93-543: Computer Technology Limited ( CTL ) was a British computer company founded in 1965. In 1984 it merged into its holding company and was called Information Technology Limited ( ITL ). Founder Iann Barron had worked for Elliott Automation but left to form CTL when he couldn't persuade Elliott to incorporate his ideas in their next generation of computers. CTL was financed by the American Research and Development Corporation and Pergamon Press . The first CTL computer,
186-426: A 19-inch rack . The backplanes allowed 25 modules in a single 5-1/4 inch section of rack, and allowed the high densities needed to build a computer. 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). DEC used
279-593: 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
372-543: A high maintenance burden. Many universities were equipped with Modular One systems, in part due to the government of the time having a 'buy British' policy. Acting as a front-end processor for the ICL 1900 mainframe, driving multiple online terminals or as a remote batch job entry station, was a major market for the Modular One. It never sold widely outside of the UK, and even in the UK it
465-576: 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. The result was the VAX architecture, where VAX stands for Virtual Address eXtension (from 16 to 32 bits). The first computer to use
558-476: 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 wrapped 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
651-400: A number of interface slots bussed together, allowing connection to memory and peripheral modules as required. Memory modules had several, allowing them to be accessed by more than one processor as well as by disc controllers for DMA. Disc controllers could be connected to two processors as well as memory modules. All modules had a "1.x" type designation, for example, the original processor module
744-462: A profit at the end of its first year. 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
837-479: A report generator, formed the basis of many sales into commercial applications. Modus and many of the applications were written in the high level language Coral 66 . Compilers for COBOL and FORTRAN IV were also available for the Modular One. Founder Iann Barron left in 1971, following the collapse of a major customer. He went on to form Inmos and develop the transputer . He was replaced as Chairman by Tom Margerison , from London Weekend Television . During
930-487: A scheme well suited to the destructive read followed by rewrite required by magnetic-core memory of the time. These three phases were mediated by voltage edges rather than pulses, as this was thought to be faster. Furthermore, the input and output impedances of ECL were comparable to the characteristic impedance of ribbon cable. This, together with the small voltage swings between the "0" and "1" states made for low noise, reflection-free communication. Processors naturally had
1023-438: 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 , a machine that was small and inexpensive enough to be dedicated to
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#17330934822131116-480: A self-sustaining business, the company would be free to use them to develop a complete computer in their Phase II. The newly christened "Digital Equipment Corporation" received $ 70,000 from AR&D for a 70% share of the company, and began operations in a Civil War -era textile mill in Maynard, Massachusetts , where plenty of inexpensive manufacturing space was available. In early 1958, DEC shipped its first products,
1209-504: 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. 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. In 1962, Lincoln Laboratory used
1302-481: 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 Model B Electric typewriter that
1395-643: 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". 116 PDP-5s were produced until
1488-473: A single type of interface, comprising two identical cards to be plugged into two modules to be connected, these cards themselves linked by a flat ribbon cable either one or two metres long. Thus, memory was just another peripheral (such as a printer) but was both input and output. Every interaction over these interfaces comprised a 3-way handshake, which in the case of a processor accessing a memory module, consisted of send address, receive data, and send new data,
1581-634: A successor to the PDP-10 mainframe, and instead focused on promoting the VAX as the single computer architecture for the company. 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 inexpensive chassis. The VT52
1674-440: 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
1767-656: Is most famous as the machine for which the Unix operating system was originally written. Unix ran only on DEC systems until the Interdata 8/32 . A more dramatic upgrade to the PDP-1 series was introduced in August 1966, the PDP-9 . 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,
1860-512: Is no reason for any individual to have a computer in his home." 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 Z80 -based microcomputer running CP/M , but this product
1953-730: The Elliott 803 . On leaving University he joined the Civil Service in 1958 as a Scientific Officer on special assignment first to the Army Operational Research Group , and in 1960 to the Air Ministry . He returned to the company now called Elliott Automation as a Project Leader for the Elliott 502 computer team, later becoming the company's Head of System Research. In 1965 Barron left Elliott Automation to become Founder and Managing Director of Computer Technology Limited , where
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#17330934822132046-462: The Modular One range of computer systems was developed. In the mid-1970s he formed a new company, Microcomputer Analysis Ltd, which offered consultancy on microprocessors to the semiconductor industry . This brought him into contact with two eminent American semiconductor specialists, Richard Petritz and Paul Schroeder, and in 1978 the triumvirate founded Inmos International PLC, which produced
2139-652: The Modular One , appeared for sale in 1968. The Modular One was a 16-bit computer built with Emitter Coupled Logic (ECL) and was competitive with other first generation minicomputers . A key feature, from which it derived its name, was that it was composed of separate processor, memory and peripheral modules sharing a common interface and physical form factor, so allowing them to be put together in any combination, housed one or two high in modular racking. Standard modules were roughly 50 cm wide and deep, 70 cm tall, and complete with power supply, typically weighed in excess of 25 kg. Modules were interconnected using
2232-704: 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. 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. When
2325-526: The VAX 9000 were market failures. After several attempts to enter the workstation and file server market, the DEC Alpha product line began to make successful inroads in the mid-1990s, but was too late to save the company. DEC was acquired in June 1998 by Compaq in what was at that time the largest merger in the history of the computer industry. During the purchase, some parts of DEC were sold to other companies;
2418-802: The "11" architecture was soon the industry leader, propelling DEC back to a strong market position. The design was later expanded to allow paged physical memory and memory protection features, useful for multitasking and time-sharing . 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. Smaller PDP-11s, implemented as single-chip CPUs, continued to be produced until 1996, by which time over 600,000 had been sold. 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
2511-539: 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. The Laboratory Modules were packaged in an extruded aluminum housing, intended to sit on an engineer's workbench, although a rack-mount bay was sold that held nine laboratory modules. They were then connected together using banana plug patch cords inserted at
2604-439: 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 systems . Historically, RT-11 also served as
2697-433: 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
2790-591: The 1970s CTL operated modestly successfully in a number of niche markets, while larger American competitors, such as Digital Equipment Corporation (DEC) with their PDP range , increased market share. In 1980 two sibling companies Office Technology Limited (OTL) and Network Technology Limited (NTL), and a holding company Information Technology Limited (ITL) were created. In 1981 entrepreneur Tony Davies became Managing Director. Under Davies CTL began buying in hardware, to be re-badged as CTL systems, recognising CTL could not afford to develop hardware at all levels. The first
2883-562: The 1980s, culminating in the NVAX microprocessor implementation and VAX 7000/10000 series in the early 1990s. When a DEC research group demonstrated two prototype microcomputers 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. At the time these systems were of limited utility, and Olsen famously derided them in 1977, stating "There
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2976-447: 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. Sales were, unsurprisingly, very strong, and helped by
3069-508: 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
3162-612: The PDP-8, all in software. Although not a huge seller, 142 LINC-8s were sold starting at $ 38,500. 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. Newer circuitry designs led to the PDP-8/I and PDP-8/L in 1968. In 1975, one year after an agreement between DEC and Intersil , the Intersil 6100 chip
3255-455: The PDP-9 was a big seller, eventually selling 445 machines, more than all of the earlier models combined. 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
3348-688: The Professional was a superior machine, running inferior software. 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 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. The most popular early DEC microcomputer
3441-506: The Rainbow, and in its standard form was the first widely marketed diskless workstation . 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
3534-484: The Segment level. E4 had a primitive command line interface but a multi-access operating system known as Modus was built on top of it for much greater flexibility and ease of use. This consisted of a "Nucleus" which looked after a collection of "Engines". An Engine was typically associated with a peripheral device and processed work from a queue, for example taking print jobs from a print queue and printing them. A special case
3627-485: 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. 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
3720-465: 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. At MIT, Ken Olsen and Harlan Anderson noticed something odd: students would line up for hours to get
3813-436: The ability to address more memory, often by extending the address format to 18 or 24-bits in machines were otherwise similar to their earlier 16-bit designs. 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
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3906-505: The adoption of "\" for pathnames in MS-DOS and Microsoft Windows as opposed to "/" in Unix . 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
3999-431: The assembler.) The ease with which multiple processor, store and peripheral modules could be built into a system, plus the need to extend the upper capability limits, prompted the development of a dual processor variant of E4. This was built entirely from standard modules except for a small synchronisation board which prevented both processors operating simultaneously in special state, and a very minor modification to one of
4092-508: The basis for the new design, although when they first viewed the proposal, management was not impressed and almost cancelled it. 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 modes that were intended to make programs smaller in memory, a technique that was widely used on other DEC machines and CISC designs in general. This would mean
4185-447: The better-established vendors like IBM or Honeywell , in spite of its low cost around $ 300,000. Only 23 were sold, or 26 depending on the source, 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
4278-745: 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. The first PDP-1 was delivered to Bolt, Beranek and Newman in November 1960, and formally accepted
4371-462: The company's need for an open office plan, as well as a compressed building schedule, by designing an innovative inflatable structure or "air tent" that was critically lauded by the architectural press at the time of its unveiling. Iann Barron Iann Marchant Barron CBE (16 June 1936 – 16 May 2022) was a British computer engineer and entrepreneur. During vacation work in 1956–67 at Elliott Brothers while still at Cambridge he designed
4464-410: The company's place as a leading vendor in the computer space. As microcomputers improved in the late 1980s, especially with the introduction of RISC -based workstation machines, the performance niche of the minicomputer was rapidly eroded. By the early 1990s, the company was in turmoil as their mini sales collapsed and their attempts to address this by entering the high-end market with machines like
4557-411: 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 arrays 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
4650-643: The compiler business and the Hudson Fab were sold to Intel . At the time, Compaq was focused on the enterprise market and had recently purchased several other large vendors. DEC was a major player overseas where Compaq had less presence. However, Compaq had little idea what to do with its acquisitions, and soon found itself in financial difficulty of its own. Compaq subsequently merged with Hewlett-Packard (HP) in May 2002. Ken Olsen and Harlan Anderson were two engineers who had been working at MIT Lincoln Laboratory on
4743-479: The critical performance measurement was based upon COBOL compilation which did not fully utilize the primary design features of Jupiter technology. 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. DEC's successful entry into the computer market took place during a fundamental shift in
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#17330934822134836-503: The early 1960s. The company produced a series of machines known as the PDP line, with the PDP-8 and PDP-11 being among the most successful minis in history. Their success was only surpassed by another DEC product, the late-1970s VAX "supermini" systems that were designed to replace the PDP-11. Although a number of competitors had successfully competed with Digital through the 1970s, the VAX cemented
4929-561: The example being that restored by Redhawk Systems Ltd. The operating system kernel was referred to as the Exec. Several simple ones (E1, E2 and E3) were developed in the early years of the company. E4, first in-house release around 1973, written entirely in assembler , was a multitasking kernel using Dijkstra semaphores to protect internal data structures from conflicts. It was based on an early version of object-oriented principles, though lacking most of what are now considered essential features of
5022-468: 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, and eventually 1450 "straight eight" machines were produced before it was replaced by newer implementations of the same basic design. DEC hit an even lower price-point with the PDP-8/S, the S for "serial". As
5115-475: The first "R" (red) series " Flip-Chip " modules. Later, other Flip-Chip module series provided additional speed, much higher logic density, and industrial I/O capabilities. DEC published extensive data about the modules in free catalogs that became very popular. 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". In August 1959, Ben Gurley started design of
5208-487: The fledgling company change its business plan to focus less on computers, and even change their name from "Digital Computer Corporation". 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 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
5301-411: The front of the modules. Three versions were offered, running at 5 MHz (1957), 500 kHz (1959), or 10 MHz (1960). 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 (equivalent to $ 992,700 in 2023), turning
5394-652: The future lay in open systems and CTL attempted to make the transition to Unix with re-badged systems from Motorola and Sequoia Systems. However, sales of CTL's proprietary systems fell off before the new systems could be ramped up to replace them. The company was taken over by ACT in 1989, primarily for its customers and extensive support network, which effectively ended CTL's era as a computer manufacturer. In 1969, Computer Technology hired then up-and-coming architect Norman Foster to design their new headquarters north of London, in Hemel Hempstead . Foster responded to
5487-608: The implementation of a self-protecting operating system kernel (known as the Executive, or Exec). Such ideas were popular in British computer academia at the time. Furthermore, the power system was set up as a peripheral with interrupt capabilities that gave the machine the ability to power down gracefully in an emergency. The Modular One was comparatively expensive. It was somewhat exotic in that its modular design resulted in almost every system delivered being somewhat different, which created
5580-479: The innovative transputer , and led to the development of SpaceWire . Barron was elected a Distinguished Fellow of the British Computer Society (DFBCS) in 1986 and was appointed CBE in the 1994 New Year Honours . Barron died on 16 May 2022, at the age of 85. Digital Equipment Corporation Digital Equipment Corporation ( DEC / d ɛ k / ), using the trademark Digital ,
5673-413: 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 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
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#17330934822135766-485: 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. Instead, this effort evolved into
5859-537: 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. 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
5952-441: 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
6045-491: 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. 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
6138-438: 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. A major advance in the PDP-11 design was DEC's Unibus , which supported all peripherals through memory mapping . This allowed
6231-425: 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. 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
6324-458: The next April. The PDP-1 sold in basic form for $ 120,000 (equivalent to $ 9,269,291 in 2023). By the time production ended in 1969, 53 PDP-1s had been delivered. The PDP-1 was supplied standard with 4096 words of core memory , 18-bits 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 racks . The racks were themselves packaged into
6417-529: The object's reference count of RTNs fell to zero. Linked lists were used very extensively within E4 to manage data structures, in fact the RTN list was about the only linear list there was. (The system generation process included a phase prosaically called "knitting" comprising a combination of macro expansion and procedural elements, by which the initial data structures were dynamically "knitted" together to create an input file for
6510-616: The paradigm, such as inheritance. Objects included Activities (now more commonly known as tasks or processes), Segments (of memory), Files, Semaphores and Clocks. Another object type, the Sphere, was a run-time protection domain within which all other object types (including other Spheres) existed. Objects could be created in arbitrary quantities, and were each referenced through a Run Time Name, or RTN. Since an object could be referenced by several RTNs belonging to different spheres, they could easily be shared between programs, and were deleted only when
6603-448: The performance achieved was only of the order of 150% of that of a single processor, and no dual processor E4 systems were ever sold. There was some similarity to Unix in the use of (mainly) device-independent serial byte oriented streams in the file system and interprocess communication, in contrast to the record-oriented file systems then dominant in commercial data processing. E4 also supported real-time priorities and virtual memory at
6696-568: The price. Like the PDP-1, about 54 PDP-4s were eventually sold, most to a customer base similar to the original PDP-1. 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. An upgrade to the Flip Chip led to the R series, which in turn led to the PDP-7A in 1965. The PDP-7
6789-425: The processors' interface to store zero, allowing each processor to address a small dedicated memory area for processor-specific variables such as the current activity. However, the results were somewhat disappointing as E4 naturally spent a significant proportion of its time in special state even though efforts had always made to limit special state routines to 100uS at a time. Even running processor-bound user programs,
6882-591: The same design. 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. Only one PDP-3 appears to have been built, in 1960, by the CIA's Scientific Engineering Institute (SEI) in Waltham, Massachusetts . According to
6975-485: The underlying organization of the machines from word lengths based on 6-bit characters to those based on 8-bit words needed to support ASCII . 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. This led the leaders of the PDP-X project to leave DEC and start Data General , whose 16-bit Data General Nova
7068-463: The widely used TOPS-10 . 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. The PDP-10 was widely used in university settings, and thus
7161-527: Was 1.11, memory modules were 1.2x, character peripherals were 1.3x, discs were 1.4x and magnetic tape devices were 1.5x. The standard interface was designated 1.01. The various building blocks could be assembled and configured to produce a fault-tolerant computer system . Distinctive features of the processor were memory-mapped I/O and an early version of segmented memory (similar to the later Intel 8086 but having both base and limit). The processor had 3 segment registers referred to as X, Y and Z. The X segment
7254-462: Was a Convergent Technologies 8086 system which created a price competitive small system for CTL. In 1984 all the subsidiaries were merged into the holding company Information Technology Limited (ITL), replacing the CTL name. Nominally this was an efficiency measure, but it also positioned the company better for a possible public offering on the stock markets. During the mid 1980s, the company decided that
7347-410: Was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president until he was forced to resign in 1992, after the company had gone into precipitous decline. The company produced many different product lines over its history. It is best known for the work in the minicomputer market starting in
7440-469: 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,
7533-507: Was even sold in kit form as the Heathkit H11 , although it proved too expensive for Heathkit 's traditional hobbyist market. 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 KB on 16-bit machines. This led vendors to introduce new designs with
7626-618: 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. By late 1983 IBM was outselling DEC's personal computers by more than ten to one. 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
7719-628: 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 printers , 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
7812-709: Was initially available only to DEC employees. 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 architectures. The first, the DEC Professional , was based on the PDP-11/23 (and later, the 11/73) running the RSX-11M+ derived, but menu-driven, P/OS ("Professional Operating System"). This DEC machine easily outperformed
7905-493: 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. While the PDP-5 introduced a lower-cost line, 1963's PDP-6 was intended to take DEC into the mainframe market with a 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
7998-474: Was read/execute only and used to map code segments (corresponding to CS in the x86 architecture). It was not possible to execute code in the Y and Z segments, which were used for data (roughly corresponding to DS and ES in x86). There were 8 addressing modes allowing access to data mapped by the segment registers in various ways. The memory segmentation, together with two execution states ( Normal State and non-interruptible privileged Special State ) made possible
8091-535: Was released in 1969 and was a huge success. 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. 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
8184-410: Was surpassed in sales by Digital Equipment Corporation (DEC) and Data General before the end of the 1970s. Over the mid 1970s to mid 1980s the systems were cost reduced with TTL bitslice technology and 8-bit microprocessor communications controllers, retreating from the radical modular design, but it never gained a significant market share. Very few Modular One computers now remain, possibly only
8277-404: 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
8370-476: Was the Read Engine, which was the command processor. This was either associated with a terminal device (in which case it had a terminal device but no queue), or was a batch processor (in which case it had a queue but no device). The filing system, SDFS, was not part of the kernel but was a separate program. A multi-key indexed file system MKFS was also developed, and together with a transaction processing system and
8463-454: 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 ECL logic ); also the "KS10" (S: Small form factor ). Unified product line upgrades produced
8556-528: Was the dual-processor (Z80 and 8088) Rainbow 100 , 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 . 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
8649-441: Was used as a 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
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