49.6.1Byte¶
A byte (or octet) is a memory unit made of 8 bits.
It is used, for instance, to measure the sizes of files or transmitted data. Be careful, however, since two systems coexist to express those sizes: the decimal system and the binary system. See Table 1 and Table 2.
Table 1:Size measurement units (decimal)
Value | Unit | Fullname |
|---|---|---|
1000 (103) | kB | kilobyte |
10002 (106) | MB | megabyte |
10003 (109) | GB | gigabyte |
10004 (1012) | TB | terabyte |
10005 (1015) | PB | petabyte |
Table 2:Size measurement units (binary)
Value | Unit | Fullname |
|---|---|---|
1024 (210) | KiB | kibibyte |
10242 (220) | MiB | mebibyte |
10243 (230) | GiB | gibibyte |
10244 (240) | TiB | tebibyte |
10245 (250) | PiB | pebibyte |
49.6.2Word¶
A word is the natural unit of data handled by an architecture (virtual or physical). On a 64-bit architecture a word is 64 bits (i.e: 8 bytes), on a 32-bit architecture a word is 32 bits (i.e.: 4 bytes).
A word is the needed memory to store an integer that spans the entire memory addressing range. It is thus used to store pointers and memory sizes (array sizes, object sizes, ...).