[HECnet] DECnet Implementation and Productization of RSX-11M, 11S, 11D and IAS (was Re: Anonymous FAL (Tops-20))

[John Forecast]

> On Jul 16, 2019, at 5:44 PM, Johnny Billquist <bqt at softjar.se> wrote:
> 
> On 2019-07-16 23:38, John Forecast wrote:
>>> On Jul 16, 2019, at 2:46 PM, John Wilson <wilson at dbit.com> wrote:
>>> 
>>> From: John Forecast <john at forecast.name>
>>> [E11 on MIM]
>>>> Does the simulator actually simulate the caches or just the control registers
>>>> like SIMH?
>>> 
>>> Just the control registers.  I hate doing an emulation of a speed-up
>>> feature which actually slows it down (which is the case with the FASTBUS:
>>> emulation for dual PDP-11/45s but there was no way around that -- making
>>> the memory inherently mP-safe meant dinking with locks on every access,
>>> so it's *much* slower to touch it than non-"FAST" core).
>>> 
>> I suspected that was the case, but I just wanted to check. I wanted to run a comparison test
>> between cache bypass on for all CEX code and selectively flushing the cache at strategic points through
>> the code. What we ended up with was ~11/45 performance for the kernel code and ~n * 11/70
>> performance for the application level code. Since there were only a couple of mP machine left (our dual
>> and the RSX-11M+ quad), it wasn’t worth the extra work.
> 
> I think field service might have had one as well, but it might also have been a later combination of the other two.
> 
> You might be amused to hear that CASTOR:: and POLLUX:: were later disassembled and moved, and reemerged in Colorado Springs, and was named PHEANX:: and was kept running until approximately the year 2000, when it developed a hardware problem that was not considered worth fixing.
> By now I'm sure all bits and pieces have been lost. :-(
> 
I’m sure they have. Once our dual was installed it was very stable and became our default development machine. It ran rings around our VAX-11/780 installed abput the same time.

  John.

>  Johnny
> 
> -- 
> Johnny Billquist                  || "I'm on a bus
>                                  ||  on a psychedelic trip
> email: bqt at softjar.se             ||  Reading murder books
> pdp is alive!                     ||  tryin' to stay hip" - B. Idol