16 May
1998
16 May
'98
6:44 p.m.
<> PDP11/74,
<
<Did DEC ever market these, or were they (all four of them, or
<whatever) just a last ditch effort to save the PDP-11/70 line?
No, never marketed. Accoring to some they were built with existing
parts. It was not persued because it would eclipse the vax and the
11/70 design was not emi/rfi complient and would be very difficult to
make it so. At the time the 16 bit mini market was seen to be getting
smaller in favor of the 32bit superminis.
<Certainly, although the PDP-12s might be close to being kicked off the
<"very rare" list. I hesitate to add the KS-10s, as I think there are
<probably more of them hidden away (or maybe actually doing work!) than w
<think.
When you consider there were no more than a 1000 of either that's pretty
scarce if 1-2% still survive.
Allison
16 May
16 May
7:01 p.m.
When you consider there were no more than a 1000 of
either that's pretty
scarce if 1-2% still survive.
Oh yes, I would guess that there are only 10 PDP-12s in captivity at this
time. I would not at all be suprised if more show up from storerooms and
basements. Just about 20 months ago, the PDP-12 population "grew" by
three, as RCS/RI hauled a bunch of stuff from a university. Certianly
there are more buried.
This is where I do not agree with the 10-20 percent survival rule.
It works well for small machines, perhaps upto the large deskside
workstations, but above that, the survival rate starts to dive. Why? Small
things can be "swept under the carpet" during cleaning sessions - put on a
shelf, taken home by a hacker, placed in a crawlspace. Not so with 2 tons
of mainframe iron!
1-2 percent is probably pretty close to the survival rate for the bigger
beasts, just as Allison points out above.
William Donzelli
william(a)ans.net
11:53 p.m.
<> PDP11/74,
<
<Did DEC ever market these, or were they (all four of them, or
<whatever) just a last ditch effort to save the PDP-11/70 line?
No, never marketed. Accoring to some they were built with existing
parts. It was not persued because it would eclipse the vax and the
11/70 design was not emi/rfi complient and would be very difficult to
make it so. At the time the 16 bit mini market was seen to be getting
smaller in favor of the 32bit superminis.
Actually they were slightly different. (Different front panel,
cache memory and memory control, different backplane.) They were
pretty much the same old 11/70 cpu with CIS on em. KB11-AD=11/45,11/50
11/55 CPU. KB11-B,C=11/70 CPU, KB11-CM=11/74 CPU. I seem to remember
references to the KB11-E somewhere.
When AT&T needed the last available 11/70's for use in their
operations (SCAMOS, COSMOS etc) they bought every last one DEC could
supply. DEC was buying them up from customers on Vax trade-ins, refurbing
them and selling them to "the Telephone Company" so they could
avoid having to get them redesigned and rereleased with new FCC
specs.
DEC split up the remaining internal 11/74's and shipped them to regional
offices to use them as internal use only 11/70 replacements (ours was
the regional sales order processing RSTS/E 7.2 system. We just hoped
it would never die, because we had no spares for the beast beyond the
straight 11/70 spares kit.
Allison
Does anyone know what the "Unicorn" system was. I hear it was an even
later 11 prototype using the what would later become the VAX 11/780
SBI as it's bus. My friend saw the theory of ops on the memory while
building the earliest 11/780's -- but no one has any references to a
Unicorn being created.
There was also the design of the Bluefish 11/68 follow up to the 11/60
and 11/74 (but that was never built).
Bill
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17 May
17 May
8:21 a.m.
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1:41 p.m.
What is strange is the rarity of the Philips machines
I mentioned (the
P800 series). There were at least 10 different models. The small
P850 (maximum memory 2kW) was built from TTL and totally hardwired - no
microcode - the control logic was a state machine. The P855 and P860 had
memory management. And the P851 was an LSI version of the P855 I think. That
one was microcoded.
I can understand why they would be rare in North America. I remember
seeing ads (in 1970s era issues of Electronics - still cursed for throwing
the things away!) for them only a few times. I do not think they were
marketted here much at all.
William Donzelli
william(a)ans.net
9564
days inactive
9565
days old
4 comments
4 participants
participants (4)
-
allisonp＠world.std.com -
ard＠p850ug1.demon.co.uk -
pechter＠shell.monmouth.com -
william＠ans.net