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ICT 1900 Series
ICT 1900 was a family of mainframe computers released by International Computers and Tabulators (ICT) and later International Computers Limited (ICL) during the 1960s and 1970s. The 1900 series was notable for being one of the few non-American competitors to the IBM System/360, enjoying significant success in the European and British Commonwealth markets. Origins In early 1963, ICT was engaged in negotiations to buy the computer business of Ferranti. In order to sweeten the deal, Ferranti demonstrated to ICT the Ferranti-Packard 6000 (FP6000) machine, which had been developed by its Canadian subsidiary Ferranti-Packard, to a design known as Harriac that had been initiated in Ferranti by Harry Johnson and fleshed out by Stanley Gill and John Iliffe. The FP6000 was an advanced design, notably including hardware support for multiprogramming. ICT considered using the FP6000 as their medium-sized processor in the 1965–1968 timeframe, replacing the ICT 1302. Anoth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mainframe Computer
A mainframe computer, informally called a mainframe or big iron, is a computer used primarily by large organizations for critical applications like bulk data processing for tasks such as censuses, industry and consumer statistics, enterprise resource planning, and large-scale transaction processing. A mainframe computer is large but not as large as a supercomputer and has more processing power than some other classes of computers, such as minicomputers, server (computing), servers, workstations, and personal computers. Most large-scale computer-system architectures were established in the 1960s, but they continue to evolve. Mainframe computers are often used as servers. The term ''mainframe'' was derived from the large cabinet, called a ''main frame'', that housed the central processing unit and main computer memory, memory of early computers. Later, the term ''mainframe'' was used to distinguish high-end commercial computers from less powerful machines. Design Modern mainfr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antony Jay
Sir Antony Rupert Jay, (20 April 1930 – 21 August 2016) was an English writer and broadcaster. With Jonathan Lynn, he co-wrote the British political-satirical comedies ''Yes Minister'' and '' Yes, Prime Minister'' (1980–88). He also wrote ''The Householder's Guide to Community Defence Against Bureaucratic Aggression'' (1972). For his career as a broadcaster and in public relations, Jay received a knighthood in the 1988 New Year Honours. He also wrote the 1969 BBC television documentary ''Royal Family'' and wrote a 1992 book about Elizabeth II called ''Elizabeth R'', after which he was appointed a Commander of the Royal Victorian Order for personal services to the royal family in the 1993 New Years Honours list. Early life and education Jay was born in Paddington, London, the son of Ernest Jay, a character actor, and Catherine (Hay) Jay. He was educated at St Paul's School and Magdalene College, Cambridge, graduating with first-class honours in Classics and comparative p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Floating Point
In computing, floating-point arithmetic (FP) is arithmetic on subsets of real numbers formed by a ''significand'' (a signed sequence of a fixed number of digits in some base) multiplied by an integer power of that base. Numbers of this form are called floating-point numbers. For example, the number 2469/200 is a floating-point number in base ten with five digits: 2469/200 = 12.345 = \! \underbrace_\text \! \times \! \underbrace_\text\!\!\!\!\!\!\!\overbrace^ However, 7716/625 = 12.3456 is not a floating-point number in base ten with five digits—it needs six digits. The nearest floating-point number with only five digits is 12.346. And 1/3 = 0.3333… is not a floating-point number in base ten with any finite number of digits. In practice, most floating-point systems use base two, though base ten (decimal floating point) is also common. Floating-point arithmetic operations, such as addition and division, approximate the corresponding real number arithmetic operations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trap (computing)
In digital computers, an interrupt (sometimes referred to as a trap) is a request for the processor to ''interrupt'' currently executing code (when permitted), so that the event can be processed in a timely manner. If the request is accepted, the processor will suspend its current activities, save its state, and execute a function called an ''interrupt handler'' (or an ''interrupt service routine'', ISR) to deal with the event. This interruption is often temporary, allowing the software to resume normal activities after the interrupt handler finishes, although the interrupt could instead indicate a fatal error. Interrupts are commonly used by hardware devices to indicate electronic or physical state changes that require time-sensitive attention. Interrupts are also commonly used to implement computer multitasking and system calls, especially in real-time computing. Systems that use interrupts in these ways are said to be interrupt-driven. History Hardware interrupts were ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indirect Branch
An indirect branch (also known as a computed jump, indirect jump and register-indirect jump) is a type of program control instruction present in some machine language instruction sets. Rather than specifying the address of the next instruction to execute, as in a direct branch, the argument specifies where the address is located. An example is 'jump indirect on the r1 register', which means that the next instruction to be executed is at the address in register r1. The address to be jumped to is not known until the instruction is executed. Indirect branches can also depend on the value of a memory location. An indirect branch can be useful to make a conditional branch, especially a multiway branch. For instance, based on program input, a value could be looked up in a jump table of pointers to code for handling the various cases implied by the data value. The data value could be added to the address of the table, with the result stored in a register. An indirect jump ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GEORGE (operating System)
GEORGE was the name given to a series of operating systems released by International Computers and Tabulators (ICT) in the 1960s, for the ICT 1900 series of computers. These included GEORGE 1, GEORGE 2, GEORGE 3, and GEORGE 4. Initially, the 1900 series machines, like the Ferranti-Packard 6000 on which they were based, ran a simple operating system known as Executive (operating system), Executive, which allowed the system operator to load and run programs from a Teletype Model 33 ASR based system console. In December 1964, ICT set up an Operating Systems Branch to develop a new operating system for the 1906/7. The branch was initially staffed with people being released by the end of work on the Orion Master Program, OMP operating system for the Ferranti Orion. The initial design of the new system, named George after the head of the Basic Programming Division George E. Felton, was based on ideas from the Orion and the spooling system of the Atlas Computer (Manchester), Atlas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual Memory
In computing, virtual memory, or virtual storage, is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a very large (main) memory". The computer's operating system, using a combination of hardware and software, maps memory addresses used by a program, called '' virtual addresses'', into ''physical addresses'' in computer memory. Main storage, as seen by a process or task, appears as a contiguous address space or collection of contiguous segments. The operating system manages virtual address spaces and the assignment of real memory to virtual memory. Address translation hardware in the CPU, often referred to as a memory management unit (MMU), automatically translates virtual addresses to physical addresses. Software within the operating system may extend these capabilities, utilizing, e.g., disk storage, to provide a virtual address space ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paging
In computer operating systems, memory paging is a memory management scheme that allows the physical Computer memory, memory used by a program to be non-contiguous. This also helps avoid the problem of memory fragmentation and requiring compaction to reduce fragmentation. Paging is often combined with the related technique of allocating and freeing Page (computer memory), ''page frames'' and storing pages on and retrieving them from Computer data storage#Secondary storage, secondary storage in order to allow the aggregate size of the address spaces to exceed the physical memory of the system. For historical reasons, this technique is sometimes referred to as ''swapping''. When combined with virtual memory, it is known as Virtual memory#Paged virtual memory, ''paged virtual memory''. In this scheme, the operating system retrieves data from secondary storage in Block (data storage), blocks of the same size (pages). Paging is an important part of virtual memory implementations in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
24 Bit
4 (four) is a number, numeral and digit. It is the natural number following 3 and preceding 5. It is a square number, the smallest semiprime and composite number, and is considered unlucky in many East Asian cultures. Evolution of the Hindu-Arabic digit Brahmic numerals represented 1, 2, and 3 with as many lines. 4 was simplified by joining its four lines into a cross that looks like the modern plus sign. The Shunga would add a horizontal line on top of the digit, and the Kshatrapa and Pallava evolved the digit to a point where the speed of writing was a secondary concern. The Arabs' 4 still had the early concept of the cross, but for the sake of efficiency, was made in one stroke by connecting the "western" end to the "northern" end; the "eastern" end was finished off with a curve. The Europeans dropped the finishing curve and gradually made the digit less cursive, ending up with a digit very close to the original Brahmin cross. While the shape of the character for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Index Register
An index register in a computer's central processing unit, CPU is a processor register (or an assigned memory location) used for pointing to operand addresses during the run of a program. It is useful for stepping through String (computer science), strings and Array data structure, arrays. It can also be used for holding loop iterations and counters. In some Instruction set architecture, architectures it is used for read/writing blocks of memory. Depending on the architecture it may be a dedicated index register or a general-purpose register. Some instruction sets allow more than one index register to be used; in that case additional instruction fields may specify which index registers to use. Generally, the contents of an index register is added to (in some cases subtracted from) an ''immediate'' address (that can be part of the instruction itself or held in another register) to form the "effective" address of the actual data (operand). Special instructions are typically provided ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Processor Register
A processor register is a quickly accessible location available to a computer's processor. Registers usually consist of a small amount of fast storage, although some registers have specific hardware functions, and may be read-only or write-only. In computer architecture, registers are typically addressed by mechanisms other than main memory, but may in some cases be assigned a memory address e.g. DEC PDP-10, ICT 1900. Almost all computers, whether load/store architecture or not, load items of data from a larger memory into registers where they are used for arithmetic operations, bitwise operations, and other operations, and are manipulated or tested by machine instructions. Manipulated items are then often stored back to main memory, either by the same instruction or by a subsequent one. Modern processors use either static or dynamic random-access memory (RAM) as main memory, with the latter usually accessed via one or more cache levels. Processor registers are normal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Word Addressing
In computer architecture, ''word addressing'' means that addresses of memory on a computer uniquely identify words of memory. It is usually used in contrast with byte addressing, where addresses uniquely identify bytes. Almost all modern computer architectures use byte addressing, and word addressing is largely only of historical interest. A computer that uses word addressing is sometimes called a ''word machine''. Basics Consider a computer which provides 524,288 (219) bits of memory. If that memory is arranged in a byte-addressable flat address space using 8-bit bytes, then there are 65,536 (216) valid addresses, from 0 to 65,535, each denoting an independent 8 bits of memory. If instead it is arranged in a word-addressable flat address space using 32-bit words, then there are 16,384 (214) valid addresses, from 0 to 16,383, each denoting an independent 32 bits. More generally, the minimum addressable unit (MAU) is a property of a specific memory abstraction. Different a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
