MIT provides MULTICS source and documentation (DPS-8 simulation)

Chuck Guzis cclist at
Thu Nov 15 02:02:03 CST 2007

On 15 Nov 2007 at 2:34, Roy J. Tellason wrote:

> I seem to remember some stuff duing my CP/M days that actually had a bitmap of 
> which locations needed to be fixed,  though I'm darned if I can remember just 
> now what that was.

If you put together CP/M from the OEM kit, you used it to make your 
customized copy of MOVCPM.

> Wasn't JRT the one that got some really bad reviews in Byte or one of the 
> other magazines?  It was some early Pascal compiler anyhow.  I can't say I 
> ever encountered it or ran across it or talked with anybody who had used it.

I still have my 8" JRT disk.  Yes, it was terrible and slow, but what 
do you expect from a program that swaps to floppy?  They advertised 
that you could write programs of any size, not limited by the RAM of 
your computer.  While it was probably true that you could write 
programs much larger than available RAM, the d*mned thing was buggy 
enough to be useless.  

Curiously, I was using it as part of a validation set of programs to 
check out V20/V30 8080 emulation and turned up a big in the V20/V30.  
I still have the NEC MicroNote describing the problem.  AFAIK, the 
bug was never fixed in the V-series uPs--there just wasn't enough 
interest.  As I recall, the problem was the JRT modularized its own 
subroutines and set SP = subroutine entry point before each call to 
keep the stack local to each subroutine.  It broke the V20/V30 badly. 
 It was an object less in the fallacy of the "no one would ever want 
to do that' approach.

> I remember one of the floppies I got with my Osborne originally was 
> labeled "UCSD P-System" (or something pretty close to that).  I vaguely 
> recall poking around with it once,  but it had nothing at all to do with 
> CP/M,  wasn't compatible with anything else at all,  and at that point in 
> time I couldn't see the use of it.  I probably still have it somewhere,  and 
> some docs on it too.

Yup, UCSD P-system was its own operating system as well as the 
language support.  Not a bad implementation for the time, but a world 
unto itself.  I think at one point IBM even flogged it for the PC.


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