Digital Equipment Corporation

Digital Equipment Corporation (DEC) (pronounced deck), using the trademark Digital, was a major American company in the computer industry from the 1950s to the 1990s.

DEC was a leading vendor of computer systems, including computers, software, and peripherals. Their PDP and successor VAX products were the most successful of all minicomputers in terms of sales.

DEC was acquired in June 1998 by Compaq, in what was at that time the largest merger in the history of the computer industry. 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 2007, PDP-11, VAX, and AlphaServer systems were still produced under the HP name.

Digital Equipment Corporation
IndustryComputer manufacturing
FateAcquired by Compaq, after divestiture of major assets.
HeadquartersMaynard, Massachusetts, United States
Key people
Ken Olsen (founder, president, and chairman)
Harlan Anderson (co-founder)
C. Gordon Bell (VP Engineering, 1972–83)
ProductsPDP 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)


From 1957 until 1992, DEC's headquarters were located in a former wool mill in Maynard, Massachusetts (since renamed Clock Tower Place, and now home to many companies). DEC was acquired in June 1998 by Compaq, which subsequently merged with Hewlett-Packard (HP) in May 2002. Some parts of DEC, notably the compiler business and the Hudson, Massachusetts facility, were sold to Intel.

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, eventually selling over 600,000 units and cementing DEC's position in the industry.

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 the company into the second largest computer company in the industry. At its peak, DEC was the second largest employer in Massachusetts, second only to the Massachusetts 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[3] were outsold by lower priced x86 chips from Intel and clones such as AMD.

DEC was acquired in June 1998 by Compaq, in what was at that time the largest merger in the history of the computer industry.[4] 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. As of 2007, some of DEC's product lines were still produced under the HP name.


Beyond DECsystem-10/20, PDP, VAX and Alpha, DEC was well respected for its 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.[5]


DEC's Research Laboratories (or Research Labs, as they were commonly known) conducted DEC's corporate research. Some of them were operated 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 who were responsible for developing Alpha and StrongARM:

Some of the work of the Research Labs was published in the Digital Technical Journal,[6] which was in published from 1985 until 1998.[7]

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.


  • The first versions of the C language and the Unix operating system ran on DEC's PDP series of computers (first on a PDP-7, then the PDP-11's), which were among the first commercially viable minicomputers, although for several years DEC itself did not encourage the use of Unix.
  • DEC produced widely used and influential interactive operating systems, including OS-8, TOPS-10, TOPS-20, RSTS/E, RSX-11, RT-11, and OpenVMS. PDP computers, in particular the PDP-11 model, inspired a generation of programmers and software developers. Some PDP-11 systems more than 25 years old (software and hardware) are still being used to control and monitor factories, transportation systems and nuclear plants. DEC was an early champion of time-sharing systems.
  • The command-line interfaces found in DEC's systems, eventually codified as DCL, would look familiar to any user of modern microcomputer CLIs; those used in earlier systems, such as CTSS, IBM's JCL, or Univac's time-sharing systems, would look utterly alien. Many features of the CP/M and MS-DOS CLI show a recognizable family resemblance to DEC's OSes, including command names such as DIR and HELP and the "name-dot-extension" file naming conventions.
  • Notes-11 and its follow-on product, VAX Notes, were two of the first examples of online collaboration software, a category that has become to be known as groupware. Len Kawell, one of the original Notes-11 developers later joined Lotus Development Corporation and contributed to their Lotus Notes product.
  • The MUMPS programming language, with its built-in database, was developed on the PDP-7, 9, and 15 series machines. MUMPS is still widely used in medical informations systems, such as those provide by Meditech and Epic Systems.


  • VAX and MicroVAX computers (very widespread in the 1980s) running VMS formed one of the most important proprietary networks, DECnet, which linked business and research facilities. The DECnet protocols formed one of the first peer-to-peer networking standards, with DECnet phase I being released in the mid-1970s. Email, file sharing, and distributed collaborative projects existed within the company long before their value was recognized in the market.
  • The LA36 and LA120 dot matrix printers became industry standards and may have hastened the demise of the Teletype Corporation.
  • The VT100 computer terminal became the industry standard, implementing a useful subset of the ANSI X3.64 standard, and even today terminal emulators such as HyperTerminal, PuTTY and Xterm still emulate a VT100 (or its more capable successor, the VT220).


  • DEC, Intel and Xerox through their collaboration to create the DIX standard, were champions of Ethernet, but DEC is the company that made Ethernet commercially successful. Initially, Ethernet-based DECnet and LAT protocols interconnected VAXes with DECserver terminal servers. Starting with the Unibus to Ethernet adapter, multiple generations of Ethernet hardware from DEC were the de facto standard. The CI "computer interconnect" adapter was the industry's first network interface controller to use separate transmit and receive "rings".
  • DEC also invented clustering, an operating system technology that treated multiple machines as one logical entity. Clustering permitted sharing of pooled disk and tape storage via the HSC50/70/90 and later series of Hierarchical Storage Controllers (HSC). The HSCs delivered the first hardware RAID 0 and RAID 1 capabilities and the first serial interconnects of multiple storage technologies. This technology was the forerunner to architectures such as Network of Workstations which are used for massively cooperative tasks such as web-searches and drug research.
  • The X Window System, the network transparent window system used on Unix and Linux, and also available on other operating systems, was developed at MIT jointly between Project Athena and the Laboratory for Computer Science. DEC was the primary sponsor for this project, which was a contemporary of the GNU Project but not associated with it.
  • In the period 1994–99 Linus Torvalds developed versions of Linux on early AlphaServer systems made available to him by the engineering department. Compaq software engineers developed special Linux kernel modules.[8] A well-known Linux distribution that ran on AlphaServer systems was Red Hat 7.2.[9] Another distribution that ran on Alpha was Gentoo Linux.
  • DEC was one of the first businesses connected to the Internet, with, registered in 1985,[10] being one of the first of the now ubiquitous .com domains. DEC's was a well-known software repository during the pre-World Wide Web days, and DEC was also the first computer vendor to open a public website, on 1 October 1993.[11] The popular AltaVista, created by DEC, was one of the first comprehensive Internet search engines. (Although Lycos was earlier, it was much more limited.)
  • DEC once held the Class A IP address block[12]


  • Digital Federal Credit Union (DCU) is a credit union which was chartered in 1979 for employees of DEC. Today its field of membership is open to existing family members, over 900 different sponsors, several communities in Massachusetts and several organizations. DCU has over 700 different sponsors, including the companies that acquired pieces of DEC.
  • Matrix management

User organizations

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.


  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. ^ Alpha: The History in Facts and Comments - The Collapse of DEC. Retrieved on 2013-07-17.
  4. ^ Schultz, Randy. "Compaq to buy DEC". CNN Money. Retrieved 19 June 2017.
  5. ^ For in-depth articles regarding DEC technologies, refer to the archived Digital Technical Journal
  6. ^ Digital Technical Journal – Online Issues
  7. ^ At least some of the research reports are available online at, in the subdirectories WRL, SRC, NSL, CRL, PRL (see Research section). Verified July 2006
  8. ^ Compaq was actively participating during the period 1994–99 into the Linux development, verified July 2014
  9. ^ Red Hat and Compaq Announce Port of Red Hat Linux 7.2 to Compaq's Alpha Processors (8 January 2002), verified July 2014
  10. ^
  11. ^ DECTEI-L Archives – February 1994 (#2)
  12. ^ List of assigned /8 IPv4 address blocks


  • (Present), "Digital Equipment Corporation: Nineteen Fifty-Seven to the Present", DEC Press, 1978
  • David Donald Miller (1997). Open Vms Operating System Concepts. Elsevier. ISBN 978-1-55558-157-2.
  • Alan R. Earls (2004-06-30). Digital Equipment Corporation. Arcadia Publishing. ISBN 978-0-7385-3587-6.
  • Edgar H Schein; with P. DeLisi; P. Kampas; M. Sonduck (2003-07-01). DEC is dead, long live DEC. Berrett-Koehler Pub. ISBN 978-1-57675-225-8.
  • Jamie Parker Pearson (September 1992). Digital at work: snapshots from the first thirty-five years. Digital Press. ISBN 1-55558-092-0.
  • Glenn & George Harrar Rifkin; George Harrar (1988). The Ultimate Entrepreneur: The Story of Ken Olsen and Digital Equipment Corporation. McGraw-Hill/Contemporary. ISBN 978-0-8092-4559-8.
  • C. Gordon Bell; J. Craig Mudge; John E. McNamara; Digital Equipment Corporation (1978). Computer engineering: A DEC view of hardware systems design. ISBN 0-932376-00-2.

External links


AdvFS, also known as Tru64 UNIX Advanced File System, is a file system developed in the late 1980s to mid-1990s by Digital Equipment Corporation for their OSF/1 version of the Unix operating system (later Digital UNIX/Tru64 UNIX). In June 2008, it was released as free software under the GNU GPLv2 license. AdvFS has been used in high-availability systems where fast recovery from downtime is essential.

Code page 1287

Code page 1287, also known as CP1287, DEC Greek (8-bit) and EL8DEC, is one of the code pages implemented for the VT220 terminals. It supports the Greek language.

Code page 1288

Code page 1288, also known as CP1288, DEC Turkish (8-bit) and TR8DEC, is one of the code pages implemented for the VT220 terminals. It supports the Turkish language.

DEC Radix-50

RADIX-50, commonly called Rad-50, RAD50 or DEC Squoze, is an uppercase only character encoding created by Digital Equipment Corporation for use on their DECsystem, PDP, and VAX computers. RADIX-50's 40-character repertoire (050 in octal) can encode six characters plus four additional bits into one 36-bit word (PDP-6, PDP-10/DECsystem-10, DECSYSTEM-20); three characters plus two additional bits into one 18-bit word (PDP-9, PDP-15); or three characters into one 16-bit word (PDP-11, VAX).

The actual encoding differed between the 36-bit and 16-bit systems.

DEC Special Graphics

DEC Special Graphics is a 7-bit character set developed by Digital Equipment Corporation. This was used very often to draw boxes on the VT100 video terminal and the many emulators, and used by bulletin board software. The escape sequence Esc ( 0 switched the codes for lower-case ASCII letters to draw this set, and the sequence Esc ( B switched back.


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.

DECnet was built right into the DEC flagship operating system VMS since its inception. Later Digital ported it to Ultrix, as well as Apple Macintosh and IBM PC running variants of DOS and Microsoft Windows under the name DEC Pathworks, allowing these systems to connect to DECnet networks of VAX machines as terminal nodes.

While the DECnet protocols were designed entirely by Digital Equipment Corporation, DECnet Phase II (and later) were open standards with published specifications, and several implementations were developed outside DEC, including ones for FreeBSD and Linux. DECnet code in the Linux kernel was marked as orphaned on February 18, 2010.

FOCAL (programming language)

FOCAL is an interpreted programming language resembling JOSS. The name is an acronym for Formulating On-Line Calculations in Algebraic Language.

Largely the creation of Richard Merrill, FOCAL was initially written for and had its largest impact on the Digital Equipment Corporation's (DEC's) PDP-8 computers. Merrill wrote the original (1968) and classic FOCAL-69 interpreters for the PDP-8. Digital itself described FOCAL as "a JOSS-like language."

Like early versions of BASIC, FOCAL was a complete programming environment in itself, requiring no operating system. As in MUMPS, most commands could be, and in practice were, abbreviated to a single letter of the alphabet. Creative choices of words were used to make each command uniquely defined by its leading character. Digital made available several European-language versions in which the command words were translated into the target language.

Gordon Bell

C. Gordon Bell (born August 19, 1934) is an American electrical engineer and manager. An early employee of Digital Equipment Corporation (DEC) 1960–1966, Bell designed several of their PDP machines and later became Vice President of Engineering 1972-1983, overseeing the development of the VAX. Bell's later career includes entrepreneur, investor, founding Assistant Director of NSF's Computing and Information Science and Engineering Directorate 1986-1987, and researcher emeritus at Microsoft Research, 1995–2015.

James Rumbaugh

James E. Rumbaugh (born August 22, 1947) is an American computer scientist and object-oriented methodologist who is best known for his work in creating the Object Modeling Technique (OMT) and the Unified Modeling Language (UML).

Jeff Dean (computer scientist)

Jeffrey Adgate "Jeff" Dean (born July 1968) is an American computer scientist and software engineer. He is currently the lead of, Google's AI division.

Ken Olsen

Kenneth Harry "Ken" Olsen (February 20, 1926 – February 6, 2011) was an American engineer who co-founded Digital Equipment Corporation (DEC) in 1957 with colleague Harlan Anderson and his brother Stan Olsen.


The PDP-8 was a 12-bit minicomputer produced by Digital Equipment Corporation (DEC). It was the first commercially successful minicomputer, with over 50,000 examples being sold over the model's lifetime. Its basic design followed the pioneering LINC but had a smaller instruction set, which was an expanded version of the PDP-5 instruction set. Similar machines from DEC were the PDP-12 which was a modernized version of the PDP-8 and LINC concepts, and the PDP-14 industrial controller system.

The earliest PDP-8 model, informally known as a "Straight-8", was introduced on 22 March 1965 priced at $18,500 (equivalent to about $150,000 in 2018). It used diode–transistor logic packaged on flip chip cards in a machine about the size of a small household refrigerator. It was the first computer to be sold for under $20,000, making it the best-selling computer in history at that time. The Straight-8 was supplanted in 1966 by the PDP-8/S, which was available in desktop and rack-mount models. Using a one-bit serial arithmetic logic unit (ALU) allowed the PDP-8/S to be smaller and less expensive, although slower than the original PDP-8. A basic 8/S sold for under $10,000, the first machine to reach that milestone.Later systems (the PDP-8/I and /L, the PDP-8/E, /F, and /M, and the PDP-8/A) returned to a faster, fully parallel implementation but use much less costly transistor–transistor logic (TTL) MSI logic. Most surviving PDP-8s are from this era. The PDP-8/E is common, and well-regarded because many types of I/O devices were available for it. The last commercial PDP-8 models introduced in 1979 were called "CMOS-8s", based on CMOS microprocessors. They were not priced competitively, and the offering failed. Intersil sold the integrated circuits commercially through to 1982 as the Intersil 6100 family. By virtue of their CMOS technology they had low power requirements and were used in some embedded military systems.

The chief engineer who designed the initial version of the PDP-8 was Edson de Castro, who later founded Data General.

Paul Vixie

Paul Vixie is an American computer scientist whose technical contributions include Domain Name System (DNS) protocol design and procedure, mechanisms to achieve operational robustness of DNS implementations, and significant contributions to open source software principles and methodology. He also created and launched the first successful commercial anti-spam service. He authored the standard UNIX system programs SENDS, proxynet, rtty and Vixie cron. At one point he ran his own consulting business, Vixie Enterprises.


RSX-11 is a discontinued family of multi-user real-time operating systems for PDP-11 computers created by Digital Equipment Corporation. In widespread use through the late 1970s and early 1980s, RSX-11 was influential in the development of later operating systems such as VMS and Windows NT. It was designed (and mainly used) for process control, but was also popular for program development.

Radia Perlman

Radia Joy Perlman (born 1951) is an American computer programmer and network engineer. She is most famous for her invention of the spanning-tree protocol (STP), which is fundamental to the operation of network bridges, while working for Digital Equipment Corporation. She also made large contributions to many other areas of network design and standardization, such as link-state routing protocols.

More recently she has invented the TRILL protocol to correct some of the shortcomings of spanning-trees. She is currently employed by Dell EMC.

Robert Iannucci

Robert Alan Iannucci is a computer scientist. His areas of expertise include multiprocessing and embedded systems. He earned his PhD at MIT in 1988 with a thesis titled "A dataflow/von Neumann hybrid architecture.".

He was first at IBM at the time of the mainframes, then at Exa Corporation, where he was a founder and Vice President of Product Marketing. In November 1995 he joined Digital Equipment Corporation as Cambridge Research Lab Director, and then went on to Compaq as Vice President of Corporate Research when DEC was acquired by Compaq. From May 2007, Iannucci was head of Nokia's Research Center heading laboratories in Beijing, Tokyo, Palo Alto, Cambridge MA, Cambridge UK, Germany, and Finland. On the first of January 2008 he became the new chief technology officer of Nokia. He was also the first member of the board who is not based in Finland, remaining in Palo Alto. In September 2008 he stepped down.

He now owns and runs the RAI Laboratory LLC.

In 2012 Robert Iannucci became the Director of the Cylab Mobility Research Center at Carnegie Mellon University Silicon Valley.

Sanjay Ghemawat

Sanjay Ghemawat (born 1966 in West Lafayette, Indiana) is an Indian American computer scientist and software engineer. He is currently a Senior Fellow at Google in the Systems Infrastructure Group. Ghemawat's work at Google, much of it in close collaboration with Jeff Dean, has included big data processing model MapReduce, the Google File System, and databases Bigtable and Spanner. Wired have described him as one of the "most important software engineers of the internet age".


TOPS-10 System (Timesharing / Total Operating System-10) is a discontinued operating system from Digital Equipment Corporation (DEC) for the PDP-10 (or DECsystem-10) mainframe computer family. Launched in 1967, TOPS-10 evolved from the earlier "Monitor" software for the PDP-6 and PDP-10 computers; this was renamed to TOPS-10 in 1970.

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