June 16, 2021


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Build a New ZX81

Build a New ZX81

Build a New ZX81

[Retro Shack’s] ZX81 died, and while he tried to figure out the fix, he decided to build a new one. Of course, building a circa-1980-something computer from new parts is a bit daunting. Unless you start with an existing design that has it all ready to put together.

The PCB looks great and we like that the silkscreen shows acknowledgments of projects that helped the designer, [Alejandro Sebastian]. The case is, of course, 3D printed. At first, the power LED didn’t work, but voltages looked correct and the board powered up.

The little box can actually read cassette tapes for the original, which allowed it to load 3D Monster Maze. We aren’t sure why the power LED didn’t work, but we are guessing it is backward or it — or the dropping resistor — didn’t make a good connection.

This looks like a fun project and would be a great way to get a reasonably authentic-looking ZX80 or ZX81 without having to work too hard. All the files you need are on [Alejandro’s] website and it looks like the majority of the work would be sourcing all the components.

Of course, you can always go the FPGA route. If you build one and want to learn assembly for it, check this out.