If you're Amiga is fitted with a processor other than a 68000 (this includes the 68010), then you must use 128K ROMs. The 64K ROMs basically emulate the very old Apple Mac 512KE, with the 128K ROMs emulating the MacPlus. The cartridge has two ROM sockets for either 64K or 128K ROMs and is actually signed internally by the designers. It also has a connector to attach an Apple Mac 800K disk drive. The A-Max is an Apple Macintosh emulator in a cartridge which plugs into the Amiga's floppy drive port and includes a pass-thru for the Amiga's native drivers.