PDP-11/05 returns to life
pete at dunnington.plus.com
Tue Jan 6 16:27:03 CST 2009
On 06/01/2009 21:09, Tony Duell wrote:
> On 06/01/2009 20:19, Tobias Russell wrote:
>> I managed to coax my PDP-11/05 back into life today and ran a few simple
>> programs on it successfully.
>> As a result a few questions for the experts out there:
>> 1. To get it up and running I had to replace its two fans both of which
>> had failed which I did by scavenging another 11/05 chassis I have.
>> Does anyone have any tips on reviving failed fans? Both spin freely by
> Hmmm... Normally they suffer from bad bearings, although I don't think
> this is the problem with yours.
I agree with Tony, if they spin by hand, you don't have much of a
bearing/lubrication problem. If they do need lubrication, hot grease is
the stuff to soak the bearings in.
> This sounds, alas, like winding problems. I've never tried to rewind one....
>> recovery is impossible can anyone suggest suitable replacements? The
>> current ones are labelled Super-Boxers
I'm 99.99% certain they're 110V AC fans -- that's what almost all PDP-11
and PDP-8 fans are. Not always easy to get over here, but they do exist
(Farnell list a couple but not the right size, I think). In fact, I
think I may have one spare if you get stuck.
>> 2. Is there a chasing lights program I can run on the 11/05? Would be
>> nice to see it visibly doing something
> You have a console serial port built into the CPU board set. AFAIK it's
> current loop only (which is a bit of a pain), it's wired to the 40 pin
> Berg header on the back of the cabinet.
Yes, I think it's basically a KL11 equivalent. DEC used to make a thing
called a DLV11-KB, which is a 20mA-to-RS232 converter in small black box
about 70mm wide x 130mm long by 22mm thick, on a flange about 115mm
wide. It has a 10-way Berg on one end and the usual AMP 8-way flat
Mate-N-Lok on the other; it's actually meant to adapt a DLV11 (RS232
only) to current loop but AFAIK it'll work the other way round, so to
speak. Of course it's fairly simple to roll your own.
The on-board SLU in the KD11-B can be disabled by installing a jumper at
W1. W1 is on the M7261 board (control logic and microprogram board)
between E69 and C51 (about halfway up the board, roughly in line with
edge connector DH1/DH2). That was sometimes done in order to install a
DL11-W (SLU + LTC clock) or some other SLU that did have EIA/RS232
>> and boot RT-11. Can I make use of the 9th slot or does this have a
>> special purpose? There is a lot of wire wrap going to slot 9 so I'm
>> guessing its not suitable.
Dunno about the 9th slot but you should be able to run RT-11 V4 no
problem in 16KW, and most versions of V5 (though not the XM monitor, and
the FB might be too big to be useful).
I should have the 11/05 print set and some manuals somewhere. Maybe I
need to dig it out of storage.
Pete Peter Turnbull
University of York
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