Digital Equipment Corporation

Last updated
Digital Equipment Corporation
Industry Computer hardware
Computer software
Computer services
Founded1957;64 years ago (1957)
Founder Ken Olsen
Harlan Anderson
FateAcquired by Compaq, after divestiture of major assets.
Successor Compaq
HP Inc. and Hewlett Packard Enterprise
Headquarters Maynard, Massachusetts, United States
Key people
Ken Olsen (founder, president, and chairman)
C. Gordon Bell (VP Engineering, 1972–83)
Products PDP minicomputers
VAX minicomputers
Alpha servers and workstations
VT100 terminal
LAT and Terminal server
StrongARM microprocessors
Digital Linear Tape
Number of employees
over 140,000 (1987)

Digital Equipment Corporation (DEC /dɛk/ ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president until forced to resign in 1992, after the company had gone into precipitous decline.


Although the company produced many different product lines over their history, they are best known for their work in the minicomputer market starting in the mid-1960s. The company produced a series of machines known as the PDP line, with the PDP-8 and PDP-11 being among the most successful minis of all time. Their success was only surpassed by another DEC product, the late-1970s VAX "supermini" systems that were designed to replace the PDP-11. Although a number of competitors had successfully competed with Digital through the 1970s, the VAX cemented the company's place as a leading vendor in the computer space.

As microcomputers improved in the late 1980s, especially with the introduction of RISC-based workstation machines, the performance niche of the minicomputer was rapidly eroded. By the early 1990s, the company was in turmoil as their mini sales collapsed and their attempts to address this by entering the high-end market with machines like the VAX 9000 were market failures. After several attempts to enter the workstation and file server market, the DEC Alpha product line began to make successful inroads in the mid-1990s, but was too late to save the company.

DEC was acquired in June 1998 by Compaq in what was at that time the largest merger in the history of the computer industry. During the purchase, some parts of DEC were sold to other companies; the compiler business and the Hudson, Massachusetts facility, were sold to Intel. At the time, Compaq was focused on the enterprise market and had recently purchased several other large vendors. DEC was a major player overseas where Compaq had less presence. However, Compaq had little idea what to do with its acquisitions, [1] [2] and soon found itself in financial difficulty of its own. The company subsequently merged with Hewlett-Packard (HP) in May 2002.

As of 2012,[ needs update ] decades-old hardware (including PDP-11, VAX, and AlphaServer) is being emulated to allow legacy software to run on modern hardware; funding for this is planned to last at least until 2030. [3]


From 1957 until 1992, DEC's headquarters were located in a former wool mill in Maynard, Massachusetts. The headquarter buildings were vacated in 1993, renamed Clock Tower Place, [4] and subsequently redeveloped as Mill & Main Place, a 1.1 million square foot facility for offices and light industry. [5]

Initially focusing on the small end of the computer market allowed DEC to grow without its potential competitors making serious efforts to compete with them. Their PDP series of machines became popular in the 1960s, especially the PDP-8, widely considered to be the first successful minicomputer. Looking to simplify and update their line, DEC replaced most of their smaller machines with the PDP-11 in 1970, the year they became the third largest computer manufacturer after IBM and the UNIVAC Division of Sperry Rand. [6] The rising corporation eventually sold over 600,000 PDP-11s.

Originally designed as a follow-on to the PDP-11, DEC's VAX-11 series was the first widely used 32-bit minicomputer, sometimes referred to as "superminis". These systems were able to compete in many roles with larger mainframe computers, such as the IBM System/370. The VAX was a best-seller, with over 400,000 sold, and its sales through the 1980s propelled DEC to become the second largest computer company in the industry. At its peak, it was the second largest employer in Massachusetts, after the state government.

The rapid rise of the business microcomputer in the late 1980s, and especially the introduction of powerful 32-bit systems in the 1990s, quickly eroded the value of DEC's systems. DEC's last major attempt to find a space in the rapidly changing market was the DEC Alpha 64-bit RISC instruction set architecture. DEC initially started work on Alpha as a way to re-implement their VAX series, but also employed it in a range of high-performance workstations. Although the Alpha processor family met both of these goals, and, for most of its lifetime, was the fastest processor family on the market, extremely high asking prices [7] [ better source needed ] were outsold by lower priced workstation chips from Intel and IBM/Motorola.

DEC was acquired in June 1998 by Compaq, in what was at that time the largest merger in the history of the computer industry. [8] At the time, Compaq was focused on the enterprise market and had recently purchased several other large vendors. DEC was a major player overseas where Compaq had less presence. However, Compaq had little idea what to do with its acquisitions, and soon found itself in financial difficulty of its own. The company subsequently merged with Hewlett-Packard (HP) in May 2002. [9] [10]


DEC VAXstation DEC VAXstation 4000 96 OpenVMS 6.1.jpeg
DEC VAXstation

Beyond DECsystem-10/20, PDP, VAX and Alpha, DEC was known for its work in communication subsystem designs, such as Ethernet, DNA (DIGITAL Network Architecture: predominantly DECnet products), DSA (Digital Storage Architecture: disks/tapes/controllers), and its "dumb terminal" subsystems including VT100 and DECserver products. [11]


DEC's Research Laboratories (or Research Labs, as they were commonly known) conducted DEC's corporate research. Some of them were continued in operation by Compaq and are still operated by Hewlett-Packard. The laboratories were:

Some of the former employees of DEC's Research Labs or DEC's R&D in general include:

Some of the former employees of Digital Equipment Corp were responsible for developing DEC Alpha and StrongARM:

Some of the work of the Research Labs was published in the Digital Technical Journal, [13] which was in published from 1985 until 1998. [14]

Accomplishments and legacy

DEC supported the ANSI standards, especially the ASCII character set, which survives in Unicode and the ISO 8859 character set family. DEC's own Multinational Character Set also had a large influence on ISO 8859-1 (Latin-1) and, by extension, Unicode.





User organizations

DECUS - Logo
Digital Equipment Corporation
Users Society DECUS-logo.svg
DECUS - Logo
Digital Equipment Corporation
Users Society

Originally the users' group was called DECUS (Digital Equipment Computer User Society) during the 1960s to 1990s. When Compaq acquired DEC in 1998, the users group was renamed CUO, the Compaq Users' Organisation. When HP acquired Compaq in 2002, CUO became HP-Interex, although there are still DECUS groups in several countries. In the United States, the organization is represented by the Encompass organization; currently Connect.[ citation needed ]

Small Computer Handbook

Several editions of the Small Computer Handbook were published by DEC, giving information about their PDP line of computers. The editions were:

Web sites with photos of their covers include:


  1. "Dell topples Compaq in U.S. market share".
  2. "What was left was a stalled engine with a very expensive head count." "Buying Digital played into Eckhard's fantasy, but it's turning out to be a beast that's consuming the company," said one former executive who left before the acquisition. "Compaq Message Board - Msg: 9675868".
  3. Benj Edwards (February 19, 2012). "If it aint broke don't fix it: Ancient Computers in Use Today". PC World .
  4. "Mill & Main Place Development Project".
  5. "Multi-million dollar capital improvements completed on Mill & Main". Aug 6, 2018.
  6. Campbell-Kelly, Martin; Aspray, William (2013). Computer: A History of the Information Machine. Boulder, Colorado: Westview Press. 62%. ISBN   978-0813345901.
  7. "Alpha: The History in Facts and Comments - The Collapse of DEC". Archived from the original on 2012-06-29. Retrieved 2013-07-17.
  8. Schultz, Randy. "Compaq to buy DEC". CNN Money. Retrieved 19 June 2017.
  9. Street Journal, Nikhil Deogun, Gary McWilliams and Molly WilliamsStaff Reporters of The Wall (2001-09-04). "Hewlett-Packard Agrees to Acquire Compaq Computer in Stock Swap". Wall Street Journal. ISSN   0099-9660 . Retrieved 2021-02-18.
  10. "HP-Compaq merger completed - May. 3, 2002". Retrieved 2021-02-18.
  11. For in-depth articles regarding DEC technologies, refer to the archived Digital Technical Journal
  12. Gettys, James; Karlton, Philip L.; McGregor, Scott (December 10, 1990). "The X Window System, Version 11" (PDF). Digital Equipment Corporation and Silicon Graphics Computer Systems. p. 36. Retrieved July 2, 2020.
  13. Digital Technical Journal – Online Issues
  14. At least some of the research reports are available online at [ permanent dead link ] "Unknown" . Retrieved January 10, 2020.Cite uses generic title (help)[ dead link ], in the subdirectories WRL, SRC, NSL, CRL, PRL (see Research section). Verified July 2006
  15. Compaq was actively participating during the period 1994–99 into the Linux development Archived 2014-08-12 at the Wayback Machine , verified July 2014
  16. Red Hat and Compaq Announce Port of Red Hat Linux 7.2 to Compaq's Alpha Processors (8 January 2002) Archived 12 August 2014 at the Wayback Machine , verified July 2014
  17. "". Retrieved 2021-02-18.
  18. "LISTSERV 16.5 - Archives - Error". Retrieved 2021-02-18.
  19. List of assigned /8 IPv4 address blocks
  20. "Small Computer Handbook (1973)".
  21. "PDP8/e, PDP8/m & PDP8/f, Small Computer handbook (1973)".
  22. "Small Computer Handbook (1970 edition)" (PDF).

Related Research Articles

DEC Alpha 64-bit RISC microprocessor from DEC

Alpha, originally known as Alpha AXP, is a 64-bit reduced instruction set computing (RISC) instruction set architecture (ISA) developed by Digital Equipment Corporation (DEC). Alpha was designed to replace 32-bit VAX complex instruction set computer (CISC) as well as be a highly competitive RISC processor for Unix workstations and similar markets.

Minicomputer Mid-1960s–late-1980s class of smaller computers

A minicomputer, or colloquially mini, is a class of smaller general purpose computers that developed in the mid-1960s and sold for much less than mainframe and mid-size computers from IBM and its direct competitors. In a 1970 survey, The New York Times suggested a consensus definition of a minicomputer as a machine costing less than US$25,000, with an input-output device such as a teleprinter and at least four thousand words of memory, that is capable of running programs in a higher level language, such as Fortran or BASIC.

Programmed Data Processor Name used for several lines of minicomputers

Programmed Data Processor (PDP), referred to by some customers, media and authors as "Programmable Data Processor, is a term used by the Digital Equipment Corporation from 1957 to 1990 for several lines of minicomputers. The name "PDP" intentionally avoids the use of the term "computer" because, at the time of the first PDPs, computers had a reputation of being large, complicated, and expensive machines, and the venture capitalists behind Digital would not support Digital's attempting to build a "computer"; the word "minicomputer" had not yet been coined. So instead, Digital used their existing line of logic modules to build a Programmed Data Processor and aimed it at a market that could not afford the larger computers.

PDP-11 Series of 16-bit minicomputers

The PDP-11 is a series of 16-bit minicomputers sold by Digital Equipment Corporation (DEC) from 1970 into the 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of all models were sold, making it one of DEC's most successful product lines. The PDP-11 is considered by some experts to be the most popular minicomputer.

VAX Computer architecture, and a range of computers

VAX is a CISC instruction set architecture (ISA) and line of superminicomputers and workstations developed by the Digital Equipment Corporation (DEC) in the mid-1970s. The VAX-11/780, introduced October 25, 1977, was the first of a range of popular and influential computers implementing the VAX ISA. Over 100 models were introduced over the lifetime of the design, with the last members arriving in the early 1990s. The VAX was succeeded by the DEC Alpha, which included several features from VAX machines to make porting from the VAX easier.

OpenVMS Computer operating system

OpenVMS, often referred to as just VMS, is a multi-user, multiprocessing virtual memory-based operating system designed to support time-sharing, batch processing, transaction processing and workstation applications. It was first announced by Digital Equipment Corporation as VAX/VMS alongside the VAX-11/780 minicomputer in 1977. OpenVMS has subsequently been ported to run on DEC Alpha systems, the Itanium-based HPE Integrity family of computers, and select x86-64 hardware and hypervisors. Since 2014, OpenVMS is developed and supported by a company named VMS Software Inc. (VSI).

DECnet is a suite of network protocols created by Digital Equipment Corporation. Originally released in 1975 in order to connect two PDP-11 minicomputers, it evolved into one of the first peer-to-peer network architectures, thus transforming DEC into a networking powerhouse in the 1980s. Initially built with three layers, it later (1982) evolved into a seven-layer OSI-compliant networking protocol.

Ultrix is the brand name of Digital Equipment Corporation's (DEC) discontinued native Unix operating systems for the PDP-11, VAX, MicroVAX and DECstations.

VSI BASIC for OpenVMS is the latest name for a dialect of the BASIC programming language created by Digital Equipment Corporation (DEC) and now owned by VMS Software Incorporated (VSI). It was originally developed as BASIC-PLUS in the 1970s for the RSTS-11 operating system on the PDP-11 minicomputer. It was later ported to OpenVMS, first on VAX, then Alpha, and most recently Integrity.

Richard "Dick" Irvin Hustvedt was a renowned software engineer., designer and developer of several operating systems including Digital Equipment Corporation's RSX-11, and VMS.

DEC Professional (computer)

The Professional 325 (PRO-325), Professional 350 (PRO-350), and Professional 380 (PRO-380) were PDP-11 compatible microcomputers introduced in 1982 by Digital Equipment Corporation (DEC) as high-end competitors to the IBM PC.

Local Area Transport (LAT) is a non-routable networking technology developed by Digital Equipment Corporation to provide connection between the DECserver terminal servers and Digital's VAX and Alpha and MIPS host computers via Ethernet, giving communication between those hosts and serial devices such as video terminals and printers. The protocol itself was designed in such a manner as to maximize packet efficiency over Ethernet by bundling multiple characters from multiple ports into a single packet for Ethernet transport. Over time, other host implementations of the LAT protocol appeared allowing communications to a wide range of Unix and other non-Digital operating systems using the LAT protocol.

Terry Shannon (IT)

Terry Craig Shannon was an American information technology consultant, journalist and author. For over 30 years, he was involved in implementing PDP, VAX, and Alpha computers with their respective operating systems RSX, VAX/VMS, OpenVMS and Windows NT. He was a respected journalist and analyst, paying particular attention to Compaq and Hewlett-Packard after the merger of Digital Equipment Corporation and the high-performance computing (HPC) space, writing a series of newsletters.

Franz Lisp

In computer programming, Franz Lisp is a discontinued Lisp programming language system written at the University of California, Berkeley by Professor Richard Fateman and several students, based largely on Maclisp and distributed with the Berkeley Software Distribution (BSD) for the Digital Equipment Corporation (DEC) VAX minicomputer. Piggybacking on the popularity of the BSD package, Franz Lisp was probably the most widely distributed and used Lisp system of the 1970s and 1980s.

SIMH is a highly portable, multi-system emulator which runs on Windows, Linux, macOS, FreeBSD, OpenBSD, NetBSD and OpenVMS. It is maintained by Bob Supnik, a former DEC engineer and DEC vice president, and has been in development in one form or another since the 1960s.

PATHWORKS was the trade name used by Digital Equipment Corporation of Maynard, Massachusetts for a series of programs that eased the interoperation of Digital's minicomputers with personal computers. It was available for both PC and Mac systems, with support for MS-DOS, OS/2 and Microsoft Windows on the PC.


AlphaStation is the name given to a series of computer workstations, produced from 1994 onwards by Digital Equipment Corporation, and later by Compaq and HP. As the name suggests, the AlphaStations were based on the DEC Alpha 64-bit microprocessor. Supported operating systems for AlphaStations comprise Tru64 UNIX, OpenVMS and Windows NT. Most of these workstations can also run various versions of Linux and BSD operating systems.

<i>The Ultimate Entrepreneur</i>

The biographical book, The ultimate entrepreneur: the story of Ken Olsen and Digital Equipment Corporation, chronicles the experiences of Ken Olsen racing to design minicomputers at the company of his own founding, Digital Equipment Corporation. At the time the book was published by two computer journal writers, Ken Olsen was competing with other Massachusetts computing companies such as Data General, Prime Computer, Wang Laboratories, Symbolics, Lotus Development Corporation, and Apollo Computer. While believing in the value of software, he did not believe in the value of software separate from hardware, and missed the opportunity to fund Lotus 1-2-3 or Visicalc. He also missed the importance of the personal computer, but his futuristic vision of the Client–server model helped to launch Ethernet.

Charon is the brand name of a group of software products able to emulate several CPU architectures. The emulators available under this brand mostly cover the Digital Equipment DEC hardware platforms PDP-11, VAX, and AlphaServer, which support many of the legacy operating systems, including Tru64 and OpenVMS. The product range also includes virtualization solutions for HP 3000 using MPE/iX and SPARC. Charon software products have been developed by the Swiss software company Stromasys SA, which has its headquarters in Cointrin, near Geneva.

Digital Equipment Corporation (DEC), was a major American company in the computer industry. Founded in 1957 with $70,000 of venture capital, it became "the nation's second-largest computer company, after IBM." Its initial major impact was in minicomputers, but its later-introduced VAX and Alpha systems are still notable.


Further reading