PDP-1

There is a PDP-1 on display, but I didn't take a 3D picture of it. I thought I had taken a closeup of the console, but my digital camera disagrees with me. Since the camera keeps track of the files, it won that particular argument. To the right is the person that has to put up with my constant weirdness.

PDP-5

There was a PDP-5 on display at VCF. The fellow who was showing it is in the process of restoring it.

The PDP-5 is interesting to me for a number of reasons:

• It was introduced in 1963, just a few months after I was born.
• It executes the PDP-8 instruction set.
• Since it stores the program counter in memory location zero, it is possible to build a "pure" CPU and implement traditional functions externally. For example, the interrupt controller could be implemented externally as a DMA device. I have no idea if this is how the PDP-5 works, but it could work that way. The interrupt controller for a more complicated CPU needs lots of hooks into the machine.
• I have a front panel from a PDP-5.
• I have a PDP-5 programming card that's been autographed by Ken Olsen. And you don't. Neener neener neener.

PDP-8

The Computer History Museum has a display of three PDP-8s. That's a PDP-8/F on the left, a straight-8 in the middle, and a PDP-8/S on the right.

I've had extensive involvements with -8s over the years. I used to TA for the introductory programming class taught by the Electrical Engineering department of Utah State University back when it was all timeshared on PDP-8s. We had an -8/E with core and an -8/M with CMOS memory; you could tell which was which when thunderstorms went through and made the power flicker.

I spent much quality time with a DECmate II, although I used it primarily as a CP/M machine. I did, however, fire up OS/278 occasionally.