Reproduction micros

Paul Koning paulkoning at
Wed Jul 20 12:42:09 CDT 2016

> On Jul 20, 2016, at 1:34 PM, Cameron Kaiser <spectre at> wrote:
>> Also, RISC does not use, or need, microcode.
> I'm not sure what you mean by this, but (for example) many POWER
> implementations have microcode (example: the 970/G5, which is descended from
> POWER4).

What I meant is that I had no idea such things existed.  Very curious.  Learn something new every day.  What do they use this for?

The closest to microcode I'd ever heard of before is the "epicode" in Alpha.  Or was that Prism?  Anyway, a DEC RISC architecture where some privileged stuff was done in code running in a corner of the chip.  Not actual microcode because it was essentially the standard instruction set, somewhat extended and running in a special processor state.


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