Correction to my comment: The Atari computers read the pots via POKEY, not the xTIA chips. On Sun, Feb 7, 2021 at 2:12 PM Neil Cherry via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:
On 2/7/21 1:37 PM, David K via vcf-midatlantic 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.
It's 8 bit! ;-) Sorry watching the video.
I recall the Atari 800's supported 2 analog inputs (basically from a potentiometers) on it's DE9 along with the digital bits. But I bet the little missing dongle puts the pins in the correct place for the Atari, Commodore and TI. The button probably short the voltage to certain voltages. The chip is probably am 8 bit ADC but I couldn't see the markings.
Potentiometers allow you to give a decent x & y within the limits of the video memory a pixel locations.
The Super Sketch is pretty cool.
-- Linux Home Automation Neil Cherry ncherry@linuxha.com http://www.linuxha.com/ Main site http://linuxha.blogspot.com/ My HA Blog Author of: Linux Smart Homes For Dummies