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An eight-bit processor like the Intel 8008 addresses eight bits, but as this is the full width of the accumulator and other registers, this could be considered either byte-addressable or word-addressable. 32-bit x86 processors, which address memory in 8-bit units but have 32-bit general-purpose registers and can operate on 32-bit items with a ...
For example, the Cray X1 uses 64-bit words, but addresses are only 32 bits; when an address is stored in memory, it is stored in its own word, and so the byte offset can be placed in the upper 32 bits of the word. The inefficiency of using wide addresses on that system is just all the extra logic to manipulate this offset and extract and insert ...
Most modern computers are byte-addressable. Each address identifies a single 8-bit byte of storage. Data larger than a single byte may be stored in a sequence of consecutive addresses. There exist word-addressable computers, where the minimal addressable storage unit is exactly the processor's word.
The interface provided for reading and writing the memory is different; NOR allows random access [129] as it can be either byte-addressable or word-addressable, with words being for example 32 bits long, [130] [131] [132] while NAND allows only page access.
Historically, a byte was the number of bits used to encode a character of text in the computer, which depended on computer hardware architecture, but today it almost always means eight bits – that is, an octet. An 8-bit byte can represent 256 (2 8) distinct values, such as non-negative integers from 0 to 255, or signed integers from −128 to ...
On most modern computers, this is an eight bit string. Because the definition of a byte is related to the number of bits composing a character, some older computers have used a different bit length for their byte. [2] In many computer architectures, the byte is the smallest addressable unit, the atom of addressability, say. For example, even ...
Examples include the Intel 8080, Intel 8085, Zilog Z80, Motorola 6800, Microchip PIC18, and many others. These processors have 8-bit CPUs with 8-bit data and 16-bit addressing. The memory on these CPUs is addressable at the byte level. This leads to a memory addressable limit of 2 16 × 1 byte = 65,536 bytes or 64 kilobytes.
The DEC PDP-10, also 36-bit, had special instructions which allowed memory to be treated as a sequence of fixed-size bit fields or bytes of any size from 1 bit to 36 bits. A one-word sequence descriptor in memory, called a "byte pointer", held the current word address within the sequence, a bit position within a word, and the size of each byte.