It seems to be like [Michal Zalewski] is elevating the subsequent technology the appropriate means. First, his eldest son asks for assist constructing a one-bit pc from discrete transistors. To not be left behind, his little brother then requested for assist with an much more retro undertaking, which resulted in this partially relay-based calculator. Possibly there may be some hope for the longer term.
Now, purists will little doubt discover the ATmega64 microcontroller sitting in the midst of the primary PCB on this undertaking and cry “Foul!” However good is the enemy of finished, and as [Michal] explains, at $6 a pop for the Omron relays he and his son selected, there’s solely to this point you may go along with relay logic earlier than you’re taking out a second mortgage. So the relays are restricted to the ALU of the calculator, together with the drivers for the six seven-segment LED shows. The microcontroller is simply there for housekeeping features like scanning the keyboard and decoding digits. All of the precise calculations are within the relay logic, not silicon. And we’d be remiss to not reward his son’s stylistic decisions for this design — that it makes use of relays with clear covers, and that it has single-sided PCBs with curvy, hand-drawn traces on old-school yellow substrate. [Michal]’s coronary heart should swell with satisfaction to have fathered somebody with such beautiful style.
For his half, [Mikal] did some actually good documentation for this construct, together with wonderful descriptions of Boolean math with half- and full-adders and the way relays are used to create the essential logic gates that comprise them. The calculator itself continues to be a piece in progress, with microcontroller code nonetheless in improvement, however it’s working sufficient you can benefit from the show driver’s clickiness within the video under. If that doesn’t do it for you, we’ve bought different relay calculators to scratch that click on itch.