P-code (was: Re: Another weekend haul story

From: A.R. Duell <ard12_at_eng.cam.ac.uk>
Date: Wed May 28 08:49:11 1997

[p-code, etc]

> It was to be a machine-independent interpreted pseudo-machine code
> (hmmm...), much
> the same as Java is today. I remember versions of the P-code
> intepreter for IBM-PC and Apple II, as well as TI. (There were also
> versions for non-consumer machines such as Teraks)

There was also a thing called a Sage II (anyone else remember them) that
was a single-board 68000-based computer. The standard OS on that was the
p-system, although I am told that CP/M-68K was also available at some

The Sage II was a nice machine to repair - one big flat board instantly
visible when you pulled the cover, all chips in sockets, and the
schematics in the user manual. They don't make 'em like that any more :-).
It was a fairly standard design - 68000 + 512K RAM + floppy controller
(Western Digital I think) + 2 serial ports + 8255 parallel port + GPIB +
glue logic.

Also, the first PERQ microcode implemented something called 'Q-code' which
was (I believe) an enhanced p-code - enhanced with things like raster-op
(bitblit) instructions. PERQ, of course, stood for 'Pascal Evaluation Real
Quick', and the machine was (in part) designed to run p-code - there's a
256-way branch operation to make it easy to do an instruction dispatch on
a bytecode.

A few months ago, there was a comment doing the rounds between a few
serious PERQ-fanatics that the PERQ should be renamed the 'jerq' (Java...)
and was essentially sold 17 years too early.

The gates in my computer are AND,OR and NOT, not Bill
Received on Wed May 28 1997 - 08:49:11 BST

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