duchow@watnxt3.ucr.edu (John Duchowski) (06/08/91)
Hello Everyone,
Recently, I have observed some unusual behavior of my EGA monitor, though
I am not sure whether it is the EGA card, EGA monitor or some other source
(virus ?) that is causing all this. The symptoms are as follows: in certain
cases, usually where drawing a circle filled with white color is involved,
the process gets out of control and paints the ENTIRE screen with white
color. In certain cases, I need to reboot the system, but in others, hitting
a key which would normally allow continuation of the program, let's me keep
going, though the white background remains. This happens for example with
planets.c (Borland demo program) and Graftool (graphics package). In the
first case, I do need to reboot, but in the second, I can keep going (though
it difficult as some of the key labels get painted over).
This bizzare behavior happens in only few select instances, and running
AT diagnostics, for example, does not spot the problem. The very first oc-
curance of this was with Word Gallery (educational program from simtel20)
about a year or so ago. Since everything else worked fine, I paid no at-
tention to it until now. Has nybody else experienced anything similar ?
Is there some way which would help me to diagnose or pinpoint the problem ?
(Why is this happening to ME ? :), etc). My system is:
true blue IBM AT, with EGA Card (256 K) and EGA monitor
Phoenix BIOS (AT-specific, 3.10, I think) **
640 K RAM, 1024 Extended, 512 Expanded
** the Word Gallery problem occured even with the true blue IBM BIOS.
Thank you for any hints and/or comments,
- John Duchowskijosephc@nntp-server.caltech.edu (Joseph Chiu) (06/09/91)
duchow@watnxt3.ucr.edu (John Duchowski) writes: >Hello Everyone, > Recently, I have observed some unusual behavior of my EGA monitor, though >I am not sure whether it is the EGA card, EGA monitor or some other source >(virus ?) that is causing all this. The symptoms are as follows: in certain >cases, usually where drawing a circle filled with white color is involved, >the process gets out of control and paints the ENTIRE screen with white >color. In certain cases, I need to reboot the system, but in others, hitting >a key which would normally allow continuation of the program, let's me keep >going, though the white background remains. > This bizzare behavior happens in only few select instances, and running >AT diagnostics, for example, does not spot the problem. > Has anybody else experienced anything similar ? >Is there some way which would help me to diagnose or pinpoint the problem ? >(Why is this happening to ME ? :), etc). My system is: Hmmmm. I had a problem that may be equivalent to what you are encountering. I used to have a 4.77 MHz XT motherboard (remember THOSE?) and one day gave in to buy a <WOW!> 8 MHz mb. When I did that, I needed a new CGA card. Then when the mb fried, I got a 10 MHz mb, and I was happy. Sort of. Once in a while, weird characters would show up, and when I ran <ahem> Poker on the 10 MHz system, the 'fill' would sometimes work, but often times, it would 'bleed' and would, on a few occasions, spread out over most of the screen. Also, at times, 'gaps' appeared at various places on the screen. The problem was fixed by buying yet another CGA card, supposedly good to 12Mhz. I suspect what is happening is that when the graphic routines read the images back from the EGA RAM, it isn't reading back the correct values. If the software reads 0's from the image area, it will merrily fill the entire screen thinking that there are no fill boundaries. In most likelihood, anyways, there is a component failure on your EGA card, or at least timing problems. Can you convince someone to lend you an EGA card? That'll fix your problem mighty fast, I suspect. -- Joseph ( Now on his 5th mb (286-12), 4th I/O card, 2nd FD/HD controller, 4th video card (EGA finally!), 4th Floppy Drive (1.2 MB, just installed), and the original supply-and-case [Coming soon, a Tower configuration and High-Capacity Hard Drive!] ) Now if only I can convince my mom to shell out money for a 486 Motherboard... (And I still have an Apple II with a Z80 card back at home...) -- Joseph Chiu, Dept. of Computer Science, Caltech | Rrr Redundant Tautology System 1-57 Fleming House, Caltech, Pasadena, CA 91126 | Ttt Triplicate Archival Backup Tel/Fax:(818) 585-0393 josephc@coil.caltech.edu | Sss RTS TAB, Model RTS-333-TAB