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Sideways Address Space
The sideways address space on the Acorn BBC Microcomputer, Electron and Master-series microcomputer was Acorn's bank switching implementation, providing for permanent system expansion in the days before hard disk drives or even floppy disk drives were commonplace. Filing systems, application and utility software, and drivers were made available as sideways ROMs, and extra RAM could be fitted via the sideways address space. The BBC Micro Advanced User Guide refers to the sideways address space as "paged ROMs" because it predated the use of this address space for RAM expansion. The BBC B+, B+ 128 and BBC Master all featured sideways RAM as standard. Sideways address space The machines used the 8-bit 6502 and 65C102 processors with a 16-bit address space. The address space was split into 32 KB RAM (0x0000 to 0x7FFF), 16 KB sideways address space (0x8000 to 0xBFFF) and 16 KB operating system space (0xC000 to 0xFFFF). The sideways address space is a bank-switched (referred to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acorn Computers
Acorn Computers Ltd. was a British computer company established in Cambridge, England, in 1978. The company produced a number of computers which were especially popular in the United Kingdom, UK, including the Acorn Electron and the Acorn Archimedes. Acorn's computer dominated the UK educational computer market during the 1980s. Though the company was acquired and largely dismantled in early 1999, with various activities being dispersed amongst new and established companies, its legacy includes the development of reduced instruction set computing (RISC) personal computers. One of its operating systems, , continues to be developed by RISC OS Open. Some activities established by Acorn lived on: technology developed by Arm (company), Arm, created by Acorn as a joint venture with Apple, Inc., Apple and VLSI Technology, VLSI in 1990, is dominant in the mobile phone and personal digital assistant (PDA) microprocessor market. Acorn is sometimes referred to as the "British Apple" and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Address Space
In computing, an address space defines a range of discrete addresses, each of which may correspond to a network host, peripheral device, disk sector, a memory cell or other logical or physical entity. For software programs to save and retrieve stored data, each datum must have an address where it can be located. The number of address spaces available depends on the underlying address structure, which is usually limited by the computer architecture being used. Often an address space in a system with virtual memory corresponds to a highest level translation table, e.g., a segment table in IBM System/370. Address spaces are created by combining enough uniquely identified qualifiers to make an address unambiguous within the address space. For a person's physical address, the ''address space'' would be a combination of locations, such as a neighborhood, town, city, or country. Some elements of a data address space may be the same, but if any element in the address is different, addres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EPROM
An EPROM (rarely EROM), or erasable programmable read-only memory, is a type of programmable read-only memory (PROM) chip that retains its data when its power supply is switched off. Computer memory that can retrieve stored data after a power supply has been turned off and back on is called non-volatile. It is an array of floating-gate transistors individually programmed by an electronic device that supplies higher voltages than those normally used in digital circuits. Once programmed, an EPROM can be erased by exposing it to strong ultraviolet light source (such as from a mercury-vapor lamp). EPROMs are easily recognizable by the transparent fused quartz (or on later models resin) window on the top of the package, through which the silicon chip is visible, and which permits exposure to ultraviolet light during erasing. Operation Development of the EPROM memory cell started with investigation of faulty integrated circuits where the gate connections of transistors had broken ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Watford Electronics
Watford Electronics was a British computer electronics company. It was founded in 1972 in a bedroom belonging to brothers Nazir and Raza Jessa, and grew to become one of the best-known suppliers of microcomputers and micro peripherals during the 1980s. In the 1970s Watford Electronics sold components and kits, through advertising in electronics magazines, and a paper catalogue. They had one shop in Watford, but mostly traded as a mail-order company. In the early 1980s Watford Electronics expanded into the home computer market. It was particularly active in the BBC Micro scene, producing a variety of peripherals for the computer, as well as a version of the Disc Filing System. They sold their own hardware under the Aries brand. Watford Electronics gradually moved over to supporting the Wintel Wintel (portmanteau of Windows and Intel) is the partnership of Microsoft Windows and Intel producing personal computers using Intel x86-compatible processors running Microsoft Windows. Ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acorn MOS
The Machine Operating System (MOS) or OS is a discontinued computer operating system (OS) used in Acorn Computers' BBC computer range. It included support for four-channel sound, graphics, file system abstraction, and digital and analogue input/output (I/O) including a daisy-chained expansion bus. The system was single-tasking, monolithic and non-reentrant. Versions 0.10 to 1.20 were used on the BBC Micro, version 1.00 on the Electron, version 2 was used on the B+, and versions 3 to 5 were used in the BBC Master series. The final BBC computer, the BBC A3000, was 32-bit and ran RISC OS, which kept on portions of the Acorn MOS architecture and shared a number of characteristics (e.g. "star commands" CLI, "VDU" video control codes and screen modes) with the earlier 8-bit MOS. Versions 0 to 2 of the MOS were 16 KiB in size, written in 6502 machine code, and held in read-only memory (ROM) on the motherboard. The upper quarter of the 16-bit address space (0xC000 to 0xFFFF) is re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power-on Self-test
A power-on self-test (POST) is a process performed by firmware or software routines immediately after a computer or other digital electronic device is powered on. This article mainly deals with POSTs on personal computers, but many other embedded systems such as those in major appliances, avionics, communications, or medical equipment also have self-test routines which are automatically invoked at power-on. The results of the POST may be displayed on a panel that is part of the device, output to an external device, or stored for future retrieval by a diagnostic tool. Since a self-test might detect that the system's usual human-readable display is non-functional, an indicator lamp or a speaker may be provided to show error codes as a sequence of flashes or beeps. In addition to running tests, the POST process may also set the initial state of the device from firmware. In the case of a computer, the POST routines are part of a device's pre-boot sequence; if they complete succes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Application Programming Interface
An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build or use such a connection or interface is called an ''API specification''. A computer system that meets this standard is said to ''implement'' or ''expose'' an API. The term API may refer either to the specification or to the implementation. In contrast to a user interface, which connects a computer to a person, an application programming interface connects computers or pieces of software to each other. It is not intended to be used directly by a person (the end user) other than a computer programmer who is incorporating it into the software. An API is often made up of different parts which act as tools or services that are available to the programmer. A program or a programmer that uses one of these parts is said to ''call'' that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Accumulator (computing)
In a computer's central processing unit (CPU), the accumulator is a register in which intermediate arithmetic logic unit results are stored. Without a register like an accumulator, it would be necessary to write the result of each calculation (addition, multiplication, shift, etc.) to main memory, perhaps only to be read right back again for use in the next operation. Access to main memory is slower than access to a register like an accumulator because the technology used for the large main memory is slower (but cheaper) than that used for a register. Early electronic computer systems were often split into two groups, those with accumulators and those without. Modern computer systems often have multiple general-purpose registers that can operate as accumulators, and the term is no longer as common as it once was. However, to simplify their design, a number of special-purpose processors still use a single accumulator. Basic concept Mathematical operations often take place i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Debugger
A debugger or debugging tool is a computer program used to software testing, test and debugging, debug other programs (the "target" program). The main use of a debugger is to run the target program under controlled conditions that permit the programmer to track its execution and monitor changes in computer resources that may indicate malfunctioning code. Typical debugging facilities include the ability to run or halt the target program at specific points, display the contents of memory, CPU registers or storage devices (such as disk drives), and modify memory or register contents in order to enter selected test data that might be a cause of faulty program execution. The code to be examined might alternatively be running on an ''instruction set simulator'' (ISS), a technique that allows great power in its ability to halt when specific conditions are encountered, but which will typically be somewhat slower than executing the code directly on the appropriate (or the same) processor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disc Filing System
The Disc Filing System (DFS) is a computer file system developed by Acorn Computers, initially as an add-on to the Eurocard-based Acorn System 2. In 1981, the Education Departments of Western Australia and South Australia announced joint tenders calling for the supply of personal computers to their schools. Acorn's Australian computer distributor, Barson Computers, convinced Joint Managing Directors Hermann Hauser and Chris Curry to allow the soon to be released Acorn BBC Microcomputer to be offered with disk storage as part of the bundle. They agreed on condition that Barson adapted the Acorn DFS from the System 2 without assistance from Acorn as they had no resources available. This required some minor hardware and software changes to make the DFS compatible with the BBC Micro. Barson won the tenders for both states, with the DFS fitted, a year ahead of the UK. It was this early initiative that resulted in the BBC Micro being more heavily focused on the education market in Au ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BBC BASIC
BBC BASIC is a version of the BASIC programming language released in 1981 as the native programming language for the BBC Micro home/personal computer, providing a standardized language for a UK computer literacy project of the BBC. It was written mainly by Sophie Wilson. BBC BASIC, based on the older Atom BASIC for the Acorn Atom, extended contemporary microcomputer BASICs with named DEF PROC/DEF FN procedures and functions, REPEAT UNTIL loops, and IF THEN ELSE structures inspired by COMAL. The interpreter also included statements for controlling the BBC Micro's four-channel sound output and its low-/high-resolution eight-mode graphics display. Due to a number of optimizations, BBC BASIC ran programs much faster than Microsoft BASIC running on similar machines. The optimizations included using multiple linked lists for variable lookup rather than a single long list, pre-defining the location of integer variables, and having separate integer maths routines. Speed was furthe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operating System
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also include accounting software for cost allocation of processor time, mass storage, printing, and other resources. For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is usually executed directly by the hardware and frequently makes system calls to an OS function or is interrupted by it. Operating systems are found on many devices that contain a computer from cellular phones and video game consoles to web servers and supercomputers. The dominant general-purpose personal computer operating system is Microsoft Windows with a market share of around 74.99%. macOS by Apple Inc. is in second place (14.84%), and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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