The Motorola 68000 (MC68000) is the processor of all Amiga models. Assembly programming was essential for the demoscene and game development. The 68000 has 8 data registers (D0-D7), 8 address registers (A0-A7, where A7=Stack Pointer), 16/32-bit architecture with 16-bit data bus. Important instructions: MOVE, ADD, SUB, CMP, BRA/BEQ/BNE (branches), JSR/RTS (subroutines), LEA, MULU/MULS. The 68000 runs in the Amiga at 7.09 MHz (PAL) or 7.16 MHz (NTSC). Later Amigas use 68020/030/040/060 with up to 75 MHz.