4 ms·

It's also hard to beat conventional CPUs when transitor density doubles every two years. By the time your small team has crafted their purpose built CPU, the bi

It's also hard to beat conventional CPUs when transitor density doubles every two years. By the time your small team has crafted their purpose built CPU, the big players will have released a general purpose CPU on the next generation of manufacturing abilities. I expect that once our manufacturing abilities flatline, we will start seeing more interest in specialized CPUs again, as it will be possible to spend a decade designing your Lisp machine

yjftsjthsd-h 1y ago
There's also a matter of scale. By the time you've made your first million custom CPUs, the next vendor over has made a billion generic CPUs, sold them, and then turned the money back into R&D to make even better ones.
PaulHoule 1y ago
I never thought I could make a custom CPU until I came across https://en.wikipedia.org/wiki/Transport_triggered_architecture https://en.wikipedia.org/wiki/Transport_triggered_architectu... But when I saw that I thought, yeah, I could implement something like that on an FPGA. It's not so much a language-specific CPU as an application-specific CPU. If you were building something that might be FPGA + CPU or FPGA with a soft core it might be your soft core, particularly if you had the right kind of tooling. (Wouldn't it be great to have a superoptimizing 'compiler' that can codesign the CPU together with the program?) It has its disadvantages, particularly the whole thing will lock up if a fetch is late. For workloads where memory access is predictable I'd imagine you could have a custom memory controller but my picture of how that works is fuzzy. For unpredictable memory access though you can't beat the mainstream CPU -- me and my biz dev guy had a lot of talks with a silicon designer who had some patents for a new kind of 'vector' processor who schooled us on how many ASIC and FPGA ideas that sound great on paper can't really fly because of the memory wall.

yjftsjthsd-h 1y ago

There's also a matter of scale. By the time you've made your first million custom CPUs, the next vendor over has made a billion generic CPUs, sold them, and then turned the money back into R&D to make even better ones.

PaulHoule 1y ago

I never thought I could make a custom CPU until I came across https://en.wikipedia.org/wiki/Transport_triggered_architecture https://en.wikipedia.org/wiki/Transport_triggered_architectu... But when I saw that I thought, yeah, I could implement something like that on an FPGA. It's not so much a language-specific CPU as an application-specific CPU. If you were building something that might be FPGA + CPU or FPGA with a soft core it might be your soft core, particularly if you had the right kind of tooling. (Wouldn't it be great to have a superoptimizing 'compiler' that can codesign the CPU together with the program?) It has its disadvantages, particularly the whole thing will lock up if a fetch is late. For workloads where memory access is predictable I'd imagine you could have a custom memory controller but my picture of how that works is fuzzy. For unpredictable memory access though you can't beat the mainstream CPU -- me and my biz dev guy had a lot of talks with a silicon designer who had some patents for a new kind of 'vector' processor who schooled us on how many ASIC and FPGA ideas that sound great on paper can't really fly because of the memory wall.