Re: Why VAX Was the Ultimate CISC and Not RISC

Robert Swindells <rjs@fdy2.co.uk> writes:

On Sun, 02 Mar 2025 09:34:37 GMT, Anton Ertl wrote:
>

mitchalsup@aol.com (MitchAlsup1) writes:
 

A pipelined machine in 1978 would have had 50% to 100% more circuit
boards than VAX 11/780, making it a lot more expensive.

...

You could look at the MIT Lisp Machine, it used basically the same chips
as a VAX 11/780 but was a pipelined load/store architecture internally.

And what was the effect on the number of circuit boards?  What effect
did the load/store architecture have, and what effect did the
pipelining have?

It's been a number of years since I read about Lisp Machines and
Symbolics.  My impression was that they were both based on CISCy
ideas; it's about closing the semantic gap, no?  Load/store would
surprise me.

And when the RISC revolution came, they could not compete.  The RISCy
way to Lisp implementation was explored in SPUR (and Smalltalk in
SOAR) (one of which counts as RISC-III and the other as RISC-IV, I
don't remember which), and commercialized in SPARC's instructions with
support for tags (not used in the Lisp system that a former comp.arch
regular contributed to).

- anton
--
'Anyone trying for "industrial quality" ISA should avoid undefined behavior.'
  Mitch Alsup, <c17fcd89-f024-40e7-a594-88a85ac10d20o@googlegroups.com>