yet another pdp-11 in fgpa
bqt at softjar.se
Tue Jun 22 18:22:52 CDT 2010
Don North <ak6dn at mindspring.com> wrote:
> Johnny Billquist wrote:
>> > "Walter F.J. Mueller" <W.F.J.Mueller at gsi.de> wrote:
>>> >> The reason why I picked a 11/70 and not a J11 as target is because my
>>> >> goal is a 11/74. I've implemented the IIST already and tested against
>>> >> the IIST Diagnostic I could find in XXDP (riiab0). A dual core will
>>> >> fit into a single xc3s1200e of the NEXYS2 board. The work needed is
>>> >> quite clear and doable (changes on cache, mmu, and cpu core for asrb).
>>> >> However, I've no plans to implement the CIS, so it will always be a
>>> >> subset of a 11/74. But for sure fun to do and run.
>> > You do know that the J11 is already designed for mP usage, except that
>> > DECs testing of that was even more secret than the 11/74?
>> > The 11/74 definitely don't need CIS though. I don't think any
>> > prototype 11/74 even had it. It was planned for the next generation of
>> > the machine, that never got built. Anyway, it was to be an option for
>> > the CPU as far as I know. Just as FPP.
> Here's a front panel from a 'real 11/74', the uniprocessor one with
> CIS: http://www.ak6dn.com/stuff/1174.jpg
Thanks for sharing that, Don. Now that I see it, I realize that I have
seen it before.
> Note the CIS uADDRS and other CIS status lights selectable on the rotary
> switch on the right.
> The marketing dinks appropriated the 11/74 moniker for the wanna-be
> 11/70mp program because '11/74' sounded better for a 4 way MP system.
Yeah, as usual, name confusion is fun. Interestingly enough, RSX
identifies the 11/70mp as an 11/74.
> After the 11/74 CIS COBOL benchmarks came in, the native PDP-11 CIS
> implementation on the 11/74 blew the 11/780 benchmarks away. DEC
> marketing did not like this; it made selling business customers the just
> released 11/780 more difficult. The decision was made to kill the 11/74
> CIS option the day we released it to manufacturing in favor of the new
> VAX system.
I wasn't aware that any prototypes ever were produced and came as far as
being functional. I thought it was just paper work that had bee done.
> Johnny is right, the 11/74 option was a multiboard set (just like the
> FPP option) that could be plugged into the new 11/74 backplane (which
> was an 11/70 backplane with all the CPU and FPP slots pushed down by
> four to make room for the CIS option in the first slots).
> I wish I had saved more documentation (print sets, microcode listings,
> etc) but to my knowledge none of this survives for the 11/74 CIS. Only
> my front plex panel which I took as a souvenir.
> I was one of the three engineers who wrote the microcode for the CIS
> option subsystem (total of 4K words of 96bit wide horizontal microcode).
Nice to hear. Too bad the machine never got to production. It would have
been a nice system...
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