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Digital Equipment Corporation
Fate Assets were sold to various companies. What remained was sold to Compaq.
Successor Hewlett-Packard
Founded 1957
Defunct 1998
Headquarters Maynard, Massachusetts
 United States
Key people Ken Olsen (founder, president, and chairman)
Harlan Anderson (co-founder)
Industry Computer manufacturing
Products PDP
DEC Alpha
Employees over 140,000 (1987)

Digital Equipment Corporation was a pioneering American computer company, for a long time one of the most admired within the hacker community.

Initially focusing on the small-end of the computer market allowed DEC to grow without its potential competitors noticing, or caring enough to make serious efforts to compete with them. Their PDP series of machines became runaway best-sellers 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 examples and cementing DECs position as one of the most innovative and successful companies 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. Machines of this sort, known as "superminis", were able to compete in many roles with larger mainframes like the IBM System/370. The VAX was a runaway best-seller, with over 400,000 sold, and its sales through the 1980s propelled the company into the second largest in the industry as their systems stole billions in sales from formerly larger competitors. At its peak, DEC was the second largest employer in Massachusetts, second only to 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. Network storage was another area that the company focused on in the early 1990s, but rapid progress in cost and storage capacity of hard drives eroded this lead even more rapidly. By the mid-90's, commodity machines offered performance and capacity comparable to DEC's largest systems. The company never came up with an appropriate response to these threats, and by the mid 1990s was a shell of its former self.

DEC's last major attempt to find a space in the rapidly changing market was the DEC Alpha, a series of 64-bit RISC CPUs. DEC initially started work on these designs as a way to re-implement their VAX series, in the same fashion that IBM was successfully selling mainframes based on their own POWER CPUs. Alpha systems could also be scaled downwards to deliver the fastest workstations on the market, at a competitive price. Although the Alpha systems met both of these goals, and was, for most of its lifetime, the fastest CPU on the market, it did little to effect the bottom line or repair the company's status.

The company 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, and soon found itself in financial difficulty of its own. The company subsequently merged with Hewlett-Packard in May 2002. As of 2007 its product lines were still produced under the HP name.

The company is often referred to within the computing industry as DEC (this acronym was frequently officially used by Digital itself, but the trademark was always DIGITAL).[1] Digital Equipment Corporation should not be confused with Digital Research; the two were unrelated, separate entities; or with Western Digital (despite the fact that they made the LSI-11 chipsets used in Digital Equipment Corporation's low end PDP-11/03 computers). Note, however, that there were Digital Research Laboratories where DEC did its corporate research.




Ken Olsen and Harlan Anderson were two engineers who had been working at MIT Lincoln Laboratory on the lab's various computer projects. The Lab is best known for their work on what would today be known as "interactivity", and their machines were among the first where operators had direct control over programs running in real-time. These had started in 1944 with the famed Whirlwind which was originally developed to make a flight simulator for the US Navy, although this was never completed.[2] Instead, this effort evolved into the SAGE system for the US Air Force, which used large screens and light guns to allow operators to interact with radar data stored in the computer.[3]

When the Air Force project wound down, the Lab turned their attention to an effort to build a version of the Whirlwind using transistors in place of vacuum tubes. In order to test their new circuitry, they first built a small 18-bit machine known as TX-0 which first ran in 1956.[4] When the TX-0 successfully proved the basic concepts, attention turned to a much larger system, the 36-bit TX-2 with a then-enormous 64 kWords of core memory. Core was so expensive that parts of TX-0's memory were stripped for the TX-2, and what remained of the TX-0 was then given to MIT on permanent loan.[5]

At MIT, Olsen and Anderson noticed something odd: students would line up for hours to get a turn to use the stripped-down TX-0, while largely ignoring a faster IBM machine that was also available. The two decided that the draw of interactive computing was so strong that they felt there was a market for a small machine dedicated to this role, essentially a commercialized TX-0. They could sell this to users where graphical output or realtime operation would be more important than outright performance. Additionally, as the machine would cost much less than the larger systems then available, it would also be able to serve users that needed a lower-cost solution dedicated to a specific task, where a larger 36-bit machine wouldn't be needed.[6]

In 1957 when the pair and Ken's brother Stan went looking for capital, they found that the American business community was hostile to investing in computer companies. Many smaller computer companies had come and gone in the 1950s, wiped out when new technical developments rendered their platforms obsolete, and even large companies like RCA and General Electric were failing to make a profit in the market. The only serious expression of interest came from Georges Doriot and his American Research and Development Corporation (AR&D). Worried that a new computer company would find it difficult to arrange further financing, Doriot suggested the fledgling company change its business plan to focus less on computers, and even change their name from "Digital Computer Corporation".[6]

The pair returned with an updated business plan that outlined two-phases for the company's development. They would start by selling computer modules as separate stand-alone devices that could be purchased separately and wired together to produce a number of different digital systems for lab use. Then, if these "digital modules" were able to build a self-sustaining business, the company would be free to use them to develop a complete computer in their Phase II.[7] The newly christened DEC received $70,000 from AR&D for a 70% share of the company,[6] and began operations in a Civil War era textile mill in Maynard, Massachusetts, where plenty of inexpensive manufacturing space was available.

Digital modules

System Building Blocks 1103 hex-inverter card (both sides)

In early 1958 DEC shipped its first products, the "Digital Laboratory Module" line. The Modules consisted of a number of individual electronic components and germanium transistors mounted to a circuit board, the actual circuits being based on those from the TX-2.[8]

The Laboratory Module were packaged in an extruded aluminum housing,[9] intended to sit on an engineer's workbench. They were then connected together using banana plug patch cords inserted at the front of the modules. Three versions were offered, running at 5 MHz (1957), 500 kHz (1959), or 10 MHz (1960).[8] The Modules proved to be in high demand in other computer companies, who used them to build equipment to test their own systems. Despite the recession of the late 1950s, the company sold $94,000 worth of these modules during 1958 alone, turning a profit at the end of its first year.[6]

The original Laboratory Modules were soon supplemented with the "Digital Systems Module" line, which were identical internally but packaged differently. The Systems Modules were designed with all of the connections at the back of the module using 22-pin Amphenol connectors, and were attached to each other by inserting them into a custom 19-inch rack. These versions allowed 25 modules be to inserted into a single 5-1/4 inch section of racking, and allowed the high densities needed to build a computer.[8] DEC used the Systems Modules to build their "Memory Test" machine for testing core memory systems, selling about 50 of these pre-packaged units over the next eight years.[10]

Modules were part of DEC's product line into the 1970s, although they went through several evolutions during this time as technology changed. The same circuits were then packaged as the first "R" (red) series "Flip-Chip" modules. Later, other module series provided additional speed, much higher logic density, and industrial I/O capabilities.[11] Digital published extensive data about the modules in free catalogs that became very popular.

PDP-1 family

One of the Computer History Museum's PDP-1 systems. This is a canonical example of the type, with the CPU and main control panel on the left, the Type 30 display in the center, and the Soroban typewriter console on the right.

With the company established and a successful product on the market, DEC turned its attention to the computer market once again as part of its planned "Phase II".[7] In August 1959, Ben Gurley started design of the company's first computer, the PDP-1. In keeping with Doriot's instructions, the name was an initialism for "Programmable Data Processor", leaving off the term "computer". As Gurley put it, "We aren't building computers, we're building 'Programmable Data Processors'." The prototype was first shown publically at the Joint Computer Conference in Boston in December 1959.[12]

The PDP-1 design was based on a number of System Building Blocks packaged into several 19-inch racks to form an 18-bit word computer, supplied standard with 4 kWords of core memory and running at a basic speed of 100,000 operations per second. The racks were themselves packaged into a single large mainframe case, with a hexagonal control panel containing switches and lights mounted to lay at table-top height at one end of the mainframe. Above the control panel was the system's standard input/output solution, a punch tape reader and writer. Most systems were purchased with two peripherals, the Type 30 vector graphics display, and a Soroban Engineering modified IBM Model B Electric typewriter that was used as a printer. The Soroban system was notoriously unreliable, and often replaced with a modified Friden Flexowriter, which also contained its own punch tape system. A variety of more-expensive add-ons followed, including magnetic tape systems, punch card readers and writers, and faster punch tape and printer systems.

The first PDP-1 was delivered to Bolt, Beranek and Newman in November 1960,[13] and formally accepted the next April.[14] In 1962 DEC donated the prototype PDP-1 to MIT, where it was placed in the room next to the TX-0. In this setting the PDP-1 quickly replaced the TX-0 as the favourite machine among the budding hacker culture, and served as the platform for a wide variety of "firsts" in the computing world. Perhaps best known among these is the first computerized video game, Spacewar!, but among the list are the first text editor, word processor, interactive debugger, the first credible computer chess program, and some of the earliest computerized music.[15]

The PDP-1 sold in basic form for $120,000, or about $780,000 in 2005-era USD.[16] BBN's system was quickly followed by orders from Lawrence Livermore and Atomic Energy of Canada (AECL), and eventually 53 PDP-1s were delivered until production ended in 1969.[17][10] All of these machines were still being actively used in 1970, and several were eventually saved. MIT's example was donated to The Computer Museum, Boston, and from there ended up at the Computer History Museum (CHM). A late version of Spacewar! on paper tape was still tucked into the case. PDP-1 #44 was found in a barn in Wichita, Kansas in 1988, apparently formerly owned by one of the many aviation companies in the area, and rescued for the Digital Historical Collection, also eventually ending up at the CHM.[18] AECLs was sent to Science North, but was later scrapped.

When DEC introduced the PDP-1, they also mentioned larger machines at 24, 30 and 36-bits, based on the same design.[19] During construction of the prototype PDP-1, some design work was carried out on a 24-bit PDP-2, and the 36-bit PDP-3. Although the PDP-2 never proceeded beyond the initial design, the PDP-3 found some interest and was designed in full.[20] Only one PDP-3 appears to have been built, in 1960, by the CIA's Scientific Engineering Institute (SEI) in Waltham, Massachusetts. According to the limited information available, they used it to process radar cross section data for the Lockheed A-12 reconnaissance aircraft. Gordon Bell remembered that it was being used in Oregon some time later, but could not recall who was using it.[21]

In November 1962 DEC introduced the $65,000 PDP-4. The PDP-4 was similar to the PDP-1 and used a similar instruction set, but used slower memory and different packaging to lower the price. Like the PDP-1, about 54 PDP-4's were eventually sold, most to a customer base similar to the original PDP-1.[22]

In 1964 DEC introduced its new Flip Chip module design, and used it to re-implement the PDP-4 as the PDP-7. The PDP-7 was introduced in December 1964, and about 120 were eventually produced.[23] An upgrade to the Flip Chip led to the R series, which in turn led to the PDP-7A in 1965.[24] The PDP-7 is most famous as the original machine for the Unix operating system.[25]

A more dramatic upgrade to the PDP-1 series was introduced in August 1966, the PDP-9.[26] The PDP-9 was instruction compatible with the PDP-4 and -7, but ran about twice as fast as the -7 and was intended to be used in larger deployments. At only $19,900 in 1968,[27] the PDP-9 was a big seller, eventually selling 445 machines, more than all of the earlier models combined.[28]

Even while the PDP-9 was being introduced, its replacement was being designed, and was introduced as 1969's PDP-15, which re-implemented the PDP-9 using integrated circuits in place of modules. Much faster than the PDP-9 even in basic form, the PDP-15 also included a floating point unit and a separate input/output processor for further performance gains. Over 400 PDP-15's were ordered in the first eight months of production, and production eventually amounted to 790 examples in twelve basic models.[28] However, by this time other machines in DEC's lineup could fill the same niche at even lower price points, and the PDP-15 would be the last of the 18-bit series.

PDP-8 family

A PDP-8 on display at the Smithsonian's National Museum of American History in Washington, D.C.. This example is from the first generation of PDP-8s, built with discrete transistors and later known as the Straight 8.

In 1962, Lincoln Laboratory used a selection of System Building Blocks to implement a small 12-bit machine, and attached it to a variety of analog-to-digital (A to D) input/output (I/O) devices that made it easy to interface with various analog lab equipment. The LINC proved to attract intense interest in the scientific community, and has since been referred to as the first real minicomputer,[29] a machine that was small and inexpensive enough to be dedicated to a single task even in a small lab.

Seeing the success of the LINC, in 1963 DEC took the basic logic design but stripped away the extensive A to D systems to produce the PDP-5. The new machine, the first outside the PDP-1 mould, was introduced at WESTCON on 11 August 1963. A 1964 ad expressed the main advantage of the PDP-5, "Now you can own the PDP-5 computer for what a core memory alone used to cost: $27,000"[30] 116 PDP-5s were produced until the lines were shut down in early 1967. Like the PDP-1 before it, the PDP-5 inspired a series of newer models based on the same basic design that would go on to be more famous than its parent.

On 22 March 1965, DEC introduced the PDP-8, which replaced the PDP-5's modules with the new R-series modules using Flip Chips. The machine was re-packaged into a small tabletop case, which remains distinctive for its use of smoked plastic over the CPU which allowed one to easily see the wire-wrapped internals of the CPU. Sold standard with 4 kWords of 12-bit core memory and a ASR-33 Teletype for basic input/output, the machine listed for only $18,000. The PDP-8 is referred to as the first real minicomputer because of its sub-$25,000 price.[31][32] Sales were, unsurprisingly, very strong, and helped by the fact that several competitors had just entered the market with machines aimed directly at the PDP-5's market space, which the PDP-8 trounced. This gave the company two years of unrestricted leadership,[33] and eventually 1450 "straight eight" machines were produced before it was replaced by newer implementations of the same basic design.[30]

DEC hit an even lower price-point with the PDP-8/S, the S for "serial". As the name implies the /S used a serial arithmetic unit, which was much slower but reduced costs so much that the system sold for under $10,000.[34] DEC then used the new PDP-8 design as the basis for a new LINC, the two-processor LINC-8. The LINC-8 used one PDP-8 CPU and a separate LINC CPU, and included instructions to switch from one to the other. This allowed customers to run their existing LINC programs, or "upgrade" to the PDP-8, all in software. Although not a huge seller, 142 LINK-8s were sold starting at $38,500.[30] Like the original LINC to PDP-5 evolution, the LINC-8 was then modified into the single-processor PDP-12, adding another 1000 machines to the 12-bit family.[30][35] Newer circuitry designs led to the PDP-8/I and PDP-8/L in 1968.[11] In 1975, one year after an agreement between Digital and Intersil, the Intersil 6100 chip was launched, effectively a PDP-8 on a chip. This was a way to allow PDP-8 software to be run even after the official end-of-life announcement for the Digital PDP-8 product line.

PDP-10 family

A "B" (blue) series Flip Chip module containing nine transistors, 1971

While the PDP-5 introduced a lower-cost line, 1963's PDP-6 was intended to take DEC into the mainframe world with a 36-bit machine. However, the PDP-6 proved to be a "hard sell" with customers, as it offered few advantages over similar machines from the better established vendors like IBM or Honeywell, in spite of its low cost around $300,000. Only 23 were sold,[36] or 26 depending on the source,[37] and unlike earlier models the low sales meant the PDP-6 was not improved with intermediate versions. However, the PDP-6 is historically important as the platform that introduced "Monitor", an early time-sharing operating system that would evolve into the widely used TOPS-10.[38]

In spite of the PDP-6's limited commercial success, it introduced many features that clearly had commercial benefit. When the Flip Chip packaging allowed the PDP-6 to be re-implemented at a much lower cost, DEC took the opportunity to carry out a similar evolution of their 36-bit design and introduced the PDP-10 in 1968. The PDP-10 was as much a success as the PDP-6 was a failure; during its lifetime about 700 mainframe PDP-10's were sold before production ended in 1984.[36] The PDP-10 was widely used in university settings, and thus was the basis of many advances in computing and operating system design during the 1970s. DEC later re-branded all of the models in the 36-bit series as the "DECsystem-10", and PDP-10's are generally referred to by the model of their CPU, like "KA10". Later upgrades produced the compatible DECSYSTEM-20, along with TOPS-20 that included virtual memory.

One of the most unusual peripherals produced for the PDP-10 was the DECtape. The DECtape was a length of standard magnetic tape wound on 5-in reels. However, the recording format was a 10-track approach using fixed-length numbered 'blocks' organized into a standard file structure, including a directory. Files could be written, read, changed and deleted on a DECtape as though it were a hard drive. In fact, some PDP-10 systems had no hard drives at all, using DECtapes alone for their primary data storage. For greater efficiency, the DECtape drive could read and write to a DECtape in both directions.


In 1968 DEC was working on a PDP machine that would be based around 8-bit bytes instead of 6-bit characters. Known as the "PDP-X", the project was eventually cancelled. Several team members decamped and set up Data General in May 1968, and rapidly brought the 16-bit NOVA minicomputer to market. DEC immediately found itself behind in the industry transition to 8-bit bytes, and soon lost its crown as the largest minicomputer vendor.

The PDP-11 16-bit computer was designed in a crash program by Harold McFarland, Gordon Bell, Roger Cady, and others.[39] The project was able to leap forward in design with the arrival of Harold McFarland, who had been researching 16-bit designs at Carnegie Mellon University. One of his simpler designs became the PDP-11, although when they first presented it, management was no impressed and almost cancelled it.[39]

In particular, the new design did not include many of the addressing modes that were intended to made programs smaller in memory, a technique that was widely used on other DEC machines and CISC designs in general. This would mean the machine would spend more time accessing memory, which would slow it down. However, the machine also introduced the idea of "General Registers", which gave the programmer flexibility to use these high-speed memory caches as they needed, potentially addressing the performance issues.

A major advance in the PDP-11 design was UNIBUS, which supported all peripherals through memory mapping. This allowed new devices to be added easily, generally only requiring some sort of hardware interface and then writing software that examined the mapped memory to control them. This spawned a huge market of 3rd party add-ons for the PDP-11, which made the machine even more useful.

Its numerous architectural innovations proved superior to all competitors and the "11" architecture was soon the industry leader, propelling DEC back to their leadership position. The design was later expanded to allow paged physical memory and memory protection features, useful for multitasking and time-sharing, and some models supported separate instruction and data spaces for an effective virtual address size of 128 kB within a physical address size of up to 4 MB. PDP-11's, implemented as single-chip CPU's, continued to be produced until 1996, by which time over 600,000 had been sold.[28]

The PDP-11 supported several operating systems, including Bell Labs' new Unix operating system as well as DEC's DOS-11, RSX-11, IAS, RT-11, DSM-11, and RSTS/E. Many early PDP-11 applications were developed using standalone paper-tape utilities. DOS-11 was the PDP-11's first disk operating system, but was soon supplanted by more capable systems. RSX provided a general-purpose multitasking environment and supported a wide variety of programming languages. IAS was a time-sharing version of RSX-11D. Both RSTS and Unix were time-sharing systems available to educational institutions at little or no cost, and these PDP-11 systems were destined to be the sandbox for a generation of engineers and computer scientists. Large numbers of 11/70s were deployed in telecommunications and industrial control applications. AT&T became DEC's largest customer.

RT-11 provided a practical real-time operating system, allowing the PDP-11 to continue Digital's critical role as a computer supplier for embedded systems. RT-11 served as the inspiration for many microcomputer OS's, as these were generally being written by programmers who cut their teeth on one of the many PDP-11 models. CP/M used a command syntax similar to RT-11's, and even retained the awkward PIP program used to copy other programs. DEC's use of '/' for "switches" (command-line options) would lead to the adoption of '\' for pathnames in Windows as opposed to '/' in Unix.

The evolution of the PDP-11 followed earlier systems, eventually evolving into a single-user deskside personal computer form in the microPDP. 600,000 PDP-11's of all models were eventually sold. Many PDP-11-like machines were also introduced, and a wide variety of peripheral vendors entered the ecosystem. The PDP-11 series was cloned in COMECON countries as the SM EVM series, and was produced in quantities comparable to original PDP-11 production.


A representative VAX-11/780 system configuration

In 1976, DEC decided to extend the PDP-11 architecture to 32-bits while adding a complete virtual memory system to the simple paging and memory protection of the PDP-11, while further improving peripheral support. DEC referred to the result, the VAX-11, as a super-mini. Although it was not the first 32-bit mini, the VAX's combination of features, price and marketing almost immediately propelled it to a leadership position in the market after the VAX-11/780 was released in 1978. The systems were so successful that in 1983, DEC canceled its "Jupiter" project, which had been intended to build a successor to the PDP-10 mainframe, and instead focused on promoting the VAX as their the single computer architecture for the company.[40]

Supporting the VAX's success was the VT52, one of the most successful smart terminals. Building on earlier less successful models (the VT05 and VT50), the VT52 was the first terminal that did everything one might want in a single chassis. The VT52 was followed by the even more successful VT100 and its follow-ons, making DEC one of the largest terminal vendors in the industry. With the VT series, DEC could now offer a complete top-to-bottom system from computer to all peripherals, which formerly required collecting the required devices from different suppliers.

Desperate attempts by competitors such as Data General to win back market share failed, due not only to DEC's successes, but the emergence of the microcomputer and workstation into the lower-end of the minicomputer market.[citation needed] In 1983, DEC canceled its "Jupiter" project, which had been intended to build a successor to the PDP-10, and instead focused on promoting the VAX as their the single computer architecture for the company.[citation needed] It was believed that microprocessor technology at the low end and networking of larger systems could produce a 1:1000 range of computing power from one architecture.[citation needed]

The VAX series had an instruction set that is rich even by today's standards (as well as an abundance of addressing modes). In addition to the paging and memory protection features of the PDP series, the VAX supported virtual memory. The VAX could use both Unix and DEC's own VMS operating system.

Early microcomputer efforts

The introduction of the first general purpose microprocessors inevitably led to the first microcomputers around 1975. At the time these systems were of limited utility, and Ken Olsen famously derided them in 1977, stating "There is no reason for any individual to have a computer in his home."[41] Unsurprisingly, DEC did not put much effort into the microcomputer area in the early days of the market. In the 1980s, DEC built the VT180 (codenamed "Robin"), which was a VT100 terminal with a Z80-based microcomputer running CP/M.

It was only after IBM had successfully launched the IBM-PC that DEC responded with their own systems. Digital responded by introducing not one, but three incompatible machines which were tied to proprietary architectures. The first, the DEC Professional, was based on the PDP-11/23 (the 11/73) running the RSX-11M+ derived, menu-driven, P/OS. The idea was to introduce a machine that outperformed the PC, but in doing so they created one that was more difficult to learn and use than PC-DOS or CP/M which were more commonly used on the 8080 and 8088 based microcomputers of the time. The DECmate was the latest version of the PDP-8 based word processors, but not really suited to general computing, nor competitive with Wang Laboratories word processing that was becoming popular.

The best known of DEC's early microcomputer efforts is the Rainbow 100, which ran an 8086 implementation of CP/M. Applications from standard CP/M could be re-compiled for the Rainbow, but, by this time, users were expecting custom-built applications such as Lotus 1-2-3, which was eventually ported along with MS-DOS V2.0 and introduced in late 1983. Users also objected to having to buy preformatted floppy disks. Although the Rainbow generated some press, all three machines failed spectacularly in the market and are often derided to this day as an example of a company that just didn't "get it".

One last try was introduced in 1986 as the VAXmate along with MS-Windows V1.0 and a VAX/VMS based (file and print) server for Microsoft's network protocols (such as SMB and NetBIOS) along with integration into DEC's own DECnet-family, providing LAN/WAN connection from PC to mainframe (supermini). The VAXmate replaced the Rainbow and in its standard form was the first diskless workstation.

Networking and clusters

In 1984, DEC launched its first 10 Mbit/s Ethernet. Ethernet allowed scalable networking, and VAXcluster allowed scalable computing. Combined with DECnet and Ethernet-based terminal servers (LAT), DEC had produced a networked storage architecture which allowed them to compete directly with IBM. Ethernet replaced token ring, and went on to become the dominant networking model in use today.

In September 1985, DEC became the fifth company to register a .com domain name (

Along with the hardware and protocols, DEC also introduced the VAXcluster concept, which allowed several VAX machines to be tied together into a single larger storage system. VAXcluster's allowed a DEC-based company to scale their services by adding new machines to the cluster at any time, as opposed to buying a faster machine and using that to replace a slower one. The flexibility this offered was compelling, and allowed DEC to attack high-end markets formerly out of their reach.


Although their microcomputer efforts were eventually considered failures, the PDP-11 and VAX lines continued to sell in record numbers. Better yet, DEC was competing very well against the market leader, IBM, taking an estimated $2 billion away from them in the mid-80s. In 1986 Digital's profits rose 38 percent in an industry which was declining, and by 1987 the company was threatening IBM's number one position in the computer industry.[6]

At its peak, Digital was the second-largest computer company in the world, with over 100,000 employees. It was during this time that the company branched out development into a wide variety of projects that were far from its core business in computer machinery. In 1984, DEC launched its first 10 Mbit/s Ethernet. Ethernet allowed scalable networking, and VAXcluster allowed scalable computing. Combined with DECnet and Ethernet-based terminal servers (LAT), DEC had produced a networked storage architecture which allowed them to compete directly with IBM. Ethernet replaced token ring, and went on to become the dominant networking model in use today.

The company also invested heavily in custom software. In the 1970s and earlier most software was custom-written to serve a specific task, but by the 1980s the introduction of relational databases and similar systems allowed powerful software to be built in a modular fashion, potentially saving enormous amounts of development time. Software companies like Oracle became the new darlings of the industry, and DEC started their own efforts in every "hot" niche, in some cases several projects for the same niche. Some of these products competed with DEC's own partners, notably Rdb which competed with Oracle's products on the VAX, part of a major partnership only a few years earlier.

Although many of these products were well designed, most of them were DEC-only or DEC-centric, and customers frequently ignored them and used third-party products instead. This problem was further exacerbated by Olsen's aversion to traditional advertising and his belief that well-engineered products would sell themselves. Hundreds of millions of dollars were spent on these projects, at the same time that workstations based on RISC architecture were starting to approach the VAX in performance.

Faltering in the market

This state of affairs did not last long. As microprocessors continued to improve in the 1980s, it soon became clear that the next generation would offer performance and features equal to the best of DECs low-end minicomputer lineup. Worse, the Berkeley RISC and Stanford MIPS designs were aiming to introduce 32-bit designs that would outperform the fastest members of the VAX family, DEC's cash cow.[42]

Constrained by the huge success of their VAX/VMS products, which followed the proprietary model, the company was very late to respond to these threats. In the early 1990s, DEC found its sales faltering and its first layoffs followed. The company that created the minicomputer, a dominant networking technology, and arguably the first computers for personal use, had abandoned the "low end" market, whose dominance with the PDP-8 had built the company in a previous generation. Decisions about what to do about this threat led to infighting within the company that seriously delayed their responses.

One group suggested that every possible development in the industry be poured into the construction of a new VAX family that would leapfrog the performance of the existing machines. This would limit the market erosion in the top-end segment, where profit margins were maximized and DEC could continue to survive as a minicomputer vendor. This line of thought led, eventually, to the VAX 9000 series, which were plagued with problems when they were first introduced in October 1989, already two years late.[43] The problems took so long to work out, and the prices of the systems were so high, that DEC was never able to make the line the success they hoped.

Others within the company felt that the proper response was to introduce their own RISC designs and use those to build new machines. However, there was little official support for these efforts, and no less than four separate small projects ran in parallel at various labs around the US. Eventually these were gathered into the DEC PRISM project, which delivered a credible 32-bit design with some unique features allowing it to serve as the basis of a new VAX implementation.[44] Infighting with teams dedicated to DEC's big iron made funding difficult, and the design was not finalized until April 1988, and then cancelled shortly thereafter.[45]

Another group concluded that new workstations like those from Sun Microsystems and Silicon Graphics would take away a large part of DEC's existing customer base before the new VAX systems could address the issues, and that the company needed its own Unix workstation as soon as possible. Fed up with slow progress on both the RISC and VAX fronts, a group in Palo Alto started a skunkworks project to introduce their own systems. Selecting the MIPS processor, which was widely available, introducing the new DECstation series with the model 3100 on 11 January 1989.[46] These systems would see some success in the market, but were later displaced by similar models running the Alpha.

32-bit MIPS and 64-bit Alpha systems

Inside view of AlphaServer 2100.

Eventually, in 1992, DEC launched the DECchip 21064 processor, the first implementation of their Alpha instruction set architecture, initially named Alpha AXP (the "AXP" was a "non-acronym" and was later dropped). This was a 64-bit RISC architecture (as opposed to the 32-bit CISC architecture used in the VAX) and one of the first "pure" (not an extension of an earlier 32-bit architecture) 64-bit microprocessor architectures and implementations. The Alpha offered class-leading performance at its launch, and subsequent variants continued to do so into the 2000s. An AlphaServer SC45 supercomputer was still ranked #6 in the world in November 2004.[47] Alpha-based computers (the DEC AXP series, later the AlphaStation and AlphaServer series) superseded both the VAX and MIPS architecture in DEC's product lines, and could run OpenVMS, DEC OSF/1 AXP (later, Digital Unix or Tru64 UNIX) and Microsoft's then-new operating system, Windows NT.

DEC tried to compete in the Unix market by adding POSIX-compatibility features to the VAX/VMS operating system (becoming "OpenVMS") and by selling its own version of Unix (Ultrix on PDP-11, VAX and MIPS architectures; OSF/1 on Alpha), and began to advertise more aggressively. DEC was simply not prepared to sell into a crowded Unix market however, and the low end PC-servers running NT (based on Intel processors) took market share from Alpha-based computers. DEC's workstation and server line never gained much popularity beyond former DEC customers.[citation needed]


In the mid-1990s, Digital Semiconductor collaborated with ARM Limited to produce the StrongARM microprocessor. This was based in part on ARM7 and in part on DEC technologies like Alpha, and was targeted at embedded systems and portable devices. It was highly compatible with the ARMv4 architecture and was very successful, competing effectively against rivals such as the SuperH and MIPS architectures in the portable digital assistant market. Microsoft subsequently dropped support for these other architectures in their PocketPC platform. In 1997, as part of a lawsuit settlement, the StrongARM intellectual property was sold to Intel. They continued to manufacture StrongARM, as well as developing it into the XScale architecture. Intel subsequently sold this business to Marvell Technology Group in 2006.

Designing solutions

Beyond DECsystem-10/20, PDP, VAX and Alpha, Digital 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.[48]

Closing DEC's business

New 1993 corporate logo

In June 1992, Ken Olsen was replaced by Robert Palmer as the company's president. Digital's board of directors also granted Palmer the title of chief executive officer ("CEO"), a title that had never been used during Digital's 35-year existence. Palmer had joined DEC in 1985 to run Semiconductor Engineering and Manufacturing. His relentless campaign to be CEO, and success with the Alpha microprocessor family, made him a candidate to succeed Olsen. At the same time a more modern logo was designed[49]

Until the early 1990s, DEC was a company that was proud to say that it never had a general layoff;[citation needed] following the 1992 economic downturn, layoffs became a very regular event.[citation needed] As the board of directors came to realize that DEC's cost structure and product lines were far too complex and intermingled to allow any significant streamlining, Palmer was tasked with a 5-year plan to sell or spin-off DEC assets with an ultimate goal of dismantling the company:[citation needed]

  • Worldwide training was spun off to form an independent/new company called Global Knowledge Network.
  • Their database product, Rdb, was sold to Oracle.
  • The DLT tape technology was sold to Quantum Corporation in 1994.
  • Text terminal business (VT100 and its successors) was sold in August 1995 to Boundless Technologies.
  • In March 1997, DEC's CORBA-based product, ObjectBroker, and its messaging software, MessageQ, was sold to BEA Systems, Inc.
  • In May 1997, DEC sued Intel for allegedly infringing on its Alpha patents in designing the Pentium chips. As part of a settlement, much of DEC's chip design and fabrication business was sold to Intel. This included DEC's StrongARM implementation of the ARM computer architecture, which Intel sold as the XScale processors commonly used in Pocket PCs. The core of Digital Semiconductor, the Alpha microprocesor group, remained with DEC, while the associated office buildings went to Intel as part of the Hudson, Mass. fabrication site.
  • In 1997, the printer business was sold to GENICOM (now TallyGenicom), which then produced models bearing the Digital logo.
  • At about the same time, the networking business was sold to Cabletron Systems, and subsequently spun off as Digital Network Products Group.
  • The DECtalk and DECvoice voice products were spun off, and eventually arrived at Fonix.
  • The rights to the PDP-11 line and several PDP-11 operating systems were sold to Mentec in 1994.[50]

By 1997 Digital had subsidiary companies in more than two dozen countries including Austria, Australia, Belgium, Brazil, Canada, China (People's Republic), Columbia, Cyprus, Czech Republic, Denmark, Finland, France, Ireland, Israel, Japan, Jersey States, New Zealand, Netherlands, Norway, Russia, Singapore, Spain, Sweden, Switzerland, Taiwan, and the United Kingdom.[51]

Eventually, on January 26, 1998, what remained of the company (including Digital's multivendor global services organization and customer support centers) was sold to Compaq, which was acquired by Hewlett-Packard in 2002. The remainder of Digital Semiconductor (the Alpha microprocessor group) was sold to Intel, which placed those employees back in their Hudson, Mass. office which they had vacated when the site was sold to Intel in 1997. Compaq, and later HP, continued to sell many of the former Digital products but rebranded with their own logos. For example, HP now sells what were formerly Digital's StorageWorks disk/tape products,[52] as a result of the Compaq acquisition.

The Digital logo survived for a while after the company ceased to exist, as the logo of Digital GlobalSoft, an IT services company in India (which was a 51 percent subsidiary of Compaq). Digital GlobalSoft was later renamed "HP GlobalSoft" (also known as the "HP Global Delivery India Center" or HP GDIC) and no longer uses the Digital logo.

The and domain names are now owned by Hewlett-Packard and redirect to their US website.[53]

The Digital Federal Credit Union (DCU), which was chartered in 1979 for employees of DEC, is now open to essentially everyone, with over 700 different sponsors, including the companies that acquired pieces of DEC.


DEC's Research Laboratories (or Research Labs, as they were commonly known) conducted Digital'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 Digital's Research Labs or Digital's R&D in general include:

Some of the work of the Research Labs was published in the Digital Technical Journal,[54], which was in published from 1985 until 1998.[55]


Digital supported the ANSI standards, especially the ASCII character set, which survives in Unicode and the ISO 8859 character set family. Digital'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 programming language and the UNIX operating system ran on Digital'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 Digital itself did not encourage the use of Unix.

Digital also produced the popular VAX computer family, the first pure 64-bit microprocessor architecture (Alpha AXP), the first commercially successful workstation (the VT-78), and some commercially unsuccessful personal computers. The central computing system of the Soviet reusable Buran spaceship was based on two MicroVAX computers.[citation needed]

Digital produced widely used 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. Digital was an early champion of time-sharing systems.

Digital was to the command-line interface (CLI) what Apple was to the GUI: there was history before and innovation after, but it was Digital's operating systems that put it together in a complete and definitive form. The command-line interfaces found in Digital'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 Digital's OSes, including command names such as DIR and HELP and the "name-dot-extension" file naming conventions.

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.

Digital, Intel and Xerox through their collaboration to create the DIX standard, were champions of Ethernet, but Digital 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 controllers from Digital 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".

Digital 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. HSCs delivered the first hardware RAID 0 and 1 capabilities and the first serial interconnects of multiple storage technologies. This technology was the forerunner to systems like Network of Workstations which are used for massively cooperative tasks such as web-searches and drug research.

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).

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. Digital was the primary sponsor for this project, which was one of the first large scale free software projects,[citation needed] a contemporary of the GNU Project but not associated with it.

Dave Cutler, who led the development of RSX-11M, RSX-11M+, VMS and then VAXeln, left Digital in 1988 to lead the development of Windows NT which was initially intended to be an "open" operating system that would run on more powerful processors than the existing predominant x86 architecture. While DEC did see value in continuing its X Window System environment to support engineering customers, it understood that future mid-range based customers would demand a faster and more user friendly Graphical User Interface (GUI), potentially offered through the Windows environment.[citation needed] As Microsoft had experience, technology and patents that would give them upper hand in advancing GUI technology, DEC opted to partner with Microsoft's development of Windows NT for mid-range processors and share in the R&D process of creating faster computers using their RISC Alpha processors.[citation needed] Microsoft was not exclusively bound to the Alpha chip so it pursued other processor manufacturers such as IBM with the PowerPC architecture and eventually capitalized on the emerging strength of the Intel x86 based processors. While most would say that the market determined its own course through the more cost efficient processors produced by Intel, DEC quickly came to realize that its loose partnership with Microsoft would lead to its own undoing in terms of being a major player in the mid-range processor market.

Notes-11 and its follow-on product, VAXnotes, 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.

Digital was one of the first businesses connected to the Internet with, registered in 1985,[56] being one of the first of the now ubiquitous .com domains. was a well-known software repository during the pre-World Wide Web days, but Digital was also the first computer vendor to open a public website, on October 1, 1993.[57] The popular AltaVista, created by Digital, was one of the first comprehensive Internet search engines. (Although Lycos was earlier, it was much more limited.)

DEC invented Digital Linear Tape (DLT), formerly known as CompacTape, which began as a compact backup medium for MicroVAX systems, and later grew to capacities of 800 gigabytes.

Work on the first hard-disk-based MP3-player, the Personal Jukebox, started at the DEC Systems Research Center. (The project was started about a month before the merger into Compaq was completed.)

DEC's Western Research Lab created the Itsy Pocket Computer. This was developed into the Compaq iPaq line of PDAs, which replaced the Compaq Aero PDA.


  • The first spam in computer history was sent on May 3, 1978 by a Digital employee. Over 400 people received his promotional message via the ARPANET network.
  • In 1960, DEC engineers realized that in specifying connectors on a frame, where numbers mark the card slot locations and letters mark the connectors on individual cards, some letters cause confusion. Thus the letters G, I, O, and Q were dropped to avoid confusion with C, 1, and 0. The remaining 22 letters were since known as the DEC alphabet[citation needed]. Similar alphabet subsets are used in other applications, for example, seat numbering and record locators used by airlines, and Vehicle Identification Numbers used by motor vehicle manufacturers.
  • In 1988 word spread through the very small UNIX community within DEC that AT&T (who was a very major consumer of DEC hardware at the time) was interested in selling the UNIX operating system to DEC for a reported $100 million. As DEC's quarterly profits were anywhere from $50 million to $250 million this was a comparatively small cost. It was reported that DEC declined and dismissed the offer because its president had determined the UNIX operating system to be "a toy".[citation needed]
  • In 1977 Ken Olsen president of DEC said "There is no reason for any individual to have a computer in his home". History proved otherwise.

User organizations

Originally the users' group was called DECUS (Digital Equipment Computer User Society) during the 1960s to 1990s. When Compaq acquired Digital 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.


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  11. ^ a b Present 1978, pg. 10
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  48. ^ For in-depth articles regarding Digital technologies, refer to the archived Digital Technical Journal
  49. ^ Ned Batchelder and
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  53. ^,
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  57. ^ DECTEI-L Archives - February 1994 (#2)


  • (Present), "Digital Equipment Corporation: Nineteen Fifty-Seven to the Present", DEC Press, 1978
  • David Donald Miller, "OpenVMS Operating System Concepts", Elsevier, 1997
  • Alan R. Earls, Digital Equipment Corporation; Arcadia Publishing, 2004, ISBN 0-7385-3587-7.
  • Edgar H. Schein, Peter S. DeLisi, Paul J. Kampas, and Michael M. Sonduck, DEC Is Dead, Long Live DEC - The Lasting Legacy of Digital Equipment Corporation; San Francisco: Barrett-Koehler, 2003, ISBN 1-57675-225-9.
  • Jamie P. Pearson, Digital At Work - Snapshots of the First 35 Years; Digital Press, 1992, ISBN 1-5555-8092-0
  • Glenn Rifkin, and George Harrar, The Ultimate Entrepreneur - The Story of Ken Olsen and Digital Equipment Corporation; Contemporary Books, 1988, ISBN 0-8092-4559-0.
  • C. Gordon Bell, J. Craig Mudge, and John E. McNamara, Computer Engineering - A DEC View of Hardware Systems Design; Digital Press, 1978, ISBN 0-932376-00-2.

External links

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