[GTALUG] example of why RISC was a good idea

[Lennart Sorensen]

On Sat, May 21, 2016 at 02:48:50PM -0400, James Knott wrote:
> Many years ago, I used to maintain Data General Eclipse systems.  The
> CPU used microcode to control AMD bit slice processors and associated
> logic.  The microcode instructions were over 100 bits wide.  Now
> *THAT'S* RISC.  ;-)
> 
> BTW, those CPUs had an option called Writable Control Store (WCS) where
> one could create custom instructions.

That sounds more like the opposite of RISC.  Much more like VAX or
mainframes used to be as far as I know.  Maybe even VLIW, although
probably not.

Now being able to define new instructions using low level RISC features
might make some sense, although how much the savings would be in execution
time or binary size I don't know.  I have a hard time imagining much
gain there.

-- 
Len Sorensen