I’m completely in favor of disallowing truthy and falsey values, and I hope the core team is never swayed otherwise. Having said that, this claim caught my eye: [image] On the arbitrariness of truth(iness) But we could just as easily have had je and jo (jump if even, jump if odd) as assembly ins…

This isa is already significantly over-complicated. ADD and JMP are redundant.

Indeed, but I felt I needed to make this little concession to ergonomics/user convenience… in my defense, I do mention the one-instruction computer(s) :sweat_smile: EDIT: BTW, if you remove ADD and JMP but keep “skip if even”, then I claim the problem still can’t be solved. The problem is lack of c…

I split this into a new topic because it’s very interesting but I think it’s a bit in the weeds for the original thread.

How does this computer input or output anything? Are registers considered inputs/outputs?

Yes. The registers and instruction memory are given initial values, PC is set to zero, and then computation starts and runs until STP is reached. Results are written to registers as well.

My edit got caught in the split Bell Labs produced the CARDIAC computer: “CARDboard Illustrative Aid to Computation” CARDboard Illustrative Aid to Computation CARDIAC (CARDboard Illustrative Aid to Computation) is a learning aid developed by David Hagelbarger and Saul Fingerman for Be…

I think you’re right that it’s not as expressive. I was thinking that you’d have comparison instructions that would compare values and leave 0/1 values in a register, which you’d then check. But this simple ISA doesn’t waste those extra instructions. I can’t see a way to implement the simple add one…

I don’t see how to implement it either; I wish I knew how to prove it’s impossible, though. What is most interesting is it’d seem that “ability to compare against a fixed, known threshold” is a requirement for Turing completeness. I’ve never seen this stated so explicitly, but I think it’s stated i…

[image] mbaz: What is most interesting is it’d seem that “ability to compare against a fixed, known threshold” is a requirement for Turing completeness. I’ve never seen this stated so explicitly, but I think it’s stated implicitly in the definition of a Turing machine. Turing completeness mea…

Assembly: is "jump if not zero" more expressive than "jump if odd"?

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Assembly: is "jump if not zero" more expressive than "jump if odd"?

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