4 ms·

The MIT Lisp Machine microarchitecture looks pretty much like RISC. Pipelined load/store with a single instruction size and lots of registers. EDIT: the instru

• gumby 4y ago
  It was heavily influenced by the original Lisp Machine (PDP-10) which had a simple, regular, and orthogonal instruction set, itself practically the first RISC machine.
  • rjsw 4y ago
    The PDP-10 was not RISC by any definition.
    • gumby 4y ago
      If you look at the old Radin or Henessy papers, indeed the statement might seem far fetched. The PDP-6/10 did not start from the perspective of a powerful compiler, for example. But the big machines of the 60s and 70s had lots of features (as I alluded to in my root comment) for developers, like BCD support (survived into x86) string manipulation, variable length instructions etc. Just look at the Sperry, IBM and other big machines of the time. The ‘10s instruction set, as I noted above was quite regular and could be implemented in hardware (as it was in the KA at least): simple, regular, and easily predicted. Utterly the opposite of where the CISC guys were going. Of course the whole CPU architecture of a machine like the KA was trivial by today’s standards, with no microarchitecture, so to some degree the simplicity of design was a bottom up constraint as well, and in that regard, to loop back to the top of this comment, was the opposite of the motivations that drove the idea of “reduce” in RISC