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Acorn was a British computer company that produced computers and set-top boxes that were popular in the UK during the 1980s and 1990s . These included the BBC Micro and the Acorn Archimedes .


On July 25, 1961, Clive Sinclair founded Sinclair Radionics , a company specializing in the design and manufacture of electronic devices . After financial difficulties due to the failure of the Black Watch wristwatch and the conversion of the pocket calculator market from LED to LC displays, Sinclair asked the National Enterprise Board (NEB) for financial help in August 1976 . The NEB approved this, but demanded a 43% stake in Sinclair Radionics in return. Sinclair, reluctant to give up control of his company, encouraged co-worker Chris Curry to leave Sinclair Radionics and jointly found Science of Cambridge (SoC). SoC began selling a microcomputer kit in June 1978, which Curry wanted to develop further, but failed because of Sinclair. However, a friend of Curry's, Hermann Hauser , lecturer in physics at Cambridge University , showed an interest in this product after visiting SoC during the development of the MK 14 home computer kit .

Company history

CPU Ltd (1978–1983)

Out of their shared interest in microcomputers , Chris Curry and Hermann Hauser founded Cambridge Processor Unit Ltd (CPU) on December 5, 1978 , which became Acorn Computers (Acorn was originally a brand name used by CPU). After a short time, Ace Coin Equipment commissioned CPU to develop a controller for their gaming machines . Initially, their controller was based on an SC / MP microprocessor, but was soon converted to a 6502 .

The microcomputers

With its income from "design-and-build" consultations, CPU financed the development of a 6502-based microcomputer, which reached the market in January 1979 as the first product from Acorn Computer Ltd. This trade name should separate the two different business areas. Acorn (in German "Eichel") seemed appropriate to the possible "growth" of the expandable microcomputer and was also ahead of its competitor Apple in telephone books .

Around the same time, CPU and Andy Hopper founded Orbis Ltd to commercialize the Cambridge Ring network. Hopper, who had already worked on it during his doctorate, was soon hired as managing director of the CPU and represented its interests in the computer laboratory at Cambridge University. Hopper's shares in Orbis were exchanged for CPU shares. As the Acorn brand grew, the role of CPU gradually changed so that CPU eventually became just a holding company and now Acorn was the developing company. After a disagreement with Sinclair, Curry officially left Science of Cambridge but only after some time moved to the Acorn employees.

The Acorn System 1 display board shipped on April 9, 1979

The Acorn Microcomputer, later called Acorn System 1 , was designed by Sophie Wilson . It was primarily geared towards engineers and laboratory workers, but its low price of £ 80 made it  attractive to computer enthusiasts too. The machine itself consisted of two circuit boards, one of which contained the LED display, a keypad and a cassette interface (the components to the left of the keypad) and the other contained the rest of the computer (including the processor ). Almost all processor signals were accessible via a Eurocard socket.

The system 2 facilitated optional fittings by the incorporation of the processor card of the system 1 in a 19-inch Euro card housing. A typical system 2 has a keyboard controller together with an external keyboard, a text display and a stored on tape operating system with built-in BASIC - interpreter delivered.

The System 3 added additionally added support for floppy disk drives while the system 4 a larger housing had a second drive. For System 5 , the 6502 chip was replaced by a newer version clocked at 2 MHz .

The Acorn Atom

The Acorn Atom

Science of Cambridge began developing the Sinclair ZX80 in May 1979 . That was probably the reason for Curry to initiate the Atom project , which is also aimed at the consumer market . Curry and Nick Toop developed the machine in Curry's house in the Fens in Eastern England . At that time, the Acorn trademark was registered and Curry became a full-time employee.

The intention to enter the consumer market is largely attributed to curry, the other factions within Acorn, including the engineers, were happy to stay out of this market. They viewed the manufacture of a home computer as dubious. In order to keep costs as low as possible and thus the attack surface of the Atom for its critics as small as possible, Curry asked industrial designer Allen Boothroyd to design a housing that could also serve as an external keyboard for the microcomputer. The components of a System 3 were placed within this keyboard, making a system typical of the low-cost home computers of the early 1980s. The Atom turned out to be a comparatively successful project.

To support software development, CPU installed a proprietary Local Area Network on Market Hill and integrated support for this Econet into the Atom. When it was launched on the market in March 1980, eight networked Atoms were demonstrated at a computer fair, which could already come up with functions such as file sharing and complete remote control.

The BBC Micro and the Electron

After the Atom had successfully established itself in the market, Acorn began designing a successor. The market offered new 16-bit processors, but should they be used? After a long discussion, Hauser proposed a compromise: continuing to use the 6502 with significantly improved expansion options. Acorn's technical staff, the majority of which had rejected the atom, saw this proton as an opportunity to do it “right” this time.

One of the suggestions for the development of the Proton was the tube (in German "tube"), a proprietary interface that could integrate a second processor. This compromise made it possible to expand an inexpensive, mass-market 6502 machine with complex and expensive processors. The tube allowed calculations to be outsourced to the second processor, while the 6502 handled the input and output of data. In later years the tube played an important role in the development of Acorn's own processor.

In the early 1980s, the BBC's continuing education department devised a computer-training program. The idea came largely as a result of the documentary The Mighty Micro , in which Christopher Riche Evans of the British National Physical Laboratory predicted a revolution in microcomputers. The documentation proved to be very influential, with the issues raised even being discussed in the UK Parliament. As a result, both the Department of Industry (DoI) and the BBC Enterprises became interested in the program. The latter wanted to offer a machine for further training and instructed BBC Engineering to specify one.

Under pressure from the DoI to choose a computer made in Great Britain, the BBC ultimately chose the NewBrain from Newbury Laboratories . This election demonstrates the pressure exerted on the actually independent BBC: Newbury was owned by the National Enterprise Board (NEB), a government agency that worked closely with the DoI. Ironically, the NewBrain originally came from Sinclair Radionics, which is exactly where Sinclair's decision against Science of Cambridge's MK 14 had led Curry to leave, which in turn prompted the NEB to move the project to Newbury.

The BBC Micro

From 1980 to 1982 the British Department of Education and Science (DES) started the Microelectronics Education Program , which was to introduce concepts and teaching materials on microprocessors. From 1982 to 1986 the DoI donated third-party funds to local education authorities so that they could equip their schools with microcomputers. The BBC Micro turned out to be one of the most popular computers. At the same time, DES promoted teacher training and the development of other computer materials such as software and projects on applied IT.

Although Newbury continuously developed the NewBrain, it was soon foreseeable that it would not be available quickly enough either for the training programs or for the BBC tender. The BBC programs scheduled for autumn 1981 were postponed to spring 1982. Curry and Sinclair learned of the BBC's plans and submitted their own suggestions. After a demonstration of the Proton, which took place during a tour of Acorn in front of representatives of the BBC, the contract has now been awarded to Acorn, which began production of the Proton as BBC Micro in early 1982 . In April 1984, Acorn received the Queen's Award for Technology for this . This award went particularly to the progressive design of the BBC Micro and honored Acorn for “developing a microcomputer with many innovative features”.

In April 1982, Sinclair introduced the ZX Spectrum . As a counterpart, Curry came up with the Electron , which in many ways was a discounted BBC Micro and cost less than £ 200. The Electron used an Uncommitted Logic Array (ULA) designed by Acorn for much of its functionality . Problems in the manufacture of the ULA resulted in a supply bottleneck, so that the Electron, although introduced in August 1983, was not available in sufficient numbers for the 1983 Christmas season. Acorn decided to resolve this issue in fiscal 1984 and renegotiated its manufacturing contracts.

Acorn Computer Group AG (1983–1985)

The spectacular sales of the BBC Micro increased Acorn's profits from 3,000 in 1979 to £ 8.6 million in July 1983. In September 1983, the CPU shares were liquidated and Acorn listed as Acorn Computer Group AG on the Unlisted Securities Market in London registered. Acorn Computers Ltd was now the microcomputer division. With a minimum offer price of 120 pence, the AG was created with a stock market valuation of about 135 million pounds sterling. CPU founders Hauser and Curry became millionaires through their stakes on paper: Hauser's 53.25 million stake meant £ 64 million, while Curry still owned £ 51 million with 43 million stakes.

New RISC architecture

Acorn has been considering moving away from the 6502 since the atom. A significant example of these considerations is the 16-bit Acorn Communicator , which used the 65816 from the Western Design Center company . In addition to the Apple IIgs , this was one of the few commercial applications based on the WD 65816.

On August 12, 1981, the IBM PC was introduced, which in a version similar to the BBC Micro also aimed at the computer enthusiast market, but whose actual core area was the business area. The successor to the PC, the XT (E X tended T echnology) followed in the spring of 1983. The success of these machines and the large number of Z80 -based CP / M computers in the business sector demonstrated that there was a profitable market here. The rather subordinate importance of price in this area and the resulting high profit margins represented an additional incentive for manufacturers, so that Acorn decided to develop an office computer. A corresponding program was launched and used the main board of the BBC Micro, the "Tube" and secondary processors, with which CP / M, MS-DOS and Unix ( Xenix ) -based workstations were to be created.

For the design of this Acorn Business Computer (ABC), the tube protocols had to be implemented for various processors so that they could be used by the BBC micro platform. Acorn found in the course of 1983 that the market offered no suitable successor to the 6502. With Motorola's 68000 , for example, many instructions could not be interrupted, which often led to very long latencies when responding to interrupts . The 68000 was therefore unsuitable for the tube protocol. Developing the ABC model based on National Semiconductor's 32016 , later sold as the Cambridge Workstation , Sophie Wilson and Steve Furber demonstrated the importance of memory data transfer rate. It turned out that a 32016 clocked at 8 MHz was significantly slower than a 4 MHz 6502. With the Apple Lisa , however, it was clear to the Acorn developers that they would have to create a graphical user interface, which was extremely difficult with a 6502. Acorn needed a new architecture.

All processors tested by Acorn left something to be desired, so that an in-house development was necessary. Acorn's engineers came across publications from the Berkeley RISC project that showed them one thing: If a group of students could create a powerful 32-bit processor, Acorn should, too. A visit to the Western Design Center in Phoenix convinced Furber and Wilson that they did not need extensive resources or state-of-the-art research and development facilities.

Sophie Wilson first developed the instruction set for the new processor by writing an emulation of the processor in BBC BASIC that ran on a BBC Micro with a second 6502. This convinced the Acorn developers that they were on the right track, even if they needed additional resources. Wilson eventually got permission from Hauser to make a prototype.

The Acorn RISC Machine project officially began in October 1983. VLSI Technology , which had previously produced ROMs and specialty chips for Acorn, was chosen as a partner for the production of the processors. VLSI produced the first ARM The April 26, 1985. This ARM1 was first used as a second processor in the BBC Micro. The simulation work for the design of secondary chips (video controller, I / O controller and memory controller) could be continued with the processor. He also accelerated the CAD software that was used to design the ARM2.

Wilson then wrote an interpreter for BBC Basic in ARM assembly language . The knowledge gained when designing the instruction set enabled her to write the code in an unusually compact manner, which made the ARM-BBC-Basic a good test for any ARM emulator.

The secrecy surrounding the ARM project was so great that Olivetti only found out about it in 1985 when negotiating a partnership after it was concluded. In 1992, Acorn received the Queen's Award for Technology again , this time for the ARM.

Financial worries

Acorn's turning point was in 1984; the company went public just as the game console market collapsed. That year, Atari was sold, and Acorn solved the lack of manufacturing capacity it had been pursuing from the start.

The lack of ULAs when the Electron was launched on the market meant that only 30,000 of the 300,000 inquiries that had been received thanks to a successful advertising campaign could be met in the 1983 Christmas season. The apparent need for electrons turned out to be illusory: Many parents bought their children the C64 or ZX Spectrum instead of waiting for the electron. When the supplier Ferranti had solved the production problem and delivered the agreed quantities of ULAs in 1984, demand had collapsed so much that Acorn now had to store the Electron in large numbers. However, the contract did not allow the capacity to be renegotiated quickly, so that by the end of 1984 Acorn had 250,000 unsold electrons.

In addition, Acorn had invested a large part of its liquid funds in the development of new products: the BBC Master , the ARM project and ABC, which ultimately turned out to be a flop . Further costs arose from a planned expansion into the USA, which required the state recognition of the BBC Micro. To do this, all of the Micro's extensions had to be tested for emissions and their emissions reduced; a long and expensive process that cost Acorn about $ 20 million. Hardly any of the NTSC- modified BBC micros were sold. After all, they showed up at a school in the 1984 film Supergirl: The Movie .

Owned by Olivetti (1985-1998)

The difficult financial situation was brought to the board of directors in February 1985 after a lender called for Acorns to be liquidated. After brief negotiations, Curry and Hauser signed an agreement with Olivetti on February 20, under which the Italian company acquired a 49.3% stake in Acorn for £ 12 million. The money was mainly used to pay off the £ 11 million losses of the previous half year. Acorn's stock market valuation fell 165 million below its high of £ 190 million. In September 1985, Olivetti Acorn finally took over with a 79% stake.

The BBC Master

The BBC Master was launched in February 1986 with great success. By 1989, around 200,000 systems had been sold at £ 499 each, with buyers mostly from schools and universities. Acorn brought out a number of improved versions, for example the Master 512 with 512  kB of main memory and an internal 80186 processor for MS-DOS compatibility, or the Master Turbo , which used a 65C02 as a second processor.

The first commercial use of the ARM architecture was within the ARM Development System , a tube-integrated second processor for the BBC Master, with which programs for the new system could be written. The system cost around £ 4,000 and contained the ARM processor, three secondary chips,  4MB of main memory and development tools for an improved version of the BBC Basic.

A second ARM-based product was the Acorn Archimedes , a desktop computer released in mid-1987. The Archimedes was very popular in Great Britain , Ireland and Australasia and was significantly more advanced than most of the competing offerings of the time. Unfortunately for Acorn, the market moved in the direction of the IBM PC . Nonetheless, Acorn continued to produce improved models, including the A4 laptop , and introduced the Risc PC in 1994, the flagship of which featured a 200 MHz + StrongARM processor. Most of these computers were sold in the educational sector, to specialists and enthusiasts.

ARM Limited

Acorn's partner VLSI was commissioned to find new areas of application for the ARM processor and its secondary chips. Hauser's company Active Book developed a small, portable device for which ARM processor developers designed a static version of the processor, the ARM2aS.

Meanwhile, Apple developed a completely new platform, the PDA Newton . The processor required for this device had to meet various requirements in terms of power consumption, costs and performance and also had to operate completely statically so that the clock could be suspended at any time. Of all applicants, only the Acorn RISC Machine came close to meeting the requirements, but it still had deficiencies. For example, the ARM did not offer any integrated memory management, the function of which was instead taken over by the MEMC secondary chip. Acorn also did not have the resources to develop integrated management for the ARM.

Apple and Acorn decided to cooperate for further development in the form of their own company. The majority of the research and development department of the ARM CPU formed the basis of ARM Limited , which was founded in November 1990. The Acorn Group and Apple Computer each owned 43%, with VLSI as the investor and first licensee.

Set-top boxes

Acorn Online Media was founded in 1994 to capitalize on a predicted boom in video-on-demand (VOD). It was a form of interactive television that allowed users to select and watch video content over a network . In September 1994, Acorn Online Media, Anglia Television , Cambridge Cable and Advanced Telecommunication Modules Ltd (ATML) started a field test for VOD services in Cambridge . For this purpose, ATML created a large-scale ATM network that connected the TV companies with the subscribers and offered services such as teleshopping , training, software downloads and the World Wide Web .

The network was implemented with a combination of coaxial and fiber optic cables ; the switches necessary for segmenting the network were used in the control cabinets of the existing Cambridge Cable network. The Olivetti Research Laboratory developed the technology used. A video server from the British mainframe manufacturer International Computers Limited provided the services. The ATM switches came from ATML, another company founded by Hauser and Hopper. The experiment began with a data transfer rate of 2 Mbit / s, which was gradually increased to 5 Mbit / s.

Subscribers used the Acorn Online Media set-top box . During the first six months, the trial consisted of 10 VOD terminals, which in the second stage was expanded to 100 apartments, 8 schools and 150 other terminals in test laboratories. Other organizations gradually got involved, including NatWest Bank, the BBC, Post Office Limited , Tesco and the local education authorities.

BBC Education studied radio-on-demand programs in elementary schools and created a new education service, Education Online , which offered educational software and Open University programs, for example . The Netherhall -Hauptschule was found a low-cost video server available so that they could act during the trial as a provider. The Anglia Polytechnic University later fulfilled a similar role.

Contrary to the forecasts, however, there was no VOD boom.

Network computers

In October 1995, during the program The Money Program , the BBC2 broadcast an interview with the founder of the Oracle Corporation, Larry Ellison , who predicted the growing importance of network computers (NC). These are inexpensive data stations that do not have a hard drive, but rather load a large part of their software from a server.

Malcolm Bird, the managing director of Acorn Online Media, realized that Ellison's NC was essentially an Acorn set-top box. After some talks between Oracle and Olivetti and Hauser and Acorn, Bird was sent to San Francisco with the latest box . Although Oracle had already negotiated seriously with manufacturers such as Sun and Apple about the implementation of the NC, rumors within the industry even said that Oracle itself was working on the reference draft. After Bird's visit to Oracle and a subsequent tour of Acorn by Ellison, an agreement was reached to let Acorn define the draft NC reference.

Ellison expected to announce the NC in February 1996. Sophie Wilson headed the NC project and completed a draft of the NC specification by mid-November. By January 1996, the formal details of the contract between Acorn and Oracle had been worked out, the PCB had been designed and approved for production. For this purpose, Acorn Network Computing was founded in February 1996 , which started selling the Acorn Network Computer from August 1996 .

The NC was supposed to create a new market segment in which Acorn Network Computing was intended to play a central role as a direct seller or license holder. To this end, the new end-user operating system Galileo and, together with Digital Semiconductor and ARM, the new StrongARM chipset SA1500 / SA1501 were created. Galileo guaranteed processes Quality of Service , the individual components such as processor or memory functioned independently and reliably of the behavior of other processes. The SA1500 offered higher clock rates than other existing StrongARM processors and also a coprocessor optimized for media playback , the Attached Media Processor or AMP. The SA1500 served as the primary platform for Galileo.

After outsourcing the set-top box and network computer businesses as separate companies, Acorn relocated its PC manufacturing to an independent subsidiary, Acorn RISC Technologies (ART).

The Decay (1998-2000)

With the lack of the predicted VOD boom and the associated failure of the set-top boxes, Acorn's last hope of becoming a central manufacturer of the computer industry was shattered. The network computer was also less successful than hoped: The prices for normal PCs fell steadily, while the available data transfer rates for end customers rose only slowly. The NC was hardly attractive until the late 1990s, as sufficiently fast connections were expensive and rare.

Olivetti sold parts of the Acorn Group between 1996 and 1998 for a total of approximately £ 54 million. Acorn was restructured and subsidiaries were reintegrated. Acorn RISC Technologies took over the workstation division by the end of 1998. At that time, Acorn finally stopped producing desktop computers in favor of set-top boxes. The development of the last computer, called Acorn Phoebe or RISC PC 2 , was stopped shortly before the start of series production. The striking yellow cases of the Phoebe, on the other hand, were manufactured in large numbers and sold at low prices.

ARM's position, however, improved. After going public in 1998, it was re-registered as a stock corporation under the name ARM Holdings . The shares were traded on the London Stock Exchange and were listed on the national Nasdaq market. Morgan Stanley Dean Witter acted as coordinator and lead syndicate for the issue, as well as sponsor and broker for the listing on the London Stock Exchange .

In January 1999, the Acorn Group changed its name from Acorn Computers Limited to Element 14 Limited . Acorn attempted in this way to transform itself into an intellectual property developer in the digital signal processing (DSP) market , similar to ARM . With ARM's high stock value, the 24 percent stake Acorn held in ARM had a greater net present value than the entire Acorn Group. Shareholders put pressure on Acorn to sell its ARM stake and turn it into a profit distribution. Given the vulnerable position of its partner, ARM considered taking action against Acorn itself. Acorn Computers Group was bought on June 1, 1999 by Morgan Stanley Dean Witter Investments Limited . This transaction also resulted in the Acorn Group's withdrawal from the stock market and a payout of the ARM stake to Acorn shareholders.

Morgan Stanley sold the set-top box division and control of RISC OS to Pace for £ 200,000 . On July 26, 1999, a management team led by Stan Boland purchased Element 14 from MSDW for £ 1.5 million. This price corresponded to the liquidation value. Element 14 subsequently received £ 8.25 million (approximately $ 13 million) from Bessemer Venture Partners , Atlas Ventures and Hausers Amadeus Capital Partners. The company's headquarters were in Cambridge, a development facility in Bristol, UK. Alcatel's DSL developers were purposefully poached, including designers of analog front-end and digital ICs , software for DSL modems, as well as specialists in the field of asymmetrical DSL and VDSL . She also acquired an engineering center in Mechelen, Belgium . Element 14 continued to develop DSP products until it was acquired by Broadcom in November 2000 for £ 366 million ($ 594 million) .

The operating system RISC OS 4 ("Ursula") developed for the Phoebe was made available to the users of the Risc PC by RISCOS Limited . The company licensed the operating system and continues to develop and support it. However, there is still competition in this market due to the 26-bit RISC OS 4 sold for the Microdigital Omega and the 32-bit RISC OS 5 for the Castle Iyonix . In 2004 this competition caused a legal dispute over the licensing powers of the companies involved, which briefly questioned the continued existence of the RISC-OS platform.

The "hidden" future (since 2000)

The very energy-saving RISC processor ARM (formerly Acorn Risc Machine, now Advanced Risc Machine) is very popular with various hardware manufacturers. The British processor manufacturer ARM continues to license and develop new variants such as ARM2, Strong-ARM and Cortex-A8. Since 2005, ARM variants have been used in numerous PDAs , cell phone models , navigation systems and smartphones : Sharp Zaurus , Psion Series 5, PalmTreo 600/650 or the handheld console GP2X . The minimal power consumption is a guarantee for the long survival of this processor family. The Cortex-A8 needs only 300 milliwatts of power at 600 MHz / 2000 MIPS. An ARM CPU has been built into most smartphones since 2010. In 2010, too, up to four ARM cores can be installed in the new OMAP 5 CPUs from Texas Instruments .


Home computers

Operating systems


The film Micro Men was shot in 2009 about the creation of the BBC Micro ; he describes the competition between Acorn and Sinclair Research to produce the computer for the BBC.

See also

Web links

Commons : Acorn Computers  - collection of pictures, videos and audio files

General information

Newspaper reports

Individual evidence

  1. ^ Cambridge Processor Unit Limited - Program Listing. In: Rene Court, The Center for Computing History, Cambridge, 2019, accessed October 25, 2019 .
This version was added to the list of articles worth reading on April 2, 2006 .