The SID chip on the C64 had potentiometer inputs to handle paddle controllers. On the Ataris, paddles were handled by the TIA/CTIA/GTIA chips. The joystick pin assignments on both computers were the same, thus the compatibility. On Sun, Feb 7, 2021 at 1:38 PM David K via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:
I recently bought a Super Sketch drawing tablet for the C64 from eBay. I was surprised by how sophisticated it was and how much fun I had trying it out.
I have a video about it on YouTube that features: -unboxing of the tablet and all the extras that were included -a demonstration of drawing and the many other functions (2:57) -a look inside at how it works (21:20)
My question is about the last part; about how it works. When I opened up the drawing tablet there were two, what I believe to be, linear potentiometers. Since the tablet plugs into the joystick port I was surprised that the C64 could "read" the potentiometers. There was not an IC (?) in the tablet itself but when I opened up the plug there was indeed an IC that I assume converted the variable voltage of the potentiometers into something the C64 could read. If anyone has feedback on whether I got this right and whether this was a unique feature I would appreciate it.
The link to the video is: https://youtu.be/pLvQVJhRx2o. If that gets scrubbed you can likely search "Super Sketch vintage drawing tablet for Commodore 64 - also made for TI-99 / 4A and Atari 800 XL" to find it.
Interestingly I had initially bought another Super Sketch on eBay that said it was for the C64 but when I received it the plug was not correct (which is why I bought the second one). Interestingly the non-C64 tablet has different circuitry in it and does not have the IC in the plug or anywhere else.
So any help with this is appreciated.
David K