[comp.sys.ibm.pc.hardware] cga monitor with ega card?

daver@ux1.cso.uiuc.edu (David Ruby) (03/10/91)

I have been using a Samsung (CD-1464/W) color monitor that I bought
used with my cga system.  
I was given an old ibm ega card (64k), and according to the ibm reference
manual, you can set the jumpers and switches so that it will do CGA
(or so I thought).  With this knowledge, I put the card in, set the 
jumpers to the cga settings, and figured that I would see cga graphics
from my ega card, and then someday, I'd buy an ega monitor and set the
switches for it later.
I was pleasantly surprised when I found that my monitor was displaying
EGA graphics!  Games designed for ega looked great!
Unfortunatly, when I returned to the text screen, and did anything
heavily text oriented like "dir", random inversed characters would
appear on the screen.  Eventually, if I did this a lot, the whole
screen would have "$" across it and the machine would lock up.
In addition to that, the '286 I was using it on, stopped recognizing
the fact that my hard drive existed.  When I took out the ega
card, it recognized the hard drive like normal.

I thought that maybe it was something with my '286, and plugged it into
my xt clone.  This time, the machine the xt decided it only had 256k
of memory instead of 512.

I borrowed another ega card to check if my ega card was bad, but
it did the same thing on the '286 as before.

So, why did this happen?
Actually, why did my previously cga monitor decide to show ega
graphics?  Are all cga monitors capable of this?  or just the Samsung
CD-1464's?
Is there something I have to do with the computers before installing
an ega card?  I ran setup on my `286, and set the jumper to "color",
but I still get this problem.
I am totally baffled as to why the ega card would block off the
other 256k of memory on my xt, any hints?
Would this problem go away if I got an official ega monitor?  Why?
Can I set my card to something so that I can plug in my cga monitor
and run things until I get an ega monitor?


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David Ruby          daver@ux1.cso.uiuc.edu          University of Illinois  
"This calls for a special blend of psychology and extreme violence" vyvyan