The microprocessor contains the circuitry that performs arithmetic and logical operations. A port provides a plug for a cable that leads to device such as a printer, monitor, disk drive, or modem An expansion slot provides a way to add devices to a computer system. An expansion card plugs into a slot to provide the circuitry to control printing, video display, disk storage, or telecommunications. The way a computer represents data depends on if it is a digital device or an analog device. A computer is an electronic device.
Electricity can be on or off.
One represents on. Zero represents off. The smallest unit of information in a computer is a bit. A bit can be either 0 or 1. The electronic circuits in a computer carry 1 bit as a pulse of electricity through an open switching circuit.