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Last time we checked in on [Inkbox], he had made a 16-bit CPU in Excel. Impressive, but not really practical. Presumably, his latest project isn’t any more practical, but we suspect an 8-bit RISC CPU was easier to implement in Excel and probably runs faster, too. The new machine uses a stack architecture with a simplified instruction set of ten instructions. You can follow along with his Excel adventure in the video below.
If you think about it, you may decide that doing something like this in Excel is easy because you could just script it and use Excel as the user interface. That’s true, but that’s now how [Inkbox] does it. He won’t use scripts or IF statements in a cell. That makes things much harder.
If you are curious about what goes on in a CPU, this is worth watching, even if you don’t expect you’ll use it. If you really want to become a CPU designer, we’d suggest skipping Excel and go straight into Verilog, VHDL, or something similar that you could actually use.
Don’t get us wrong. Seeing it done in Excel can be very educational, but no one designs CPUs like this in practice.
If you want to see the 16-bit version, we covered that, too. We always say that building the CPU is the easy part of developing a new architecture.