The pdp-8I was one of DECs most successful systems prior to the pdp-8e. It was a 12-bit machine descended from the original pdp-8, and the pdp-5 before that. This is the one of the oldest systems I have in my collection, being built in 1967. It is a Real Computer: Real Computers have the octal listing for the RIM loader printed on the front panel! :-)

It came in two flavours; the rackmount model which everyone knows, and a much rarer standalone model which looked... wierd!

For some reason I'm very short on decent photographs of this system - the above is what it's supposed to look like, if the photographer is competent!

An incompentent photographer produces results like this:

An old polaroid from the early days of the Corestore... in the foreground, the two cabs of the 8/I - the second cab virtually empty, except for the Lab/8 box in the top position. In the background, a couple of 8/e systems, an 11/35, and an 11/70 - with assorted DECtapes and disks. On the floor, an ASR 33 and the monitor from a Xerox 6085 workstation.

A slightly better shot of the front: front panel, PC04 paper tape reader/punch, RM503 scope, and some interfacing stuff in the top.

The front panel, complete with RIM loader text! A 'proper' front panel with seperate rows of lights, so you can see PC, MA, MB, AC, MQ, instruction, and major states - all at once. No silly pdp-8e knobs here!

The entire system with the exception of the PSU slides out as a single unit. Note the two 4k core stacks.

Hopefully some better pictures of this machine will be up soon! This machine is in a 'lab-8' configuration, has a paper tape reader/punch, and a data acquisition and display subsystem with a/d converters(in the left rack) and an old Tektronic 503 'scope. It was used in Cambridge University for physical chemistry research until I collected it in 1992.

It's currently in full working order, except for a recently blown bulb on the paper tape reader which I haven't got round to replacing, and runs very nicely - it's probably my most reliable machine! I've had various diagnostics, Fortran and Focal (a 'programmable calculator' program) running on it. I haven't quite figured out how to display stuff on the 'scope yet, but it works fine as a pdp-8.
I could use any information about an 'auto single-step' circuit for it, which would allow me to vary the machine speed from 1 instruction per second to full speed - this ability was built-in on the 12 and 15, but I believe a circuit for the 8I was published at some point.

When I picked up my first pdp-8/L from the Mersey Tunnel, where it had been used to control the ventilation system, I also got a pdp-8/I - or most of one. The chassis, backplane, and front panel were lying behind the rack the 8/L was in. I was told it had been used simply as a convenient rack for storing M-series modules!

In the last couple of days (8/2003), I think I've actually located a spare 8/I power supply... repair it, get the required modules into it, and hey presto! I have a second 8/I :-)

There are quite a few other 8/Is out there...
http://www.pdp8.net/pdp8i/pdp8i.shtml David Gesswein has one... and a much better site than mine!
http://www.parse.com/~pdp8/pdp8i/restore.html Robert Krten has an excellent page on a restoration project