A user interface is the method by which the user and the computer exchange information and instructions. There are three main types: command-line, menu driven and graphical user interface (GUI).

Command-line interfaces

A command-line interface allows the user to interact with the computer by typing in commands [command: a directive given to a computer program ]. The computer displays a prompt, the user keys in the command and presses enter or return.

The command line screen

In the early days of personal computers, all PCs used command-line interfaces.

Features of a command-line interface

• Commands must be typed correctly and in the right order or the command will not work.
• Experienced users who know the commands can work very quickly without having to find their way around menus.
• An advantage of command driven programsprogram: a list of instructions written in a programming language is that they do not need the memorymemory: Where a program or data is stored on a computer. and processing powerprocessing power: a measurement of a processor's ability to process instructions, the greater its power the faster it processes instructions of the latest computer and will often run on lower spec machines.
• Command driven programs do not need to run inWindowsWindows: Microsoft's branding that precedes the operating systems name, eg Windows 98, Windows XP, Windows Vista etc..
• A command-line interface can run many programs, for example a batch file could launch half a dozen programs to do its task.
• An inexperienced user can sometimes find a command driven program difficult to use because of the number of commands that have to be learnt.

An example of a common command driven interface is MS-DOS. The MS-DOS command to display all files on c:\ would be: dir…