The IDE64 cartridge is a device for connecting an IDE hard disk drive and CD-ROM drive to a C64. It is plugged into the Expansion Port and connected to the hard drive by means of a 40 wire cable. IDE harddrive transfer rate is more than 100 times the rate of the floppy drive 1541. Good compatibity, patches for many games are available here and here. The IDE cartridge contains a 64kB ROM (EPROM or flash EPROM with IDE DOS, Machine Code Monitor, File Manager and Setup), a 28kB RAM (used for internal buffers), a realtime clock chip (powered by a battery), two LEDs (to indicate the presence of the cartrige and HDD activity), a Short-BUS for new peripherals and an ispLSI chip.