Hacker News Reader

NOR (like NAND) is a universal logic gate. You can build any other logic gate out of just NORs.

For this ALU, you’d presumably write a subroutine that computed XORs in terms of NORs, and then use that as a primitive for building an adder.

View on HN

Yes, but this thing advertises that it uses a single NOR gate as an ALU.

That’s just moving the composition between hardware and software - the equivalence still applies. I can build any logic (software) function out of a function that evaluates NOR.

False advertising, then, IMO.

...but that's exactly the claim, restated.

Not really. It's completely trivial, if extremely slow (which the article acknowledges) to emulate an ALU in software, with access to a single, universal hardware gate. Why don't they just say "we put a NOR gate on a chip, then added all this other stuff (RAM, boot EEPROM, etc.) to make it function as a computer." That would, at least, be a non-misleading statement of the claim.

Yes, it's a "Single board computer with 20 ICs, and a single-gate ALU".

To me it's not really an ALU either, since the NOR gate doesn't really do the job I expect from an ALU.

That’s how I interpreted the OP though... I really don’t know what you were reading into it.

No, AFAIU the computation is serialized, driven by the microcode and this gate is reused for every step

Reply on news.ycombinator.com