CBUS stands for Cartridge Back-Up System. CBUS I produces backup copies of cartridges for the Commodore 64. Using CBUS I saves wear and tear on ths Commodore 64  expansion connector by tricking the computer into running an image of the cartridge without having the cartridge physically present. Up to 17 cartridges can be stored on a single diskettae. With CBUS I, cartridges can be storad out of harms way rather than cluttering up the work area. CBUS I incorporates a RESET switch allowing you to perform a COLD Start without having to turn the machine off and on again. This permits study of cartridge object code, opening up the possibility of custom modifications.