PDP-8/I

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.

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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.

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.

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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.

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

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