Fact Files

PDP-8/A Documentation

[   ] EK-8A002-MM-02_PDP8A_UsersMan.pdf 21-Apr-2003 02:21 37M
[   ] EK-FPP8A-MM-001_FPP8-A_Maint_Sep76.pdf 24-Aug-2007 02:02 7.8M
[   ] EK-FPP8A-OP-001_FPP8-A_UsersMan_Dec76.pdf 22-Jan-2007 00:45 1.0M
[   ] EK-KL80A-OP-001_KL8-A_jan78.pdf 19-Dec-2003 06:19 3.6M
[   ] EK-KT08A-UG_jul78.pdf 19-Aug-2001 21:44 1.8M
[   ] EK-MS8CD-TM-001_MS8-C_MOS_Memory_Technical_Manual_Sep80.pdf 24-Aug-2007 17:56 2.0M
[   ] FPP8-A_EngrDrws_Feb76.pdf 06-Oct-2006 17:56 2.8M
[   ] KC8-A_engrDrws_Dec74.pdf 12-Mar-2003 19:42 1.2M
[   ] KC8-A_schem.pdf 29-Oct-2003 20:39 1.2M
[   ] MP-00KL8-A0_KL8-A_Engineering_Drawings_Dec75.pdf 14-Jun-2009 19:03 2.7M
[   ] MP00057_FPP8-A_Mar76.pdf 22-Jan-2007 00:37 6.3M
[   ] MP00415_8Asemi_Schem_Apr81.pdf 21-Jun-2005 20:26 21M
[   ] PDP8A_Schems_Apr81.pdf 28-Mar-2002 17:19 21M
[DIR] firmware/ 20-Dec-2009 17:59 -

PDP-8/L: Card Locations

This table details locations of cards on a PDP-8/L backplane. I’ve put it together to aid in working out what is missing from my 8/L. I believe it to be accurate but you are encouraged to double check!

SLOT A B C D
1 G921 – PDP-8/L control panel
2 M220 M113 M111
3 M220 M700
4 M220 M216 M115
5 M220 M113 M310
6 M220 M216 M310
7 M220 M111 M310
8 M617 M617 M216 M310
9 M617 M617 M115 M160
10 M160 M160 M119 M216
11 M115 M216 M117 M113
12 M160 M111 M115 M113
13 M160 M113 M117 M111
14 M115 M119 M113 M310
15 M162 M119 M113 M310
16 M162 M162 M111 M216
17 G020 M162 M360 M617
18 G020 G020 G221 G221
19 G020 G020 G221 G221
20 G020 G020 G610
21 W825 Memory Stack
22 W825 G611
23 G228 G228 G221 G221
24 G228 G228 G221 G221
25 G624 G624 G220 G220
26 G624 G624 M002
27 G826 M623 M623
28 G785 M115 M623
29 M715 M660 M906
30 M795 M660 M906
31 M718 M707
32 M516 M986 (?) M706 -
33 M516 M986 (?) M452 M076 cable
34 M111 M983 (?) M901 cable M903 cable
35 M111 M983 (?) M903 cable M908 (?) cable
36 M783 M983 (?) M903 cable M903 cable
Key:

Optional data break interface
Optional memory parity
Optional power fail
Optional high speed reader and/or punch

FACT FILE: The OMNIBUS

This guide is provides comprehensive information on the OMNIBUS used in the PDP-8/E,F,M and A series of machines.

A 20 slot PDP-8/E backplane

A 20 slot PDP-8/E backplane

Overview of the bus

The OMNIBUS is a general purpose bus consisting of 144 signals.

OMNIBUS backplanes consist of 1 or more 10 slot backplanes and are normally quad width. The later 8/A is the exception to the rule where some slots, designated for core memory are five wide.

Each slot is general purpose and in theory cards can be positioned in any slot, only limited by timing and noise considerations. Due to the general purpose nature of the bus, inter-board signals are made by way of over the top H851 edge connectors.

The OMNIBUS signals are 5V based with Logic 1 represented by -0.4-0.5V and logic level 0 by 3V-5V.

OMNIBUS Signal Reference

The following signals are presented on the omnibus. (NOTE TO SELF: This map needs to be QA-ed)

Pin D1 D2 C1 C2 B1 B2 A1 A2
A +15V +5V +5V +5V
B -15V -15V -15V -15V
C GND GND GND GND GND GND GND (SP) GND
D MA8 L IR0 L IO PAUSE L TP1 H MA4 L INT STB L MA0 L EMA 0 L
E MA9 L IR1 L C0 L TP2 H MA5 L BRK PROG L MA1 L EMA 1 L
F GND GND GND GND GND GND GND GND
H MA10 L IR2 L C1 L TP3 H MA6 L MA,MS LD L MA2 L EMA 2 L
J MA11 L F L C2 L TP4 H MA7 L OVERFLOW L MA3 L MEM START L
K MD8 L D L BUS STB L TS1 L MD4 L BRK DA CT L MD0 L MD DIR L
L MD9 L E L INT I/O L TS2 L MD5 L BRK CYC L MD1 L SOURCE H
M MD10 L USR MD H N L XFR L TS3 L MD6 L LA EN L MD2 L STROBE H
N GND GND GND GND GND GND GND GND
P MD11 L F SET L INT RQST L TS4 L MD7 L INT PROG H MD3 L INHIBIT H
R DATA 8 L PULSE LA H INIT H LNK DATA L DATA 4 L RES 1 H DATA 0 L RETURN H
S DATA 9 L STOP L SKIP L LNK LOAD L DATA 5 L RES 2 H DATA 1 L WRITE H
T GND GND GND GND GND GND GND GND
U DATA 10 L KEY CTL L CPMA DIS L IND 1 L DATA 6 L RGN L DATA 2 L ROM ADDR L
V DATA 11 L SW L M3, IR DIS L IND 2 L DATA 7 L POWER OK H DATA 3 L LINK L

OMNIBUS Cards

The following OMNIBUS cards are known to exist

Module Number Option Name Description
54-9057 KC8EA PDP-8/E Programmer’s Console
54-9668 KC8FL PDP-8/F Programmer’s Console
54-9668 KC8ML PDP-8/M Programmer’s Console
. KC8AA PDP-8/A Programmer’s Console
A231 AD8EA Analog to Digital Converter
A231 AD8E Analog to Digital Converter
A232 AH8EA Multiplexor for AD8EA
A841 AD8EA Analog to Digital Converter
G111 MM8EJ 8K Memory sense/inhibit
G111C MM8EJ 8K Memory sense/inhibit
G104 MM8E 4K Memory sense/inhibit
G104C MM8E 4K Memory sense/inhibit
G105 MP8E Memory sense/inhibit
G227 MM8E Memory X/Y drivers
G227C MM8E Memory X/Y drivers
G227 MP8E Memory X/Y drivers
G233E MM8EJ 8K Memory X/Y drivers
G619 MM8E Memory stack
G619A MM8E Memory stack (B,M)
H649 MM8AA PDP8A 8K Memory stack (hex wide)
G646C MM8EJ 8K Memory stack
H650 MM8AB PDP8A 16K Memory stack (hex wide)
H212 MM8EJ 8K Memory stack
G219A MM8AA PDP8A 8K Memory control (hex wide)
G219B MM8AB PDP8A 16K Memory control (hex wide)
H220 MM8E Memory stack
H220 MP8E Memory stack
MS8DJ PDP8A 32K semiconductor memory module
M1703 . 12 bit word 8/e bus interface (input only?)
M1703C .
M1705 . dual 12 bit omnibus output interface
M1709 . Omnibus foundation module (multiword custom I/O)
M512 DK8ED
M518 DK8EP Lab Programmable Real Time Clock (requires M860)
M518 DK8EF Lab Programmable Real Time Clock with lab panel DK8ES
M518 DS8EA Schmidt Trigger
M7104 RK8E RK05 Disk Interface
M7105 RK8E RK05 Disk Interface
M7106 RK8E RK05 Disk Interface
M8300 KK8E Major registers
M8310 KK8E Major register control
M8311 MS8-AA PDP-8/A Read/Write RAM (1K)
M8311 MS8-AB PDP-8/A Read/Write RAM (2K)
M8311 MS8-AD PDP-8/A Read/Write RAM (4K)
M8315 KK8A PDP-8/A CPU board (hex wide)
M8316 DKC8AA PDP-8/A I/O serial/parallel/clock (hex wide)
M8317 KM8AA PDP-8/A bootstrap, powerfail (hex wide)
M8317 KM8AB PDP-8/A Memory extender (hex wide)
M8317YC KM8AC PDP-8/A Memory extender, bootstrap, powerfail (hex wide)
M8319 KL8A PDP-8/A 4 channel serial I/O
M8320 KK8E Bus loads
M8321 TM8E Magtape output control module
M8322 TM8E Magtape control and data break module
M8323 TM8E Magtape transport status and control module
M8326 DB8EA Interprocessor buffer
M8327 TM8E Magtape register module
M8329 LC8E Parallel interface to DEC-writer I
M833 KK8E Timing board, good only for 4K TTY systems
M8330 KK8E Timing board, replaces M833
M8330YA KK8E Timing board, replaces M8330, handles MR8E memory stalls
M8330YB KM8F Timing board, replaces M8330
M8331 TA8E DEC Cassette control
M8335 VT8E
M8336 VT8E Video Display Clock and Frequency Divider
M8337 VT8E Video Display Line Buffer Module
M8340 KE8E Extended arithmetic element
M8341 KE8E Extended arithmetic element
M8342 LP8E Centronics printer control (replaces M8329)
M835 .
M8350 KA8E External positive I/O bus interface
M8357 RX8E RX01/RX02 interface
M8360 KD8E Data Break Interface
M8365 LC8P LA180 printer control
M8366 LQP8E LQP01 printer control
M837 MC8E Extended Memory and Time Share Control
M837 KM8E Extended Memory and Time Share Control
M839 DP8EA Synchronous Modem
. DP8EB Synchronous Modem (Bell series 300 modem)
M840 PC8E High speed paper tape reader/punch
M841 LE8 Data Products line printer control
M8416 KT8AA PDP8A Memory Management (hex wide)
M8417 MSC8AA PDP8A 16K MOS Memory (hex wide)
M8417 MSC8AB PDP8A 32K MOS Memory (hex wide)
M8417 MSC8DJ PDP8A 128K MOS Memory (hex wide)
M842 XY8E X/Y Plotter Control
M843 CR8E Card reader control
M8430 KW8EW Alarm timer
M8433 RL8A Disk controller for RL01/02 (hex wide)
M847 MI8E Hardware Bootstrap Loader
M847 MI8EN Hardware Bootstrap Loader for RK8E
M847 MI8EP Hardware Bootstrap Loader for RX01/RX02
M848 KP8E Power fail and auto-restart
M849 KK8E RFI shield
M860 DK8ED Programmable Real Time Clock
M860 DK8EF Programmable Real Time Clock
M860 DK8EP Programmable Real Time Clock
M863 DR8E 12 Channel Buffered Digital I/O
. DR8EA 12 Channel Buffered Digital I/O
M866 DP8EA Synchronous Modem (Bell series 200 modem)
. DP8EB Synchronous Modem (Bell series 300 modem)
M865 . Console Teletype Control (current loop only)
M8650 KL8E Asynchronous Data Control (current loop or RS232)
M8653 KL8M Modem Control, used with KL8* to provide data ready stuff
M8655 KL8JA Terminal Control (UART based substitute for M8650)
M868 TD8E DECtape Control
M869 VC8E (requires M885)
M882 DK8EA Real Time Clock (Line Frequency)
M8830 DK8EC Real Time Clock (Crystal, 100Hz)
M884 KG8E Parity Generator Detector for DP8E
M885 VC8E (requires M869)
M935 OMNIBUS bridge (joins two adjacent backplane segments)
Credit: Doug Jones [original document]