Home Computer: Jargon buster

Add-on: any piece of hardware added to the system, often by means of an 'option card', a circuit board that can be plugged into the computers main processing board.

Error message: A message from the operating system or other program running on the computer, usually displayed on the screen, indicating that something has gone wrong which requires the user to take some action to cure it.

Graphical user interface: A 'Point-and-click' operating system which display icons or 'menu' lists of instructions. These can be selected by moving an arrow on screen to point at the required instruction and activated by clicking on the mouse button or pressing the keyboard execute key. Generally known as windows systems.

Icon: a small pictogram or logo which represents a computer instruction.

Macro: A series of instructions memorised by a program and activated by one key-stroke of a special function key or combination of keys. A word processig macro, for instance, might load a text file, change it into a particular typeface and perform a word count.

Port: The sockets on the back of the computer where peripheral devices are attached. The serial port usually connects the cable from an external modem or other communications device; the parallel port is usually used to attach the printer.