Path: utzoo!mnetor!uunet!husc6!bloom-beacon!gatech!purdue!i.cc.purdue.edu!j.cc.purdue.edu!pur-ee!uiucdcs!uxc.cso.uiuc.edu!uxe.cso.uiuc.edu!mcdonald
From: mcdonald@uxe.cso.uiuc.edu
Newsgroups: comp.sys.ibm.pc
Subject: Re: programming an ega
Message-ID: <45900104@uxe.cso.uiuc.edu>
Date: 17 Jan 88 18:01:00 GMT
References: <10216@mimsy.UUCP>
Lines: 28
Nf-ID: #R:mimsy.UUCP:10216:uxe.cso.uiuc.edu:45900104:000:1200
Nf-From: uxe.cso.uiuc.edu!mcdonald    Jan 17 12:01:00 1988


>I am trying to write some graphics functions using an ega card
>in 640x350 mode.  Can anyone provide me with the gory details
>about the memory mapping scheme that these cards use.  In
>particular I need to know how to do the memory bank switching
>for the different bit planes.  I understand the theory but
>I don't have the port addresses or the bit patterns that
>need to be written to them.

>If you can tell me a good reference to look this stuff up that
>would be nice too.  Most of the books that I have don't go into
>enough detail to be useful.

Gory is right, and as far as I know, there is no good reference available
easily. You will need the appropriate Tech Reference manual and lots of
example code. There was a fairly good graphics package posted in comp.sources.
misc many moons ago; you could get it from the archives. I will post my own
there soon. 

You are warned that my package uses the "set/reset" register method of
using colors. This is not how the BIOS works normally; hence you must be 
carefull about cntl-breaking out of graphics programs.

My programs will be called "egafast". If they don't appear soon,
I could e-mail them to you.

Doug McDonald
(mcdonald@uiucuxe)