gloriouscowHere is my light pen demonstration video.
Photosensitivity warning: There are some brief flashes of bright white.
YouTube
I might as well post this here rather than make another light pen thread -
One of the light pen cards I got off eBay came with this mysterious connector I was having trouble ID'ing.
Turns out it's a tap for the MCGA connector in an IBM PS/2 models 25 and 30.
The thing is I didn't even know this card supported MCGA. Notice the empty footprint for a crystal - I had assumed that the versions of this card sold for use with EGA and Olivetti PCs would have had a faster clock installed, while the CGA version used the OSC pin, which is, of course also the dot clock on a CGA.
It's always possible that this cable does not actually go with this card. You never really know the background of this sort of thing. It's possible that if the seller (or previous owner) just happened to stick on something that looked like it fit.
But I have a feeling that it might be legit. I've never actually seen a PXL-350 with a the crystal footprint populated, so I could just be assuming they ever bothered to install one. The card could still work at 14MHz in any mode, just at reduced resolution.
I'd probably be more inclined to use this cable with the PXL-380, which has a 48MHz crystal.
Aha, and now with the added context - we have a hit.
Adding to the 3 existing SKUs I already knew about, we have a fourth SKU for the PS/2.
Unfortunately this is one of those google books results that pulls up a completely useless preview.
I appreciate the Google books service quite a bit, but whomever over at Google decided that "fair use" meant you got to see approximately half an inch of the relevant page needs to be smacked.
I don't own a PS/2 and I don't see myself collecting one at least for a few years yet, but if you are a PS/2 owner and want to play around with a light pen, get in touch!