David Cantrell 🏏
gloriouscowThis is my latest acquisition. The Tech-Sketch Light Pen.
This is the McPen, a light pen by Madison Computer of Madison, WI.
Little known fact, the third largest export of the state of Wisconsin behind cheese and beer is light pens.
I'm continually surprised at the depth of content that can be found relating to light pens.
Given how niche they were, you'd think I'd run out of material by now.
Check out this awesome advertisement for the Arfon Microelectronics Light Pen.
Note they operated out of Wales, the same as Trojan Products. Now, what are the chances there were two light pen manufacturers in Wales?
Of course you would!
This is the Trojan light pen for the Commdore Plus 4 and C16, two systems I was previously unfamiliar with.
#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)
