Editing Atari interface (section)

===Chalk Board PowerPad===
The ''Chalk Board PowerPad'' was a pressure-sensitive [[graphics tablet]] for the Commodore 64, intended to be used with fingers, with different overlays for different applications.
Overlays often had a hexagonal grid of buttons, but it could also be used freehand.
It communicated via serial communication using pins 1 through 4 (Data, Clear, Clock, Sense). The manual for its ''Programming Kit''<ref>Archive.org—[https://archive.org/details/power-pad-programming-kit-chalk-board-inc/ Chalk Board Inc's Power Pad Programming Kit manual] (1983) by Chalk Board Inc. Added 2021-01-04. Retrieved 2021-04-25</ref> explains its workings and contains source code examples of how to ''bit-bang'' the port in BASIC.