Abbreviation for Central Processing Unit. The chip on a computer’s motherboard which ultimately controls all the activity of the computer. Standard Macs have a 680×0 chip (x = 0, 2, 3, or 4) manufactured by Motorola. PowerPC Macintoshes use a new RISC (Reduced Instruction Set Computing) chip designed by a conglomerate of computer hardware manufactures, including Apple, IBM, and Motorola. Most IBM compatible computes use a chip based on Intel’s X86 architecture. These days most electronic instruments (keyboards, drum machines, etc.) and digital tape machines have a CPU which controls all of the functions of the machine.