascal, simply by calling Port[$2da]).

Not surprisingly, this doesn't work on my new NEC equipment!
And I haven't been able to figure out from the NEC documentation
what I should do.  Ideally, I would like to be able to simply
look at a port, just as I do with the SR-12/Color-400
setups.  
I.e., if it can be done directly in Turbo Pascal without
BIOS calls or what not, that will be much easier.

Does anyone know what I should do?  [If it isn't already obvious,
only simple-minded concrete answers will be understood!].

Thanks you!

Hal Pashler
UC San Diego

[pashler@nprdc]