Byte and is also combined with metric prefixes for multiples, for example ko and Mo. The usage of the term "octad(e)" for eight bits is no longer common. Despite standardization efforts, ambiguity still exists in the meanings of the SI (or metric) prefixes used with the unit byte, especially concerning the prefixes "kilo" (k or K), "mega" (M), and "giga" (G). Computer memory has a binary architecture in which multiples are expressed in powers of 2. In some fields of the software and computer hardware industries a binary prefix is used for bytes and bits, while producers of computer storage devices
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