Editing Digital Equipment Corporation (section)

== History ==
=== Origins (1944–1958) ===
[[File:Digital Equipment Corporation 1987 logo.svg|thumb|Original Digital Equipment Corporation logo designed by Elliot Hendrickson in 1957,<ref>{{cite web|url=https://nedbatchelder.com/blog/200712/ancient_history_the_digital_logo.html|title=Ancient history: the Digital logo|last=Batchelder|first=Ned|date=December 16, 2007}}</ref> used from 1957 to 1993]]
[[File:Digital Equipment Corporation stacked logo.svg|thumb|upright=0.25|Alternate logo, briefly used concurrently]]
[[File:Maynard MA Clock Tower Place.jpg|thumb|upright|DEC was headquartered at a former wool mill in Maynard, Massachusetts, from 1957 until 1992.]]
[[Ken Olsen]] and [[Harlan Anderson]] were two engineers who had been working at [[MIT Lincoln Laboratory]]<ref>{{cite news |newspaper=The New York Times |date=February 8, 2011
|title=Ken Olsen, Founder of DEC, Dies at 84
|first=Glenn|last=Rifkin
|url=https://www.nytimes.com/2011/02/08/technology/business-computing/08olsen.html}}</ref> 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 (computer)|Whirlwind]], which was originally developed to make a [[flight simulator]] for the [[US Navy]], although this was never completed.<ref>{{cite press release|url=http://www.mitre.org/news/releases/09/whirlwind_07_01_2009.html|title=MITRE's Project Whirlwind Computer Collection Transferred to MIT|publisher=MITRE|date=July 1, 2009|archive-url=https://web.archive.org/web/20100620113119/http://www.mitre.org/news/releases/09/whirlwind_07_01_2009.html|archive-date=June 20, 2010|url-status=dead}}</ref> Instead, this effort evolved into the [[Semi Automatic Ground Environment|SAGE]] system for the [[US Air Force]], which used large screens and [[light gun]]s to allow operators to interact with [[radar]] data stored in the computer.<ref>{{cite web|url=http://www.mitre.org/about/sage.html|title=Semi-Automatic Ground Environment (SAGE)|archive-url=https://web.archive.org/web/20090513053849/http://www.mitre.org/about/sage.html|archive-date=May 13, 2009|url-status=dead|website=MITRE|date=January 25, 2005}}</ref>

When the Air Force project wound down, the Lab turned their attention to an effort to build a version of the Whirlwind using [[transistor]]s in place of [[vacuum tube]]s. In order to test their new circuitry, they first built a small [[18-bit computing|18-bit]] machine known as [[TX-0]], which first ran in 1956.<ref>{{cite web|url=https://dspace.mit.edu/bitstream/1721.1/4132/1/RLE-TR-627-42827671.pdf |archive-url=https://web.archive.org/web/20070629111143/http://dspace.mit.edu/bitstream/1721.1/4132/1/RLE-TR-627-42827671.pdf |archive-date=2007-06-29 |url-status=live|title=TX-0 Computer History|first=John A.|last=McKenzie|date=October 1, 1974}}</ref> When the TX-0 successfully proved the basic concepts, attention turned to a much larger system, the [[36-bit computing|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.<ref name="cm">{{cite web|url=http://ed-thelen.org/comp-hist/TheCompMusRep/TCMR-V08.html|title=Highlights from ''The Computer Museum Report'' Volume 8 Spring 1984|archive-url=https://web.archive.org/web/20060615180503/http://ed-thelen.org/comp-hist/TheCompMusRep/TCMR-V08.html|archive-date=June 15, 2006|url-status=dead|publisher=[[The Computer Museum, Boston|The Computer Museum]], Boston, MA|via=ed-thelen.org|access-date=February 19, 2010}}</ref>

At MIT, [[Ken Olsen]] and [[Harlan 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 the graphical output or real-time 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 would not be needed.<ref name=companyhistory/>{{dead link|date=February 2020}}{{better source needed|date=February 2020}}

In 1957, when the pair and Ken's brother Stan sought 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".<ref name=companyhistory/>{{dead link|date=February 2020}}{{better source needed|date=February 2020}}

The pair returned with an updated [[business plan]] that outlined two phases for the company's development. They would start by selling [[computer module]]s as 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.<ref name="proposal">{{cite web|url=http://archive.computerhistory.org/resources/text/dec/pdp-1/DEC.pdp_1.1957.102664472.pdf|title=A Proposal to American Research and Development Corporation 27 May 1957|archive-url=https://web.archive.org/web/20160416092909/http://archive.computerhistory.org/resources/text/dec/pdp-1/DEC.pdp_1.1957.102664472.pdf|archive-date=April 16, 2016|url-status=dead}}</ref> The newly christened "Digital Equipment Corporation" received $70,000 from AR&D for a 70% share of the company,<ref name=companyhistory/>{{dead link|date=February 2020}}{{better source needed|date=February 2020}} and began operations in a [[American Civil War|Civil War]]-era textile mill in [[Maynard, Massachusetts]], where plenty of inexpensive manufacturing space was available.

=== Digital modules (1958) ===
[[File:Dec SYSTEM BUILDING BLOCKS 1103.jpg|thumb|System Building Blocks (System Module) 1103 hex-inverter card (both sides)]]
[[File:PDP-1 System Building Block No. 4106.jpg|thumb|PDP-1 System Building Block #4106, circa 1963 - note that one transistor (yellow) has been replaced]]

In early 1958, DEC shipped its first products, the "Digital Laboratory Module" line. The Modules consisted of a number of individual electronic components and [[Bipolar junction transistor#Germanium transistors|germanium transistors]] mounted to a [[circuit board]], the actual circuits being based on those from the TX-2.<ref name="modules">{{cite book|first1=Richard|last1=Best|first2=Russell|last2=Doane|first3=John|last3=McNamara|chapter-url=http://research.microsoft.com/en-us/um/people/gbell/computer_engineering/00000125.htm|chapter=Digital Modules, The Basis for Computers|url=http://bitsavers.org/pdf/dec/_Books/Bell-ComputerEngineering.pdf |archive-url=https://web.archive.org/web/20100312072729/http://www.bitsavers.org/pdf/dec/_Books/Bell-ComputerEngineering.pdf |archive-date=2010-03-12 |url-status=live|title=Computer Engineering, A DEC view of hardware systems design|publisher=Digital Press|date=1978}}</ref>

The Laboratory Modules were packaged in an extruded aluminum housing,<ref>{{cite web |url=http://www.computerhistory.org/collections/accession/102633142 |title=DEC Laboratory Module&nbsp;– FLIP-FLOP 201 |website=Computer History Museum|date=1960 }}</ref> intended to sit on an engineer's workbench, although a [[19-inch rack|rack-mount]] bay was sold that held nine laboratory modules.<ref name="BuildingBlock1960">{{cite book|url=http://ed-thelen.org/comp-hist/DECbuildingBlockLogic2ndEd.pdf |archive-url=https://web.archive.org/web/20130702192719/http://ed-thelen.org/comp-hist/DECbuildingBlockLogic2ndEd.pdf |archive-date=2013-07-02 |url-status=live|title=DEC Building Block Logic|edition=Second|publisher=Digital Equipment Corporation|date=November 1960}}</ref> They were then connected together using [[4 mm plug|banana plug]] [[patch cord]]s inserted at the front of the modules. Three versions were offered, running at 5&nbsp;MHz (1957), 500&nbsp;kHz (1959), or 10&nbsp;MHz (1960).<ref name="modules" /> The Modules proved to be in high demand by 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 ({{Inflation|US|94000|1958|r=-2|fmt=eq}}), turning a profit at the end of its first year.<ref name=companyhistory/>{{dead link|date=February 2020}}{{better source needed|date=February 2020}}

The original Laboratory Modules were soon supplemented with the "Digital [[System 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 plugging them into a backplane that could be mounted in a [[19-inch rack]]. The backplanes allowed 25 modules in a single 5-1/4&nbsp;inch section of rack, and allowed the high densities needed to build a computer.<ref name=modules/>

The original laboratory and system module lines were offered in 500 kilocycle, 5 megacycle and 10 megacycle versions. In all cases, the supply voltages were -15 and +10 volts, with logic levels of -3 volts (passive pull-down) and 0 volts (active pull-up).<ref name="BuildingBlock1960" />

DEC used the System 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.<ref name="present3">''Present'' 1978, pg. 3</ref> The [[PDP-1]] and [[LINC]] computers were also built using System Modules (see below).

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 module|Flip-Chip]]" modules. Later, other Flip-Chip module series provided additional speed, much higher logic density, and industrial I/O capabilities.<ref name=present10/> DEC published extensive data about the modules in free catalogs that became very popular.

=== PDP-1 family (1960) ===
{{Main|PDP-1}}
[[File:Steve Russell and PDP-1 - Vintage Computer Fair 2006.jpg|thumb|right|A [[PDP-1]] system, with [[Steve Russell (computer scientist)|Steve Russell]], developer of [[Spacewar!]] at the console. This is a canonical example of the PDP-1, with the console typewriter on the left, CPU and main control panel in the center, the Type 30 display 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".<ref name=proposal/> 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 publicly at the Joint Computer Conference in Boston in December 1959.<ref>[http://www.computerhistory.org/collections/accession/102634161 Eastern Joint Computer Conference and Exhibition], official program of 1959 meeting in Boston</ref> The first PDP-1 was delivered to [[Bolt, Beranek and Newman]] in November 1960,<ref>{{cite web |date=January 30, 1998 |title=1960 Timeline |url=https://research.microsoft.com/en-us/um/people/gbell/Digital/timeline/1960.htm |access-date=September 6, 2022 |work=DIGITAL Computing Timeline}}</ref> and formally accepted the next April.<ref>''Computers and Automation'', April 1961, pg. 8B</ref> The PDP-1 sold in basic form for $120,000 ({{Inflation|US|120000 |1961|r=0|fmt=eq}}).<ref>[http://www.bls.gov/data/inflation_calculator.htm "Bureau of Labor Statistics Inflation Calculator, 1961–2025"]</ref> By the time production ended in 1969, 53 PDP-1s had been delivered.<ref name=present3/><ref>"History of Computing", Lexikon Services, {{ISBN|0-944601-78-2}}</ref>

The PDP-1 was supplied standard with 4096 words of [[core memory]], [[18-bit computing|18-bit]]s per word, and ran at a basic speed of 100,000 operations per second. It was constructed using many System Building Blocks that were packaged into several [[19-inch rack]]s. The racks were themselves packaged into a single large mainframe case, with a hexagonal control panel containing switches and lights mounted to lie at table-top height at one end of the mainframe. Above the control panel was the system's standard [[input/output]] solution, a [[punched tape]] reader and writer. Most systems were purchased with two [[peripherals]], the Type 30 [[vector graphics]] display, and a [[Soroban Engineering]] modified [[IBM Electric typewriter|IBM Model B Electric typewriter]] that was used as a [[printer (computing)|printer]]. The Soroban system was notoriously unreliable, and often replaced with a modified [[Friden Flexowriter]], which also contained its own punched tape system. A variety of more-expensive add-ons followed, including [[magnetic tape]] systems, [[punched card]] readers and punches, and faster punched tape and printer systems.

When DEC introduced the PDP-1, they also mentioned larger machines at 24, 30 and 36 bits, based on the same design.<ref>''Datamation'', Volume 5 Number 6 (November/December), pg. 24</ref> 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.<ref>{{cite book|url=https://www.gutenberg.org/ebooks/29461|title=Preliminary Specifications: Programmed Data Processor Model Three (PDP-3)|publisher=DEC|date=October 1960}}</ref> 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.<ref>{{cite web|url=http://www.decconnection.org/announcements.htm|title=Announcements from The DEC Connection|at=Anyone seen a PDP-3 lately?|website=The DEC Connection|date=January 14, 2007|access-date=March 8, 2010|archive-date=February 25, 2019|archive-url=https://web.archive.org/web/20190225233751/http://www.decconnection.org/announcements.htm|url-status=dead}}</ref>

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-4s were eventually sold, most to a customer base similar to the original PDP-1.<ref>{{cite web |date=January 30, 1998 |title=PDP-4 |url=http://research.microsoft.com/en-us/um/people/gbell/digital/timeline/1962-1.htm |access-date=September 6, 2022 |work=DIGITAL Computing Timeline}}</ref>

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.<ref>{{cite web |date=January 30, 1998 |title=PDP-7 |url=http://research.microsoft.com/en-us/um/people/gbell/digital/timeline/1964-3.htm |access-date=January 9, 2014 |work=DIGITAL Computing Timeline}}</ref> An upgrade to the Flip Chip led to the R series, which in turn led to the PDP-7A in 1965.<ref>{{cite web |date=January 30, 1998 |title=PDP-7A |url=http://research.microsoft.com/en-us/um/people/gbell/digital/timeline/1965-1.htm |access-date=September 6, 2022 |work=DIGITAL Computing Timeline}}</ref> The PDP-7 is most famous as the machine for which the [[Unix]] operating system was originally written.<ref>{{cite web|first=Eric Steven|last=Raymond|author-link=Eric S. Raymond|url=http://www.catb.org/~esr/writings/taoup/html/ch02s01.html|title=Origins and History of Unix, 1969–1995|date=September 19, 2003}}</ref> Unix ran only on DEC systems until the [[Interdata 8/32]].<ref name="fiedler198310">{{cite magazine | url=https://archive.org/stream/byte-magazine-1983-10/1983_10_BYTE_08-10_UNIX#page/n133/mode/2up | title=The Unix Tutorial / Part 3: Unix in the Microcomputer Marketplace | magazine=[[Byte (magazine)|Byte]] |volume=8 |issue=10 | date=October 1983 | access-date=January 30, 2015 | last=Fiedler |first=Ryan | page=148}}</ref>

A more dramatic upgrade to the PDP-1 series was introduced in August 1966, the [[PDP-9]].<ref>{{cite web |date=January 30, 1998 |title=PDP-9 |url=http://research.microsoft.com/en-us/um/people/gbell/digital/timeline/1966-1.htm |access-date=September 6, 2022 |work=DIGITAL Computing Timeline}}</ref> 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,<ref>DEC Advertisement, ''Chemical and Engineering News'', Volume 46 (1968), pg. 85</ref> the PDP-9 was a big seller, eventually selling 445 machines, more than all of the earlier models combined.<ref name="miller452">Miller 1997, pg. 452</ref>

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 12 basic models.<ref name=miller452/> 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 (1962) ===
{{Main|PDP-8}}
[[File:PDP-8.jpg|thumb|upright|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]],<ref>{{cite web|url=https://www.historyofinformation.com/detail.php?id=786|title=Wesley Clark Builds the LINC, Perhaps the First Mini-Computer|first=Jeremy|last=Norman|website=HistoryofInformation.com}}</ref> 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 August 11, 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".<ref>{{cite web |url=http://ed-thelen.org/comp-hist/pdp-5.html |title=PDP-5}}{{better source needed|date=August 2022}}</ref> 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 March 22, 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 logic modules plugged into the wire-wrapped backplane of the CPU. Sold standard with 4 kWords of 12-bit core memory and a [[Teletype Model 33]] ASR 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.<ref>{{cite web |url=http://www.sciencemuseum.org.uk/objects/computing_and_data_processing/1982-960.aspx |title=DEC PDP-8 minicomputer, 1965 |website=The Science Museum |archive-url=https://web.archive.org/web/20100318023031/http://www.sciencemuseum.org.uk/objects/computing_and_data_processing/1982-960.aspx |archive-date=March 18, 2010 |url-status=dead}}</ref><ref>{{cite web |url=https://www.computerhistory.org/internethistory/1960s/ |title=Internet History of 1960s |at=1965 |website=Computer History Museum}}</ref> 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,<ref>''Present'' 1978, pg. 7</ref> and eventually 1450 "straight eight" machines were produced before it was replaced by newer implementations of the same basic design.<ref name=faqpdp8>{{cite web |url=https://ed-thelen.org/comp-hist/pdp-8.html |title=PDP-8}}{{better source needed|date=August 2022}}</ref>

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.<ref>''Present'' 1978, pg. 8</ref> 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 LINC-8s were sold starting at $38,500.<ref name=faqpdp8/> 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.<ref name=faqpdp8/><ref name="miller456">Miller 1997, pg. 456</ref> Newer circuitry designs led to the PDP-8/I and PDP-8/L in 1968.<ref name="present10">''Present'' 1978, pg. 10</ref> In 1975, one year after an agreement between DEC 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 DEC PDP-8 product line.

=== PDP-6 and PDP-10 families (1963 and 1968) ===
{{Main|PDP-6|PDP-10}}
[[File:KA10 mod end.jpg|thumb|right|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 computer|mainframe]] market with a [[36-bit computing|36-bit]] machine. However, the PDP-6 proved to be a "hard sell" with customers, as it offered few obvious 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,<ref name="miller457">Miller 1997, pg. 457</ref> or 26 depending on the source,<ref>{{cite web |date=January 30, 1998 |title=PDP-6 |url=http://research.microsoft.com/~gbell/Digital/timeline/1964-1.htm |access-date=September 6, 2022 |work=DIGITAL Computing Timeline}}</ref> and unlike other models the low sales meant the PDP-6 was not improved with successor 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]].<ref>{{cite web|url=http://www.bitsavers.org/pdf/dec/pdp6/PDP-6_TimsharingBroch.pdf |archive-url=https://web.archive.org/web/20040827060926/http://www.bitsavers.org/pdf/dec/pdp6/PDP-6_TimsharingBroch.pdf |archive-date=2004-08-27 |url-status=live|title=PDP-6 Timesharing Software|id=DEC Publication F-61B}}</ref>

When newer Flip Chip packaging allowed the PDP-6 to be re-implemented at a much lower cost, DEC took the opportunity to refine their 36-bit design, introducing the [[PDP-10]] in 1968. The PDP-10 was as much a success as the PDP-6 was a commercial failure; about 700 mainframe PDP-10s were sold before production ended in 1984.<ref name=miller457/> 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-10s are generally referred to by the model of their CPU, starting with the "KA10", soon upgraded to the "KI10" (I:Integrated circuit); then to "KL10" (L:Large-scale integration [[Emitter-coupled logic|ECL logic]]); also the "KS10" (S: Small [[Computer form factor|form factor]]). Unified product line upgrades produced the compatible [[DECSYSTEM-20]], along with a [[TOPS-20]] operating system that included [[virtual memory]] support.

The Jupiter Project was supposed to continue the mainframe product line into the future by using [[gate array]]s with an innovative Air Mover Cooling System, coupled with a built-in floating point processing engine called "FBOX". The design was intended for a top tier scientific computing niche, yet the critical performance measurement was based upon COBOL compilation which did not fully utilize the primary design features of Jupiter technology.{{citation needed|date=September 2015}} When the Jupiter Project was cancelled in 1983, some of the engineers adapted aspects of the 36-bit design into a forthcoming 32-bit design, releasing the high-end VAX8600 in 1985.

=== PDP-11 (1970) ===
{{Main|PDP-11}}
[[File:Digital PDP11-IMG 1498 cropped.jpg|thumb|PDP-11/20, the first model of PDP-11 on display at [[École Polytechnique Fédérale de Lausanne|EPFL]] ]]

DEC's successful entry into the computer market took place during a fundamental shift in the underlying organization of the machines from [[Word (computer architecture)|word]] lengths based on 6-bit characters to those based on 8-bit words needed to support [[ASCII]].{{efn|Although ASCII is a 7-bit standard, units-of-8-bits are typically used for machines that support it.}} DEC began studies of such a machine, the PDP-X, but [[Ken Olsen]] did not support it as he could not see how it offered anything their existing 12-bit or 18-bit machines didn't.<ref>{{cite web |url=http://simh.trailing-edge.com/docs/pdpx.pdf |archive-url=https://web.archive.org/web/20041210092501/http://simh.trailing-edge.com/docs/pdpx.pdf |archive-date=2004-12-10 |url-status=live |title=What Was The PDP-X? |first=Bob |last=Supnik |date=January 10, 2004}}</ref> This led the leaders of the PDP-X project to leave DEC and start [[Data General]], whose 16-bit [[Data General Nova]] was released in 1969 and was a huge success.<ref>{{cite interview |interviewer=Gardner Hendrie |first=Edson |last=de Castro |author-link=Edson de Castro |title=Oral History of Edson (Ed) D. de Castro |date=November 22, 2002 |url=http://archive.computerhistory.org/resources/access/text/2012/07/102702207-05-01-acc.pdf |archive-url=https://web.archive.org/web/20141227091345/http://archive.computerhistory.org/resources/access/text/2012/07/102702207-05-01-acc.pdf |archive-date=2014-12-27 |url-status=live}}</ref>

The success of the Nova finally prompted DEC to take the switch seriously, and they began a crash program to introduce a 16-bit machine of their own. The new system was designed primarily by Harold McFarland, [[Gordon Bell]], Roger Cady, and others.<ref name="birth">{{cite web|first=Larry|last=McGowan|url=http://hampage.hu/pdp-11/birth.html|title=How the PDP-11 Was Born, according to Larry McGowan|date=August 19, 1998}}</ref> 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 basis for the new design, although when they first viewed the proposal, management was not impressed and almost cancelled it.<ref name=birth/>

The result was the [[PDP-11]], released in 1970. It differed from earlier designs considerably. In particular, the new design did not include many of the [[addressing mode]]s that were intended to make programs smaller in memory, a technique that was widely used on other DEC machines and [[Complex instruction set computing|CISC]] designs in general. This would mean the machine would spend more time accessing memory, which would slow it down. However, the machine also extended the idea of multiple "General Purpose Registers" (GPRs), which gave the programmer flexibility to use these high-speed memory caches as they needed, potentially addressing the performance issues.

[[File:PDP-11-34 unibus slots.jpg|thumb|PDP-11/34 top view, showing the [[:en:Unibus|Unibus]] slots with the CPU, [[:en:RK05|DK drive controller]] and other options]]
A major advance in the PDP-11 design was DEC's [[Unibus]], which supported all peripherals through [[Memory-mapped I/O|memory mapping]]. This allowed a new device to be added easily, generally only requiring plugging a hardware interface board into the backplane and possibly adding a jumper to the [[wire wrap]]ped backplane, and then installing software that read and wrote to the mapped memory to control it. The relative ease of interfacing spawned a huge market of third party add-ons for the PDP-11, which made the machine even more useful.

The combination of architectural innovations proved superior to competitors and the "11" architecture was soon the industry leader, propelling DEC back to a strong market position. The design was later expanded to allow [[Paging|paged physical memory]] and [[memory protection]] features, useful for [[Computer multitasking|multitasking]] and [[time-sharing]]. Some models supported separate instruction and data spaces for an effective virtual address size of 128&nbsp;KB within a physical address size of up to 4&nbsp;MB. Smaller PDP-11s, implemented as single-chip CPUs, continued to be produced until 1996, by which time over 600,000 had been sold.<ref name=miller452/>

[[File:RT-11 help.jpg|thumb|The [[RT-11]] interactive help screen displayed on a [[VT100]] display terminal]]

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 [[computer multitasking|multitasking]] environment and supported a wide variety of [[programming language]]s. 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 rising generation of engineers and computer scientists. Large numbers of PDP-11/70s were deployed in telecommunications and industrial control applications. [[AT&T Corporation]] became DEC's largest customer.

RT-11 provided a practical real-time operating system in minimal memory, allowing the PDP-11 to continue DEC's critical role as a computer supplier for [[embedded system]]s. Historically, RT-11 also 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. For example, [[CP/M]] used a command syntax similar to RT-11's, and even retained the awkward [[Peripheral Interchange Program|PIP]] program used to copy data from one computer device to another. As another historical footnote, DEC's use of "/" for "switches" (command-line options) would lead to the adoption of "\" for pathnames in [[MS-DOS]] and [[Microsoft Windows]] as opposed to "/" in [[Unix]].<ref name="afu-faq">{{cite web|url=http://www.netwhatever.com/faq/inicio.html#queIII15|title=III.15 - Why does MS-DOS use '\' as the path separator, while Unix uses '/'?|work=alt.folklore.computers List of Frequently Asked Questions}}</ref>

The evolution of the PDP-11 followed earlier systems, eventually including a single-user deskside personal computer form, the MicroPDP-11. In total, around 600,000 PDP-11s of all models were sold, and a wide variety of third-party peripheral vendors had also entered the computer product ecosystem. It was even sold in kit form as the [[Heathkit H11]], although it proved too expensive for [[Heathkit]]'s traditional hobbyist market.

=== VAX (1977) ===
[[File:LCM - DEC VAX 11-780-5 - 01.jpg|thumb|DEC VAX 11/780-5 at [[Living Computers: Museum + Labs]] ]]
{{Main|VAX}}

The introduction of [[semiconductor memory]] in the early 1970s, and especially [[dynamic RAM]] shortly thereafter, led to dramatic reductions in the price of memory as the effects of [[Moore's Law]] were felt. Within years, it was common to equip a machine with all the memory it could address, typically 64&nbsp;KB on 16-bit machines. This led vendors to introduce new designs with the ability to address more memory, often by extending the address format to 18 or 24 bits in machines that were otherwise similar to their earlier 16-bit designs.{{efn|An example is the DG Nova 840, which used a 17-bit format, up from the previous 15-bits.}}

In contrast, DEC decided to make a more radical departure. In 1976, they began the design of a machine whose entire architecture was expanded from the 16-bit PDP-11 to a new 32-bit basis. This would allow the addressing of very large memories, which were to be controlled by a new [[virtual memory]] system, and would also improve performance by processing twice as much data at a time. The system would, however, maintain compatibility with the PDP-11, by operating in a second mode that sent its 16-bit words into the 32-bit internals, while mapping the PDP-11's 16-bit memory space into the larger virtual 32-bit space.<ref name=VAX/>

The result was the [[VAX]] architecture, where VAX stands for Virtual Address eXtension (from 16 to 32 bits). The first computer to use a VAX CPU was the [[VAX-11/780]], announced in October 1977, which DEC referred to as a ''[[superminicomputer]]''. Although it was not the first 32-bit minicomputer, the VAX-11/780's combination of features, price, and marketing almost immediately propelled it to a leadership position in the market after it was released in 1978. VAX 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 the single computer architecture for the company.<ref name=VAX>{{cite book| title = Electronic Business| url = https://books.google.com/books?id=W7skAQAAIAAJ&pg=PA76| year = 1984| publisher = Cahners| page = 76 }}</ref>

Supporting the VAX's success was the [[VT52]], one of the most successful [[Computer terminal|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 inexpensive 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. This was supported by a line of inexpensive [[computer printer]]s, the [[DECwriter]] line. With the VT and DECwriter 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.

The VAX processor architecture and family of systems evolved and expanded through several generations during the 1980s, culminating in the [[NVAX]] [[microprocessor]] implementation and [[VAX 7000/10000]] series in the early 1990s.<ref name="nvax">{{cite web|url=http://simh.trailing-edge.com/semi/nvax.html|title=DEC Microprocessors: NVAX (1991)}}</ref>

=== Early microcomputers (1982–1986) ===
When a DEC research group demonstrated two prototype [[microcomputer]]s in 1974—before the debut of the [[MITS Altair]]—Olsen chose to not proceed with the project. The company similarly rejected another personal computer proposal in 1977.<ref name="ahl198403">{{cite news | url=https://archive.org/stream/creativecomputing-1984-03/Creative_Computing_v10_n03_1984_Mar#page/n39/mode/2up | title=Digital | work=Creative Computing | date=March 1984 | access-date=February 6, 2015 | author=Ahl, David H. | pages=38–41 | authorlink=David H. Ahl}}</ref> At the time these systems were of limited utility, and Olsen famously derided them in 1977, stating "There is no reason for any individual to have a computer in his home."{{efn|Olsen later claimed he was referring to [[home automation]], see [http://www.snopes.com/quotes/kenolsen.asp "Ken Olsen"]}} Unsurprisingly, DEC did not put much effort into the microcomputer area in the early days of the market. In 1977, the [[Heathkit H11]] was announced; a PDP-11 in kit form. At the beginning of the 1980s, DEC built the [[VT180]] (codenamed "Robin"), which was a [[VT100]] terminal with an added [[Zilog Z80|Z80]]-based microcomputer running [[CP/M]], but this product was initially available only to DEC employees.<ref name="Croxton">{{cite web|last=Croxton|first=Greg|title=DEC Robin (VT-180) & documentation|url=http://www.digibarn.com/collections/systems/dec-robin/|work=DigiBarn Computer Museum|access-date=March 21, 2011}}</ref>

It was only after IBM had successfully launched the [[IBM PC]] in 1981 that DEC responded with their own systems. In 1982, DEC introduced not one, but three incompatible machines which were each tied to different [[Proprietary hardware|proprietary]] architectures. The first, the [[DEC Professional (computer)|DEC Professional]], was based on the PDP-11/23 (and later, the 11/73) running the [[RSX-11|RSX-11M+]] derived, but menu-driven, [[P/OS]] ("Professional Operating System"). This DEC machine easily outperformed the PC, but was more expensive than, and completely incompatible with IBM PC hardware and software, offering far fewer options for customizing a system.

Unlike CP/M and DOS microcomputers, every copy of every program for the Professional had to be provided with a unique key for the particular machine and CPU for which it was bought. At that time this was mainstream policy, because most computer software was either bought from the company that built the computer or custom-constructed for one client. However, the emerging third-party software industry disregarded the PDP-11/Professional line and concentrated on other microcomputers where distribution was easier. At DEC itself, creating better programs for the Professional was not a priority, perhaps from fear of cannibalizing the PDP-11 line. As a result, the Professional was a superior machine, running inferior software.<ref>Katan, M.B., Scholte, B.A., 1984. Application of a Professional 350 in a university department&nbsp;— a consumer's report, in: Proceedings Digital Equipment Computer Users Society. Amsterdam, p. 368.</ref> In addition, a new user would have to learn an awkward, slow, and inflexible menu-based user interface which appeared to be radically different from [[PC DOS]] or [[CP/M]], which were more commonly used on the 8080- and 8088-based microcomputers of the time. A second offering, the [[DECmate|DECmate II]] was the latest version of the PDP-8-based word processors, but not really suited to general computing, nor competitive with [[Wang Laboratories]]' popular word processing equipment.

[[File:DEC Rainbow 100 floor model.JPG|thumb|right|upright|DEC [[Rainbow 100]], floor-mounted]]
The most popular early DEC microcomputer was the dual-processor (Z80 and 8088) [[Rainbow 100]],{{r|ahl198403}} which ran the 8-bit [[CP/M]] operating system on the Z80 and the 16-bit [[CP/M-86]] operating system on the [[Intel 8088]] processor. It could also run a [[UNIX System III]] implementation called [[Venix|VENIX]]. Applications from standard CP/M could be re-compiled for the Rainbow, but by this time users were expecting custom-built (pre-compiled binary) applications such as [[Lotus 1-2-3]], which was eventually ported along with [[MS-DOS]] 2.0 and introduced in late 1983. Although the Rainbow generated some press, it was unsuccessful due to its high price and lack of marketing and sales support.<ref name="rainbow-faq">{{cite web|title=Q: What is a Rainbow 100 anyway?|work=The Rainbow 100 Frequently Asked Questions|url=http://rainbow-100.com/faq/question/1/|publisher=Approximatrix, LLC|access-date=December 15, 2010|year=2009|archive-url=https://web.archive.org/web/20110825144124/http://rainbow-100.com/faq/question/1/|archive-date=August 25, 2011|url-status=dead}}</ref> By late 1983 IBM was outselling DEC's personal computers by more than ten to one.{{r|ahl198403}}

A further system was introduced in 1986 as the [[VAXmate]], which included [[Microsoft Windows 1.0]] and used VAX/VMS-based file and print servers along with integration into DEC's own [[DECnet]]-family, providing LAN/WAN connection from PC to mainframe or supermini. The VAXmate replaced the Rainbow, and in its standard form was the first widely marketed [[diskless workstation]].

=== Networking and clusters (1984) ===
In 1984, DEC launched its first 10&nbsp;Mbit/s [[Ethernet]]. Ethernet allowed scalable networking, and [[VAXcluster]] allowed scalable computing. Combined with [[DECnet]] and Ethernet-based terminal servers ([[Local Area Transport|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 [[List of the oldest currently registered Internet domain names|fifth company to register]] a [[.com]] [[domain name]] (dec.com).

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. VAXclusters 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.

=== Late 1980s diversification ===
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&nbsp;billion away from them in the mid-1980s. In 1986, DEC's profits rose 38% when the rest of the computer industry experienced a downturn, and by 1987 the company was threatening IBM's number one position in the computer industry.<ref name="companyhistory">[http://www.answers.com/topic/digital-equipment-corporation "Digital Equipment Corporation"], ''International Directory of Company Histories'', Volume 6, St. James Press, 1992 [Note this link is to answers.com, not the International Directory of Company Histories]</ref> Not long thereafter came IBM's "VAX killer" offerings,<ref>{{cite web  |url=https://www.nytimes.com/1987/03/24/business/company-news-ibm-to-ship-computers-early.html
 |title=I.B.M. to Ship Computers Early |date=March 24, 1987 |publisher=NY Times |access-date=September 21, 2023}}</ref> at a time when DEC had twice the sales of IBM in the mid-range computer market.

At its peak, DEC 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 equipment. The company 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 Corporation|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 [[Oracle Rdb|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 using [[RISC]] microprocessors were starting to approach VAX CPUs in performance.

=== Early 1990s faltering and attempted turnaround ===
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]].<ref>{{cite book| author = John L. Hennessy|author2=David A. Patterson |author3=David Goldberg | title = Computer Architecture: A Quantitative Approach| url = https://archive.org/details/computerarchitec0003henn| url-access = registration| year = 2003| publisher = Morgan Kaufmann| isbn = 978-1-55860-596-1| page = [https://archive.org/details/computerarchitec0003henn/page/152 152] }}</ref>

Constrained by the huge success of their [[VAX]] and [[OpenVMS|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 margin]]s 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.<ref>{{cite news|first=John|last=Markoff|title=Market Place; Digital Finally Follows a Trend|newspaper=[[The New York Times]]|date=July 16, 1990|url=https://www.nytimes.com/1990/07/16/business/market-place-digital-finally-follows-a-trend.html}}</ref> 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|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.<ref>{{cite conference|first1=Dileep|last1=Bhandarkar|first2=D.|last2=Orbits|first3=Richard|last3=Witek|first4=W.|last4=Cardoza|first5=Dave|last5=Cutler|author-link5=Dave Cutler|url=https://ieeexplore.ieee.org/document/63667|title=High performance issue oriented architecture|book-title=Proceedings of Compcon Spring '90|pages=153–160}}</ref> Infighting with teams dedicated to DEC's [[Mainframe computer|big iron]] made funding difficult, and the design was not finalized until April 1988, and then cancelled shortly thereafter.<ref>{{cite web|first=Mark|last=Smotherman|url=http://www.cs.clemson.edu/~mark/prism.html|title=PRISM (Parallel Reduced Instruction Set Machine)|website=Clemson University School of Computing|date=October 2009}}</ref> The PRISM project was accompanied by the [[DEC MICA|MICA]] project, which intended to consolidate VMS and ULTRIX into a single operating system.<ref name="mica-business-plan">{{cite web|url=http://www.bitsavers.org/pdf/dec/prism/mica/Mica_Software_Business_Plan_Mar87.pdf |archive-url=https://web.archive.org/web/20081201133102/http://bitsavers.org/pdf/dec/prism/mica/Mica_Software_Business_Plan_Mar87.pdf |archive-date=2008-12-01 |url-status=live|title=MICA Software Business Plan|author1=Catherine Richardson|author2=Terry Morris|author3=Rockie Morgan|author4=Reid Brown|author5=Donna Meikle|date=March 1987|access-date=January 4, 2021|website=bitsavers.org}}</ref>

Another group concluded that new [[workstation]]s 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, California|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 January 11, 1989.<ref>{{cite journal|first1=Thomas C.|last1=Furlong|first2=Michael J. K.|last2=Nielsen|first3=Neil C.|last3=Wilhelm|url=http://www.dtjcd.vmsresource.org.uk/pdfs/dtj_v02-02_1990.pdf |archive-url=https://web.archive.org/web/20110128164108/http://www.dtjcd.vmsresource.org.uk/pdfs/dtj_v02-02_1990.pdf |archive-date=2011-01-28 |url-status=live|title=Development of the DECstation 3100|journal=Digital Technical Journal|volume=2|issue=2|date=Spring 1990|pages=84–88}}</ref> 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 (1992) ====
[[File:AlphaServer-2100-guts.jpg|thumb|Inside view of AlphaServer 2100]]

Eventually, in 1992, DEC launched the [[Alpha 21064|DECchip 21064]] processor, the first implementation of their [[DEC Alpha|Alpha]] [[instruction set architecture]], initially named Alpha&nbsp;AXP; the "AXP" was a "non-acronym" and was later dropped. This was a [[64-bit computing|64-bit]] [[RISC]] architecture as opposed to the 32-bit [[Complex instruction set computer|CISC]] architecture used in the VAX. It is one of the first "pure" 64-bit [[microprocessor]] architectures and implementations rather than an extension of an earlier 32-bit architecture. The Alpha offered class-leading performance at its launch and was used in the massively-parallel [[Cray T3D]]. Subsequent variants continued that performance trend into the 2000s, along with the Alpha-derived Pentium Pro, II, and III CPUs.<ref>{{Cite magazine|url=https://www.wired.com/1997/10/intel-dec-settle-alpha-chip-dispute/|title=Intel, DEC Settle Alpha Chip Dispute|magazine=[[Wired (magazine)|Wired]]|last1=Levine|first1=Daniel S.|date=October 27, 1997}}</ref><ref>{{Cite web|url=https://www.hpcwire.com/1997/05/16/dec-sues-intel-alleges-architecture-patent-infringement/|title = Dec Sues Intel, Alleges Architecture Patent Infringement|date = May 16, 1997}}</ref> An AlphaServer SC45 supercomputer was still ranked No.&nbsp;6 in the world in November 2004.<ref>{{cite web|url=http://www.top500.org/lists/2004/11|work=TOP500 Top 10 Supercomputing Sites|title=November 2004}}</ref> Alpha-based computers comprising the DEC AXP series, later the [[AlphaStation]], and [[AlphaServer]] series respectively superseded both the VAX and MIPS architecture in DEC's product lines. They supported [[OpenVMS]], DEC [[OSF/1]] AXP (later known as [[Tru64 UNIX|Digital Unix]] or Tru64 UNIX) and Microsoft's then-new operating system, [[Windows NT]], an operating system made possible by ex-Digital Equipment Corporation engineers.<ref>{{Cite web|url=https://www.itprotoday.com/compute-engines/windows-nt-and-vms-rest-story|title=Windows NT and VMS: The Rest of the Story|first=Mark|last=Russinovich|date=November 30, 1998|website=ITPro Today}}</ref>

In 1998, following the takeover by Compaq Computer Corporation, a decision was made that Microsoft would no longer support and develop Windows NT for the Alpha series computers, a decision that was seen as the beginning of the end for the Alpha series computers.

==== StrongARM (1995) ====
{{Main|StrongARM}}

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 system]]s 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 architecture]]s in the [[portable digital assistant]] market. [[Microsoft]] subsequently dropped support for these other architectures in their [[Pocket PC]] platform. In 1997, as part of a lawsuit settlement, the [[StrongARM]] intellectual property was sold to [[Intel]]. They continued to produce [[StrongARM]], as well as developing it into the [[XScale]] architecture. Intel subsequently sold this business to [[Marvell Technology Group]] in 2006.

=== Palmer's reign (1992–1998) ===
[[File:Digital Equipment Corporation 1993 logo.svg|thumb|Redesigned logo introduced in 1993]]
At its peak in the late 1980s, DEC had $14 billion in sales and ranked among the most profitable companies in the US. With its strong staff of engineers, DEC was expected to usher in the age of personal computers, but the commonly misunderstood belief then argued by the board to its shareholders was that Mr. Olsen was openly skeptical of the desktop machines, stating "the personal computer will fall flat on its face in business", and regarding them as "toys" used for playing video games. This was made in 1977 about what could be more characterised as home automation devices.<ref>{{Cite web |last=Mikkelson |first=David |date=2004-09-21 |title=Ken Olsen |url=https://www.snopes.com/fact-check/ken-olsen/ |access-date=2023-04-29 |website=Snopes |language=en}}</ref>

The board forced Olsen to resign as president in July 1992<ref>{{Cite news|url=https://www.nytimes.com/2011/02/08/technology/business-computing/08olsen.html?_r=0|title = Ken Olsen, Who Built DEC into a Power, Dies at 84|newspaper = The New York Times|date = February 8, 2011|last1 = Rifkin|first1 = Glenn}}</ref> after two years of losses in operating income.<ref>{{Cite web |title=Digital Equipment Corporation |url=https://sutherla.tripod.com/infsoc/computers/dec_pl.html |access-date=2023-04-29 |website=sutherla.tripod.com}}</ref> He was replaced by [[Robert Palmer (computer businessman)|Robert Palmer]] as the company's president. DEC's board of directors also granted Palmer the title of chief executive officer ("CEO"), a title that had never been used during DEC'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<ref>[[Ned Batchelder]] and [http://vt100.net/dec/logo Vt100.net].</ref>

Palmer restructured DEC into nine business units that reported directly to him. Nonetheless, DEC continued to suffer record losses, including a loss of $260.5 million for the quarter that ended on September 30, 1992. It reported $2.8 billion in losses for its fiscal year 1992. January 5, 1993, saw the retirement of John F. Smith as senior vice president of operations, the second in command at DEC, and his position was not filled. A 35-year company veteran, he had joined DEC in 1958 as the company's 12th employee, passing up a chance to work for Bell Laboratories in New Jersey to work for DEC. Smith rose to become one of the three senior vice presidents in 1987 and was widely considered among the potential successors to Ken Olsen, especially when Smith was appointed chief operating officer in 1991. Smith became a corporate spokesman on financial issues, and had filled in at trouble spots for which Olsen ordered more attention. Smith was passed over in favor of Palmer when Olsen was forced to resign in July 1992, though Smith stayed on for a time to help turn around the struggling company.<ref>{{cite news|url=https://www.nytimes.com/1993/01/06/business/company-news-no-2-officer-retires-at-digital-equipment.html|title=COMPANY NEWS; No. 2 Officer Retires at Digital Equipment|newspaper=[[The New York Times]]|date=January 6, 1993|access-date=April 12, 2014}}</ref>

In June 1993, Palmer and several of his top lieutenants presented their reorganization plans to applause from the board of directors, and several weeks later DEC reported its first profitable quarter in several years. However, on April 15, 1994, DEC reported a loss of $183 million—three to four times higher than the loss many people on Wall Street had predicted (compared with a loss of $30 million in the comparable period a year earlier), causing the stock price on the NYSE to plunge $5.875 to $23, a 20% drop. The losses at that point totaled $339 million for the current fiscal year. Sales of the VAX, long the company's biggest moneymaker, continued to decline, which in turn also hurt DEC's lucrative service and maintenance business (this made up more than a third of DEC's revenue of $14 billion in the 1993 fiscal year), which declined 11% year over year to $1.5 billion in the most recent quarter.

Market acceptance of DEC Alpha computers and chips had been slower than the company had hoped, even though Alpha's sales for the quarter estimated at $275 million were up significantly from $165 million in the December quarter. DEC had also made a strong push into personal computers and workstations, which had even lower margins than Alpha computers and chips. Also, DEC was playing catchup with its own Unix offerings for client-server networks, as it long emphasized its own VMS software, while corporate computer users based their client-server networks on the industry-standard Unix software (of which Hewlett Packard was one of the market leaders). DEC's problems were similar to that of larger rival IBM, due to the fundamental shift in the computer industry that made it unlikely that DEC could ever again operate profitably at its former size of 120,000 employees, and while its workforce had been reduced to 92,000 people many analysts expected that they would have to cut another 20,000.<ref>{{cite news|url=https://www.nytimes.com/1994/04/16/business/company-reports-a-deepening-of-losses-at-digital-equipment.html|title=COMPANY REPORTS; A Deepening of Losses at Digital Equipment|first=Glenn|last=Rifkin|date=April 16, 1994|newspaper=[[The New York Times]]|access-date=April 12, 2014}}</ref>

==== Selloffs ====
[[File:DECpc 425SE Color.JPG|thumb|[[DECpc]] 425SE Color: a notebook computer released by Digital in 1993]]
During the profitable years up until the early 1990s, DEC was a company that boasted that it never had a general layoff.<ref>Schein, ''et al'', pp. 67, 109.</ref> Following the [[Early 1990s recession|1992 economic downturn]], layoffs became regular events as the company continually downsized to try to stay afloat.<ref>Schein, ''et al'', p. 233.</ref> Palmer was tasked with the goal of bringing DEC back to profitability, which he attempted to do by changing the established DEC business culture, hiring new executives from outside the company, and selling off various non-core business units:<ref>Schein, ''et al'', pp. 128, 144, 234.</ref>
* Worldwide training was spun off to form an independent/new company called Global Knowledge Network.
* [[Oracle Rdb|Rdb]], DEC's database product, was sold to [[Oracle Corporation|Oracle]].
* Rights to the [[PDP-11]] line and several PDP-11 operating systems were sold to [[Mentec]] in 1994, though DEC continued to produce some PDP-11 hardware for a few years.<ref>{{cite web|url=http://www.mentec-inc.com/|title=PDP-11 RSX RT RSTS Emulator Osprey Charon|archive-url=https://web.archive.org/web/20060813131029/http://www.mentec-inc.com/|archive-date=August 13, 2006|url-status=dead}}</ref>
* Disk and [[Digital Linear Tape|DLT]] technologies was sold to [[Quantum Corporation]] in 1994.
* [[Text terminal]] business ([[VT100]] and its successors) was sold in August 1995 to [[Boundless Technologies]].
* [[CORBA]]-based product, ObjectBroker, and its messaging software, MessageQ, were sold to [[BEA Systems|BEA Systems, Inc]] in March 1997.
* Printer business was sold in 1997 to [[GENICOM]] (now TallyGenicom), which then produced models bearing the Digital logo.
* Networking business was sold c.1997 to [[Cabletron Systems]], and subsequently spun off as [[Digital Network Products Group]].
* [[DECtalk]] and [[DECvoice]] voice products were spun off, and eventually arrived at [[Fonix Speech Group]].

=== Acquisition by Compaq (1998) ===
Through 1997, DEC began discussions with [[Compaq]] on a possible merger. Several years earlier, Compaq had considered a bid for DEC but became seriously interested only after DEC's major divestments and refocusing on the Internet in 1997. At that time, Compaq was making strong moves into the enterprise market, and DEC's multivendor global services organization and customer support centers offered a real opportunity to expand their support and sales worldwide. Compaq was not interested in a number of DEC's product lines, which led to the series of sell-offs. Notable among these was DEC's [[Hudson Fab]], which made most of their custom chips, a market that made little sense to Compaq's "industry standard" marketing. DEC had previously sold its semiconductor plant in [[South Queensferry]] to Motorola in 1995, with an understanding that Motorola would continue to produce Alpha processors at the facility, along with continuing a two-year foundry agreement with AMD to continue producing the Am486 processor.<ref name="electronicnews19950109_motorola">{{ cite magazine | url=https://archive.org/details/sim_electronic-news_1995-01-09_41_2047/mode/1up | title=Motorola To Take Over Digital's Scottish Plant | magazine=Electronic News | volume=41 | issue=2047 | date=January 9, 1995 | access-date=June 10, 2022 | last1=DeTar | first1=Jim | pages=1, 4 | issn=1061-6624}}</ref>

This led to an interesting solution to the problem of selling off the division for a reasonable profit. In May 1997, DEC sued [[Intel]] for allegedly infringing on its Alpha patents in designing the [[Original Intel Pentium (P5 microarchitecture)|original Pentium]], [[Pentium Pro]], and [[Pentium II]] chips.<ref>{{cite magazine|title=DEC, Cyrix sue Intel|first1=Gale|last1=Bradley|first2=Jim|last2=DeTar|magazine=Electronic News|volume=43|issue=2168|pages=1, 60|date=May 19, 1997|issn=1061-6624|url=https://archive.org/details/sim_electronic-news_1997-05-19_43_2168/mode/1up}}</ref> 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 architecture|ARM computer architecture]], which Intel marketed as the [[Intel XScale|XScale]] processors commonly used in [[Pocket PC]]s. The core of Digital Semiconductor, the Alpha microprocessor group, remained with DEC, while the associated office buildings went to Intel as part of the Hudson fab.<ref>{{cite interview |first=Allan |last=Baum |interviewer= David Brock |title=Oral History of Allen Baum |date=July 18, 2018 |url=https://archive.computerhistory.org/resources/access/text/2018/06/102717165-05-01-acc.pdf |archive-url=https://web.archive.org/web/20210207063355/https://archive.computerhistory.org/resources/access/text/2018/06/102717165-05-01-acc.pdf |archive-date=2021-02-07 |url-status=live |page=60}}</ref>

On January 26, 1998, what remained of the company was sold to Compaq in what was the largest merger up to that time in the computer industry. At the time of Compaq's acquisition announcement, DEC had a total of 53,500 employees, down from a peak of 130,000 in the 1980s, but it still employed about 65% more people than Compaq to produce about half the volume of sales revenues. After the merger closed, Compaq moved aggressively to reduce DEC's high selling, general, and administrative (SG&A) costs (equal to 24% of total 1997 revenues) and bring them more in line with Compaq's SG&A expense ratio of 12% of revenues.<ref name="mhhe.com">{{cite web|url=http://www.mhhe.com/business/management/updates/thompson12e/case/dell10.html|work=Dell Computer Corporation Online Case|title=Profiles of Selected Competitors in the PC Industry|publisher=[[McGraw Hill Education]]|access-date=April 12, 2014|archive-url=https://web.archive.org/web/20190331022052/http://www.mhhe.com/business/management/updates/thompson12e/case/dell10.html|archive-date=March 31, 2019|url-status=dead}}</ref>

Compaq used the acquisition to move into enterprise services and compete with IBM, and by 2001 services made up over 20% of Compaq's revenues, largely due to the DEC employees inherited from the merger.<ref>{{cite encyclopedia|url=https://www.encyclopedia.com/economics/encyclopedias-almanacs-transcripts-and-maps/digital-equipment-corp|title=Digital Equipment Corp|at=Takeover By Compaq Computer Corp.|encyclopedia=Encyclopedia.com|access-date=September 7, 2022}}</ref> DEC's own PC manufacturing was discontinued after the merger closed. As Compaq did not wish to compete with one of its key partner suppliers, the remainder of Digital Semiconductor (the Alpha microprocessor group) was sold to Intel, which placed those employees back in their Hudson (Massachusetts) office, which they had vacated when the site was sold to Intel in 1997.

Compaq struggled as a result of the merger with DEC,<ref name="mhhe.com"/> and was acquired by [[Hewlett-Packard]] in 2002. Compaq, and later HP, continued to sell many of the former DEC products but re-branded with their own logos. For example, HP now sells what were formerly DEC's StorageWorks disk/tape products,<ref>{{cite web|url=http://h18006.www1.hp.com/storage/|title=HP StorageWorks&nbsp;– Data and Network Storage Products and Solutions|access-date=March 8, 2006|archive-date=March 2, 2006|archive-url=https://web.archive.org/web/20060302053928/http://h18006.www1.hp.com/storage/|url-status=dead}}</ref> as a result of the Compaq acquisition.

The Digital logo was used up until 2004, even after the company ceased to exist, as the logo of Digital GlobalSoft, an IT services company in India (which was a 51% 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.