Digital Equipment Corporation PDP-11/73

Specifications

chunga

Aaah, my very own PDP-11! Although it's unfortunate that it isn't a model with a big front panel with lights and switches, it's still a very wonderful machine. Besides, it's probably a good thing that it isn't huge or sucks up power like it's going out of fashion.

I originally thought this was actually a PDP-11/83 because it had a quad-width CPU board and PMI (Private Memory Interconnect) memory. I recently found out that the dual-width CPU board with the KDJ11 processor is a PDP-11/53. Mine is as stated on the box as the CPU is clocked at 15 MHz.

I had received this with a single 1M Qbus RAM board and had since upgraded it with a pair of 2M PMI RAM boards. This brings it up to its full 4M of RAM. Another addition is a Dilog SCSI controller and a 320M SCSI hard disk to replace the old dead 70M RD53 MFM hard disk. The RD53 used to work and, although I have another to replace it, they are notorious for premature death. Besides, SCSI drives are more common, have more storage, and are more relaible. QBus SCSI cards have shot up in price since I got mine but you can occasionally still get lucky.

Another nice thing is that it's relatively small, compared to a refrigerator, and one of the more powerful models from the PDP-11 family. It offers power and features comparable to the PDP-11/70, which is quite a magnitude larger and consumes considerably more power, like the kernel/supervisor/user modes and split instruction/data spaces. Mind you, the fans are still loud and sitting near the machine for extended periods can temporarily fuck up your hearing. One of the cool things about this machine is that it can run Unix quite nicely. This specimen has 2.11BSD on it which is the most modern Unix that can run on it.

Below is a list of the cards installed in it.