Top Document: PDP-8 Frequently Asked Questions (posted every other month) Previous Document: News Headers Next Document: What is a PDP-8? See reader questions & answers on this topic! - Help others by sharing your knowledge In 1957, Ken Olson and Harlan Anderson founded Digital Equipment Corporation (DEC), capitalized at $100,000, and 70% owned by American Research and Development Corporation. Olson and Anderson had designed major parts of the AN/FSQ-7, the TX-0 and the TX-2 computers at Lincoln Labs. They wanted to call their company Digital Computer Corporation, but the venture capitalists insisted that they avoid the term Computer and hold off on building computers. With facilities in an old woolen mill in Maynard Massachusetts, DEC's first product was a line of transistorized digital "systems modules" based on the modules used in building TX-2 at Lincoln Labs; these were plug-in circuit boards with a few logic gates per board. Starting in 1960, DEC finally began to sell computers (the formal acceptance of the first PDP-1 by BBN is reported in Computers and Automation, April 1961, page 8B). Soon after this, there were enough users that DECUS, the Digital Equipment Computer User's Society was founded. DEC's first computer, the PDP-1, sold for only $120,000 at a time when other computers sold for over $1,000,000. (A good photo of a PDP-1 is printed in Computers and Automation, Dec. 1961, page 27). DEC quoted prices as low as $85,000 for minimal models. The venture capitalist's insistance on avoiding the term computer was based on the stereotype that computers were big and expensive, needing a computer center and a large staff; by using the term Programmable Data Processor, or PDP, DEC avoided this stereotype. For over a decade, all digital computers sold by DEC were called PDPs. (In early DEC documentation, the plural form "PDPs" is used as a generic term for all DEC computers.) In the early 1960's, DEC was the only manufacturer of large computers without a leasing plan. IBM, Burroughs, CDC and other computer manufacturers leased most of their machines, and many machines were never offered for outright sale. DEC's cash sales approach led to the growth of third party computer leasing companies such as DELOS, a spinoff of BB&N. DEC built a number of different computers under the PDP label, with a huge range of price and performance. The largest of these are fully worthy of large computer centers with big support staffs. Some early DEC computers were not really built by DEC. With the PDP-3 and LINC, for example, customers built the machines using DEC parts and facilities. Here is the list of PDP computers: MODEL DATE PRICE BITS NUMBER COMMENTS ===== ==== ======== ==== ====== ======== PDP-1 1960 $120,000 18 50 DEC's first computer PDP-2 NA 24 - Never built? Prototype only? PDP-3 NA 36 One built by a customer*, not by DEC. PDP-4 1962 $60,000 18 45 Predecessor of the PDP-7. PDP-5 1963 $27,000 12 1,000 The ancestor of the PDP-8. PDP-6 1964 $300,000 36 23 A big computer; 23 built, most for MIT. PDP-7 1965 $72,000 18 120 Widely used for real-time control. PDP-8 1965 $18,500 12 ~50,000 The smallest and least expensive PDP. PDP-9 1966 $35,000 18 445 An upgrade of the PDP-7. PDP-10 1967 $110,000 36 **~700 A PDP-6 followup, great for timesharing. PDP-11 1970 $10,800 16 >600,000 DEC's first and only 16 bit computer. PDP-12 1969 $27,900 12 725 A PDP-8 relative. PDP-13 NA - Bad luck, there was no such machine. PDP-14 *** A ROM-based programmable controller. PDP-15 1970 $16,500 18 790 A TTL upgrade of the PDP-9. PDP-16 1972 NA 8/16 ? A register-transfer module system. * Scientific Engineering Institute of Waltham MA. SEI was aledgedly founded in 1956 by the CIA to study the effects of microwaves (radar) on the human brain. If so, the PDP-3 may have been used as an instrumentation computer. More info on the CIA connection and the use of the PDP-3 would be nice! ** Includes DECsystem 20. Corrections and additions to this list are welcome! The prices given are for minimal systems in the year the machine was first introduced. Most of the production run numbers come from "Computer Engineering" by Bell, Mudge and McNamara, 1978, or from Computers and Automation's computer census figures published regularly throughout the 1960's. The bits column in the table indicates the word size. Note that the DEC PDP-10 became the DECSYSTEM-20 as a result of marketing considerations, and DEC's VAX series of machines began as the Virtual Address eXtension of the never-produced PDP-11/78. It is worth mentioning that it is widely (but somewhat incorrectly) accepted that the Data General Nova (see photo, Computers and Automation, Nov. 1968, page 48) grew out of the PDP-X, a 16-bit multi-register version of the PDP-8 designed by Edson DeCastro, Henry Burkhardt and Dick Soggee. (DeCastro was one of DEC's key design engineers; his name appears on many of the blueprints for machines from the PDP-5 up through the PDP-8/L). A prototype PDP-X was built at DEC; this and a competing 16-bit design were apparently submitted to Harold McFarland at Carnegie-Mellon University for evaluation; McFarland (and perhaps Gordon Bell, who was at C-MU at the time) evaluated the competing designs and rejected both in favor of what we now know as the PDP-11. (I was at Carnegie-Mellon at the time, and McFarland gave a guest lecture in a class I attended telling part of this story.) Some speculate, incorrectly, that Bell rejected the Nova design because the competing proposal used the register-transfer notation he had introduced in "Bell and Newell, Computer Structures -- Readings and Examples". An alternate and equally unfounded story is that the reason DEC never produced a PDP-13 was because the number 13 had been assigned to what became the Nova. In any case, when DeCastro, Burkhardt and Soggee founded Data General, Ken Olson at DEC was very angry, claiming for a long time that the Nova design was stolen. Gordon Bell and others concluded that the Nova design was sufficiently original that a lawsuit was unwarranted, but the feud between DeCastro and Olson lasted until after Ken Olson left DEC. It is more correct to say that the Nova is a reaction to the PDP-X than to say that it is based on the PDP-X. I am indebted to Jim Campbell, retired VP at Data General, for some of the details of this story. Today, all of the PDP machines are in DEC's corporate past, except the PDP-11 family, which survives as a line of microcomputers; DEC has promised to discontinue PDP-11 sales on Sept. 30, 1996. Occasionally, some lab has built a machine out of DEC hardware and called it a PDP with a new number. For example, the Australian Atomic Energy Commission once upgraded a PDP-7 by adding a PDP-15 on the side; they called the result a PDP-22. There is also a story about the PDP-2 1/2, built by Ed Rawson of the American Science Institute out of surplus modules that were originally used in the prototype PDP-2. In 1998, Compaq purchased DEC, and it is unclear how long DEC will retain any semblance of its original identity as a division of a larger company. User Contributions:Top Document: PDP-8 Frequently Asked Questions (posted every other month) Previous Document: News Headers Next Document: What is a PDP-8? Single Page [ Usenet FAQs | Web FAQs | Documents | RFC Index ] Send corrections/additions to the FAQ Maintainer: jones@cs.uiowa.edu (Douglas W. Jones)
Last Update March 27 2014 @ 02:11 PM
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