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.
Would it be theoretically possible to emulate a 64 bits CPU in Excel, and have it run emulated Windows within Excel? Doesn’t need to work at decent speed, just work at all.
Excel can not access your hardware or peripherals, so you could not emulate windows. Excel can be used to emulate cpu instruction sets, but this would require writing custom machine code software to run on it. This code would likely need to be manually input, and the cpu clock stepped manually. This level of emulation could be useful to build models of cpus to study behavior, but is not scalable to do perform the work a cpu does. So debugging instructions is doable. Running code, much less an entire OS, is a no go.