20 Sep
2001
20 Sep
'01
3:38 p.m.
"Michael L. Drew" wrote:
Bob Shannon wrote:
Not at all. If a machine has a writable control store, it simply has an extensible
instruction set. Its only emulation if you use that microcode to implement another
processor, like the worlds fasted PDP-8, coded on an 11/60.
Does anyone on this thread even understand
microprogramming?
Apparently not.
Well, I understand microprogramming. I though we were speaking figuratively.
The "microprogramming" we were talking about was treating the Pentium as
a very complicated micro engine.... Which IMHO it really is.
Using your definition every machine that has writeable microcode is
"emulating"
something
else... I recall that MIT built a native LISP machine using
2901 bit slice processors.
Wasn't
this the basis of the Symbolics machines???
Almost.
MIT developed the CADR, I have one in my garage, and I serviced them at the MIT AI
lab. The CADR uses a TTL cpu based on the 74S181 ALU chips. The MIT CADR became the
LM2, and the Lisp Machines Inc CADR's.
The LM2 begat the whole line of Symbolics machines like the 3600's, etc.
Does anyone recall the name of the 2901 based machine
that could be transformed
into 8080,Z80,6800,68000, etc. I believe that it came out in the 1980's.
I have a dim memory of that machine, but can't recall its name. Wasn't it a
Digital
Research machine?