Numeric Data Types Other data types are often needed by computers and are frequently supported by ISA-level instructions. It is not uncommon for the ISA level to have special instructions that are intended for handling character strings . These strings are sometimes delimited by a special character at the end. Alternatively a string length field can be used to keep track of the end. The instructions can perform copy, search, edit, and other functions on strings.
Boolean values can take on a true of false value.
In theory, a single bit can represent a Boolean. In practice, a byte or word is used per Boolean value because individual bits in a byte do not have their own addresses and thus are hard to access. A common system interprets 0 as false and everything else as true. One situation in which a Boolean value is normally represented by 1 bit, called a bit map , is when there is an array of them, so a 32-bit word can hold 32 Boolean values. A bit map occurs in many contexts.