Character (computing) of the “basic execution character set” and (in newer C standards) UTF-8 code units which implies a minimum size of 8 bits. The exact number of bits can be checked via codice_2 macro. By far the most common size is 8 bits, and the POSIX standard "requires" it to be 8 bits. Since Unicode requires at least 21 bits to store a single code point, it is usually impossible to store one inside a single codice_1; instead a variable-length encoding such as UTF-8 must be used. Unfortunately, the fact that a character was historically stored in a single byte led
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