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

[Dean Notarnicola]

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 at 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 at linuxha.com
> http://www.linuxha.com/                         Main site
> http://linuxha.blogspot.com/                    My HA Blog
> Author of:      Linux Smart Homes For Dummies
>