DEC PDP-12, System Number 696

This December 1973 vintage PDP-12 was originally purchased by the Leesona Corporation in Warwick, RI. It was used to test a pneumatic computer (ALPS) that was an accessory to a weaving machine. It has some special I/O that was added by Leesona and is connected to the LINC Sense Lines. The in 2015 dollars this machine would cost $310,000.

The architecture of this system is a merge of a LINC (Laboratory Instrumentation Computer from MIT) and a PDP-8/I, so it has two modes for the processor, LINC and PDP-8/I. A single I/O instruction changes the instruction stream from one processor mode to the other. The LINC processor manages the digital and analog I/O, graphics, and the LINCtape. The PDP-8/I processor handles the disk, diskette, and other peripherals.

This system was built very late in the life of PDP-12s, so it has the Priority Interrupt and Data Multiplexer options pre-wired in the backplane. It also has an Omnibus expansion chassis so that it could have a large (2.5MB) disk drive.

The RX02 diskette drives and the RX8-E controller, and the paper tape reader/punch and the PC8E controller came from Brown & Sharpe.

Current Status:

DEC_PDP-12_Front-Panel

The console for the PDP-12.

The indicators and switches are a combination of PDP-8/I and LINC processor functions.

Features and serial numbers from the labels in the system:

M36 #696 (System Number)

MC #619

MEM #822

PC8E #SP57779

PC04 #SP15627

TU56 #8698

KW12A #646

RX02

RK05

M22VR14 #WF 558

LP01FA #739, 5060 DP2310 80 Column, 64 Character Line Printer

Installed Options:

AD12    Analog to Digital Converter

AG12    A-D Additional PreAmps

AM12    A-D Expanded Multiplexer

DP12-B Teletype Data Phone, EIA Levels, Missing M706 in MN9, M707 in MN10

DR12    Relays and Control

EM12    Basic 4K Memory

EP12    PDP-12 Processor

KE12    Extended Arithmetic Element

KF12    Automatic Priority Interrupt

KW12-A  Programmable Real-Time Clock

MC12    Memory Extension Control

TC12    LINCtape Control

VC12    Scope Control

Wired But Not Installed Options:

DM12    3 Channel Data Break MUX

KP12    Power Fail/Restart

KT12    Timesharing

TC12-F  DECtape Control (This needs just 2x M216 modules so we will install this)

XY12    Plotter Control

This is the swing-out frame that holds the processor electronics.

The upper part is the 8kW core memory, analog input, and LINC tape controller.

The lower part is the combined PDP-8/I and LINC processor, the serial console interface, and the priority interrupt controller.

DW8E-PC Omnibus Expansion Chassis populated for Posibus I/O Bus Converter

4x M7102 Omnibus-Posibus Interface

M7171 Bus Control

M8357 RX8-E RX01/RX02 Diskette Controller (From Brown & Sharpe) Added

M841 LE8-0 LE8-FA LP01 Printer Controller (From Brown & Sharpe) Removed

M7104-YA, M7105, M7106, RK8F RK05 Disk Drive Controller

M840 PC8-E PC04 Paper Tape Reader/Punch Controller (From Brown & Sharpe) Added

M8320 Omnibus Bus Loads

This is the DW8E-PC Omnibus Expansion Chassis.

The boards at the top convert the Posibus I/O signals from the PDP-12 to Omnibus signals on the backplane.

The Omnibus contains an LE8-FA LP01 controller, RK8-F RK05 controller, and a PC8-E PC04 paper tape reader/punch controller.

It only supports one data-break controller per Omnibus.

We removed the LE8-FA printer controller to make room for the RX8-E controller for the RX02 floppies.

To Do:

Done:

Items that came with the PDP-12

BOX #1

BOX #2

BOX #3

BOX #4, Paper Tapes

BOX #5, Manuals

The LP01FA 80 Column, 64 Character Drum Line Printer

The printer mechanism is a Data Products DP2310.

This printer and the LE8-FA controller came from Brown & Sharpe.

Lunar Lander on the PDP-12

Scan and publish diagnostic documents

Diagnostic Tests Passed

MAINDEC-801-3A Inst test 3A EAE 12/18/2015

MAINDEC-08-D02B PDP-8 Instruction Test Part 2B, 11/13/24

MAINDEC-08-D04B Random JMP Test 11/13/24

MAINDEC-08-D05B Random JMP-JMS Test 11/13/24

MAINDEC-08-D07B Random ISZ test 11/13/24

MAINDEC-08-D0AA Instruction Test (EAE) 3A 7/7/21

MAINDEC-08-D0BA Instruction Test 3B  7/7/21

MAINDEC-08-D1AC Memory Power On/Off Test 1/2/16

MAINDEC-08-D1B1 Memory Address Test Low 7/7/21

MAINDEC-08-D1B2 Memory Address Test High 7/7/21

MAINDEC-08-D1EC Extended Memory Checkerboard 7/7/21

MAINDEC-08-D1GD Extended Memory Control 7/7/21

MAINDEC-08-D1HA Extended Memory Address Test 7/7/21

MAINDEC-08-DHRKA-B RK8E Diskless Control Test 6/4/16

MAINDEC-08-DHRKB-G RK8-E Disk Drive Control Test 6/25/16

MAINDEC-08-DHRKD-D RK8-E_RK8-L Disk Formatter Program 6/4/16

MAINDEC-08-DIRXA-D RX8-RX01 Diagnostic Program

MAINDEC-8I-D01C Instruction Test 1 11/13/24

MAINDEC-8I-D02B Instruction Test 11/13/24

MAINDEC-8I-D0AA INSTRUCTION TEST PART 3A 7/7/21

MAINDEC-8I-D0BA EXT ARITH TST PART 3B 1/2/16, failed 7/7/21

MAINDEC-12-D0AB CP Test 2, Tests SKIPs and data handling in LINC mode 11/13/24

MAINDEC-12-D0BA Extended Instruction Test, LINC Instructions 11/13/24

MAINDEC-12-D0CB CP Test 3 11/13/24

MAINDEC-12-D0GA Tape Quickie 2/25/17

MAINDEC-12-D0SA Automatic Priority Interrupt ?

MAINDEC-12-D1AC Extended Memory Control (EXTMC12) 11/13/24

MAINDEC-12-D1BA JMP Self 1/2/16

MAINDEC-12-D1DA Memory Checkerboard 11/13/24

MAINDEC-12-D1EA Float 1s and 0s Through Memory 1/2/16

MAINDEC-12-D1FA Basic Memory Control Test 1/2/16

MAINDEC-12-D3AD Tape Control Test Part 1 of 2 10/2/15

MAINDEC-12-D3AE Tape Control Test Part 1 of 2, Tests tape control logic and inter register transfers, 12/30/17

MAINDEC-12-D3DB TAPE DATA EXERCISER (Ran for a long time before it halted) 2/25/17

MAINDEC-12-D3GA Tape Control Test Part 2 of 2 12/30/17

MAINDEC-12-D6BA VR12 Display 7/13/21

MAINDEC-12-D6BC VR12 Display, Tests display system using DIS and DSC instructions 11/13/24

MAINDEC-12-D6CC A To D Converter Test 7/13/21

MAINDEC-12-D8AB Relay Register Test 7/13/21

MAINDEC-12-D8CD KW12 Clock Test 11/13/24

Diagnostic Tests Failed

MAINDEC-801-3A Inst test 3A EAE, ran but hung running after 8 seconds at 2616. Looks like the SHL instruction is broken. Replaced the M160 in slot M35 and it runs OK now.

MAINDEC-08-D1KA KP8I POWER FAIL TEST, don't have the option

MAINDEC-12-D1BA JMP Self won't load. Probably a bad paper tape image.  7/3/15

MAINDEC-12-D3DB Tape Data Exerciser. Runs OK now.

MAINDEC-12-D3FB Tape Data Test, ran for a while but halted with E3 in T3 6/27/15

MAINDEC-12-D7CD System Exerciser, ran for a while and displayed "ERROR".

MAINDEC-12-D8CC KW12A Clock Test, Will not work on this system because ECO #55 is installed.  7/11/15

MAINDEC-12-D8CD KW12A Clock Test, replaced M103 in D25, the M216 module in F19 and it runs OK now.

MAINDEC-12-DAEXA System Exerciser (replaces D7CD), ran for a while and displayed "ERROR".

Diagnostic Tests That We Need to Run

MAINDEC-08-D03A Basic JMP-JMS Test

MAINDEC-08-D1AC Memory Power On/Off Test

MAINDEC-08-D1L0 Memory Checkerboard

MAINDEC-12-D1BA JMP Self

MAINDEC-12-D1CA PDP-12 Address Test, need paperwork

MAINDEC-12-D1EB Float 1s and 0s Through Memory

MAINDEC-12-D1FA Basic Memory Control Test

MAINDEC-12-D3EB TC12-F Option, Need to install the TC12-F option

MAINDEC-12-DAEXA PDP-12 System Exerciser, Need to get the LINCtapes working

Replaced or Repaired Flip-Chips

A225 in A3 in the VR14, replaced the trimpot.

G221 in C09, 5/23/15 with a repaired and tested flip-chip.

G221 in D10, 5/25/15 with a repaired and tested flip-chip.

G221 in C07, 9/2/19 with a repaired and tested flip-chip.

G938 in AB05 of the RK05, we replaced the LM301 comparator E3 and the SN7004 inverter E1.

M044 in A05 in the PC04, 5/30/16 with tested spare flip.chip.

M103 in D25, 12/19/15 with a repaired and tested flip-chip.

M105 in D25, 12/19/15 with a tested flip-chip.

M113 in J22, 5/25/15 with a tested flip-chip.

M113 in K30, 5/25/15 with a repaired and tested flip-chip.

M119 in H28, 5/25/15 with a tested flip-chip.

M121 in B32, 9/14/15 replaced IC E1, SN7450.

M160 in M35, 12/19/16 replaced with repaired and tested flip-chip.

M161 in J40, 9/14/15 replaced IC E8, SN7420.

M216 in E08, 5/23/15 with a repaired and tested flip-chip.

M216 in F19, 12/19/15 with a repaired and tested flip-chip, and again on 9/17/16 with a repaired and tested flip-chip

M216 in H40, 5/23/15 with a repaired and tested flip-chip.

M617 in J21, 12/12/15 with a NOS tested flip-chip. Had a IC E3, 7440 with an output stuck active.

M706 in MN06 6/6/15 replaced IC E13, SN7474.

M900 in N29, 5/23/15 replaced IC E3, SN7400.

M7102 in AB17 in DW8E, 12/4/15 replaced IC E14, SP380.

Replaced or Repaired Components

Q39 on the front panel for the LINK indicator.

Q60 and Q32 on the front panel with 2N3569 parts to fix IR(06) and PC(05)

Replaced the shorted +/-43VDC Diode Block in the VR14.

Servo Power Amplifier in the RK05 disk drive.

Replaced 2N5302 Q2 in the VR14  with a higher voltage rated 2N5303.

Replaced or Repaired Flip-Chips before the donation to RICM

2/6/74 M155 in API, replaced by DEC

8/16/74 M216 in slot B37, E3 SN7474

9/26/74 M221 in slot HJ20, E9 SN7400, E12 SN7453

8/14/75 VR14, Horizontal Deflection, 2N4399

10/3/75 M222 in slot A19, SN7453

10/6/75 M222 in slot A19, E1 SN7453

12/31/75 M160 in slot M36, E1 SN7453

1/1/76 M160 in slot M35, E2 SN7460

1/28/76 M310 in slot H07, Q3 2N3009 with 2N4124

10/18/76 VR14, Horizontal Deflection, 2N4399

2/8/83 M221 in slot HJ16, E9 SN7400, E12 SN7453

3/19/83 M222 in slot AB19, E2 SN7453

3/22/83 M222 in slot AB18, E1 SN7453

3/24/83 M113 in slot E23, E1 SN7400

3/24/83 M169 in slot A16, E1 SN7453

3/25/83 TU56, G848 in slot AB20, Q7 2N3791 with 2N3790

3/29/83 TU56, G847 in slot B18, Q2 MPSA55 with 2N4404

6/14/83 M111 in slot H34, E3 SN7400

7/1/83 M111 in slot H34, E1 SN7400

7/5/83 M221 in slot h15, E3 SN7453

9/5/83 TU56, G848 in slot AB20, resoldered Q5 & Q7

1/1/84 A405 in slot EF34, disabled hold state

1/9/84 M113 in slot D29, E3 SN7400

1/13/84 M7106, E48 SN75452

11/16/84 M706 in slot MN06, E1 SN7430

1/6/88 M900 in slot N31, E3 SN7400

7/21/90 M617 in slot B10, E2 SN7440