Computer museum: Dissection of a PDP 11/60

Dissection of a PDP 11/60

Finding a PDP 11/60

This is probably the most difficult part of the whole dissection. These days PDP's are difficult to find.

PDP 11/60's exist in two models :

1. the compact model (lowboy), here the two discs are mounted above the processor. The whole system weights 240 kg and measures 130x120x80 cm.
2. In the highboy model the discs are mounted in separate racks. Above the processor there is some space for other devices. The system weights 250 kg and measures 150x120x80 cm.

Since the cost of a highboy model is the same as a lowboy model, the department did choose a highboy model.

In the rest of the dissection we will only use pictures. In the computer museum of the department you can find several parts of our PDP 11/60 :

• the complete processor module with switch panel
• disc controller on Unibus
• RK07 disc unit (28 Mb)

Open the front

Here we have "lowboy" PDP 11/60 with removed front. Before opening a PDP make sure that the extra pedestals are extended. This prevent that the rack falls over.

The lowboy setup had as main advantage its compactness, but because the discs were mounted on top, the whole chassis was severely shaken under heavy disc use.

Open the printed circuit bays.

The two bays containing printed circuits can be turned to access the backside with the "wire wrapped" backplane. This allowed measurements and the breaking of some connections e.g. when installing cards which needed DMA access.

Remove the front of the processor module

The leftmost bay contains the processor. From left to right we see:

1. memory: 1 card with the memory controller and maximum 4 memory cards each with 64 Kbytes.
2. an open space with only the controller for a terminal (LA36).
3. the floating point processor (4 cards). The model shown here does not have a floating point processor.
4. the central processor (6 cards)
5. the microprogramming module (1 card, not present here)

The rightmost (closed bay) has a Unibus backplane is used for controllers of input/output devices.

Open the backside of the PDP

The backside of a PDP 11/60 contains the power supplies. On the picture we see the minimal set of power supplies. The PDP 11/60 of the department also contained power supplies on the right side for the floating point processor and for the microprogramming module.

A PDP 11/60 did consume 4000 à 5000 watt.

Remove the processor cards

The memory cards of the PDP are extracted.

RK07 disc

An RK07 disc could store 28 Mbyte of information, the average access time was 50 milliseconds.

Copyright ©2001, Katholieke Universiteit Leuven, Departement Computerwetenschappen Comments to: Curator URL of this page: http://www.cs.kuleuven.be/museum/pdp/dissect-E.html : Click here to print this page