#retrocomputing #emulation #lightpen
I could do a simple pixel hit test to check for lit pixels, but a real pen will pick up light from what I imagine is a small cone around the tip, so I'm guessing a 3x3 or 5x5 averaged kernel might work best.
#retrocomputing #emulation #lightpen
The main issue remaining is that the pen works in dark regions of the screen, where it really shouldn't. You might just think this is a harmless improvement, but the software actually expects the pen not to work - if i tap the pen in a dark area it takes it as a valid selection from the four options in that menu.
...which one did we actually select? No idea. So that's not good.
Working on fixing up MartyPC's light pen emulation - I can't really be the light pen expert and not have my own emulator do it right.
This fixes the latching logic so we can latch the light pen strobe regardless of whether the pen switch is pressed. So now we have the live cursor!
For the first time in maybe - decades? Someone has a complete, high-resolution CGA light pen system for the original IBM PC.
(It's me. I'm the someone)
This artifact vexes me.
I assumed it was a sync cable header for a light pen card, because you know, DE9 and all says "CGA video" to me. I assumed that it was plugged into the wrong header in the eBay auction by mistake. Because of course it was the sync cable header, right?
It is not a sync cable header. It is a connector for a light pen.
Cue record scratch. I have the light pen connector header for the very first card FTG made and it's just an RJ11 wall box, just like the Warp Speed pen is.
... so where does a DE9 light pen connector come from?
Here is my light pen demonstration video.
Photosensitivity warning: There are some brief flashes of bright white.
This is it. This is what it was all for. All the penposting. The hundreds of dollars of irresponsible eBay purchases.
For this moment.
And it was all worth it.
Everything on the PXL-380 CGA/EGA light pen card is a standard component. All 74 series logic.
It looks like the card is not actually doing cursor position calculation, it's just running two binary counters that reset on hsync and vsync which the driver can read and do the math in software.
Its also a two layer board. So the good news is we can make new light pen boards!
gloriouscow