memory - What's the difference between a word and byte? - Stack Overflow
Byte = a sequence of 8 bits = , , , or Word = a sequence of N bits where N = 16, 32, 64 depending on the computer. There are. In computing and telecommunications, a unit of information is the capacity of some standard A group of four bits, or half a byte, is sometimes called a nibble or nybble. This unit Some machine instructions and computer number formats use two words (a "double word" or "dword"), or four words (a "quad word" or " quad"). In computing, a word is the natural unit of data used by a particular processor design. A word is In most computers, the unit is either a character (e.g. a byte) or a word. (A few computers have used bit . In some cases this relationship can also avoid the use of division operations. As a result, most modern computer designs.
Units of information
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. In input-output transmission the grouping of bits may be completely arbitrary and have no relation to actual characters.
The term is coined from bitebut 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.
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. Archived PDF from the original on Figure 2 shows the Shift Matrix to be used to convert a bit wordcoming from Memory in parallel, into charactersor 'bytes' as we have called them, to be sent to the Adder serially.
The 60 bits are dumped into magnetic cores on six different levels. The original intention was that, when storing text, 8 bits would be enough to assign a unique number every possible language character you might want to use in your document. The idea was that each character in a file would take up one byte of memory in most cases, this is still true.
Then there's a few characters for creating newlines, a tab character for indentations, there's even a 'bell' character which programs would output in order to make the user's terminal beep.
You can see how it all adds up In practice, only characters up to were ever standardised the standard is called ASCII, which stands for American Standard Code for Information Interchange, because in the early days, one of the eight bits was set aside for error testing purposes back when computers were far less reliableand 7 bits only gives you different combinations. What is a word?Understanding Bits and Computer Storage
You often hear about bit or bit computer architectures. A word is basically the number of bits a particular computer's CPU can deal with in one go. Before the mids, 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 bit wordwhich is also a good size for the numeric properties of a floating point format.
Units of information - Wikipedia
Word sizes thereafter were naturally multiples of eight bits, with 16, 32, and 64 bits being commonly used. Variable word architectures[ edit ] 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, often called word markwas encountered.
Such machines often used binary coded decimal for numbers. 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 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.
Word (computer architecture) - Wikipedia
Instruction execution took a completely variable number of cycles, depending on the size of the operands. Word and byte addressing[ edit ] 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 byterather 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.
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The word size needs to be an integer multiple of the character size in this organization. This addressing approach was used in the IBMand has been the most common approach in machines designed since then. 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: