Computer number format still split that memory into eight-bit pieces. This is called byte-addressable memory. Historically, many CPUs read data in some multiple of eight bits. Because the byte size of eight bits is so common, but the definition is not standardized, the term octet is sometimes used to explicitly describe an eight bit sequence. A "nibble" (sometimes "nybble"), is a number composed of four bits. Being a half-byte, the nibble was named as a play on words. A person may need several nibbles for one bite from something; similarly, a nybble is a part of a byte. Because four bits allow for
64-bit computing in 64 bits depends on the integer representation used. With the two most common representations, the range is 0 through 18,446,744,073,709,551,615 (2 − 1) for representation as an (unsigned) binary number, and −9,223,372,036,854,775,808 (−2) through 9,223,372,036,854,775,807 (2 − 1) for representation as two's complement. Hence, a processor with 64-bit memory addresses can directly access 2 bytes (=16 exabytes) of byte-addressable memory. With no further qualification, a "64-bit computer architecture" generally has integer and addressing processor registers that are 64 bits wide, allowing direct support for 64-bit data types and addresses. However, a CPU might have external data buses or address