What is a word in computer science - Word и Excel - помощь в работе с программами

In computing, a word is the natural unit of data used by a particular processor design. A word is a fixed-sized datum handled as a unit by the instruction set or the hardware of the processor. The number of bits or digits^[a] in a word (the word size, word width, or word length) is an important characteristic of any specific processor design or computer architecture.

The size of a word is reflected in many aspects of a computer’s structure and operation; the majority of the registers in a processor are usually word-sized and the largest datum that can be transferred to and from the working memory in a single operation is a word in many (not all) architectures. The largest possible address size, used to designate a location in memory, is typically a hardware word (here, «hardware word» means the full-sized natural word of the processor, as opposed to any other definition used).

Documentation for older computers with fixed word size commonly states memory sizes in words rather than bytes or characters. The documentation sometimes uses metric prefixes correctly, sometimes with rounding, e.g., 65 kilowords (KW) meaning for 65536 words, and sometimes uses them incorrectly, with kilowords (KW) meaning 1024 words (2¹⁰) and megawords (MW) meaning 1,048,576 words (2²⁰). With standardization on 8-bit bytes and byte addressability, stating memory sizes in bytes, kilobytes, and megabytes with powers of 1024 rather than 1000 has become the norm, although there is some use of the IEC binary prefixes.

Several of the earliest computers (and a few modern as well) use binary-coded decimal rather than plain binary, typically having a word size of 10 or 12 decimal digits, and some early decimal computers have no fixed word length at all. Early binary systems tended to use word lengths that were some multiple of 6-bits, with the 36-bit word being especially common on mainframe computers. The introduction of ASCII led to the move to systems with word lengths that were a multiple of 8-bits, with 16-bit machines being popular in the 1970s before the move to modern processors with 32 or 64 bits.^[1] Special-purpose designs like digital signal processors, may have any word length from 4 to 80 bits.^[1]

The size of a word can sometimes differ from the expected due to backward compatibility with earlier computers. If multiple compatible variations or a family of processors share a common architecture and instruction set but differ in their word sizes, their documentation and software may become notationally complex to accommodate the difference (see Size families below).

Uses of wordsEdit

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

Fixed-point numbers: Holders for fixed point, usually 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, so often the size used is the word though it can also be a multiple or fraction of the word size.
Registers: Processor 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 are capable of storing data in multiple representations.
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. Historically, this amount of bits which could be transferred in one cycle was also called a catena in some environments (such as the Bull GAMMA 60 [fr]).^[2]^[3] 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 at the cost of added complexity to access individual characters. On the other hand, if the unit is a byte, then individual characters can be addressed (i.e. selected during the memory operation).
Instructions: Machine instructions are normally the size of the architecture’s word, such as in RISC architectures, or a multiple of the «char» size that is a fraction of it. 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, as instructions and data are stored in different memories; for example, the processor in the 1ESS electronic telephone switch has 37-bit instructions and 23-bit data words.

Word size choiceEdit

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 was in the past (pre-variable-sized character encoding) one of the influences on unit of address resolution and the choice of word size. Before the mid-1960s, characters were most often stored in six bits; this allowed no more than 64 characters, so the alphabet was 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.

After the introduction of the IBM System/360 design, which uses eight-bit characters and supports lower-case letters, the standard size of a character (or more accurately, a byte) becomes eight bits. Word sizes thereafter are naturally multiples of eight bits, with 16, 32, and 64 bits being commonly used.

Variable-word architecturesEdit

Early machine designs included some that used what is often termed a variable word length. In this type of organization, an operand has no fixed length. Depending on the machine and the instruction, the length might be denoted by a count field, by a delimiting character, or by an additional bit called, e.g., flag, or word mark. Such machines often use binary-coded decimal in 4-bit digits, or in 6-bit characters, for numbers. This class of machines includes the IBM 702, IBM 705, IBM 7080, IBM 7010, UNIVAC 1050, IBM 1401, IBM 1620, and RCA 301.

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 (160 μs) just to read the 12 digits of the instruction (the Model II reduced this to 6 cycles, or 4 cycles if the instruction did not need both address fields). Instruction execution takes a variable number of cycles, depending on the size of the operands.

Word, bit and byte addressingEdit

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, the word-addressable machine 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. Address values which differ by one designate adjacent bytes in memory. 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 integer 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.

When the workload involves processing fields of different sizes, it can be advantageous to address to the bit. Machines with bit addressing may have some instructions that use a programmer-defined byte size and other instructions that operate on fixed data sizes. As an example, on the IBM 7030^[4] («Stretch»), a floating point instruction can only address words while an integer arithmetic instruction can specify a field length of 1-64 bits, a byte size of 1-8 bits and an accumulator offset of 0-127 bits.

In a byte-addressable machine with storage-to-storage (SS) instructions, there are typically move instructions to copy one or multiple bytes from one arbitrary location to another. In a byte-oriented (byte-addressable) machine without SS instructions, moving a single byte from one arbitrary location to another is typically:

LOAD the source byte
STORE the result back in the target byte

Individual bytes can be accessed on a word-oriented machine in one of two ways. Bytes can be manipulated by a combination of shift and mask operations in registers. Moving a single byte from one arbitrary location to another may require the equivalent of the following:

LOAD the word containing the source byte
SHIFT the source word to align the desired byte to the correct position in the target word
AND the source word with a mask to zero out all but the desired bits
LOAD the word containing the target byte
AND the target word with a mask to zero out the target byte
OR the registers containing the source and target words to insert the source byte
STORE the result back in the target location

Alternatively many word-oriented machines implement byte operations with instructions using special byte pointers in registers or memory. For example, the PDP-10 byte pointer contained the size of the byte in bits (allowing different-sized bytes to be accessed), the bit position of the byte within the word, and the word address of the data. Instructions could automatically adjust the pointer to the next byte on, for example, load and deposit (store) operations.

Powers of twoEdit

Different amounts of memory are used to store data values with different degrees of precision. The commonly used sizes are usually a power of two multiple of the unit of address resolution (byte or word). Converting the index of an item in an array into the memory address offset of the item then requires only a shift operation 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 two times the size of a byte.

Size familiesEdit

As computer designs have grown more complex, the central importance of a single word size to an architecture has decreased. Although more capable hardware can use a wider variety of sizes of data, market forces exert pressure 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. The original word size remains available in future designs, forming the basis of a size family.

In the mid-1970s, DEC designed the VAX to be a 32-bit successor of the 16-bit PDP-11. They used word for a 16-bit quantity, while longword referred to a 32-bit quantity; this terminology is the same as the terminology used for the PDP-11. This was in contrast to earlier machines, where the natural unit of addressing memory would be called a word, while a quantity that is one half a word would be called a halfword. In fitting with this scheme, a VAX quadword is 64 bits. They continued this 16-bit word/32-bit longword/64-bit quadword terminology with the 64-bit Alpha.

Another example is the x86 family, of which processors of three different word lengths (16-bit, later 32- and 64-bit) have been released, while word continues to designate a 16-bit quantity. As software is routinely ported from one word-length to the next, some APIs and documentation define or refer to an older (and thus shorter) word-length than the full word length on the CPU that software may be compiled for. Also, similar to how bytes are used for small numbers in many programs, a shorter word (16 or 32 bits) may be used in contexts where the range of a wider word is not needed (especially where this can save considerable stack space or cache memory space). For example, Microsoft’s Windows API maintains the programming language definition of WORD as 16 bits, despite the fact that the API may be used on a 32- or 64-bit x86 processor, where the standard word size would be 32 or 64 bits, respectively. Data structures containing such different sized words refer to them as:

WORD (16 bits/2 bytes)
DWORD (32 bits/4 bytes)
QWORD (64 bits/8 bytes)

A similar phenomenon has developed in Intel’s x86 assembly language – because of the support for various sizes (and backward compatibility) in the instruction set, some instruction mnemonics carry «d» or «q» identifiers denoting «double-«, «quad-» or «double-quad-«, which are in terms of the architecture’s original 16-bit word size.

An example with a different word size is the IBM System/360 family. In the System/360 architecture, System/370 architecture and System/390 architecture, there are 8-bit bytes, 16-bit halfwords, 32-bit words and 64-bit doublewords. The z/Architecture, which is the 64-bit member of that architecture family, continues to refer to 16-bit halfwords, 32-bit words, and 64-bit doublewords, and additionally features 128-bit quadwords.

In general, new processors must use the same data word lengths and virtual address widths as an older processor to have binary compatibility with that older processor.

Often carefully written source code – written with source-code compatibility and software portability in mind – can be recompiled to run on a variety of processors, even ones with different data word lengths or different address widths or both.

Table of word sizesEdit

key: bit: bits, c: characters, d: decimal digits, w: word size of architecture, n: variable size, wm: Word mark
Year	Computer architecture	Word size w	Integer sizes	Floatingpoint sizes	Instruction sizes	Unit of address resolution	Char size
1837	Babbage Analytical engine	50 d	w	—	Five different cards were used for different functions, exact size of cards not known.	w	—
1941	Zuse Z3	22 bit	—	w	8 bit	w	—
1942	ABC	50 bit	w	—	—	—	—
1944	Harvard Mark I	23 d	w	—	24 bit	—	—
1946 (1948) {1953}	ENIAC (w/Panel #16^[5]) {w/Panel #26^[6]}	10 d	w, 2w (w) {w}	—	— (2 d, 4 d, 6 d, 8 d) {2 d, 4 d, 6 d, 8 d}	— — {w}	—
1948	Manchester Baby	32 bit	w	—	w	w	—
1951	UNIVAC I	12 d	w	—	1⁄2w	w	1 d
1952	IAS machine	40 bit	w	—	1⁄2w	w	5 bit
1952	Fast Universal Digital Computer M-2	34 bit	w?	w	34 bit = 4-bit opcode plus 3×10 bit address	10 bit	—
1952	IBM 701	36 bit	1⁄2w, w	—	1⁄2w	1⁄2w, w	6 bit
1952	UNIVAC 60	n d	1 d, … 10 d	—	—	—	2 d, 3 d
1952	ARRA I	30 bit	w	—	w	w	5 bit
1953	IBM 702	n c	0 c, … 511 c	—	5 c	c	6 bit
1953	UNIVAC 120	n d	1 d, … 10 d	—	—	—	2 d, 3 d
1953	ARRA II	30 bit	w	2w	1⁄2w	w	5 bit
1954 (1955)	IBM 650 (w/IBM 653)	10 d	w	— (w)	w	w	2 d
1954	IBM 704	36 bit	w	w	w	w	6 bit
1954	IBM 705	n c	0 c, … 255 c	—	5 c	c	6 bit
1954	IBM NORC	16 d	w	w, 2w	w	w	—
1956	IBM 305	n d	1 d, … 100 d	—	10 d	d	1 d
1956	ARMAC	34 bit	w	w	1⁄2w	w	5 bit, 6 bit
1956	LGP-30	31 bit	w	—	16 bit	w	6 bit
1957	Autonetics Recomp I	40 bit	w, 79 bit, 8 d, 15 d	—	1⁄2w	1⁄2w, w	5 bit
1958	UNIVAC II	12 d	w	—	1⁄2w	w	1 d
1958	SAGE	32 bit	1⁄2w	—	w	w	6 bit
1958	Autonetics Recomp II	40 bit	w, 79 bit, 8 d, 15 d	2w	1⁄2w	1⁄2w, w	5 bit
1958	Setun	6 trit (~9.5 bits)^[b]	up to 6 tryte		up to 3 trytes		4 trit^?
1958	Electrologica X1	27 bit	w	2w	w	w	5 bit, 6 bit
1959	IBM 1401	n c	1 c, …	—	1 c, 2 c, 4 c, 5 c, 7 c, 8 c	c	6 bit + wm
1959 (TBD)	IBM 1620	n d	2 d, …	— (4 d, … 102 d)	12 d	d	2 d
1960	LARC	12 d	w, 2w	w, 2w	w	w	2 d
1960	CDC 1604	48 bit	w	w	1⁄2w	w	6 bit
1960	IBM 1410	n c	1 c, …	—	1 c, 2 c, 6 c, 7 c, 11 c, 12 c	c	6 bit + wm
1960	IBM 7070	10 d^[c]	w, 1-9 d	w	w	w, d	2 d
1960	PDP-1	18 bit	w	—	w	w	6 bit
1960	Elliott 803	39 bit
1961	IBM 7030 (Stretch)	64 bit	1 bit, … 64 bit, 1 d, … 16 d	w	1⁄2w, w	bit (integer), 1⁄2w (branch), w (float)	1 bit, … 8 bit
1961	IBM 7080	n c	0 c, … 255 c	—	5 c	c	6 bit
1962	GE-6xx	36 bit	w, 2 w	w, 2 w, 80 bit	w	w	6 bit, 9 bit
1962	UNIVAC III	25 bit	w, 2w, 3w, 4w, 6 d, 12 d	—	w	w	6 bit
1962	Autonetics D-17B Minuteman I Guidance Computer	27 bit	11 bit, 24 bit	—	24 bit	w	—
1962	UNIVAC 1107	36 bit	1⁄6w, 1⁄3w, 1⁄2w, w	w	w	w	6 bit
1962	IBM 7010	n c	1 c, …	—	1 c, 2 c, 6 c, 7 c, 11 c, 12 c	c	6 b + wm
1962	IBM 7094	36 bit	w	w, 2w	w	w	6 bit
1962	SDS 9 Series	24 bit	w	2w	w	w
1963 (1966)	Apollo Guidance Computer	15 bit	w	—	w, 2w	w	—
1963	Saturn Launch Vehicle Digital Computer	26 bit	w	—	13 bit	w	—
1964/1966	PDP-6/PDP-10	36 bit	w	w, 2 w	w	w	6 bit 7 bit (typical) 9 bit
1964	Titan	48 bit	w	w	w	w	w
1964	CDC 6600	60 bit	w	w	1⁄4w, 1⁄2w	w	6 bit
1964	Autonetics D-37C Minuteman II Guidance Computer	27 bit	11 bit, 24 bit	—	24 bit	w	4 bit, 5 bit
1965	Gemini Guidance Computer	39 bit	26 bit	—	13 bit	13 bit, 26	—bit
1965	IBM 1130	16 bit	w, 2w	2w, 3w	w, 2w	w	8 bit
1965	IBM System/360	32 bit	1⁄2w, w, 1 d, … 16 d	w, 2w	1⁄2w, w, 11⁄2w	8 bit	8 bit
1965	UNIVAC 1108	36 bit	1⁄6w, 1⁄4w, 1⁄3w, 1⁄2w, w, 2w	w, 2w	w	w	6 bit, 9 bit
1965	PDP-8	12 bit	w	—	w	w	8 bit
1965	Electrologica X8	27 bit	w	2w	w	w	6 bit, 7 bit
1966	SDS Sigma 7	32 bit	1⁄2w, w	w, 2w	w	8 bit	8 bit
1969	Four-Phase Systems AL1	8 bit	w	—	?	?	?
1970	MP944	20 bit	w	—	?	?	?
1970	PDP-11	16 bit	w	2w, 4w	w, 2w, 3w	8 bit	8 bit
1971	CDC STAR-100	64 bit	1⁄2w, w	1⁄2w, w	1⁄2w, w	bit	8 bit
1971	TMS1802NC	4 bit	w	—	?	?	—
1971	Intel 4004	4 bit	w, d	—	2w, 4w	w	—
1972	Intel 8008	8 bit	w, 2 d	—	w, 2w, 3w	w	8 bit
1972	Calcomp 900	9 bit	w	—	w, 2w	w	8 bit
1974	Intel 8080	8 bit	w, 2w, 2 d	—	w, 2w, 3w	w	8 bit
1975	ILLIAC IV	64 bit	w	w, 1⁄2w	w	w	—
1975	Motorola 6800	8 bit	w, 2 d	—	w, 2w, 3w	w	8 bit
1975	MOS Tech. 6501 MOS Tech. 6502	8 bit	w, 2 d	—	w, 2w, 3w	w	8 bit
1976	Cray-1	64 bit	24 bit, w	w	1⁄4w, 1⁄2w	w	8 bit
1976	Zilog Z80	8 bit	w, 2w, 2 d	—	w, 2w, 3w, 4w, 5w	w	8 bit
1978 (1980)	16-bit x86 (Intel 8086) (w/floating point: Intel 8087)	16 bit	1⁄2w, w, 2 d	— (2w, 4w, 5w, 17 d)	1⁄2w, w, … 7w	8 bit	8 bit
1978	VAX	32 bit	1⁄4w, 1⁄2w, w, 1 d, … 31 d, 1 bit, … 32 bit	w, 2w	1⁄4w, … 141⁄4w	8 bit	8 bit
1979 (1984)	Motorola 68000 series (w/floating point)	32 bit	1⁄4w, 1⁄2w, w, 2 d	— (w, 2w, 21⁄2w)	1⁄2w, w, … 71⁄2w	8 bit	8 bit
1985	IA-32 (Intel 80386) (w/floating point)	32 bit	1⁄4w, 1⁄2w, w	— (w, 2w, 80 bit)	8 bit, … 120 bit 1⁄4w … 33⁄4w	8 bit	8 bit
1985	ARMv1	32 bit	1⁄4w, w	—	w	8 bit	8 bit
1985	MIPS I	32 bit	1⁄4w, 1⁄2w, w	w, 2w	w	8 bit	8 bit
1991	Cray C90	64 bit	32 bit, w	w	1⁄4w, 1⁄2w, 48 bit	w	8 bit
1992	Alpha	64 bit	8 bit, 1⁄4w, 1⁄2w, w	1⁄2w, w	1⁄2w	8 bit	8 bit
1992	PowerPC	32 bit	1⁄4w, 1⁄2w, w	w, 2w	w	8 bit	8 bit
1996	ARMv4 (w/Thumb)	32 bit	1⁄4w, 1⁄2w, w	—	w (1⁄2w, w)	8 bit	8 bit
2000	IBM z/Architecture (w/vector facility)	64 bit	1⁄4w, 1⁄2w, w 1 d, … 31 d	1⁄2w, w, 2w	1⁄4w, 1⁄2w, 3⁄4w	8 bit	8 bit, UTF-16, UTF-32
2001	IA-64	64 bit	8 bit, 1⁄4w, 1⁄2w, w	1⁄2w, w	41 bit (in 128-bit bundles)^[7]	8 bit	8 bit
2001	ARMv6 (w/VFP)	32 bit	8 bit, 1⁄2w, w	— (w, 2w)	1⁄2w, w	8 bit	8 bit
2003	x86-64	64 bit	8 bit, 1⁄4w, 1⁄2w, w	1⁄2w, w, 80 bit	8 bit, … 120 bit	8 bit	8 bit
2013	ARMv8-A and ARMv9-A	64 bit	8 bit, 1⁄4w, 1⁄2w, w	1⁄2w, w	1⁄2w	8 bit	8 bit
Year	Computer architecture	Word size w	Integer sizes	Floatingpoint sizes	Instruction sizes	Unit of address resolution	Char size
key: bit: bits, d: decimal digits, w: word size of architecture, n: variable size

^[8]^[9]

NotesEdit

^ Many early computers were decimal, and a few were ternary
^ The bit equivalent is computed by taking the amount of information entropy provided by the trit, which is . This gives an equivalent of about 9.51 bits for 6 trits.
^ Three-state sign

ReferencesEdit

^ ^a ^b Beebe, Nelson H. F. (2017-08-22). «Chapter I. Integer arithmetic». The Mathematical-Function Computation Handbook — Programming Using the MathCW Portable Software Library (1 ed.). Salt Lake City, UT, USA: Springer International Publishing AG. p. 970. doi:10.1007/978-3-319-64110-2. ISBN 978-3-319-64109-6. LCCN 2017947446. S2CID 30244721.
^ Dreyfus, Phillippe (1958-05-08) [1958-05-06]. Written at Los Angeles, California, USA. System design of the Gamma 60 (PDF). Western Joint Computer Conference: Contrasts in Computers. ACM, New York, NY, USA. pp. 130–133. IRE-ACM-AIEE ’58 (Western). Archived (PDF) from the original on 2017-04-03. Retrieved 2017-04-03. […] Internal data code is used: Quantitative (numerical) data are coded in a 4-bit decimal code; qualitative (alpha-numerical) data are coded in a 6-bit alphanumerical code. The internal instruction code means that the instructions are coded in straight binary code.
As to the internal information length, the information quantum is called a «catena,» and it is composed of 24 bits representing either 6 decimal digits, or 4 alphanumerical characters. This quantum must contain a multiple of 4 and 6 bits to represent a whole number of decimal or alphanumeric characters. Twenty-four bits was found to be a good compromise between the minimum 12 bits, which would lead to a too-low transfer flow from a parallel readout core memory, and 36 bits or more, which was judged as too large an information quantum. The catena is to be considered as the equivalent of a character in variable word length machines, but it cannot be called so, as it may contain several characters. It is transferred in series to and from the main memory.
Not wanting to call a «quantum» a word, or a set of characters a letter, (a word is a word, and a quantum is something else), a new word was made, and it was called a «catena.» It is an English word and exists in Webster’s although it does not in French. Webster’s definition of the word catena is, «a connected series;» therefore, a 24-bit information item. The word catena will be used hereafter.
The internal code, therefore, has been defined. Now what are the external data codes? These depend primarily upon the information handling device involved. The Gamma 60 [fr] is designed to handle information relevant to any binary coded structure. Thus an 80-column punched card is considered as a 960-bit information item; 12 rows multiplied by 80 columns equals 960 possible punches; is stored as an exact image in 960 magnetic cores of the main memory with 2 card columns occupying one catena. […]
^ Blaauw, Gerrit Anne; Brooks, Jr., Frederick Phillips; Buchholz, Werner (1962). «4: Natural Data Units» (PDF). In Buchholz, Werner (ed.). Planning a Computer System – Project Stretch. McGraw-Hill Book Company, Inc. / The Maple Press Company, York, PA. pp. 39–40. LCCN 61-10466. Archived (PDF) from the original on 2017-04-03. Retrieved 2017-04-03. […] Terms used here to describe the structure imposed by the machine design, in addition to bit, are listed below.
Byte denotes a group of bits used to encode a character, or the number of bits transmitted in parallel to and from input-output units. A term other than character is used here because a given character may be represented in different applications by more than one code, and different codes may use different numbers of bits (i.e., different byte sizes). In input-output transmission the grouping of bits may be completely arbitrary and have no relation to actual characters. (The term is coined from bite, but respelled to avoid accidental mutation to bit.)
A word consists of the number of data bits transmitted in parallel from or to memory in one memory cycle. Word size is thus defined as a structural property of the memory. (The term catena was coined for this purpose by the designers of the Bull GAMMA 60 [fr] computer.)
Block refers to the number of words transmitted to or from an input-output unit in response to a single input-output instruction. Block size is a structural property of an input-output unit; it may have been fixed by the design or left to be varied by the program. […]
^ «Format» (PDF). Reference Manual 7030 Data Processing System (PDF). IBM. August 1961. pp. 50–57. Retrieved 2021-12-15.
^ Clippinger, Richard F. [in German] (1948-09-29). «A Logical Coding System Applied to the ENIAC (Electronic Numerical Integrator and Computer)». Aberdeen Proving Ground, Maryland, US: Ballistic Research Laboratories. Report No. 673; Project No. TB3-0007 of the Research and Development Division, Ordnance Department. Retrieved 2017-04-05.{{cite web}}: CS1 maint: url-status (link)
^ Clippinger, Richard F. [in German] (1948-09-29). «A Logical Coding System Applied to the ENIAC». Aberdeen Proving Ground, Maryland, US: Ballistic Research Laboratories. Section VIII: Modified ENIAC. Retrieved 2017-04-05.{{cite web}}: CS1 maint: url-status (link)
^ «4. Instruction Formats» (PDF). Intel Itanium Architecture Software Developer’s Manual. Vol. 3: Intel Itanium Instruction Set Reference. p. 3:293. Retrieved 2022-04-25. Three instructions are grouped together into 128-bit sized and aligned containers called bundles. Each bundle contains three 41-bit instruction slots and a 5-bit template field.
^ Blaauw, Gerrit Anne; Brooks, Jr., Frederick Phillips (1997). Computer Architecture: Concepts and Evolution (1 ed.). Addison-Wesley. ISBN 0-201-10557-8. (1213 pages) (NB. This is a single-volume edition. This work was also available in a two-volume version.)
^ Ralston, Anthony; Reilly, Edwin D. (1993). Encyclopedia of Computer Science (3rd ed.). Van Nostrand Reinhold. ISBN 0-442-27679-6.

Источник

In computing, a word is the natural unit of data used by a particular processor design.The number of bits in a word (the word size, word width, or word length) is an important characteristic of any specific processor design or computer architecture.

Contents

1 What is word in memory?
2 What is computer easy word?
3 What is a word in binary?
4 How many bits make a word?
5 What is word in PLC?
6 How are words stored in a computer?
7 What are the 4 types of computer?
8 What are the 7 types of computers?
9 What is a computer for kids?
10 Why is a word 2 bytes?
11 What is word length in computer?
12 What is opposite word?
13 What is a bit word?
14 What is the name of 4 bit data?
15 What are 4 bits called?
16 Is a word 16 or 32 bits?
17 What is difference between word and integer?
18 How many words are in a PLC?
19 Which is word addressable RAM?
20 What is digital word?

What is word in memory?

A group of memory bits in a RAM or ROM block.In Verilog HDL, a memory word is a register in a memory (that is, RAM or ROM) block that contains the same range of bits as the other registers in the memory. For example, the memory reg [5:0] EXAMPLE [0:2] defines 3 memory words, each containing a bit range of 5 to 0 .

A computer is an electronic device that manipulates information, or data. It has the ability to store, retrieve, and process data. You may already know that you can use a computer to type documents, send email, play games, and browse the Web.

What is a word in binary?

Quick Reference. A binary word of length n is a string of n binary digits, or bits. For example, there are 8 binary words of length 3, namely, 000, 100, 010, 001, 110, 101, 011 and 111.

How many bits make a word?

16 bits
Fundamental Data Types
A byte is eight bits, a word is 2 bytes (16 bits), a doubleword is 4 bytes (32 bits), and a quadword is 8 bytes (64 bits).

What is word in PLC?

A word refers to the size of data the processor handles. This will vary by PLC model. If the PLC uses a 16 bit processor a word refers to 16 contiguous bits (2bytes). A 32 bit processor uses a 32 bit word. Older PLCs used 8 bit words, there are still alot of these out there.

How are words stored in a computer?

Text is stored on a computer by first converting each character to an integer and then storing the integer. For example, to store the letter `A’, we will actually store the number 65; `B’ is 66, `C’ is 67, and so on. The conversion of letters to numbers is called an encoding.

What are the 4 types of computer?

The four basic types of computers are as under: Supercomputer. Mainframe Computer. Minicomputer.

Analog Computer.
Digital Computer.
Hybrid Computer.

What are the 7 types of computers?

Types of computers

Supercomputer.
Mainframe.
Server Computer.
Workstation Computer.
Personal Computer or PC.
Microcontroller.
Smartphone. 8 References.

What is a computer for kids?

A computer is a. device for working with information. The information can be numbers, words, pictures, movies, or sounds. Computer information is also called data. Computers can process huge amounts of data very quickly.

Why is a word 2 bytes?

If a character is 8 bits, or 1 byte, then a WORD must be at least 2 characters, so 16 bits or 2 bytes.

What is word length in computer?

The word length of the processor in a computer refers to the maximum number of bits it can take as input. It is the number of bits processed by a computer CPU in a single pass. The computer further takes this input for process and gives the output.

What is opposite word?

The word which is a pronoun that means what one? It may also be used to introduce restrictive and nonrestrictive clauses. There are no categorical antonyms for this word.

What is a bit word?

A bit (short for binary digit) is the smallest unit of data in a computer. A bit has a single binary value, either 0 or 1.In many systems, four eight-bit bytes or octets form a 32-bit word. In such systems, instruction lengths are sometimes expressed as full-word (32 bits in length) or half-word (16 bits in length).

What is the name of 4 bit data?

From there, a group of 4 bits is called a nibble, and 8-bits makes a byte. Bytes are a pretty common buzzword when working in binary.

What are 4 bits called?

nibble
In computing, a nibble (occasionally nybble or nyble to match the spelling of byte) is a four-bit aggregation, or half an octet. It is also known as half-byte or tetrade. In a networking or telecommunication context, the nibble is often called a semi-octet, quadbit, or quartet.

Is a word 16 or 32 bits?

In x86 assembly language WORD , DOUBLEWORD ( DWORD ) and QUADWORD ( QWORD ) are used for 2, 4 and 8 byte sizes, regardless of the machine word size. A word is typically the “native” data size of the CPU. That is, on a 16-bit CPU, a word is 16 bits, on a 32-bit CPU, it’s 32 and so on.

What is difference between word and integer?

Integer is a signed value 16-bit (+32767 to -32768 range), WORD is an unsigned 16-bit value (0 to +65535 range).

How many words are in a PLC?

Most PLCs use 16-bit words. a 16-bit unsigned integer (0 to 65,535). a 16-bit signed integer (-32,768 to 32,767). 16 individual bits (such as a group of boolean values).

Which is word addressable RAM?

A memory word is certain bytes that bidirectional data bus can carry at a time.And such memory are called word addressable memory. In a 32 bit machine, size of the data bus is 32 bits or 4 bytes. So, a 32 bit machine has word size of 4 bytes.

What is digital word?

1 : relating to or using calculation directly with digits rather than through measurable physical quantities. 2 : of or relating to data in the form of numerical digits digital images digital broadcasting. 3 : providing displayed or recorded information in numerical digits from an automatic device a digital watch.

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What is a word in computer science?

A word is a fixed-sized piece of data handled as a unit by the instruction set or the hardware of the processor. … The number of bits in a word (the word size, word width, or word length) is an important characteristic of any specific processor design or computer architecture.

What is another word for computer science?

artificial intelligence	computer technology
information processing	information technology
IT	robotics
computer-aided learning	computer-aided testing
computing	cybernetics

Why is it called computer science?

The term was fought about in the early to mid 1960s, but the thinking was that computer science is really about the ability to solve problems using computers, rather than about the design of computers themselves or the engineering of particular solutions.

Who is the father of computer science?

Alan Turing

Who is known as father of computer Why?

Charles Babbage, who was born in 1791, is regarded as the father of computing because of his research into machines that could calculate. Babbage’s Difference Engine Number 1 was the first device ever devised that could calculate and print mathematical tables.

Why was computer invented?

Early computers were only conceived as calculating devices. Since ancient times, simple manual devices like the abacus aided people in doing calculations. Early in the Industrial Revolution, some mechanical devices were built to automate long tedious tasks, such as guiding patterns for looms.

Who invented laptop?

Adam Osborne

Which laptop is best?

Best Laptops 2021

MacBook Air (late 2020) The best laptop of 2021. …
HP Spectre x360 14. The best Windows laptop. …
HP Envy x360 (2020) The best budget laptop you can buy. …
MacBook Pro 13 (late 2020) …
Dell XPS 13 2-in-1. …
Dell XPS 13 (late 2020) …
Asus ROG Zephyrus G14. …
MacBook Pro (16-inch, 2019)

What is the full meaning of laptop?

Lightweight Analytical Platform Total Optimized Power

What is the full form of computer?

Some people say that COMPUTER stands for Common Operating Machine Purposely Used for Technological and Educational Research. … «A computer is a general purpose electronic device that is used to perform arithmetic and logical operations automatically.

What logo means?

A logo is a graphic mark, emblem, symbol, or stylized name used to identify a company, organization, product, or brand. It may take the form of an abstract or figurative design, or it may present as a stylized version of the company’s name if it has sufficient brand recognition.

What is a computer logo?

Alternatively referred to as turtle graphics, Logo is pronounced as Low-go and is a high-level programming language known for its graphics capabilities, created by Seymour Papert in 1967. Logo is often used for young school children as a basic method of programming instructions into a computer to create a graphic.Il y a 4 jours

What is a logo and its purpose?

Logos are intended to be the face of a company. They’re meant to visually communicate the unique identity of the brand and what it represents. Depending on your design philosophy, simple logos comprised of only essential elements are often the most difficult and also successful.

What are logo commands called?

primitives

How do I install a logo?

You may be asked to reboot your computer during the installation process….Step 2 — Install Logos

Open the “LogosSetup.exe” file downloaded in Step 1 to begin the installation.
Choose «Run.» …
When the Logos Bible Software Setup screen appears, click «Next» and follow the on-screen prompts to complete installation.

What is a logo procedure?

Advertisements. Procedures provide a way to encapsulate a collection of commands. Once a procedure has been created, it can be used just the way a built-in command is used. The “meaning” of a procedure is the meaning of its individual commands.

How do you use a logo?

The following are some ideas to use your logo on your website:

Idea 1: Place the logo at the top center of the page. …
Idea 2: Place the logo in the upper right corner of your website. …
Idea 3: Place the logo in the upper-left corner of every page on your website. …
Idea 4: Use it in the sidebar and footer of your website.

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A word is a set number of bits managed as a unit.

1 Hardware Word
2 Common Names for Various Word Sizes
- 2.1 Bit
- 2.2 Byte
- 2.3 Octet
- 2.4 Nibble
- 2.5 Half word, Single word, Double word, Quad word

Hardware Word

A hardware word is the group of bits normally managed by a processor. The word size is a distinguishing feature of a processor, and is typically a power-of-two multiple of eight bits (8, 16, 32, or 64 bits), although some rare or early processors used different word sizes.

The word size is usually associated with the size of general-purpose registers and the amount of data read from or written to memory at one time. Most modern processors can read/write alternate word sizes (for example, a «64-bit» x86_64 system can also read/write 32, 16, and 8 bit values to/from memory, and 64-bit registers can be accessed as 32, 16, or 8-bit subsets). Additionally, many modern systems use a different memory word size than CPU word size (for example, a «64-bit» system may be built to read/write memory 128 bits at a time), but this is transparent to the programmer and user.

Common Names for Various Word Sizes

Bit

A bit is a single binary digit, a value that can take one of two states. These states may be referred to as:

1 or 0
True or False
On or Off (electrically)
Positive or Negative charge, or Forward or Reverse current flow (electrically — differential signalling)

Byte

A byte is a collection of eight bits. It is a convenient size for use with many small character sets such as ASCII, ISO8859, and EBCDIC, and can also be used with the UTF-8 encoding of Unicode. It is often viewed as the smallest hardware word size that makes sense for general-purpose computing.

Most computers with larger hardware word sizes continue to rank memory, storage, and data sizes in bytes (or prefixed multiples of bytes) for comparability. For example, an x86_64 system will be advertised as having «16 gigabytes» of memory instead of «2 gigawords».

Octet

Another name for byte, commonly used in telecommunication standards and in French.

Nibble

A nibble (or nybble) is a half-byte, corresponding to one hexadecimal or BCD digit.

Half word, Single word, Double word, Quad word

The terms half word (or halfword or half-word), single word, double word, and quad word are often used in contemporary computing to refer to common word sizes relative to a 32-bit base word size:

half word = 16 bits
single word = 32 bits
double word = 64 bits
quad word = 128 bits

This terminology can be seen, for example, in the lane naming conventions for AArch64 SIMD (where v0.8h refers to the 128-bit vector register 0 divided in eight half word lanes) and x86_86 instruction suffixes (MOVQ to move a quad word).

The 32-bit base size is reflective of the 32-bit standard integer size used in the predominant LP64 (and less common ILP32) programming models.

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Processors
1-bit	4-bit	8-bit	12-bit	16-bit	18-bit	24-bit	31-bit	32-bit	36-bit	48-bit	60-bit	64-bit	128-bit
Applications
		8-bit		16-bit				32-bit				64-bit
Data Sizes
bit nibble octet byte
halfword word dword qword
IEEE floating-point standard
Single precision floating-point format (32-bit) Double precision floating-point format (64-bit) Quadruple precision floating-point format (128-bit)

In computing, word is a term for the natural unit of data used by a particular processor design. A word is basically a fixed sized group of bits that are handled as a unit by the instruction set and/or hardware of the processor. The number of bits in a word (the word size, word width, or word length) is an important characteristic of a specific processor design or computer architecture.

The size of a word is reflected in many aspects of a computer’s structure and operation; the majority of the registers in a processor are usually word sized and the largest piece of data that can be transferred to and from the working memory in a single operation is a word in many (not all) architectures. The largest possible address size, used to designate a location in memory, is typically a hardware word (in other words, the full-sized natural word of the processor, as opposed to any other definition used).

Modern processors, including embedded systems, usually have a word size of 8, 16, 24, 32 or 64 bits, while modern general purpose computers usually use 32 or 64 bits. Special purpose digital processors, such as DSPs for instance, may use other sizes and many different sizes have been used historically, including 8, 9, 12, 18, 24, 36, 39, 40, 48 and 60 bits. The slab is an example of a system with an earlier word size. Several of the earliest computers (and a few modern as well) used BCD rather than plain binary, typically having a word size of 10 or 12 decimal digits, and some early decimal computers had no fixed word length at all.

1 Uses of words
2 Word size choice
- 2.1 Variable word architectures
- 2.2 Word and byte addressing
- 2.3 The power of two
3 Size families
4 Table of word sizes
5 See also
6 References

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, so often the size used is the word though it can also be a multiple or fraction of the word size.

Registers: Processor 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, these registers must be sized to hold the largest of the types, historically this is the word size of the architecture though increasingly special purpose, larger, registers have been added to deal with newer types.

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).

Instructions: Machine 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.

Word size choice

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.

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.

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 often 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.

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, or 4 cycles if the instruction did not need both address fields). Instruction execution took a completely variable number of cycles, depending on the size of the operands.

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 two

Different amounts of memory are used to store data values with different degrees of precision. The commonly used sizes are usually a power of two multiple of the unit of address resolution (byte or word). Converting the index of an item in an array into the address of the item then requires only a shift operation 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 two times the size of a byte.

Size families

In the mid-1970s, DEC designed the VAX to be a successor of the PDP-11. They used word for a 16-bit quantity, while longword referred to a 32-bit quantity. This was in contrast to earlier machines, where the natural unit of addressing memory would be called a word, while a quantity that is one half a word would be called a halfword. In fitting with this scheme, a VAX quadword is 64 bits.

Another example is the x86 family, of which processors of three different word lengths (16-bit, later 32- and 64-bit) have been released. As software is routinely ported from one word-length to the next, some APIs and documentation define or refer to an older (and thus shorter) word-length than the full word length on the CPU that software may be compiled for. Also, similar to how bytes are used for small numbers in many programs, a shorter word (16 or 32 bits) may be used in contexts where the range of a wider word in not needed (especially where this can save considerable stack space or cache memory space). For example, Microsoft’s Windows API maintains the programming language definition of WORD as 16 bits, despite the fact that the API may be used on a 32- or 64-bit x86 processor, where the standard word size would be 32 or 64 bits, respectively. Data structures containing such different sized words refer to them as WORD, DWORD and QWORD respectively. A similar phenomenon has developed in Intel’s x86 assembly language – because of the support for various sizes (and backward compatibility) in the instruction set, some instruction mnemonics carry «d» or «q» identifiers denoting «double-«, «quad-» or «double-quad-«, which are in terms of the architecture’s original 16-bit word size.

Table of word sizes

key: b: bits, d: decimal digits, w: word size of architecture, n: variable size
Year	Computer Architecture	Word Size w	Integer Sizes	Floating Point Sizes	Instruction Sizes	Unit of Address Resolution	Char Size
1837	Babbage Analytical engine	50 d	w	—	5 different cards were used for different functions, exact size of cards not known	w	—
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^[1]) {w/ Panel #26^[2]}	10 d	w, 2w (w) {w}	—	— (2d, 4d, 6d, 8d) {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	Fast Universal Digital Computer M-2	34 b	w?	w	34 b = 4 b opcode plus 3× 10b address	10 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
1957	Autonetics Recomp I	40 b	w, 79 b, 8d, 15d	—	½w	½w, w	5 b
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	CDC 1604	48 b	w	w	½w	w	6 b
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	Autonetics D-17B Minuteman I Guidance Computer	27 b	11 b, 24 b	—	24 b	w	—
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	—
1963	Saturn Launch Vehicle Digital Computer	26 b	w	—	13 b	w	—
1964	CDC 6600	60 b	w	w	¼w, ½w	w	6 b
1964	Autonetics D-37C Minuteman II Guidance Computer	27 b	11 b, 24 b	—	24 b	w	4 b, 5 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
1972	Calcomp 900	9 b	w	—	w, 2w	w	8 b
1974	Intel 8080	8 b	w, 2w, 2d	—	w, 2w, 3w	w	8 b
1975	ILLIAC IV	64 b	w	w, ½w	w	w	—
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	Cray-1	64 b	24 b, w	w	¼w, ½w	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	Intel 80386	32 b	½w, w, 2d w, 2w, 4w	2w, 4w, 5w, 17d	½w, w, … 7w	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	Motorola 68040	32 b	¼w, ½w, w, 2d	w, 2w, 2½w	½w, w, … 7½w	8 b	8 b
1991	Alpha	64 b	¼w, ½w, w	w, 2w	½w	8 b	8 b
1991	Cray C90	64 b	32 b, w	w	¼w, ½w, 48b	w	8 b
1991	PowerPC	32–64 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

^[3]^[4]

References

^ Computer History, Eniac coding, US: ARL, http://ftp.arl.mil/~mike/comphist/48eniac-coding/
^ «8», Computer History, Eniac coding, US: ARL, http://ftp.arl.mil/~mike/comphist/48eniac-coding/sec8.html
^ Gerrit A. Blaauw & Frederick P. Brooks (1997). Computer Architecture: Concepts and Evolution. Addison-Wesley. ISBN 0-201-10557-8.
^ Anthony Ralston & Edwin D. Reilly (1993). Encyclopedia of Computer Science Third Edition. Van Nostrand Reinhold. ISBN 0-442-27679-6.

v · d · eData types

Uninterpreted	Bit Byte Trit Tryte Word

Numeric	Integer Fixed-point Floating-point Rational Complex Bignum Interval Decimal

Text	Character String

Pointer	Address Reference

Composite	Algebraic data type (generalized) Array Associative array Class List Object Option type Product Record Set Union (tagged)

Other	Boolean Bottom type Collection Enumerated type Exception Function type Opaque data type Recursive data type Semaphore Stream Top type Type class Unit type Void

Related topics	Abstract data type Data structure Interface Kind Primitive data type Subtyping Template Type constructor Parametric polymorphism

Источник

Uses of wordsEdit

Word size choiceEdit

Variable-word architecturesEdit

Word, bit and byte addressingEdit

Powers of twoEdit

Size familiesEdit

Table of word sizesEdit

See alsoEdit

NotesEdit

ReferencesEdit

What is word in memory?

What is a word in binary?

How many bits make a word?

What is word in PLC?

How are words stored in a computer?

What are the 4 types of computer?

What are the 7 types of computers?

What is a computer for kids?

Why is a word 2 bytes?

What is word length in computer?

What is opposite word?

What is a bit word?

What is the name of 4 bit data?

What are 4 bits called?

Is a word 16 or 32 bits?

What is difference between word and integer?

How many words are in a PLC?

Which is word addressable RAM?

What is digital word?

What is a word in computer science?

What is another word for computer science?

Why is it called computer science?

Who is the father of computer science?

Who is known as father of computer Why?

Why was computer invented?

Who invented laptop?

Which laptop is best?

What is the full meaning of laptop?

What is the full form of computer?

What logo means?

What is a computer logo?

What is a logo and its purpose?

What are logo commands called?

How do I install a logo?

What is a logo procedure?

How do you use a logo?

Contents

Hardware Word

Common Names for Various Word Sizes

Bit

Byte

Octet

Nibble

Half word, Single word, Double word, Quad word

Contents

Uses of words

Word size choice

Variable word architectures

Word and byte addressing

The power of two

Size families

Table of word sizes

See also

References