Fun, But Sketchy
Etch-a-sketchy is a Z80-based digital Etch A Sketch built with hardware modules from the RC2014 retro computer kit.
What is better than an Etch A Sketch? A digital Etch A Sketch powered by an 8-bit Z80 CPU, of course! Only a 6502-based Etch A Sketch would be better yet, but I will just leave that alone for now to avoid a war among retro computing fans.
The team over at RC2014 exhibited at the Liverpool Makefest this summer, and to capture the attention of the visitors they built a digital Etch A Sketch, not surprisingly named Etch-a-sketchy, for the event. The build is pretty simple. It consists of a modern, retro-inspired, Z80-based computer built from RC2014 kit modules. It was also the perfect opportunity to showcase the new Dual Paddle Analogue Module, which allows an RC2014 computer to capture inputs from a pair of analog potentiometers. With some clever design work, a pair of arcade-style push buttons were also fed into the Analogue Module. For the display, an 8 x 8 pixel NeoPixel Matrix Module was selected.
A somewhat makeshift, yet very sturdy, interface was made for the Etch-a-sketchy. A couple Pot Noodle containers were turned upside down and 3D-printed inserts were used to interface them with the potentiometers. These served as the controls to adjust the X- and Y-position on the display. The arcade buttons were used to switch the drawing color or clear the display.
It is a pretty simple design that the team came up with, but that is good, because simple is usually stable. And that proved to be the case here. Even the best efforts of children at the Makefest could not damage or destroy the Etch-a-sketchy.
The Etch-a-sketchy looks like it would be a ton of fun to play with, but of course that is only secondary in a project like this. The main purpose of this type of build is that it gives us an excuse to play with classic computing hardware and brush up on our Z80 assembly language skills.
The project write-up is far from a step-by-step guide, but it is a pretty simple device. If you know your way around a Z80, you should not have any trouble at all making your own Etch-a-sketchy. And if you know the 6502 like the back of your hand, then it will be even easier. Sorry, I couldn’t resist the dig. But in any case, be sure to check it out for some inspiration in your own retro projects.