[vcf-midatlantic] Super Sketch drawing tablet for Commodore 64

Neil Cherry ncherry at linuxha.com
Sun Feb 7 19:11:52 UTC 2021

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 at linuxha.com
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