Simon Boak's Upcycled Forth Clock Features a Raspberry Pi Zero-Powered Thinking Machines Animation
A dying mains-powered '70s digital clock is reborn, with a nod to a classic supercomputer series for good measure.
Maker Simon Boak has merged two pieces of history into one desktop time-telling aesthetic accessory, by upgrading a vintage digital clock with new innards driving a Thinking Machines-inspired light display.
"I recently picked up an interesting digital clock for only £3 [around $3.75] at, of all places, an agricultural show," Boak explains of the original device. "Branded 'Forth' on both the back and on the PCB inside I have not been able to find any information on the manufacturer of this. The internals are nicely designed and very compact in a solid wooden case (no veneer!) There's holes on top of the case which line up with a connector inside suggesting there may have been something like a lamp originally mounted above."
Driven by a single AY-5-1224 chip dated to the mid- to late-1970s, the clock uses four Fairchild FND500 seven-segment displays that, sadly, are beginning to fail. With the actual clock hardware also showing its age — and being driven directly from the mains without modern safety features or even earthing — Boak decided it was time for an upgrade.
"Using a spare first generation Raspberry Pi Zero combined with a 256×64 white OLED display I programmed up a clock animation based on the LED patterns of the Thinking Machines Corporation CM-5 supercomputer," Boak explains, referring to one of a number of super computing systems notable for their exterior visualizations. "There’s an implementation of this animation available in C and it was fairly simple to convert this into Python to create a 64×16 pixel pattern."
This pattern is then displayed behind a pixel-font time at a lower brightness, bursting to full brightness upon each minute change and colored red using the clock's original acrylic fascia. "Using the existing hole in the wooden case I added a rotary encoder to give control over the speed of the animation. Pressing the rotary encoder in triggers a safe shutdown of the Pi. All the internal brackets and mounts, as well as the rotary encoder housing on top, are 3D printed to fit the wooden case without any need for customization."
The project is documented in full on Boak's blog, with Python source code available on GitHub under the reciprocal GNU General Public License 3.