Byte using six-bit and nine-bit bytes were common into the 1960s. These machines most commonly had memory words of 12, 24, 36, 48 or 60 bits, corresponding to two, four, six, eight or 10 six-bit bytes. In this era, bytes in the instruction stream were often referred to as "syllables", before the term byte became common. The modern "de-facto" standard of eight bits, as documented in ISO/IEC 2382-1:1993, is a convenient power of two permitting the values 0 through 255 for one byte (2 in power of 8 = 256, where zero signifies number as well). The international standard IEC 80000-13
Mask (computing) Mask (computing) In computer science, a mask is data that is used for bitwise operations, particularly in a bit field. Using a mask, multiple bits in a byte, nibble, word etc. can be set either on, off or inverted from on to off (or vice versa) in a single bitwise operation. To turn certain bits on, the bitwise codice_2 operation can be used, following the principle that codice_3 and codice_4. Therefore, to make sure a bit is on, codice_2 can be used with a codice_1. To leave a bit unchanged, codice_2 is used with a codice_8. Example: Masking "on" the