PDP-8/I

PDP-8/I, S/N M-26 L-647, DEC #62768, System S/N 1362

This system was used by the United Electronics Company, 42 Spring St, Newark, N. J., a part of GE, for testing vacuum tubes. It was donated to the RICM by Mark Blanchard. Geoffrey G. Rochat and Chris Tucker drove to NJ, picked up the system, and delivered it to the RICM in one very long day. The hour meter reads just 2472.7 hours, hardly run at all.

As of 1/12/12 the processor, the TC01 DECtape controller, and one TU55 DECtape are working.

We had to replace/repair 53 of the 127 flip-chip modules in this system.

It will boot the 4k Disk Monitor from DECtape.

On 09/28/13 Jack Rubin came for a visit to see the 8/I run, because he had just purchased an 8/I. Unfortunately it would not run.

On 01/25/15, after a two months of Saturdays repair effort, the 8/I booted the 4k Disk Monitor from DECtape.

As of 10/10/15, three of the TU55 DECtape drives are now working.

We modified the Teletype cable for the PDP-12 so that the Teletype works as an 8/I system console.

This system was integrated with the Kleinschmidt printer by Data Processing International.

They even put overlays with the Data Processing International name on top if the DEC overlays.

The front of the DEC PDP-8/I.

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The processor takes up the whole bottom section of the right cabinet.

It has 4K of Core memory, and five TU55 DECtape drives.

The TC01 DECtape controller is behind the upper and middle filler panels.

The special Kleinschmidt printer controller is below the lower filler panel.

There is an unusual Phoenix Engineering controller below the TC01 controller.

Click on the image to see a larger view.

The controller is a Negibus printer interface for the Kleinschmidt printer shown below.

The rear of the PDP 8I.

The 704A power supply at the bottom left powers the CPU.

The 779 power supply at the middle left powers the two TU55s that are above the CPU.

The 779 power supply at the upper right powers the three TU55s and the TC01 controller in the right cabinet.

This is one of the boards from the Phoenix Engineering controller.

The PDP-8/I processor chassis as viewed from the module side.

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Looking at the right side of the processor chassis board location A40 is in the top left corner.

Kleinschmidt Printer. Click on the image to see a larger image.

It looks like it was originally packaged like a Teletype or typewriter. It is actually a drum printer like the large line printers used on mainframes. Unlike a line printer this printer has a single print head that moves across the drum. I am sure that it is much faster than a Teletype and it is a lot less complicated.

There is a significant amount of corrosion on the tape guides on the TU55 tape drives.

We will have to fix this or it will scrape the oxide off the tapes.

Click on the image to see a larger view.

The PDP-8/I module locations. The empty locations are for processor options that are not implemented in this system.

This chart is rotated 90 degrees clockwise from the picture of the chassis.

CR8/I is the Punched Card reader option.

DL8/I is the Data Line Interface option.

KB8/I is the Line Clock option.

KE8/I is the Extended Arithmetic Element option.

KP8/I is the Power Fail option.

KT8/I is the timesharing option.

KV8/I is the ? option

MC8/I is the 8K memory expansion option.

MM8/I is the Extended Memory option.

MP8/I is the Memory Parity option.

PP8/I is the High-Speed Paper Tape Punch option.

PR8/I is the High-Speed Paper Tape Reader option..

VM08 is the ? option.

VP8/I is the Plotter option.

You can see oxide in the machined pocket in the tape guide.

The oxide has been scraped off the tape by the tape guides.

This is the original TU55 guide design.

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DMS, the 4k Monitor, is a minimal disk based operating system that will run in just 4k of core. Since a DECtape is treated like a disk, DMS works OK with a DECtape only system. It is perfect for our 4k core 3x DECtape PDP-8/I.

To list the directory of files on a DECtape you need to run the PIP program, tell PIP that you want a directory listing, and then tell PIP which device to get the directory listing from. We have the FOCAL language interpreter on the DMS DECtape. The easiest way to load a FOCAL program is to run FOCAL, load the FOCAL program, and then save FOCAL and the FOCAL program as a single binary file. That is what we did with the Lunar Lander and Hammurabi games.

.PIP

*OPT-L

*IN-S:

FB=1755

NAME TYPE BLK

AF

PIP .SYS (0) 0025

EDIT.SYS (0) 0016

LOAD.SYS (0) 0011

.CD..SYS (0) 0007

PALD.SYS (0) 0037

FORT.SYS (0) 0010

.FT..SYS (0) 0035

FOSL.SYS (0) 0007

.OS..SYS (0) 0025

STBL.SYS (0) 0001

DIAG.SYS (0) 0004

DDT .SYS (0) 0002

.DDT.USER(0) 0022

CDE1.ASCII 0007

STAT.ASCII 0003

STAT.FTC BIN 0003

FRMT.SYS (0) 0013

COPY.SYS (0) 0007

FOCL.SYS (0) 0037

FC01.SYS (0) 0037

LUNR.SYS (0) 0037

HAMI.SYS (0) 0037

CLNR.SYS (0) 0037

ZERO.SYS (0) 0001

DTCR.SYS (0) 0015

DUMP.SYS (0) 0004

REST.SYS (0) 0004

D801.BINARY 0004

D802.BINARY 0002

D803.BINARY 0001

D01A.BINARY 0004

D02A.BINARY 0003

D03A.BINARY 0001

D04B.BINARY 0003

D05A.BINARY 0003

D07A.BINARY 0004

D111.BINARY 0003

D112.BINARY 0003

D1L1.BINARY 0003

D1L2.BINARY 0001

D2AA.BINARY 0002

D2CA.BINARY 0002

D2BA.BINARY 0003

D1AA.BINARY 0001

D1CA.BINARY 0003

D1EC.BINARY 0003

D1GD.BINARY 0003

D3BB.BINARY 0003

D3BC.BINARY 0003

D3EB.BINARY 0003

D3RA.BINARY 0003

The PDP-8/I processor chassis as viewed from the module side.

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From the rear of the chassis board location A40 is in the top right corner.

The yellow wires are all originals from the factory.

The additional colors are for optional peripheral controllers, repairs, or modifications.

This is where the term "blue wire" comes from.

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The PDP-8/I has Data-Ram Core memory.

This core stack has three broken sense wires so it was replaced with a spare.

Front view of the TC01 DECtape controller. This is S/N 451.

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Click on the image for a larger view.

The TC01 status panel while it was formatting a DECtape.

The Type 779 power supply and power control relays on a the back door.

This feeds the TC01 DECtape controller and three TU55 DECtapes.

A close up of the Ebert Electronics Mercury Relay show at the top left of the image above.

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