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.
The processor and memory have been working well for more than six months.
The RK05 disk drive, RX01 floppy disks, VR14 display, paper tape reader/punch, both serial ports, analog inputs, relay outputs, and speaker all work.
It will boot and run OS/8 from the RK05 or the RX01, including the special handlers for the PDP-12 devices.
We are still having problems with the TC12/TU56 LINCtapes, but we are working on it.
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)
M22VR14 #WF 558
LP01FA #739, 5060 DP2310 80 Column, 64 Character Line Printer
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
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.
Install the batteries in the RK05 disk drive.
Try powering the TC12 from a laboratory power supply to see if a really clean power source helps with the TC12 LINCtape controller problem.
Put the logic analyzer on the M222 modules and see what the tape block number signals look like.
Maybe replace the SN7453 E5 on the M222 module from slot AB21.
Look at the signal outputs from the VC20 that drive a VR14. We should be able to display the output in X-Y mode on the oscilloscope.
Clean the switches in the TU56 DECtape drive.
Run more processor and TC12 DECtape controller diagnostics. Need documentation.
Scan and publish more diagnostic documents. (Done)
Clean the fingers on the M222 modules, reload MAINDEC-12-D3AD, and try it again. (Done)
Bolt the two cabinets together and connect DW8E-PC Omnibus Expansion Chassis to the PDP-12 CPU. (Done)
Remove the Omnibus boards from the chassis, reform the caps in the DW8E-PC, and power it on. (Done)
Reinstall the PC8-E PC04 paper tape reader/punch controller, reform the caps in the PC04, and see if the reader/punch works. (Done)
Reinstall the RK8F disk controller, reform the caps in the RK05 and see if the disk works. (Done)
Test the RX8-E in my personal PDP-8/e. (Done)
Install the RX8-E in the Omnibus Expansion Chassis and connect to the RX02. (Done)
Replace the broken trimpot in the A225 flip-chip in slot A3. (Done)
Reinstall the processor cabinet fan that Dan (the donor) took apart and lubricated.(Done)
Determine why the JMP instruction does not mask off the upper three bits. (Done)
Determine why the front panel does not display the correct register state. (Tested and repaired)
Replace the Line fuse in the VR14 and try a slow power up with a Variac. (Blew the fuse.)
Fix the VR14 display. (Done)
Measure the ripple on the power supplies with a 'scope. (done, and again after more run time)
Disconnect the really noisy fan in the top of the processor cabinet. It has a bad bearing. (Done, Dan the donor oiled it)
Recable the VR14 and TU56. (Done)
Try setting the MODE switch to LINC and then press I/O Preset. (Done, and works correctly)
Fix the M706 flip-chip. (done)
Other PDP-12 Systems:
Items that came with the PDP-12
Data Products 2310 (DEC LP01) Prints
AA-D319A-TA OS/8 Device Extensions User's Guide
DEC PDP-8A Prints
DEC-12-HR4B-D Maintenance Prints, Modules, Volume IV
DEC-12-HRZC-D VR14 User's Manual
DEC-08-HPDMA-A-D RK8-E, RK8-F/RK05 Maintenance Procedure
DEC-00-HRK05-C-D RK05 Maintenance
EK-RX01-OP-001 RX8/RX11 Floppy Disk System User's Manual
EK-RX01-MM-001 RX8/RX11 Floppy Disk System Maintenance Manual
MAINDEC-08-DIRXB-D-D RX8/RX01 Data Reliability/Exerciser Program
RK05 Engineering Drawings
RX8 Engineering Drawings
RX02 Field Maintenance Print Set
TU56 Engineering Drawings
VR14 Field Maintenance Print Set
DEC-12-HVRTP-A-D VR14 & VR20 Troubleshooting Procedures
VT52-0-4 VT52 Field Maintenance Print Set
ASR33 Prints and Inspection Report
Blank Rack filler panel mounting parts
EK-VT50-OP-002 VT50 Video Terminal
LA36 Engineering Drawings
310B Volume 1 ASR33 Technical Manual
310B Volume 2 ASR33 Technical Manual
Data Products 2310 Line/Printer Technical Manual, 10/2/71
Data Products 2310 Line/Printer Technical Manual, 10/6/70
DEC Diagnostic Binder Containing
MAINDEC-08-DHRKA-B RK8E Diskless Test, 4/19/73
MAINDEC-08-DHRKB-C RK8E Drive Control, 1/1/74
MAINDEC-08-DHRKC-C RK8E Data Reliability, 7/16/73
MAINDEC-08-DHRKD-A RK8E Disk Formatter, 10/2/72
MAINDEC-12-D0GA-A Tape Quickie, 4/21/70
MAINDEC-12-D3AE-D PDP-12 Tape Control 1/2, 8/12/70
MAINDEC-12-D3DB-D Tape Data Exerciser, 2/1/70
MAINDEC-12-D3FB-D Tape Data Test, 11/1/70
MAINDEC-12-D3GA-D PDP-12 Tape Control 2/2, 5/1/70
MAINDEC-12-D6BC-D VR14/VR20 Display Test, 8/1/71
MAINDEC-12-D6CC-D A to D Test, 9/21/70