14 Apr
2013
14 Apr
'13
12:55 p.m.
On 04/13/2013 07:13 PM, William Barnett-Lewis wrote:
I've been learning about the PDP-11 lately thanks
to the wonder that
is Simh, running various software on it and generally having fun. I
don't have any purpose other than that at this time. I've been running
everything I can get my hands on though I find, given my background,
tastes and biases, that it's usually either Unix Version 7 or,
especially, 2.11BSD that I'm firing up and exploring rather than, say
the more DEC traditional RSTS/E.
That said, I've been wondering what would be different (aside from
noise & heat ;) about running 2.11BSD on hardware rather than in Simh
on my increasingly decrepit Dell C640 running Xubuntu. Logically I
should spend the money on a new intel based laptop but what's the fun
in that?
But then that turns on the question - is there even a cheap PDP-11
that can run 2.11BSD? I don't need a speed demon but how small is too
small vs big enough?
Let me see if I understand correctly what I would need:
A BA23 or BA123 chassis. Would others work as well?
A CPU with separate I/D space. 11/23, 11/53, 11/73, 11/83 or 11/93
would work with the Q-bus chassis above.
the 11/53 is a system designation. the
CPUs are F11 (11/23),
J11 (11/73, 83, 93).
For separate I&D any of the J11 cpus. There is V2.11 that runs on 11/23.
1mb to 4mb memory, 1mb is absolute minimum for 2.11
BSD & 4mb is
highly desirable.
Memory is generally easy.
Disk controller - though more expensive, sanity really
says I should
find a SCSI controller like RQZX1, Emulex UC-7 or CMD CQD-220. I have
old SCSI disks; ESDI & the like? Not so much ...
A RQDX3 & RX50 or TQK70 & TK70 would probably be in the 'nice to
have' category as well.
DELQA ethernet controller
Disk is key, anything over 10-20MB will do, tape not so
much.
Would this work? What are the going rates for
hobbyists (rather than
resellers to those with production equipment)? Are there any, hmm,
less expensive bits here or there?
Hobbyists pay more, always been true.
Usual reasons is they don't know what they want and even more
don't know the systems. Resellers only care about selling not helping.
Cheap is by hunting for systems people are junking/offering or
trying to get off the premises. Dumpster diving is a good way too.
This is mostly a thought experiment as I don't
really have the
disposable cash right now for the various parts right now. OTOH, I
find the process of learning more about the hardware, what would be
required and how it functions, to give me a better understanding of
what I'm doing with the emulator.
Thanks to all here (the 11/23 thread has been of great value to me)
and to bitsavers ;) and all the other fun resources out there.
The biggest difference between SIMH is that it allows for software
study and preservation. The hardware is required to understand
the systems and all it takes to make, maintain and run said software
on them. The hardware based skills are dying very fast.
Allison