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Encyclopedia > Word (computer science)

In computing, "word" is a term for the natural unit of data used by a particular computer design. A word is simply a fixed-sized group of bits that are handled together by the machine. The number of bits in a word (the word size or word length) is an important characteristic of a computer architecture. Originally, the word computing was synonymous with counting and calculating, and a science and technology that deals with the original sense of computing mathematical calculations. ... A bit (binary digit) refers to a digit in the binary numeral system, which consists of base 2 digits (ie. ... A typical vision of a computer architecture as a series of abstraction layers: hardware, firmware, assembler, kernel, operating system and applications (see also Tanenbaum 79). ...


The size of a word is reflected in many aspects of a computer's structure and operation. The majority of the registers in the computer are usually word-sized. The typical numeric value manipulated by the computer is probably word sized. The amount of data transferred between the processing part of the computer and the memory system is most often a word. An address used to designate a location in memory often fits in a word. In computer architecture, a processor register is a small amount of very fast computer memory used to speed the execution of computer programs by providing quick access to commonly used values—typically, the values being in the midst of a calculation at a given point in time. ... CPU redirects here. ... The terms storage (U.K.) or memory (U.S.) refer to the parts of a digital computer that retain physical state (data) for some interval of time, possibly even after electrical power to the computer is turned off. ... Look up address in Wiktionary, the free dictionary. ...


Modern computers usually have a word size of 16, 32, or 64 bits. Many other sizes have been used in the past, including 8, 12, 18, 24, 36, 39, 40, 48, and 60 bits; the slab is an example of an early word size. Some of the earliest computers were decimal rather than binary, typically having a word size of 10 or 12 decimal digits, and some early computers had no fixed word length at all. A slab is the word in the NCR 315 computer architecture. ... The decimal (base ten or occasionally denary) numeral system has ten as its base. ... The binary numeral system (base 2 numerals) represents numeric values using two symbols, typically 0 and 1. ...


The most common microprocessors used in personal computers have the x86 architecture (for instance, the Intel Pentiums and AMD Athlons). The x86 family includes several generations of achitecture. In the Intel 8086, 80186, and 80286, the word size is 16 bits. In IA-32, the word size is 32 bits. In x86-64, the word size is 64 bits. Yet each implementation also implements the earlier instruction sets too. So Intel calls 16 bits a word in all of them; clearly this usage of word is different from that of this article. Microprocessors, including an Intel 80486DX2 and an Intel 80386 A microprocessor (abbreviated as µP or uP) is an electronic computer central processing unit (CPU) made from miniaturized transistors and other circuit elements on a single semiconductor integrated circuit (IC) (aka microchip or just chip). ... x86 or 80x86 is the generic name of a microprocessor architecture first developed and manufactured by Intel. ... Intel Corporation (NASDAQ: INTC, SEHK: 4335), founded in 1968 as Integrated Electronics Corporation, is an American multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ... Pentium logo, with MMX enhancement The Pentium is a fifth-generation x86 architecture microprocessor by Intel. ... Advanced Micro Devices, Inc. ... Athlon is the brand name applied to a series of different x86 processors designed and manufactured by AMD. The original Athlon, or Athlon Classic, was the first seventh-generation x86 processor and, in a first, retained the initial performance lead it had over Intels competing processors for a significant... The 8086 is a 16-bit microprocessor chip designed by Intel in 1978, which gave rise to the x86 architecture. ... The 80186 is a microprocessor that was developed by Intel circa 1982. ... The Intel 80286 is an x86-family 16-bit microprocessor that was introduced by Intel on February 1, 1982. ... It has been suggested that this article or section be merged with X86 assembly language. ... The AMD64 or x86-64 is a 64-bit processor architecture invented by AMD. It is a superset of the x86 architecture, which it natively supports. ...

Contents

Uses of words

Depending on how a computer is organized, units of the word size may be used for:

  • Integer numbers – Holders for integer numerical values may be available in one or in several different sizes, but one of the sizes available will almost always be the word. The other sizes, if any, are likely to be multiples or fractions of the word size. The smaller sizes are normally used only for efficient use of memory; when loaded into the processor, their values usually go into a larger, word-sized holder.
  • Floating point numbers – Holders for floating point numerical values are typically either a word or a multiple of a word.
  • Addresses – Holders for memory addresses must be of a size capable of expressing the needed range of values, but not be excessively large. Often the size used is that of the word, but it can also be a multiple or fraction of the word size.
  • RegistersProcessor registers are designed with a size appropriate for the type of data they hold, e.g. integers, floating point numbers, or addresses. Many computer architectures use "general purpose" registers that can hold any of several types of data; those registers are sized to allow the largest of any of those types, and typically that size is the word size of the architecture.
  • Memory-processor transfer – When the processor reads from the memory subsystem into a register, or writes a register's value to memory, the amount of data transferred is often a word. In simple memory subsystems, the word is transferred over the memory data bus, which typically has a width of a word or half word. In memory subsystems that use caches, the word-sized transfer is the one between the processor and the first level of cache; at lower levels of the memory hierarchy larger transfers (which are a multiple of the word size) are normally used.
  • Unit of address resolution – In a given architecture, successive address values designate successive units of memory; this unit is the unit of address resolution. In most computers, the unit is either a character (e.g. a byte) or a word. (A few computers have used bit resolution.) If the unit is a word, then a larger amount of memory can be accessed using an address of a given size. On the other hand, if the unit is a byte, then individual characters can be addressed (i.e. selected during the memory operation).
  • InstructionsMachine instructions are normally fractions or multiples of the architecture's word size. This is a natural choice since instructions and data usually share the same memory subsystem. In Harvard architectures the word sizes of instructions and data need not be related.

In computer science, the term integer is used to refer to any data type which can represent some subset of the mathematical integers. ... A floating-point number is a digital representation for a number in a certain subset of the rational numbers, and is often used to approximate an arbitrary real number on a computer. ... In computer architecture, a processor register is a small amount of very fast computer memory used to speed the execution of computer programs by providing quick access to commonly used values—typically, the values being in the midst of a calculation at a given point in time. ... In computer architecture, a bus is a subsystem that transfers data or power between computer components inside a computer or between computers. ... Look up cache in Wiktionary, the free dictionary. ... The hierarchical arrangement of storage in current computer architectures is called the memory hierarchy. ... A system of codes directly understandable by a computers CPU is termed this CPUs native or machine language. ... The term Harvard architecture originally referred to computer architectures that used physically separate storage and signal pathways for their instructions and data (in contrast to the von Neumann architecture). ...

Word size choice

When a computer architecture is designed, the choice of a word size is of substantial importance. There are design considerations which encourage particular bit-group sizes for particular uses (e.g. for addresses), and these considerations point to different sizes for different uses. However, considerations of economy in design strongly push for one size, or a very few sizes related by multiples or fractions (submultiples) to a primary size. That preferred size becomes the word size of the architecture.


Character size is one of the influences on a choice of word size. Before the mid-1960s, characters were most often stored in six bits; this allowed no more than 64 characters, so alphabetics were limited to upper case. Since it is efficient in time and space to have the word size be a multiple of the character size, word sizes in this period were usually multiples of 6 bits (in binary machines). A common choice then was the 36-bit word, which is also a good size for the numeric properties of a floating point format. 36-bit word length describes the number of bits, 36, used in some early computers to represent data in the form of words—their basic units of addressing and calculation. ...


After the introduction of the IBM System/360 design which used eight-bit characters and supported lower-case letters, the standard size of a character (or more accurately, a byte) became eight bits. Word sizes thereafter were naturally multiples of eight bits, with 16, 32, and 64 bits being commonly used. Big Blue redirects here. ... System/360 Model 65 operators console, with register value lamps and toggle switches (middle of picture) and emergency pull switch (upper right). ... A byte is commonly used as a unit of storage measurement in computers, regardless of the type of data being stored. ...


Variable word architectures

Early machine designs included some that used what is often termed a variable word length. In this type of organization, a numeric operand had no fixed length but rather its end was detected when a character with a special marking was encountered. Such machines used binary coded decimal for numbers. This class of machines included the IBM 702, IBM 705, IBM 7080, IBM 7010, UNIVAC 1050, IBM 1401, and IBM 1620. Binary-coded decimal (BCD) is a numeral system used in computing and in electronics systems. ... The IBM 700/7000 series was a series of incompatible large scale (mainframe) computer systems made by IBM through the 1950s and early 1960s. ... The IBM 7080 was a transistorized variable word length BCD computer in the IBM 700/7000 series commercial architecture line, introduced in August 1961, that provided an upgrade path from the vacuum tube IBM 705 computer. ... The IBM 700/7000 series was a series of incompatible large scale (mainframe) computer systems made by IBM through the 1950s and early 1960s. ... The UNIVAC 1050 was a variable wordlength (1 to 16 characters) decimal and binary computer. ... The IBM 1401 was a variable wordlength decimal computer that was announced by IBM on October 5, 1959 and marketed as an inexpensive Business Computer. It was withdrawn on February 8, 1971. ... The IBM 1620 was announced by IBM on October 21, 1959 and marketed as an inexpensive scientific computer. It was withdrawn on November 19, 1970. ...


Most of these machines work on one unit of memory at a time and since each instruction or datum is several units long, each instruction takes several cycles just to access memory. These machines are often quite slow because of this. For example, instruction fetches on an IBM 1620 Model I take 8 cycles just to read the 12 digits of the instruction (the Model II reduced this to 6 cycles, but reduced the fetch times to 4 cycles if one or 1 cycle if both address fields were not needed by the instruction). The IBM 1620 Model I was the original implementation of the IBM 1620 scientific computer, introduced in 1959. ... The IBM 1620 Model II (commonly called simply the Model II) was a vastly improved implementation, compared to the original Model I, of the IBM 1620 scientific computer architecture. ...


Word and byte addressing

The memory model of an architecture is strongly influenced by the word size. In particular, the resolution of a memory address, that is, the smallest unit that can be designated by an address, has often been chosen to be the word. In this approach, address values which differ by one designate adjacent memory words. This is natural in machines which deal almost always in word (or multiple-word) units, and has the advantage of allowing instructions to use minimally-sized fields to contain addresses, which can permit a smaller instruction size or a larger variety of instructions.


When byte processing is to be a significant part of the workload, it is usually more advantageous to use the byte, rather than the word, as the unit of address resolution. This allows an arbitrary character within a character string to be addressed straightforwardly. A word can still be addressed, but the address to be used requires a few more bits than the word-resolution alternative. The word size needs to be an integral multiple of the character size in this organization. This addressing approach was used in the IBM 360, and has been the most common approach in machines designed since then.


The power of 2

Data values may occupy differing sizes of memory, because, for instance, some numbers need to be capable of having greater precision than others. The commonly used sizes are usually chosen to be a power of 2 multiple of the unit of address resolution (byte or word). This is convenient because converting the index of an item in an array into the address of the item then requires only a shift operation (which is just a conductor routing in hardware) rather than a multiplication. In some cases this relationship can also avoid the use of division operations. As a result, most modern computer designs have word sizes (and other operand sizes) that are a power of 2 times the size of a byte. In mathematics, a power of two is any of the nonnegative integer powers of the number two; in other words, two times itself a certain number of times. ...


Size families

As computer designs have grown more complex, the obvious central importance of a single word size to an architecture has decreased. This is due to the more capable hardware making use of a wider variety of sizes of data since differing sizes are most effective in differing contexts. One pressure in this direction is the need to maintain backward compatibility while extending processor capability. As a result, what might have been the central word size in a fresh design has to coexist as an alternative size to the original word size in a backward compatible design. This article or section does not cite its references or sources. ...


A major example of this can be seen in the x86 designs. The original 8086 architecture clearly used a word size of 16 bits. The significantly-enhanced design of the 80386 added to the 8086 base an organization which was based around units of 32 bits. If it were an unencumbered design, it would have had a 32-bit word size, but as an extension of the 8086, its word size continued to be considered to be 16 bits. (As a result of this, one hears of the 80386 and successor processors as being "32-bit", but usually not as having a 32-bit word.) This same situation has recently reoccurred in the same line, as the AMD64 architectural extensions bring the 64-bit size into a major position without dropping any of the 16- and 32-bit support. x86 or 80x86 is the generic name of a microprocessor architecture first developed and manufactured by Intel. ... The 8086 is a 16-bit microprocessor chip designed by Intel in 1978, which gave rise to the x86 architecture. ... The Intel 80386 is a microprocessor which was used as the central processing unit (CPU) of many personal computers from 1986 until 1994 and later. ... AMD64 Logo AMD64 (also x86-64 or x64) is a 64-bit microprocessor architecture and corresponding instruction set designed by Advanced Micro Devices. ...


Thus one sees that today a computer architecture is based on a family of closely related sizes more than on a single omnipresent word size. The sizes are intimately related to one another by integral factors, usually a power of two. Calling any one of them the architecture's word size may be somewhat arbitrary, and a size may be so designated due to the history of the architecture's evolution rather than the properties of the size itself in a recent design.


Dword and Qword

In computer science, a dword (double word) is a unit of data that is double the size of a word and half the size of a qword. On the x86 platform with a wordsize of 16 bits, a dword unit of data would be 32 bits long. To print a dword using printf, fprintf or similar functions use %ld as the designator. In the Microsoft Windows API, a DWORD is a typedef for an unsigned long. To print a DWORD using printf or similar functions use %lu as the designator. x86 or 80x86 is the generic name of a microprocessor architecture first developed and manufactured by Intel. ... A bit (binary digit) refers to a digit in the binary numeral system, which consists of base 2 digits (ie. ... A bit (binary digit) refers to a digit in the binary numeral system, which consists of base 2 digits (ie. ... Several programming languages implement a printf function, to output a formatted string. ... Several programming languages implement a printf function, to output a formatted string. ... The Windows API, informally WinAPI, is the name given by Microsoft to the core set of application programming interfaces available in the Microsoft Windows operating systems. ... typedef is a keyword in the C Programming Language. ... Signedness is a property of an integer number used by a compiler to indicate if variables of a numeric type are capable of storing both positive and negative numbers, or just positive. ... In computer science, a long integer is a variable that can hold a positive or negative whole number whose range is greater or equal to that of a standard integer on the same machine. ... Several programming languages implement a printf function, to output a formatted string. ...


In computer science, a qword (quadruple word) is a unit of data that is twice the size of a dword or four times the size of a word. On the common 32-bit x86 platform, this unit of data would be 64 bits because the size of a Word on an x86 system is 16 bits. On the more recent AMD64/EM64T, which are 64-bit x86 architecture, this unit of data would be 256 bits long, because the Word size on a 64-bit system is 64 bits. AMD64 Logo AMD64 (also x86-64 or x64) is a 64-bit microprocessor architecture and corresponding instruction set designed by Advanced Micro Devices. ... Extended Memory 64-bit Technology (EM64T) is Intels implementation of AMD64, a 64-bit extension to the IA-32 architecture. ...


Table of word sizes

Year Computer
Architecture
Word Size
w
Integer
Sizes
Floating Point
Sizes
Instruction
Sizes
Unit of Address
Resolution
Char
Size
1941 Zuse Z3 22 b w 8 b w
1942 ABC 50 b w
1944 Harvard Mark I 23 d w 24 b
1946
(1948)
{1953}
ENIAC
(w/Panel #16)
{w/Panel #26}
10 d w, 2w
(w)
{w}

(2d, 4d, 6d, 8d)


{w}
1951 UNIVAC I 12 d w ½w w 1 d
1952 IAS machine 40 b w ½w w 5 b
1952 IBM 701 36 b ½w, w ½w ½w, w 6 b
1952 UNIVAC 60 n d 1d, ... 10d 2d, 3d
1953 IBM 702 n d 0d, ... 511d 5d d 1 d
1953 UNIVAC 120 n d 1d, ... 10d 2d, 3d
1954
(1955)
IBM 650
(w/IBM 653)
10 d w
(w)
w w 2 d
1954 IBM 704 36 b w w w w 6 b
1954 IBM 705 n d 0d, ... 255d 5d d 1 d
1954 IBM NORC 16 d w w, 2w w w
1956 IBM 305 n d 1d, ... 100d 10d d 1 d
1958 UNIVAC II 12 d w ½w w 1 d
1958 SAGE 32 b ½w w w 6 b
1958 Autonetics Recomp II 40 b w, 79 b, 8d, 15d 2w ½w ½w, w 5 b
1959 IBM 1401 n d 1d, ... d, 2d, 4d, 5d, 7d, 8d d 1 d
1959
(TBD)
IBM 1620 n d 2d, ...
(4d, ... 102d)
12d d 2 d
1960 LARC 12 d w, 2w w, 2w w w 2 d
1960 IBM 1410 n d 1d, ... d, 2d, 6d, 7d, 11d, 12d d 1 d
1960 IBM 7070 10 d w w w w, d 2 d
1960 PDP-1 18 b w w w 6 b
1961 IBM 7030
(Stretch)
64 b 1b, ... 64b,
1d, ... 16d
w ½w, w b, ½w, w 1 b, ... 8 b
1961 IBM 7080 n d 0d, ... 255d 5d d 1 d
1962 UNIVAC III 25 b, 6 d w, 2w, 3w, 4w w w 6 b
1962 UNIVAC 1107 36 b 1/6w, ⅓w, ½w, w w w w 6 b
1962 IBM 7010 n d 1d, ... d, 2d, 6d, 7d, 11d, 12d d 1 d
1962 IBM 7094 36 b w w, 2w w w 6 b
1963 Gemini Guidance Computer 39 b 26 b 13 b 13 b, 26 b
1963
(1966)
Apollo Guidance Computer 15 b w w, 2w w
1964 CDC 6600 60 b w w ¼w, ½w w 6 b
1965 IBM 360 32 b ½w, w,
1d, ... 16d
w, 2w ½w, w, 1½w 8 b 8 b
1965 UNIVAC 1108 36 b 1/6w, ¼w, ⅓w, ½w, w, 2w w, 2w w w 6 b, 9 b
1965 PDP-8 12 b w w w 8 b
1970 PDP-11 16 b w 2w, 4w w, 2w, 3w 8 b 8 b
1971 Intel 4004 4 b w, d 2w, 4w w
1972 Intel 8008 8 b w, 2d w, 2w, 3w w 8 b
1974 Intel 8080 8 b w, 2w, 2d w, 2w, 3w w 8 b
1975 Cray-1 64 b 24 b, w w ¼w, ½w w 8 b
1975 Motorola 6800 8 b w, 2d w, 2w, 3w w 8 b
1975 MOS Tech. 6501
MOS Tech. 6502
8 b w, 2d w, 2w, 3w w 8 b
1976 Zilog Z80 8 b w, 2w, 2d w, 2w, 3w, 4w, 5w w 8 b
1978
(1980)
Intel 8086
(w/Intel 8087)
16 b ½w, w, 2d
(w, 2w, 4w)

(2w, 4w, 5w, 17d)
½w, w, ... 7w 8 b 8 b
1978 VAX-11/780 32 b ¼w, ½w, w, 1d, ... 31d, 1b, ... 32b w, 2w ¼w, ... 14¼w 8 b 8 b
1979 Motorola 68000 32 b ¼w, ½w, w, 2d ½w, w, ... 7½w 8 b 8 b
1982
(1983)
Motorola 68020
(w/Motorola 68881)
32 b ¼w, ½w, w, 2d
(w, 2w, 2½w)
½w, w, ... 7½w 8 b 8 b
1985 ARM1 32 b w w 8 b 8 b
1985 MIPS 32 b ¼w, ½w, w w, 2w w 8 b 8 b
1989 Intel 80486 16 b ½w, w, 2d
w, 2w, 4w
2w, 4w, 5w, 17d ½w, w, ... 7w 8 b 8 b
1989 Motorola 68040 32 b ¼w, ½w, w, 2d w, 2w, 2½w ½w, w, ... 7½w 8 b 8 b
1991 PowerPC 32 b ¼w, ½w, w w, 2w w 8 b 8 b
2000 IA-64 64 b 8 b, ¼w, ½w, w ½w, w 41 b 8 b 8 b
2002 XScale 32 b w w, 2w ½w, w 8 b 8 b
key: b: bits, d: decimal digits, w: word size of architecture, n: variable size

Konrad Zuses Z3 was the first working programmable, fully automatic machine, whose attributes, with the addition of conditional branching, have often been the ones used as criteria in defining a computer. ... Atanasoff-Berry Computer replica at 1st floor of Durham Center, Iowa State University electronic digital computing device[1]. The machine, conceived in 1937, was capable of solving up to 29 simultaneous linear equations and was successfully tested, though its input/output mechanism was still unreliable in 1942 when its inventors... Portion of the Harvard-IBM Mark 1, left side. ... ENIAC ENIAC, short for Electronic Numerical Integrator and Computer[1], was the first large-scale, electronic, digital computer capable of being reprogrammed to solve a full range of computing problems[2], although earlier computers had been built with some of these properties. ... UNIVAC I Central Complex, containing the central processor and main memory unit. ... The IAS Computer, 1952 (courtesy of the Smithsonian) The IAS machine was the first electronic digital computer built by the Institute for Advanced Study (IAS), Princeton, NJ, USA. The paper describing the design of the IAS machine was edited by John von Neumann, (see Von Neumann architecture). ... The IBM 701, known as the Defense Calculator while in development, was announced to the public on April 29, 1952, and was IBM’s first commercial scientific computer. ... UNIVAC 120 The Remington Rand 409 plugboard programmed punch card calculator, designed in 1949, was sold in two models: the UNIVAC 60 (1952) and the UNIVAC 120 (1953). ... The IBM 700/7000 series was a series of incompatible large scale (mainframe) computer systems made by IBM through the 1950s and early 1960s. ... UNIVAC 120 The Remington Rand 409 plugboard programmed punch card calculator, designed in 1949, was sold in two models: the UNIVAC 60 (1952) and the UNIVAC 120 (1953). ... IBM 650 front panel, showing bi-quinary indicators IBM 650 front panel, rear view The IBM 650 was one of IBM’s early computers, and the world’s first mass-produced computer. ... The IBM 704, the first mass-produced computer with floating point arithmetic hardware, was introduced by IBM in April, 1956. ... The IBM Naval Ordnance Research Calculator (NORC) was a one-of-a-kind first-generation (vacuum tube) electronic computer built by IBM for the United States Navys Bureau of Ordnance. ... IBM 305 at U. S. Army Red River Arsenal The IBM RAMAC 305 was the first commercial computer that used magnetic disk storage. ... The American company UNIVAC began as the business computer division of Remington Rand formed by the purchase of the Eckert-Mauchly Computer Corporation (EMCC) in 1950. ... SAGE Sector Control Room. ... The IBM 1401 was a variable wordlength decimal computer that was announced by IBM on October 5, 1959 and marketed as an inexpensive Business Computer. It was withdrawn on February 8, 1971. ... The IBM 1620 was announced by IBM on October 21, 1959 and marketed as an inexpensive scientific computer. It was withdrawn on November 19, 1970. ... The UNIVAC LARC (Livermore Advanced Research Computer) was Remington Rands first attempt at building a supercomputer. ... The IBM 1410 was a variable wordlength decimal computer that was announced by IBM on September 12, 1960 and marketed as a midrange Business Computer. It was withdrawn on March 30, 1970. ... IBM 7070 was a Decimal Architecture intermediate data processing system that was introduced by IBM in 1960. ... The PDP-1 (Programmed Data Processor-1) was the first computer in Digital Equipments PDP series and was first produced in 1960. ... The IBM 7030, also known as Stretch, was IBMs first attempt at building a supercomputer. ... The IBM 7080 was a transistorized variable word length BCD computer in the IBM 700/7000 series commercial architecture line, introduced in August 1961, that provided an upgrade path from the vacuum tube IBM 705 computer. ... The UNIVAC III, designed as improvement to the UNIVAC I and UNIVAC II, was introduced in June 1962. ... The UNIVAC 1107 was the first member of Sperry Rands UNIVAC 1100 series of computers, introduced in October 1962. ... The IBM 700/7000 series was a series of incompatible large scale (mainframe) computer systems made by IBM through the 1950s and early 1960s. ... The IBM 7094 the fourth member of the most popular family of IBMs large second-generation transistorized mainframe computers and was designed for large-scale scientific and technological applications. The first 7094 installation was in September 1962. ... The Apollo Guidance Computer (AGC) was the first recognizably modern embedded system, used in real-time by astronaut pilots to collect and provide flight information, and to automatically control all of the navigational functions of the Apollo spacecraft. ... The CDC 6600 was a mainframe computer from Control Data Corporation, first manufactured in 1965. ... The IBM System/360 (S/360) is a computer system family announced by International Business Machines on April 7, 1964. ... The UNIVAC 1108 was the second member of Sperry Rands UNIVAC 1100 series of computers, introduced in 1964. ... A PDP-8 on display at the Smithsonians National Museum of American History in Washington, D.C.. This example is from the first generation of PDP-8s, built with discrete transistors and later known as the Straight 8. ... The PDP-11 was a 16-bit minicomputer sold by Digital Equipment Corp. ... The Intel 4004, a 4-bit central processing unit (CPU) released by Intel Corp. ... Intel 8008 The Intel 8008 was an early microprocessor designed and manufactured by Intel and introduced in April, 1972. ... Intel C8080A processor. ... CRAY-1 at the EPFL in Switzerland. ... Motorola 6800 Microprocessor The 6800 is a microprocessor produced by Motorola and released shortly after the Intel 8080 in 1975. ... The 6501 is an eight-bit microprocessor, the first sold by MOS Technology. ... The MOS Technology 6502 is an 8-bit microprocessor designed by MOS Technology in 1975. ... One of the first Z80 microprocessors manufactured; the date stamp says well before July 1976. ... It has been suggested that Microprocessor 8086 be merged into this article or section. ... Intel C8087 Math Coprocessor The 8087 was the first math coprocessor designed by Intel and it was built to be paired with the ass] microprocessors. ... VAX is a 32-bit computing architecture that supports an orthogonal instruction set (machine language) and virtual addressing (i. ... The Motorola 68000 is a 32-bit CISC microprocessor from Motorola. ... Motorola 68020 The Motorola 68020 is a microprocessor from Motorola. ... The Motorola 68881 was a floating-point coprocessor chip that was utilized in some computer systems that used the 68020 or 68030 CPU. The addition of the 68881 chip added substantial cost to the computer, but added a floating point unit that could rapidly perform floating point math calculations. ... The ARM architecture (previously, the Advanced RISC Machine, and prior to that Acorn RISC Machine) is a 32-bit RISC processor architecture that is widely used in a number of embedded designs. ... A MIPS R4400 microprocessor made by Toshiba. ... // Overview The exposed die of an Intel 80486DX2 microprocessor. ... The Motorola 68040 is a microprocessor from Motorola. ... IBM PowerPC 601 Microprocessor PowerPC is a RISC microprocessor architecture created by the 1991 Apple–IBM–Motorola alliance, known as AIM. Originally intended for personal computers, PowerPC CPUs have since become popular embedded and high-performance processors as well. ... In computing, IA-64 (or ia64, short for Intel Architecture-64) is a 64-bit processor architecture developed in cooperation by Intel and Hewlett-Packard, implemented by processors such as Itanium and Itanium 2. ... XScale is Intels name for their line of StrongARM-based RISC microprocessors and microcontrollers, which they aquired from DECs Digital Semiconductor division as the side-effect of a lawsuit between the two companies. ...

See also

A byte is commonly used as a unit of storage measurement in computers, regardless of the type of data being stored. ... 32-bit is a term applied to processors, and computer architectures which manipulate the address and data in 32-bit chunks. ... Headline text Media:Example. ...

References

  • Gerrit A. Blaauw & Frederick P. Brooks, Computer Architecture: Concepts and Evolution (Addison-Wesley, 1997, ISBN 0-201-10557-8)
  • Anthony Ralston & Edwin D. Reilly, Encyclopedia of Computer Science Third Edition (Van Nostrand Reinhold, 1993, ISBN 0-442-27679-6)

  Results from FactBites:
 
Word (computer science) - Wikipedia, the free encyclopedia (1649 words)
In computing, "word" is a term for the natural unit of data used by a particular computer design.
The number of bits in a word (the word size or word length) is an important characteristic of a computer architecture.
Some of the earliest computers were decimal rather than binary, typically having a word size of 10 or 12 decimal digits, and some early computers had no fixed word length at all.
Integer (computer science) - Wikipedia, the free encyclopedia (1041 words)
In computer science, the term integer is used to refer to any data type which can represent some subset of the mathematical integers.
The term word is used for a small group of bits which are handled simultaneously by processors of a particular architecture.
The 36-bit word length was common in the early days of computers, but word sizes that are not a multiple of 8 have vanished along with non-8-bit bytes.
  More results at FactBites »

 
 

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