Personal computer systems vary from model to model, but usually feature the essential components shown here. Your input is entered with a keyboard or a joystick or a mouse, connected to the electronic guts of the system located on the motherboard. Here can be found the microprocessor (central processor), memory chips (permanent, ROM; temporary, RAM), and other integrated circuits for translating input and output. Here too are the expansion slots for interface cards to connect with devices to the outside world. Programs and information can be read or recorded by a disk drive onto magnetic disks. Output can also be displayed on a monitor, preserved on paper with a printer, or sent to another computer via a modem.