That is, they could deal with eight binary digits, or bits, of data, at every cycle. A group of eight bits is called a byte, each byte containing 256 possible patterns of ONs and OFFs (or 1s and 0s). Each pattern is the equivalent of an instruction, a part of an instruction, or a particular type of datum, such as a number or a character or a graphics symbol. The pattern 11010010, for example, might be binary data-in this case, the decimal number 210 (see Number Systems)-or it might be an instruction telling the computer to compare data stored in its switches to data stored in a certain memory-chip location.
The development of processors that can handle 16, 32, and 64 bits of data at a time has increased the speed of computers. The complete collection of recognizable patterns-the total list of operations-of which a computer is capable is called its instruction set. Both factors-the number of bits that can be handled at one time, and the size of instruction sets-continue to increase with the ongoing development of modern digital computers.