Motorola 68000

Motorola · 1979 · Motorola MC68000

The 68000 was the 16/32-bit processor that powered the Amiga, Atari ST, and Sega Genesis — three platforms whose creative cultures differed dramatically despite sharing identical central processing. Its clean instruction set made it a favourite for game development.

The Motorola 68000 was introduced in 1979 as a transitional processor — technically 32-bit internally but with a 16-bit external data bus and 24-bit address bus, straddling the 8-bit and 32-bit eras. Its 68 instruction set was regular and orthogonal, meaning that most instructions worked with most addressing modes in consistent ways — a significant improvement over the complexity and inconsistency of Intel's x86 family. Game developers appreciated the 68000's large register set (eight data registers and eight address registers, each 32 bits) and its support for efficient memory management. The platforms built around the 68000 demonstrate how the same processor can support radically different design philosophies. The Amiga paired it with three custom chips (Agnus, Denise, Paula) for graphics, I/O, and audio, creating a multimedia computer ahead of its time. The Atari ST used a simpler architecture that was cheaper to produce. The Sega Genesis paired it with a Zilog Z80 for audio and backwards compatibility with Master System code. The Neo Geo used it in its MVS arcade hardware, running uncompromised to provide the processing power for the system's 2D sprite capabilities. The 68000 family — extended through the 68020, 68030, and 68040 — remained commercially relevant through the early 1990s in Apple Macintosh computers before Apple's 1994 transition to PowerPC.