Looking for testers with original IBM EGA/VGA/MCGA/8514/XGA graphics cards

[juj]

Some days ago, I stumbled onto an interesting feature that a technical manual from Headland mentions they have been emulating from original IBM EGA/VGA cards - Light Pen Address Counter registers.

VGA officially dropped support for Light Pens, but curiously, Headland's technical manual claimed that the registers were still kept around (in an odd crippled form it seems) in the actual VGA graphics cards.

Based on that, I developed a silly game that should work only if the graphics adapter still supports those registers.

I do not own any original IBM manufactured graphics cards, but I am curious how accurate Headland's claim would be. If any of you guys own any original IBM graphics adapters (or replica clones from the day), it would be nice to get data about how well supported these registers actually were.

Please check out this thread for more information and a download link to test code and the game: https://www.vogons.org/viewtopic.php?p=1187630#p1187630 . If you are able to contribute tests from original IBM hardware, I'd be super interested in reading about your results. Thanks!

 

[modem7]

I have an IBM AT (IBM 5170) fitted with an IBM EGA card (card is fully RAM populated).

Running RNGADVEN.EXE results in the 2-line error message that ends with, "but none was detected."

And in case relevant, it made the left five columns of the 80x24 display go invisible, requiring me to run 'mode co80' to make them visible again.

 

[juj]

Thank you, this was super helpful! So it seems that the Light Pen Address Counter registers on an IBM EGA card did not work as free-running like they apparently are doing on an IBM VGA card, and as result, there is no entropy source to draw from in this case.

Not completely sure yet what then causes the missing columns. I'll investigate that a bit more.