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DEC PDP 11/45

Digital Equipment Corporation

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Manufacturer Digital Equipment Corporation
Model PDP 11/45
Age Introduced 1972
Service Data Yes
Condition Good, it almost works!
Dimensions Cabinet is 71" high, 21" wide and 30" deep (1810 x 540 x 760 mm)
Comments I rescued this mini-computer from the scrap pile at work recently. The cabinet contains the computer chassis, two power modules and a power distribuition unit.

This view shows the internals of the computer chassis. The CPU consists of six printed circuit boards, and there is also memory, a real time clock, and a printer interface. Unfortunatly, I don't yet have a card to interface to a VDU, or any mass storage devices (paper tape, magnetic tape or disk).

This shows the backplane, which is mostly of wire-wrap construction, the front of the two power supply units (at the right of the picture), and the power distribuition unit in the bottom of the cabinet.

This shows the plug in regulator units in the power supply modules.

The front panel console, so you can monitor the computer, and enter programs (in binary) via the front panel switches. The indicator lamps are all small plug-in filament lamps (a few have been replaced with plug in LED equivalents).

I have had some succes with this machine, and have the console working now (a faulty power regulator), but can not yet talk to the processor yet!

4th April 2005 Update.

I have now managed to run a couple of small programs from the console - the UBC module was faulty (the output of one chip was stuck high - this computer has a CPU that you can repair!), but there are still processor faults - I can't write to one of the registers at the moment. There are still a number of power supply faults, mainly high frequency "spikes" caused by faulty capacitors in the regulator units.

The machine is currently in its most basic form, containing only the processor, memory management unit, timing generator and memory. I need to get this all working properly before I start adding any of the other cards back in.

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Copyright J.Beacon & M.Wroe-Parker 2005