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|Manufacturer ||DEC - Digital Equipment Corporation
|Date of first manufacture||1960
|Number produced ||-
|Estimated price or cost||$120,000 (1960 dollars)
|location in museum ||-
Contents of this page:
The PDP-1 was the first of the DEC 18 bit computer series,
consisting of PDP-1, PDP-4, PDP-7, PDP-9, PDP-15.
See Instruction List of PDP-9
From "Digital at Work" , Digital Press, copyright 1992
Specification - PDP-1
5-microsecond cycle time
4K word core
Memory address instruction
Operate class, 1/O class
Typewriter, paper tape
Cathode ray tube
Options: Light pen, magnetic tape,
4 cabinets: 8' x 2 V5' x 6'
Diagnostics, assembler, debugger,
Editor, conversion routines for punching tapes
Nothing as Affordable at the Time
Its short word length and high speed suited the PDP-1 to laboratory
and scientific control applications that required its computation ability
and real-time control. Lawrence Livermore Laboratory first used the
PDP-1 for periphery support processing for their large scientific
calculators and for graphics input and output. Atomic Energy of Canada
used a PDP-1 for pulse-height analysis and Van de Graaff generator
experiment control, and International Telephone and Telegraph used
PDP-1 computers in message-switching systems.
Digital brought the prototype PDP-1 to demonstrate at the Joint
Computer Conference in Boston in December of 1959.
From "Digital at Work" , Digital Press, copyright 1992, page 30
In the early 1960s, MIT wasn't the only institute of advanced research
on the north bank of the Charles
River. The augustly named Hingham Institute was, in reality, a dingy
tenement on Hingham Street a few
blocks from MIT. Home to two programmers, the institute served as a
meeting place for assorted students
who shared one common trait: a growing addiction to MIT's new PDP-1.
When he wasn't pursuing his avocation, Steve "Slug" Russell
assisted John McCarthy's artificial intelligence
research on MIT's IBM System 704. But he preferred the PDP-1:
"It had a switch. You could turn it on. You
got a satisfying clunk. You could type a single character
at it and it would type a little message back. It
gave you a great feeling of power."
Fueled by this sense of power, which was supplemented
by their interest in Japanese monster movies
and the pulp science fiction of E.E. "Doc" Smith, Russell
and his Hingham Institute associates created the
most elaborate computer "hack" of their era: a two-player
game called "Spacewar!" played on the PDP-1's CRT screen.
After Slug wrote the main control routine, Shag Graetz,
a Hingham fellow, recalls, "it was like Tom Sawyer
with the whitewash brush." Unimpressed with Russell's
random stars, one hacker wrote a program that
put them in their proper constellations (and respective
magnitudes, naturally). Another found the whole
thing annoyingly nonNewtonian, so he added gravity to
the paths of the spaceships and missiles.
Robert Garner points out in Jan 2004
For your PDP-1.org web site, [a PDP-1 restoration effort]
here's a better link to Graetz's entertaining "The Origin of Spacewar"
(This one has the pics, unlike one from ed-thelen.org.)
http://www.wheels.org/spacewar/ also has some other interesting
A video of the restoration and demo of this PDP-1
From "Digital at Work" , Digital Press, copyright 1992, page 16
18-Bit Family Timeline
1960 PDP-1, Digitals first 18-bit computer
1964 PDP-7, uses flip chip modules; used by Ritchie and
Thompson to develop UNIX
1966 PDP-9, program compatible with PDP-7
1969 PDP-15 replaces PDP-9
1972 MUMPS-15 (Massachusetts General Hospital
Utility Microprogramming System), PDP-15 -based
timesharing system designed to handle medical
records, still in use
1979 PDP-1 with working Spacewar! game installed at
The Computer Museum, Boston
1988 A PDP-1 system (serial no. 44) is saved from a barn
in Wichita, Kansas, and donated to the Digital
Presentation at decworld2001 (Computer History Museum) June 16, 2001
the name PDP-2 was reserved for a 20 bit machine
- never produced
the name PDP-3 was to be a 36 bit TX-2
- sold to the AirForce - never produced
- sold the AirForce two PDP-1 machines instead
does an 18 bit machine
and an 18 bit machine
add up to a 36 bit machine?
From "Digital at Work" , Digital Press, copyright 1992, page 33
A distinguished Lineage
with the PDP-1
Edited by Bob Hofmann from interviews with
Digital's PDP-1 was the direct descendant of the TX-0 computer, developed
along with the larger TX-2 system at Lincoln Laboratory in the late 1950s.
Designed by Wesley Clark, the TX-0 and TX-2 were among the first transistor
driven computers in the world.
With many of the features pioneered on the massive Whirlwind system CRTs,
consoles,paper-tape input and output-the TX-0 and TX-2 effected many advances
in interactive computing.
The TX-2 was planned as a large-scale 36-bit system for advanced graphic
display research. The smaller TX-0 was built first, to test the transistor
circuitry and complex core memory of the larger system. That process produced
the TX-0 Direct Input Utility System, a set of programs that made it possible
to communicate directly with the computer with an online typewriter. This
primitive operating system was the first ever developed for a real-time computer.
Soon the power of the TX-0 was applied to other tasks. A program to
analyze electroencephalograph recordings for sleep research utilized the
first moving window display ever to appear on a CRT. To create scientific
characters on the display for mathematical equations, team member (and
later PDP-1 architect) Ben Gurley developed a light pen. "The TX-0 could
do everything a personal computer does today," remembers Ken Olsen, another
member of the team, "limited only by the fact that the memory was small."
The much larger TX-2 was less limited, especially after 65 K of memory
from the TX-0 was added to it. At the first official meeting on interactive
graphics, a young graduate student named Ivan Sutherland introduced his
TX-2-based Sketchpad system, a new kind of simulation language that enabled
the computer to translate abstractions into concrete visual forms. Many of
Sketchpad's capabilities were sophisticated even by the workstation standards
of the1980s."If had known how hard it was to do," Sutherland said later,
"I probably wouldn't have done it."
Stripped of most of its memory, the TX-0 was sent on a long-term loan to
MIT, where it inspired a new generation of graphics pioneers. Assistant Professor
Jack Dennis gave access to the system to members of the Signals and Power
Subcommittee of the MIT Model Railroad Club, students who were to win fame
as the first computer "hackers." Dennis himself designed a symbolic debugger
for the system. Called FLIT, after a popular insecticide, this Flexowriter
Interrogation Tape was the first of many playfully named but useful programs
created by the group. The TX-0 was considered the ultimate in interactivity
by the hackers-until the first PDP-1 arrived a few years later.
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Updated January 26, 2004