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From: colin@vu-vlsi.UUCP (Colin Kelley)
Newsgroups: net.micro.pc
Subject: EGA card programming
Message-ID: <362@vu-vlsi.UUCP>
Date: Thu, 4-Sep-86 16:39:02 EDT
Article-I.D.: vu-vlsi.362
Posted: Thu Sep  4 16:39:02 1986
Date-Received: Thu, 4-Sep-86 22:13:10 EDT
Organization: Villanova Univ. EE Dept.
Lines: 27

Can anyone provide me with info on programming graphics for EGA cards?  We've
got lots of STB EGA clones in Zenith ATs, but I have not had any success
getting to the EGA's enhanced graphics.  I'm programming in Microsoft C 4.0
(which is, by the way, excellent!), with assembly language routines to do the
dirty work of actually calling the BIOS routines.  We've got the EGA Technical
Reference Manual, but it is sadly too technical--it's got schematics and BIOS
listings, information on programming the individual registers of the EGA card,
but no explanation of how to use the graphics.  I can get the CGA-compatible
modes by using INT10H to set the video mode, and then the Set Pixel function;
however, I get a completely blank screen when attempting this with one of
the new EGA modes...

So...does this mean that the BIOS doesn't support Set Pixel in EGA modes?
(Do I actually have to go and poke pixels into memory???)  Or is their a
different BIOS call to do so?  Or is my problem just with palettes?

If you know of a publication that explains this all, please let me know.  I'm
only posting because I've exhausted all the possible sources of info I can
find!

BTW:  I've run quite a few commercial programs on the STB cards, and those
that support the new EGA modes all work fine, which means that my problem
probably isn't a compatibility problem...

Thanks for any help!

			-Colin Kelley ..{cbmvax,pyrnj,psuva1}!vu-vlsi!colin