🚀 go-pugleaf

> > Not exactly a
> > general purpose instruction, but still a bona-fide 360 op code.
>
> Are you sure about that?  I think those instructions were designed and
> microcoded specifically for the 9020E to interface with the Raytheon PVD.
I
> have a vague recollection that some standard 360 instructions had to be
> deleted to make room in ROS for the display-oriented instructions.
>
> --
>      John Varela

I'm pretty sure the 9020s had the full complement of standard instructions,
as evidenced by the 360 compatibilty mode mentioned elsewhere. In this mode
the machines complied with the 360 PoO instruction set. I've a vague idea
that the 9020 -65s *may* have had a larger ROS address space. They used the
maximum 16 ROS planes, anyone know if the standard -65s used less than this?

I'm sure you're right about the display instructions being specific to the
9020E (and D) - but that was still a large number of processors(*1). What I
meant by "bona-fide" is that they were (are) 'official' op codes (not RPQs)
factory installed in S/360 machines. Of course, this assumes that the 9020
processors are eligible for membership of the 'S/360 Club' in the first
place. IMHO they are, but I'm biased! I'd hate for them to be orphaned.

(*1) How many 9020 360-65s were made? Educated guesstimate by me - say 15 x
9020Ds and 15 x 9020 Es, assume all are Triplex (were there any Quad
systems - the design maximum?), that comes to 90. Add 10(?) for NAFEC, OKC,
and UK (4), giving ~100 in total.

John, it's really good to talk to someone who was around when these things
were being put together. I just fixed them (most times) when they went
wrong - I really admire you guys for your foresight in providing all those
systems tools that you did to assist us. FLTs, microtrace, blinkenlights,
logouts, marginal voltages, etc., etc.

    Regards, Chris

Email: Chris...@COLDmail.com
(Make the obvious temperature change to the spam deflector)