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PDP-8/E and PDP-8/M Computer Information

The PDP-8/E and PDP-8/M were similar computers. The 8/E was introduced in 1970 and had a linear power supply and room for 20 cards including the slots used by the processor. It sold for $6,500. The 8/M and 8/F were introduced in 1972. The M and F only had room for 10 slots and used a switching power supply to reduce the cost of the machine. They used the same cards as the 8/E. The 8/M was an OEM version of the 8/F for people who resold it as part of a system. The 8/M frequently didn't have the full front panel my unit has. All of these models were discontinued in 1978.

Programming information by Douglas Jones.

These machines used the omnibus which all the cards plugged into. The omnibus has 144 lines, 96 of which are signal lines. If boards needed special connections between them H851 connectors were used on the top of the boards. With external expansion chassis up to 60 cards could be used. These machines were made almost entirely with standard SSI TTL chips except for analog functions such as the core memory drivers. The TI 7400 series and Signetics SP300 series were the most commonly used chips.

PDP-8/E Specifications
Word size 12 bits
Maximum memory 32k words (8 4k banks)
Minimum instruction time 1.2 microseconds
Add memory to accumulator 2.6 microseconds
12 x 12 multiply with 24 bit result  256.5 microseconds (subroutine)
12 x 12 multiply with 24 bit result  40 microseconds (with EAE option)
Operating Environment 0 to 55 C (32-130F)   10% to 90% Humidity
Power <= 450 watts (varies with option cards)
Size (HeightxWidthxDepth)  10.5x19x24 inches
Weight 100 lbs total, 45 lbs power supply
Cost Minimum Configuration 4k memory $4490 installation included from DEC in 1974
  $53 per month for maintenance
Cost in configuration shown, excluding I/O devices
and third party boards
$14835 from DEC in 1974
  $134 per month for maintenance

Documents related to PDP-8/E & PDP-8/M

Option cards installed in PDP-8/E

The following picture links also have descriptions of what is shown in the pictures.

Thumbnail Picture Selector

Current size med. Select picture size for links below   Small  Medium  Large

Top view of 8E and boards (127K)  Up on blocks (101K)

Core memory pictures Core memory information
Front of G619 core memory board (142K)  G619 core without cover (119K)  Back of G619 ( 88K)
Closeup of core mat (371K)  Closeup of core mat for single bit (149K)  Closeup of core with pin (151K)
G227 X-Y core driver (156K)  G227 back (157K)
G104D core sense inhibit board (152K)  Back of G104D (164K)

Other Board Pictures
PDP-8 Control Board (135K)  Back of PDP-8 Control Board (168K)
PDP-8 Power Control Board (199K)
Front of M869 Point Plot Control Board (151K)  Back of M869 (156K)
Front of M885 Point Plot D/A board (185K)  Back of M885 (174K)
Front of M882 Line Frequency Real Time Clock (139K)  Back of M882 (124K)

h724 Power supply pictures h724 information
Top view ( 35K)  Front view (116K)  Fan side ( 50K)  End view (131K)
Side view electronics ( 63K)  Side view other side ( 57K)
Input section (111K)  Input section other side (103K)
Middle section (110K)  Middle section other side (104K)
Transformer section ( 95K)  Transformer section other side ( 85K)
Regulator boards (104K)

Videos of operation of PDP-8/E. How to view The large realvideo files are the best but slow to download. The large MPEG has some artifacts from being recorded with interlaced video from a camcorder and is larger than the realvideo.

Booting PDP-8/E From RK05. This is the smallest bootstrap for any device, only 2 instructions. The TD8E DECtape is 27 instructions, paper tape (RIM) loader16.
Realvideo: large (549K) Small not available yet.
MPEG: MPEG not available yet.

Feel free to contact me, David Gesswein djg@pdp8online.com with any questions, comments on the web site, or if you have related equipment, documentation, software etc. you are willing to part with.  I am interested in anything PDP-8 related, computers, peripherals used with them, DEC or third party, or documentation. 

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