I acquired the use of a PDP8/E in the fall of
1998 and spent the next several months learning everything I could
about it. The system that I have was originally purchased as a machine
controller in 1970 and was the front end for a PDP14 programmable
controller (some of which I also have). I don't think the PDP14 was
really used as a controller, but more as an I/O interface, with the
PDP8/E running the control program.
The computer was stored away in a basement closet
around 1978. Fortunately is was stored essentially complete. I have an
ASR-33, TU56 dual DECtape, and the PDP8/E with 12KW core. All of the
documentation was there including print sets. The system had some
DECtapes with OS/8 V3D and after toggling in the bootstrap started
right up.
Originally the system was equipped with 12KW of
core. This is the minimum necessary to run OS/8 with a TD8E DECtape
controller. I designed and built a 32KW semiconductor memory board for
the OMNIBUS. This was an interesting design because the bus is quite
different from modern buses. It is open-collector and negative logic
instead of the more familiar tri-state, positive logic buses of today.
The design included battery backup for the CMOS RAM chips.
I added an ATA interface to the memory board so
that I could use a small IDE drive. The difficult part of this was not
the hardware, but writing the device driver. OS/8 restricts a device
driver to either 128 words or 256 words and makes it difficult if you
choose the larger. The system handler is further restricted because
part of its memory page is allocated for other things. After trying
several times, I placed the driver in the highest field by itself and
wrote a simple driver for OS/8 that just linked to the high memory
field driver. Eventually, OS/8 recognized the disk as the SYS: device.
I was surprised by how fast the machine became after it had a fast
system device. OS/8 does a lot of swapping of its various components
between memory and the SYS: device and a disk made this much faster.
I also constructed a LE8-E software compatible
printer interface to allow the use of a printer with a standard
Centronics parallel interface. I have since found a real LE8-E and also
and LC8-E. Both seem capable of interfacing Centronics style printers.
My latest efforts have been towards an RX02
emulator which can be used both by PDP8 and PDP11 hosts. The emulator
runs on a Linux PC and uses a parallel port and an interface board.
32KW
Semiconductor Memory - One of my first hardware projects with
the PDP8/E. I have some notes,
but they are not very good. (8/15/2006) I am in the process of drawing
up some schematics. Here are the pages that I have half done: control, SRAMs, bus interface, and battery backup. Here is a set of marked up drawings that were used by a visitor to make his own version. (Thanks Lou.) After
looking this over, it is truely naive. It connects directly to the
OMNIBUS with little or no buffering. It has not been tested with any
data break devices. This memory has the ability to write protect the
high field. I wrote a loader that can load
any of several bootstraps from a menu.
Toggling is fun, but after a few crashes it becoms tedious.
ATA Disk Adapter - This was added to the
memory board and almost functioned. Some time I am going to finish it.
LE8-E Compatible Printer Interface - I added
this to the memory board and it worked fine with an OKIDATA dot matrix
printer. I have since acquired a REAL LE8-E. I am not sure if it will
work with a Centronics interface or not.
VC8/I Point
Plot Controller - Point plot and vector graphics have
interested me for a while. One day I noticed that I had enough Flip
Chips to construct a VC8/I so I did it.
PDP8/e Printers - I connected a centronics printer to
the PDP8/e using a M8365 interface.
PDP8 Links
One of the great things about the PDP8 is the
amount of information that is available about them. These are some
sources that I have found helpful.
Doug
W. Jones - The PDP8 FAQ he maintains is excellent.
www.pdp-8.org
- A lot of paper tapes including the MAINDEC tapes.
Al
Kossow's Archive - An excellent general archive of computing
machines of all types. I check his updates most mornings to see what
has been added overnight. What amazes me, is that if somebody asks
about something in a news group, the answer will often suddenly appear
in this archive.
PDP8 Documentation
The computer that I have came with a nearly
complete set of documentation. The following is a list of those
documents and print sets. A lot of this is online, check out some of
the sites listed above.
Teletype Model 33 Line Set - Prints for the
stock ASR-33 from Teletype Corporation.
LT33 Teletype Model 33 Modifications Print Set
- Prints for modifications to stock ASR-33 for paper tape reader
control.
TU56 Dual DECtape Print Set - Prints for dual
DECtape drive and drive electronics. Not all schematics for Flip-Chip
modules shown on placement diagrams are included.
TD8-E - M868 - DECtape Control Print Set - The
non-data break OMNIBUS DECtape controller, includes TU56 print set.
KA8-E - M835 - Positive I/O Bus Interface
Print Set
KA8-E - M8350 - Positive I/O Bus Interface
Print Set - Used with this machine as an interface to the PDP-14
programmable controller.
KD8-E - M8360 - Data Break Interface Print Set
KM8-E - M837 - Memory Extension & Time
Share Control Print Set
BE8-E - OMNIBUS Expander - PDP8/E OMNIBUS
backplane assembly.
DK8-E - M860, M518 - Programmable Real Time
Clock
KP8-E - M848 - Power Fail and Auto-Restart
LAB8-E - Print Set - Lists of constituent
parts and basic interconnect diagrams.
PDP8/E - Print Set - Processor, memory, TTY,
and chassis drawings.
PDP14 Maintenance Manual - Single bit
processor based programmable controller.
PDP14 Maintenance Manual - Vol. II
PDP14 Print Set
I also have several books.
PDP8/E Maintenance Manual Vol. 1
PDP8/E Maintenance Manual Vol. 3
Introduction to Programming (1) 1970
Programming Languages (2) 1970
Small Computer Handbook 1971
Small Computer Handbook 1972
Logic Handbook 1971
Logic Handbook 1973-74
Control Handbook 1971
Logic System Design Handbook 1972
PDP16 Computer Designers Handbook 1971
OS/8 Handbook 1974
PDP-8 Software
I also have many paper tapes.
Description
Tape Number
Date
DDT-8
DEC-08-CDDB-PB
8/14/69
CONFIG Tape 1 of 2
DEC-P8-MW3A-PA
11/7/70
CONFIG Tape 2 of 2
DEC-P8-MW3A-PA
11/7/70
CONFIG (RK8)
DEC-P8-MW1A-PB
11/6/70
CONFIG (DF32)
DEC-P8-MW3A-PB
11/7/70
CONFIG (RF08)
DEC-P8-MW2A-PB
11/7/70
PAL III
DEC-08-ASC1-PB
4/13/70
PS/8 BINARY TAPE
DEC-P8-MWZA-PB
11/7/70
LOAD 14
DEC 14 LZPB-PB
6/18/70
VER-14
MAINDEC-14-D1AB-PB
6/18/70
TEST-14L
MAINDEC-14-D7LA-PB
9/4/70
SET-14
DEC-14-EIZA-PB
4/30/70
SIM-14
DEC-14-EDZC-PB
4/30/70
PAL-14 (V3)
DEC-14-ASZB-PB
6/18/70
PS/8 CREF
DEC-P8-YRXA-PB
11/7/10
PS/8 CREF
DEC-P8-YRXA-PB
4/1/71
PS/8 CREF
DEC-P8-YRXA-PB
11/7/70
LIB 8
DEC-P8-SFXB-PR
6/18/70
SYMBOLIC EDITOR
DEC-08-ESAC-PB
2/4/70
PIP
DEC-P8-PWXB-PB
11/7/70
EDIT
DEC-P8-ESAB-PB
11/7/70
SABR
DEC-P8-ARXB-PB
11/7/70
FORT
DEC-P8-KFXB-PB
11/7/70
ODT (HIGH)
DEC-O8-COC2-PB
11/10/67
COMMAND DECODER
DEC-P8-SWXB-PB
11/7/70
ODT (LOW)
DEC-08-COC1-PB
11/10/67
PAL 8
DEC-P8-ASAB-PB
11/7/70
LIBSET
DEC-P8-SYXB-PB
11/7/70
LOADER
DEC-P8-LLXB-PB
11/7/70
OS/8 MONITOR
DEC-S8-OOS8A-B-PB
10/2/72
OS/8 COMMAND DECODER V6
DEC-S8-0CMDA-B-PB
10/2/72
OS/8 PIP-C
DEC-S8-OPIPB-A-PB
2/73
RF08 CONFIG V6
DEC-S8-ODRFA-B-PB
10/2/72
DF32 CONFIG V6
DEC-S8-ODDFA-B-PB
10/2/72
RK8 CONFIG V6
DEC-S8-ODRKA-B-PB
10/2/72
CONVRT
DEC-P8-SUTB-PB
11/7/70
TD8E DECTAPE SUBROUTINE
DEC-8E-UZTA-PB
7/8/71
PDP-8 FLOATING POINT PACKAGE 1
DEC-08-YQ1B-PB
4/17/70
PDP-8 FLOATING POINT PACKAGE 2
DEC-08-YQ2B-PB
4/17/70
PDP-8 FLOATING POINT PACKAGE 3
DEC-08-YQ3B-PB
4/17/70
PDP-8 FLOATING POINT PACKAGE 4
DEC-08-YQ4B-PB
4/17/70
FOCAL, 1969 + INIT
DEC-08-AJAE-PB
7/9/69
UTILITY OVERLAYS FOR FOCAL, 1969 (4 WORD,
8K)
DEC-08-AJ1E-PB
7/9/69
PDP-8E INSTRUCTION TEST 1
DEC-8E-00AB-PB
5/10/71
PDP-8E INSTRUCTION TEST 2
DEC-8E-DOBB-PB
6/10/71
HIGH MEMORY RIM PUNCH 33
DEC-08-PMP2-PB
11/22/66
KP8E TEST
MAINDEC-8E-D0KC-PB
6/10/71
DK8E CLOCKS DIAGNOSTIC
MAINDEC-8E-D8AC-PB
10/8/71
BINARY LOADER
DEC-08-LBAA-PM
5/10/67
OCTAL MEMORY DUMP
DEC-08-YPPA-PB
11/10/69
TD8E DECTAPE FORMATTER
DEC-8E-EUZC-PB
12/7/71
TD8E DECTAPE FORMATTER
DEC-8E-EUZA-PB
7/12/71
TD8E DECTAPE DIAGNOSTIC
MAINDEC-8E-D3AA-PB1
9/24/71
TD8E DECTAPE FORMATTER
DEC-8E-EUZC-PB
12/7/71
PDP8E TELETYPE AND KL8E TESTS
MAINDEC-8E-D2AB-PB
5/14/71
TD8E DECTAPE SUBROUTINE
DEC-8E-UZTA-PA
7/8/71
12K TD8E BOOTSTRAP (RIM)
DEC-S8-OTBSA-A-PM
2/10/72
TD8E DECTAPE SUBROUTINE
DEC-8E-UZTA-PB
7/8/71
TD8E DIAGNOSTIC OVERLAY
DEC-8E-D3AA-PB2
9/24/71
PDP-8E MEORY POWER ON/OFF TEST
MAINDEC-8E-D1GB-PB
6/11/71
MEMORY ADDRESS TEST
MAINDEC-8E-D1EC-PB
6/11/71
BINARY PUNCH TELETYPE
DEC-08-XY1A-PB
10/1/69
MM8E 4K MEMORY CHECKERBOARD
MAINDEC-8E-D1AB-PB
6/7/71
PDP-8E MEMORY EXTENSION AND TIMESHARE
CONTROL TEST
MAINDEC-8E-D1HA-PB
11/1/70
KM8E EXTENDED MEMORY CHECKERBOARD
MAINDEC-8E-D1BC-PB
6/7/71
PDP-8E EXTENDED MEMORY ADDRESS TEST (EA8E)
MAINDEC-8E-D1FB-PB
6/14/71
PDP-8E ADDER TESTS
MAINDEC-8E-D0CC-PB
9/1/71
BASIC JMP-JMS TEST
MAINDEC-8E-D0IB-PB
6/11/71
RANDOM JUMP TEST
MAINDEC-8E-D0HC-PB
6/11/71
RANDOM ISZ TEST
MAINDEC-8E-D0F0-PB
6/11/71
RANDOM TAD TEST
MAINDEC-8E-D0EB-PB
6/71
RANDOM DCA TEST
MAINDEC-8E-D0GC-PB
6/11/71
RANDOM AND TEST
MAINDEC-8E-D0DB-PB
6/71
RANDOM JMP-JMS TEST
MAINDEC-8E-D0JC-PB
6/11/71
I also have some DECTapes.
Description
Tape Number
Date
OS/8 VIII SYSTEM DECTAPE #1
DEC-S8-OSYSB-A-UC1
1/18/74
OS/8 VIII SYSTEM DECTAPE #2
DEC-S8-OSYSB-A-UC2
1/18/74
If any of this is unique, let me know. The
newsprint that DEC used for these old books is deteriorating rapidly.
