BBC Micro Expansion Unit
A BBC Micro expansion unit, for the BBC Micro is one of a number of peripherals in a box with the same profile and styling as the main computer. Second Processors The second processors are connected to Acorn's proprietary and trademarked ''Tube'' interface. Only one second processor unit could be connected at a time to a BBC Micro, although a Master 128 could also have a co-processor fitted internally at the same time. The terminology of ''second'' processor was slightly misleading, since connected and switched on, the system worked on a "host-parasite" model, with the processor in the external unit taking control while the 6502 in the "main" computer simply took on responsibility for I/O. 6502 Second Processor The 6502 Second Processor (using a 65C02) was clocked at 3 MHz, a full 50% faster than the 6502 inside a BBC Model B, and also had 64 KB of RAM, of which typically 30–44 KB was free for application data (compared to as little as 8.5 KB on an unexpa ...
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BBC Teletext Adapter
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Telesoftware
The term telesoftware was coined by W.J.G. Overington who invented the concept in 1974; it literally means “software at a distance” and it often refers to the transmission of programs for a microprocessor or home computer via broadcast teletext, though the use of teletext was just a convenient way to implement the invention, which had been invented as a theoretical broadcasting concept previously. The concept being of producing local interactivity without the need for a return information link to a central computer. The invention arose as spin-off from research on function generators for a hybrid computer system for use in simulation of heat transfer in food preservation, and thus from outside of the broadcasting research establishments. Software bytes are presented to a terminal as pairs of standard teletext characters, thus utilizing an existing and well-proven broadcasting system. History Telesoftware was pioneered in the UK during the 1970s and 1980s, and a paper on the ...
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Teletext
A British Ceefax football index page from October 2009, showing the three-digit page numbers for a variety of football news stories Teletext, or broadcast teletext, is a standard for displaying text and rudimentary graphics on suitably equipped television sets. Teletext sends data in the broadcast signal, hidden in the invisible vertical blanking interval area at the top and bottom of the screen. The teletext decoder in the television buffers this information as a series of "pages", each given a number. The user can display chosen pages using their remote control. In broad terms, it can be considered as Videotex, a system for the delivery of information to a user in a computer-like format, typically displayed on a television or a dumb terminal, but that designation is usually reserved for systems that provide bi-directional communication, such as Prestel or Minitel. Teletext was created in the United Kingdom in the early 1970s by John Adams, Philips' lead designer for video di ...
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Daisy Chain (electrical Engineering)
In electrical and electronic engineering, a daisy chain is a wiring scheme in which multiple devices are wired together in sequence or in a ring, similar to a garland of daisy flowers. Daisy chains may be used for power, analog signals, digital data, or a combination thereof. The term ''daisy chain'' may refer either to large scale devices connected in series, such as a series of power strips plugged into each other to form a single long line of strips, or to the wiring patterns embedded inside of devices. Other examples of devices which can be used to form daisy chains are those based on Universal Serial Bus (USB), FireWire, Thunderbolt and Ethernet cables. Signal transmission For analog signals, connections usually consist of a simple electrical bus and, especially in the case of a chain of many devices, may require the use of one or more repeaters or amplifiers within the chain to counteract attenuation (the natural loss of energy in such a system). Digital signal ...
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Sinclair QL
The Sinclair QL (for ''Quantum Leap'') is a personal computer launched by Sinclair Research in 1984, as an upper-end counterpart to the ZX Spectrum. The QL was aimed at the serious home user and professional and executive users markets from small to medium-sized businesses and higher educational establishments, but failed to achieve commercial success. While the ZX Spectrum has an 8-bit Zilog Z80 as the CPU, the QL uses a Motorola 68008. The 68008 is a member of the Motorola 68000 family with 32-bit internal data registers, but an 8-bit external data bus. History left, Sinclair QL ROM "dongle" – needed to expand the internal 32 KB ROM to 48 KB in early QLs The QL was originally conceived in 1981 under the code-name ''ZX83'', as a portable computer for business users, with a built-in ultra-thin flat-screen CRT display similar to the later TV80 pocket TV, printer and modem. As development progressed it eventually became clear that the portability features were over- ...
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Torch Computers
Torch Computers Ltd was a computer hardware company with origins in a 1982 joint venture between Acorn Computers and Climar Group that led to the development of the Communicator or C-series computer, a system based on the BBC Micro with a Z80 second processor and integral modem, intended as a viewdata terminal. Establishing itself in Great Shelford, near Cambridge, UK, the company became well known for its computer peripherals for the VIC-20 and BBC Micro. Torch produced an expansion unit originally developed by Arfon Microelectronics for the VIC-20, having acquired Arfon, and several second processor units for the BBC Micro, many with integrated floppy disk or hard disk drives. History Arfon acquisition and financing Arfon Microelectronics was a producer of a cartridge expansion system for the VIC-20 and a speech generator expansion for the VIC-20 and other microcomputers. Arfon had been founded by Kerr Borland, former North American Semi managing director, in Caernarfon, N ...
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Arthur (operating System)
RISC OS, the computer operating system developed by Acorn Computers for their ARM-based Acorn Archimedes range, was originally released in 1987 as ', and soon followed by ', and '. The next version, ', became ' and was completed and made available in April 1989. ' was released with the very earliest version of the A5000 in 1991 and contained a series of new features. By 1996 RISC OS had been shipped on over 500,000 systems. ' was released by RISCOS Ltd (ROL) in July 1999, based on the continued development of . ROL had in March 1999 licensed the rights to RISC OS from Element 14 (the renamed Acorn) and eventually from the new owner, Pace Micro Technology. According to the company, over 6,400 copies of on ROM were sold up until production was ceased in mid-2005. ' was launched in May 2001 by ROL. This is a subscription scheme allowing users access to the latest OS updates. These upgrades are released as soft-loadable ROM images, separate to the ROM where the boot OS is stored, ...
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Acorn Archimedes
Acorn Archimedes is a family of personal computers designed by Acorn Computers of Cambridge, Cambridge, England. The systems are based on Acorn's own ARM architecture processors and the proprietary operating systems Arthur and RISC OS. The first models were introduced in 1987, and systems in the Archimedes family were sold until the mid-1990s. ARM's Reduced instruction set computer, RISC design, a 32-bit CPU (using 26-bit addressing), running at 8 Hertz, MHz, was stated as achieving 4.5+ Million instructions per second, MIPS, which provided a significant upgrade from 8-bit home computers, such as Acorn's previous machines. Claims of being the fastest micro in the world and running at 18 MIPS were also made during tests. Two of the first models—the A305 and A310—were given the BBC branding, with BBC Worldwide, BBC Enterprises regarding the machines as "a continuing part of the original computer literacy project". Dissatisfaction with the branding arrangement was ...
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ARM Architecture
ARM (stylised in lowercase as arm, formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a family of reduced instruction set computer (RISC) instruction set architectures for computer processors, configured for various environments. Arm Ltd. develops the architectures and licenses them to other companies, who design their own products that implement one or more of those architectures, including system on a chip (SoC) and system on module (SOM) designs, that incorporate different components such as memory, interfaces, and radios. It also designs cores that implement these instruction set architectures and licenses these designs to many companies that incorporate those core designs into their own products. There have been several generations of the ARM design. The original ARM1 used a 32-bit internal structure but had a 26-bit address space that limited it to 64 MB of main memory. This limitation was removed in the ARMv3 series, which ...
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RISC
In computer engineering, a reduced instruction set computer (RISC) is a computer designed to simplify the individual instructions given to the computer to accomplish tasks. Compared to the instructions given to a complex instruction set computer (CISC), a RISC computer might require more instructions (more code) in order to accomplish a task because the individual instructions are written in simpler code. The goal is to offset the need to process more instructions by increasing the speed of each instruction, in particular by implementing an instruction pipeline, which may be simpler given simpler instructions. The key operational concept of the RISC computer is that each instruction performs only one function (e.g. copy a value from memory to a register). The RISC computer usually has many (16 or 32) high-speed, general-purpose registers with a load/store architecture in which the code for the register-register instructions (for performing arithmetic and tests) are separate fr ...
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80186
The Intel 80186, also known as the iAPX 186, or just 186, is a microprocessor and microcontroller introduced in 1982. It was based on the Intel 8086 and, like it, had a 16-bit external data bus multiplexed with a 20-bit address bus. The 80188 variant, with an 8-bit external data bus was also available. Description The 80186 series was generally intended for embedded systems, as microcontrollers with external memory. Therefore, to reduce the number of integrated circuits required, it included features such as clock generator, interrupt controller, timers, wait state generator, DMA channels, and external chip select lines. The initial clock rate of the 80186 was 6 MHz, but due to more hardware available for the microcode to use, especially for address calculation, many individual instructions completed in fewer clock cycles than on an 8086 at the same clock frequency. For instance, the common ''register+immediate'' addressing mode was significantly faster than on th ...
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