I started designing the ARITH-MATIC S1-AU Mk1 in late 2016 after a visit to the Museum of Computing in Swindon, England. Inspired by the computational objects on display, I sat down at a kitchen table late one evening and started building a 4-bit arithmetic unit from spare 7400 series ICs.
My idea was to design and build a mechanism which visually and aesthetically showed computation in the simplest form possible.
After creating a relatively unwieldy breadboard proof of concept (as you do in all great hardware projects), I've started developing a prototype PCB. You can read more about this here: http://arith-matic.com/the-soul-of-a-new-pcb
The S1-AU performs 4-bit binary addition, subtraction and accumulation using 74HC173 registers for temporary data storage and a 74HC283 full adder for binary calculations. A 74HC157 multiplexer is used to enable accumulation. The board also shows the result of logical operations (A=B, A>B, A<B) via the onboard flags. The flags and binary data used within the calculations are represented visually through onboard LEDs.
I started the ARITH-MATIC S1-AU project in 2016 and since then it has taken on a life of its own. Next is preparation for a crowdfunding campaign to release the S1-AU as a DIY hardware kit. I thought I'd share details of the board and progress on this page - as there is still a long way to go!
Here's a clip of the latest PCB prototype working in 'accumulation' mode: