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(Mac II) A version of Apple's Macintosh personal computer, released in March 1987, using the Motorola 68020 CPU, which runs at a higher clock rate than the Motorola 68000 used in the original Mac. The Mac II has a full 32-bit data bus instead of a 16-bit bus. Mac II models have built-in 40 to 160 megabyte hard disks and can take up to eight megabytes of RAM (and more as denser memory chips arive).
The Mac II was the first Macintosh to provide a colour graphics option, with up to 256 colours on screen at a 640x480 resolution. Mac II models are designed for expandability with three (Macintosh IIcx) or six (II & IIx) built-in NuBus expansion slots for additional peripheral and coprocessor boards.