The PDP-8 Hardware Collection

Part of the PDP-8 Collection
by Douglas W. Jones
THE UNIVERSITY OF IOWA Department of Computer Science


This machine is in pieces. The CPU box, with serial number 8L 3068 (and an added 80 on an auxiliary sticker by the name plate), was given to me by Michael Begley, who got it from a surplus sale at Iowa State University. On the front is a plaque saying Donated By Harnischfeger Corp.; my guess is that the machine began its career as a machine tool controller, but I have no evidence to back this up. The date codes on the chips in the machine suggest that it was built in mid 1970. PDP-8/L serial numbers appear to be in a single series, from 1 (sold in late 1968) to 3902 (sold in 1971); interpolating the serial number relative to published production figures for the 8/L suggests a sale date in the third quarter of 1970.

The expansion box is, serial number BA08A 141; this ought to allow me to configure the machine to support 8K of memory. I have a BE01 DECtape controller, and 2 TU55 DECtape drives that came from the basement of Ryerson Hall at the University of Chicago, and 3 additional TU55 drives that came from David Razler. I also have an ASR33 TTY for it that ought to be restorable.

The CPU is missing its TTY interface cable! the material from Chicago was originally an Astrotype typesetting system (the BE01 DecTape controller is an OEM version of the TC01, and the TU55 drives were OEM versions, with Astrotype labels instead of the usual DEC paint job). I have the original Astrotype rack; it is in fair condition, but missing its side skins; I have begun to re-mount all these pieces in that rack.


My second PDP-8/L system came from the U of Iowa Psych department; it was to be tossed in the trash. It includes both a CPU and a BA08A expansion box, plus cables. The system was mounted in an off brand relay rack with very strange rack mounting slides; I pulled it from the rack and saved only the homebrew high speed paper-tape drive and interface.

I have a rack I got at U of Iowa surplus that used to house a PDP-11/44; I have begun mounting this system in the rack. I hope to assemble the system configured roughly like the Astrotype system, but I need a TC01 and BC01V to do so.


This machine, serial number PDP8/E PR03 09114, is dated 3-18-74. It should be easy to debug, but has not been tried. I got this machine from the University of Iowa surplus outlet. A plate on the back says Struthers Dunn 2256; this was presumably the original owner. It has a KC8E front panel, with the paint job on the panel saying Industrial 8 in a Red/Blue color scheme.

Inside is an MM8EJ 8K core memory, and a MMI (third party) 8K semiconductor memory board. I also have a two KL8E boards for terminal, printer and modem interfacing, and an RX8E interface board for the RX01 diskette drive. The CPU is mounted in a full-height DEC rack along with a dual 8-inch disk drive, serial number RX01 WS17271.

The rack and diskette drive all came from the University of Iowa Surplus outlet; I believe the drive and rack originally belonged to different PDP-11 systems. The RX8E interface board came from Tim Shoppa.

I need a trim panel for the top of the rack that matches the Industrial-8 color scheme; the current label on the rack top says PDP-11 in maroon and purple. Additional peripherals and their interface boards would be nice.


This machine, serial number PDP8/F PR03 01239, is dated 8-11-75. It works, although the KC8F front panel required repairs. It has an MM8EJ 8K core memory, with a repaired MM8E 4K core memory added, and two KL8E boards. It is mounted in a full height DEC rack with a trim panel on top in PDP-8 colors.

Other than the KL8E console interface boards, the only peripheral I've got up and running at this point is an IOmec (Digitronics) model 2540 high speed paper-tape reader and interface; I had to reverse engineer the IOmec 9602-1 Omnibus interface board in order to build the cable between the two, but it is upward compatable with DEC's high speed readers.

In addition, I have an untested RX01, serial number RX01 BA WF10589, and RX8E interface for this machine, a Remex high speed paper-tape punch, but no interface or documentation, and a COI LincTape II drive.

The configuraton of this machine deliberately emphasizes third-party hardware! This is in keeping with the open architecture of the PDP-8. I know, from the boot sequence penciled on the inside of the IOmec reader's cover, that it was originally used on a PDP-8. I suspect that the Remex punch also came from an -8 system. I need documentation for the Remex punch and COI tape drive, but I believe I've reverse engineered the tape drive to the point that I can attach it to a TD8E simple DECtape controller. I need the latter, however!

This CPU, most of the interfaces, and the disk drive came from the University of Iowa Psychology department, via the University Surplus outlet. Professor Fox, in the Psych department, was an early user of PDP-8 computers, and he continued to use them into the 1980's. The rack and PDP-8 trim panel came from the University of Minnesota, via Lawrence LeMay. The 4K core set came from Michael L. Ardai, who found it in a junk pile. The paper-tape hardware is from the Rockwell International Corporate Surplus Store in Cedar Rapids Iowa, and the LincTape II drive is also from Rockwell, which donated it, along with a Data General Nova to the University of Iowa, where it sat unused for at least 10 years prior to being discarded.