The 68000 is a cpu made by Motorola. The exact part number used in the Saturn is the MC68EC000. Motorola has since divested their semi-conductor business into Freescale Semiconductor, Inc. For documentation regarding the 68000 hardware, instruction set and programming information this Freescale Page should be helpful. The cpu is basically used as a kind of controller for the SCSP, handling data transfers, manipulating sound data, etc. By default the cpu is disabled.