Most peripheral devices are plugged into the computer through sockets called ports. This allows them to communicate with the computer by giving them access to the computer's main data lines. Sockets or ports with holes are sometimes referred to as "female", and sockets or plugs with the tiny prongs, called pins, are sometimes referred to as "male".
The keyboard plugs into a small circular socket often called the keyboard port. It is reserved only for keyboards.
The input and output devices such as mice and modems commonly plug into a socket called the serial port or COMM port. Through this port devices can send and receive data in a series. The serial port is either a 9-pin female or a 25-pin male, trapezoid-shaped socket. There are typically two serial ports on a microcomputer, and only one device may use a serial port at any time.
Printers and other devices that require faster data communication often plug into parallel ports. Parallel ports communicate in a similar fashion to serial ports but instead of a single communication line they have a parallel set of wires over which information can be sent and received simultaneously. A serial port, by contrast, can only send or receive information at any given time, thus forcing the computer and peripheral to alternate sending information to each other.
Devices such as scanners can be hooked up to a SCSI port (small computer system interface). SCSI ports are extremely fast and versatile. They can handle multiple devices concurrently, hooked up in a chain. SCSI ports come in various sizes and shapes.
The computer's main circuit board is called the mother board. It is a fiberglass and copper board on which reside the processing components and other various components. The mother board does not always contain specific components to carry out specialized tasks, however it allows you to add these components by providing receptacles or slots into which you can plug expansion cards.
An expansion card is like a small circuit board. It contains what is necessary to perform a specialized task. For example, a sound card contains a signal processor, digital and analog circuitry, and some memory. It is plugged into an expansion slot on the mother board. This enables the computer to capture and produce sound.
Expansion cards are also used with laptop computers and handheld computers which have limited physical space on the mother board. One type of expansion card that is increasingly used for laptops, personal digital assistants (PDAs), and other small devices, is the credit-card sized PC card (also known as a PCMCIA card.) They slide into slots at the side or back of the device.
There are numerous expansion cards available for the microcomputer. They include:
Introduction to Computers
IHC - 2E03
Humanities Computing Centre