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Seymour Cray and the Development of Supercomputers (linuxvoice.com)
An anonymous reader writes: Linux Voice has a nice retrospective on the development of the Cray supercomputer. Quoting: "Firstly, within the CPU, there were multiple functional units (execution units forming discrete parts of the CPU) which could operate in parallel; so it could begin the next instruction while still computing the current one, as long as the current one wasn't required by the next. It also had an instruction cache of sorts to reduce the time the CPU spent waiting for the next instruction fetch result. Secondly, the CPU itself contained 10 parallel functional units (parallel processors, or PPs), so it could operate on ten different instructions simultaneously. This was unique for the time." They also discuss modern efforts to emulate the old Crays: "...what Chris wanted was real Cray-1 software: specifically, COS. Turns out, no one has it. He managed to track down a couple of disk packs (vast 10lb ones), but then had to get something to read them in the end he used an impressive home-brew robot solution to map the information, but that still left deciphering it. A Norwegian coder, Yngve Ådlandsvik, managed to play with the data set enough to figure out the data format and other bits and pieces, and wrote a data recovery script."
No; CPUs didn't /have/ to do that. MIPS toyed with both models for a while - initially MIPS was like "we don't interlock pipeline stages, so programmers need to be smart." Then the R4000 came out that attempted to implement that, and it was .. complicated. So it got reverted.
Not all CPUs are like Intel CPUs (which aren't all like earlier intel cpus, which aren't all like 8080s, etc..)
I think the first is what we would call the pipeline today and the second means parallel execution units. Using the word "functional units" for both is a bit confusing. Early RISC pipelines had 5 stages that are described in that link (and that brings back some memories - I remember studying it in college).
Funny thing is, I actually read the article to learn about what my first girlfriend's dad did - he was an engineer that worked on that thing (and yeah, she was a total nerd girl). I'm still Facebook friends with her, should point her to the article.