Digital Equipment Corporation

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Digital Equipment Corporation

legal form Corporation
founding 1957
resolution 1998
Seat Maynard United StatesUnited StatesUnited States 
Number of employees 126,000 (1990)
sales $ 14.6 billion (1996)
Branch Information technology

Digital Equipment Corporation , also known as DEC or Digital , was a US company based in Maynard , Massachusetts .

The company founded by Ken Olsen produced modules in the first few years. Just a few years later, DEC built its first own computer, the PDP-1, from such modules . This was the beginning of the development of a large number of very different computer families, of which above all the PDP-11 and later the VAX under the VMS operating system were very successful on the market. This led DEC to become the second largest computer manufacturer in the world by sales after IBM in the 1980s .

The company was a pioneer in the computer industry and was acquired in 1998 by Compaq , which has been part of Hewlett-Packard since 2002 .

Company history

Headquarters from DEC until 1992 in a former wool mill in Maynard , Massachusetts

In 1957, the engineer Ken Olsen (1926–2011) and his then partner Harlan Anderson (* 1929) founded the Digital Equipment Corporation with start-up capital of 70,000 US dollars. In an old cotton mill (“The Mill”) they first began to produce system modules with electronic logic circuits from which complex digital controls could be built. In its first fiscal year, the company generated $ 94,000. In 1959, Olsen hired the engineer Ben Gurley, who developed the first DEC computer PDP-1 based on his own modules within three months .

In the 1960s DEC produced a series of computers that were supposed to be less powerful, but also much cheaper than the IBM mainframe computers. The company's breakthrough came with the production of the famous PDP-8 in 1964. The PDP-8 used 12- bit words and was sold for around 16,000 US dollars. Due to the portability and the relatively simple structure, this computer could also be used in smaller industrial companies and fill gaps in the market that could not be reached with mainframes up to now. Historically, this is an important aspect because the PDP-8 was the first computer that was also bought by private individuals and used for a special purpose, while mainframe computers were still so large and expensive that they could only be used for several purposes by several Users. The PDP-8 was later dubbed the world's first small computer.

The abbreviation PDP stands for " Programmed Data Processor ", which actually means nothing more than "Computer". However, DEC avoided the word computer to differentiate itself from its big competition, IBM. IBM built computers and DEC PDPs.

Ten years after it was founded, the company had sales of 38 million US dollars. The PDP15 model series was created around 1970 - a graphic design system with a monochrome green screen and " Lightpen " with a digitizing tablet .

The most successful model of the well-known PDP computer series was the PDP-11 , which used 16-bit words because ASCII had established itself as the de facto standard in the computer industry. PDP-11 computers were intended as a further development of the PDP-8 for the same purposes and were later available in housings that were no larger than modern PCs. The space savings could be achieved by using integrated circuits . The PDP-10 (36-bit architecture) was intended for data centers and larger data processing systems and was sold under the name DECSystem-10 and DECSystem-20, depending on the operating system. Several operating systems that are still known today could be operated on the PDP-11, including Bell Labs Unix and DEC's own RT-11 , RSX-11 and RSTS. Both RSTS and Unix could be purchased very cheaply or free of charge for training and teaching purposes. As a result, the PDP-11 developed into a playground for several generations of computer technicians and researchers. The PDP-11 architecture had a directly addressable address space of 64K. All early systems were equipped with magnetic core memory .

VAX 11/780 from the inside

In 1976 DEC developed a new and extremely small 32-bit architecture, which was first used in the VAX 11/780, which was first sold in 1978. DEC was able to dominate the small computer market for a considerable time with this product, despite competitors such as Data General (which was founded by a former DEC employee who proposed a 16-bit architecture that was rejected by management) tried to regain market share. The success of DEC was based not only on DEC's technical superiority, but above all on the market development in the field of workstations , which developed in favor of small computers. As a result, the “Jupiter” project, which provided for the development of a successor model for the PDP-10, was canceled, and DEC concentrated on the development and marketing of the VAX computers.

The VAX had a very large instruction set and many addressing modes, even by today's standards. In addition to paging and protected memory, the VAX supports virtual memory: The name VAX stands for "Virtual Address eXtension". Both UNIX and DEC's own VMS could be used.

DECstation 5000/200 open

In its prime (the late 1980s), Digital Equipment Corporation was the second largest computer manufacturer in the world with over 100,000 employees. During this period, the commercially successful workstations based on the MIPS architecture called DECstation and servers called DECsystem were brought onto the market. At the same time, the corporate management seemed to be enforcing a corporate policy that suggested a feeling of invulnerability, and expanded the product range to include self-developed software for almost every promising niche in the market . This also included the development of its own network system ( DECnet ), software for file and printer sharing, relational database systems and even software for transaction-based processing. Although the software was well thought out and implemented, it was difficult to integrate as it was developed with a focus on DEC's own products. As a result, many potential customers ignored the software and instead procured software from other manufacturers. This problem was compounded by Olsen's aversion to advertising and the idea that well-designed software sells itself. Hundreds of millions of US dollars were invested in the implementation of these software projects, while workstations based on the RISC architecture increasingly came close to the performance of the VAX. Blinded by the success of the proprietary VAX / VMS products, the competition from Intel-based personal computers (PCs) and the fact that off-the-shelf hardware and software based on standards prevailed went unnoticed. Own workstation computers such as Rainbow 100 or Professional 350 and 325 did not have great market success. In the early 1990s, the Digital Equipment Corporation suffered a surprising decline in sales and laid off employees.

A little later, DEC tried to push through a new generation of mass storage systems called the RA-90. This development project, the second largest in the company's entire history, was to contain some important technical innovations that were also to be incorporated into the new, at the time very modern-looking product. The product could not be marketed in time due to difficulties with the product design, so that there was strong competition when it came to market and the flagship project, which could have been a big win for the company, turned into a huge mistake.

Inside the DEC AlphaServer 2100

Then a novel was as a consequence CPU with 64-bit RISC architecture developed (as opposed to 32-bit CISC architecture, which came into the VAX computers used), both for servers and for workstations could be used . The result, the alpha processor , which was able to shine with its speed even in the new (third) millennium, gave the user the opportunity to choose one of three operating systems that could run on the new architecture: DEC's VMS , UNIX and Microsoft's Windows NT . DEC itself then tried to gain a foothold in the field of UNIX operating systems and, in addition to the proprietary " OpenVMS " , marketed its own UNIX "OSF / 1", initially as "Digital Unix" and later as " Tru64 UNIX ". Although more advertising campaigns were used, DEC did not succeed in gaining sufficient shares in the overcrowded UNIX market. In addition, the success of the Intel- based low-end PC server with Windows NT operating system made it difficult to sell systems based on the Alpha processor. So DEC was able to convince only a few of the new system apart from long-term loyal customers. DEC software and hardware developers migrated - Windows NT and AMD hardware developments participated in their knowledge. The decades of direct support by the system developers from Maynard via the global and country-specific DEC user association DECUS expired.

Ken Olsen resigned as CEO on October 1, 1992 and was replaced by Robert Palmer; the company was still in the red. The company's database division was sold to Oracle . In May 1997, DEC sued Intel , claiming that Intel had infringed the patent rights for Alpha processors by developing the Pentium CPU. The companies reached an agreement, and DEC sold its entire processor division to Intel. The company's network division was sold to Cabletron Systems .

DEC itself was sold to Compaq on January 26, 1998 . Compaq, in turn, was taken over by Hewlett-Packard in 2002. In 1998 Robert Boers, one of the former DEC managers, bought the “DEC European Migration and Porting Center”. This initially resulted in the company "Software Resources International", now Stromasys ; this develops emulators like Charon for the old DEC servers PDP-11, VAX and Alpha.

A major reason for the failure of the company was the very confusing range of products. Of the computers produced under the name PDP alone , there were more than 60 models between 1959 and 1982, which were spread across four system families and which in some cases also competed with one another.

Technical concept

The technical concept, especially that of the PDP-11 series, was kept impressively simple. A standardized "universal BUS system" made it possible to upgrade and convert the PDP-11 for a variety of process applications. That is precisely why the PDP-11 began its triumphal march, especially in the experimental science and research area. There was also a wide field of application in the control of power plants , traffic routes and telephone networks.

The open bus system naturally also called on a large number of third-party hardware providers who brought low-cost, high-performance peripheral devices to the market for connection to the PDP-11. Above all, the English manufacturer Plessey should be mentioned here , which caused unrest at DEC through its US subsidiary on the European market and was also able to access its own service network. These "mixed hardware providers" were bitterly fought by DEC, and under the title of "technology transfer" it has already happened that DEC set up its own definitions of high-tech products in order to make market access more difficult for OEM customers and third-party providers.

This “fight” was often fought on the backs of end customers who had to bear reprisals in the service area. This annoyed those customers in the academic and academic sectors who had helped write the success story of DEC.

Economical way

After the resounding successes in the field of process computer technology , which catapulted DEC to second place among computer manufacturers after IBM , newly designed computers came onto the market around 1978 (PDP-11/34, 11/70, 11/44, VAX 11/750), aimed at the business market, which was the domain of IBM at the time. At the same time, in order to force the various “mixed hardware providers” out of the market, the service philosophy was changed. Hardware and DEC software had to be serviced together in the event of a maintenance contract (approx. 1990). Thus, due to a lack of software knowledge, all third-party providers were locked out of the DEC market. This led to the fact that the third-party providers ceased their activities. Many customers who wanted to use the technical concept of the PDP series, but at the same time wanted to buy peripherals on the alternative market at low cost, could no longer be addressed as DEC customers.

The rigid attitude in the service area as well as in the area of ​​dealer support prompted many companies that had previously acted as resellers for DEC systems to withdraw from DEC and offer computers from Compaq , HP, or even from "non-name" manufacturers.

Furthermore, a discussion broke out about the increasing complexity of the operating system (VMS) and network (DECnet) - employees who founded the company Apollo Computer and set the standards of technology to this day with convincing Ethernet services were split off . Apollo Computer was acquired by Hewlett-Packard in 1989.

As history has shown, the change in direction towards business applications was not a success either; You played here in the big league with IBM as your opponent. The profitable PC market was also overslept. Until 1994, DEC practiced networking with the expensive VAX stations, while customers had long since switched to powerful PC networks.

The end of DEC must be seen in close connection with the non-appearance of a Windows 2000 for Digital Alpha platform. At the time, the Alpha was the company's driving force, but relied on a special kernel variant of NT-4. Whether there is a causal connection can be viewed critically, but it is noticeable that the price of the DEC shares rose and fell synchronously with Microsoft's release reports on "Windows 2000 for 64bit".

Corporate successes

  • The Alpha processor was the first commercially available 64-bit RISC processor and the first laptop was produced. Under the domain , Digital was the first company to be connected to the Internet and founded AltaVista, at times the most successful search engine .
  • DEC was a leader in the field of networking ( DECnet ). The VMS operating system is considered flexible and extremely stable. DEC also made a name for itself with cluster solutions. These solutions worked - like the relational database RdB - only within the DEC world. DEC never tried to port these solutions to other platforms.
  • DEC supported many ANSI standards, especially the ASCII standard, which lives on in Unicode and the ISO character sets.
  • The first version of the C programming language and the UNIX operating system ran on DEC's PDP computers.
  • DEC produced several operating systems specifically designed for the PDP series, e.g. B. OS / 8 , TOPS-10 , TOPS-20 , RT-11 , RSX-11 , RSTS / E and (for the VAX computers) VMS .
  • The PDP-11 inspired a whole generation of programmers and software developers . In 2004 there were 25-year-old PDP-11 systems (hardware and software) that were still used for machine monitoring and control in factories (and also in nuclear power plants ).
  • DEC was instrumental in promoting the use of time-sharing systems, like everyone who knows other operating systems such as B. MVS or VM / CMS from IBM can confirm.
  • With the LA36, DEC brought a dot matrix printer onto the market around 1974, which was the first to successfully compete with the Teletype ( ASCII - teleprinter ) previously used everywhere in the IT sector .
  • In 1976, DEC launched the VT100, an inexpensive and robust ASCII terminal whose command set is still the de facto standard for terminal emulation programs.
  • On May 3, 1978, what was probably the first spam mail in Internet history went out from DEC employee Gary Thuerk .
  • Around 1980 DEC pushed the standardization of Ethernet together with the providers 3Com , Intel and Xerox .
  • DEC developed DLT technology (DEC LINEAR TAPE) around 1984 and launched the legendary TK50, a very inexpensive and reliable safety tape system for the time.
  • DEC had a relationship with customers that was never to be found with any manufacturer afterwards via the DECUS (DIGITAL Equipment Users Society), where operating system and tool developers spend a week in legendary meetings with customers in Germany (Munich) and Europe (changing locations) every year Compose symposia. Even after the takeover by Compaq and later HP, this user association continues to meet at regular intervals; in Germany it operates under the name HP User Society DECUS Munich eV
  • Former DEC employees developed software (Apollo: networking; Microsoft: Windows NT operating system, from which the VISTA and Windows 7 versions) developed with the mother’s know-how at the companies Apollo and Microsoft.
  • DEC was able to achieve a great prestige success by the fact that during the Cold War the DEC computers were reproduced and widely used in many Eastern European countries ( GDR , Hungary , VR Poland , Soviet Union ). Most of the time, the original DEC software was used. From 1968 to 1988, the PDP8, PDP11, and VAX computers were built in large numbers without paying license fees. The use of new, highly integrated circuits by DEC meant the technological end of these black copies. At the same time, the market in Eastern European countries was opened up for the original products, the replicas had to be discontinued and DEC was able to take on highly qualified specialists for local support.
  • At DEC, the concept of numeronym was born.


  • AlphaServer - Server with Alpha processor
  • AlphaStation - workstations with an Alpha processor
  • DECstation - desktop workstations from DEC for Ultrix
  • DECsystem - server systems from DEC for Ultrix
  • Ultrix - UNIX variant of DEC
  • Tru64 UNIX - A Unix from the System V family for Alpha processor based machines
  • VAXstation - DEC desktop workstations for VMS
  • DEC Multia - Slim desktop workstation from DEC with 21064-Alpha-CPU for VMS and Tru64 UNIX or with Intel Pentium-CPU for Windows NT 3.51 or 4.0
  • Digital Personal Workstation - high-performance workstations based on Intel Pentium Pro / Pentium II (180–333 MHz) and Alpha processors (433/500/600 MHz) and operated as standard with Windows NT for Alpha (a-series) or Tru64 Unix / OpenVMS ( au series)
  • Virtual Memory System - later OpenVMS, is a multi-user operating system with a graphical user interface for VAX, Alpha and Itanium based computers
  • RSX-11 An early predecessor to VMS and Windows NT


  • Schein, Edgar H .: DEC is dead, long live DEC. The lasting legacy of Digital Equipment Corporation . San Francisco: Berrett-Koehler 2003. - Dt .: The rise and fall of Digital Equipment Corporation. A learning history or: DEC is dead - long live DEC . Bergisch Gladbach: EHP 2006

Web links

Commons : Digital Equipment Corporation  - Collection of pictures, videos, and audio files

Individual evidence

  1. Digital wants market share back . Retrieved September 29, 2017.
  2. Compaq buys DEC
  3. Hewlett-Packard buys Compaq
  4. Pedigree of PDP computers
  5. "HP Seeks To Reassure Apollo Workers". Boston Globe. May 23, 1989
  6. [1] ,
  7. HP User Society DECUS Munich eV current website of the German association