Home‎ > ‎Large Systems Collection‎ > ‎

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.

TU55 #
S/N
1
2600
2
2607
3
2593
4
2987
5
2656
 
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.

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

 
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.

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.
Click on the image to see a larger view.

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 front of the DEC PDP-8/I.
Click on the image to see a larger view.
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.

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.
 
The PDP-8/I processor chassis as viewed from the module side.
Click on the image to see a larger view.
Looking at the right side of the processor chassis board location A40 is in the top left corner.
 
Slot
J
H
F
E
D
C
B
A
40
Empty   
Empty
FP Cab
FP Cab
FP Cab
FP Cab
FP Cab
FP Cab
39
KB8/I-B
KB8/I-B 
M220
M220
G228
G228
G624
G624
38
 KB8/I-B Cab
 KB8/I-A Cab
M220
M220
G221
G221
G624
G624
37
KB8/I-A 
 KB8/I-A
M220
M220
G221
G221
G228
 MP8/I
36
 KB8/I-A
 KB8/I-A
M220
M220
4K Core Stack
G228
G228
35
VM08 
VM08
M220
M220
W025
W025
34
 CR8/I
CR8/I
M220
M220
W025
W025
33
CR8/I
VM08 
M160
M216
G221
G221
G020
G020
32
 CR8/I
CR8/I
M113
M617
G221
G221
G020
G020
31
 KW8/I
KW8/I
M617
M617
MC8/I 
 MC8/I
G020
G020
30
 KW8/I
KW8/I
M617
M160
MC8/I 
 MC8/I
M617
MP8/I
29
VP8/I 
 VP8/I
M113
M160
 MC8/I
 MC8/I
MC8/I 
MC8/I 
28
PP8/I
PP8/I 
M115
M160
 MC8/I
MC8/I 
 MC8/I
 MC8/I
27
PR8/I 
PR8/I 
M117
M160
MC8/I 
 MC8/I
MC8/I 
 MC8/I
26
PR8/I 
PR8/I 
M115
M160
 MC8/I
 MC8/I
 MC8/I
 MC8/I
25
 KV8/I
KV8/I 
M113
M115
 MC8/I
MC8/I 
 MC8/I
 MC8/I
24
 KV8/I
KV8/I 
M117
M113
 KE8/I 
 KE8/I 
MC8/I 
M310
23
 KV8/I
KV8/I 
M117
M216
 KE8/I 
 KE8/I 
M360
M310
22
 KV8/I
 KV8/I
M113
M113
KE8/I  
 KE8/I 
M216
M310
21
KV8/I
KV8/I
M113
M115
 KE8/I 
 KE8/I 
M113
M310
20
M506
M651
M113
M216
 KE8/I 
 KE8/I 
MC8/I 
MC8/I 
19
M506
M651
M117
M216
KE8/I  
 KE8/I 
 MC8/I
 MC8/I
18
M506
M651
M310
M216
 KE8/I 
 KE8/I 
 MC8/I
 MC8/I
17
M506
M651
M310
M310
 KE8/I 
 KE8/I 
 MC8/I
 MC8/I
16
M506
M651
M310
M310
 KE8/I 
KE8/I  
 MC8/I
 MC8/I
15
M506
M651
M310
M113
 KE8/I 
 KE8/I 
 MC8/I
 MC8/I
14
M506
M651
M310
M115
 KE8/I 
 KE8/I 
 MC8/I
 MC8/I
13
M506
M651
M310
M160
 KE8/I 
KE8/I 
 MC8/I
 MC8/I
12
TTY Cab
M651
M310
M113
KE8/I  
M617
 MC8/I
 MC8/I
11
Data Break Cab
M651
M117
M113
 DL8/I
DL8/I
 MC8/I
MC8/I 
10
Data Break Cab
M651
M700
M700
DL8/I
DL8/I
MC8/I 
MP8/I 
9
Data Break Cab
M651
M119
M113
DL8/I
DL8/I
MP8/I
 MP8/I
8
Data Break Cab
M651
MM8/I
Empty 
DL8/I
 DL8/I
MP8/I
MP8/I 
7
Data Break Cab
M651
Empty
Empty
DL8/I
DL8/I
MP8/I 
 MP8/I
6
Data Break Cab
 Empty
Empty 
Empty
DL8/I
PP8/I 
KT8/I 
M113
5
I/O Bus Cab
MM8/I Cab
Empty 
Empty
DL8/I
PP8/I 
KT8/I
KT8/I 
4
I/O Bus Cab
MM8/I Cab
Empty
Empty
DL8/I
PP8/I 
 KT8/I
KP8/I On/Off
3
I/O Bus Cab
MM8/I Cab
M452
Empty
KV8/I Cab 
 PP8/I
Cable to PSU
2
I/O Bus Cab
MM8/I Cab
M707
M707
VP8/I Cab 
PP8/I 
G826
1
I/O Bus Cab
MM8/I Cab
M706
M706
CR8/I Cab 
PP8/I Cab 
G805 Power Regulator
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.

The PDP-8/I processor chassis as viewed from the module side.
Click on the image to see a larger view.
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.

Click on the image for a larger view.
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.
Click on the image to see a larger view.

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.
Click on the image for a larger view.
Subpages (1): DEC PDP-8/I Restoration
Comments