User Interfaces

An interface is what you see on your monitor: the collection of words, pictures, buttons, and menus that allows you to interact with the computer. It is the visible service provided by the operating system. An interface is the place where interaction takes place between the user and the computer program.

Command Line Interface (CLI), Menu Driven Interface (MDI), Graphical User Interface (GUI)

The simplest user-interactive interface where the OS provides a prompt for typing textual commands interpreted by a command interpreter. Examples: MS-DOS, PowerShell, UNIX, LINUX.

Relatively simple commands can be connected to achieve flexible results and it does not require a high-end computer system.

User needs to know specific commands to use the interface and it does not cater for non-IT literate users.

An interface that presents a menu of alternatives on the screen, where the user selects an option using a mouse or other input methods. Examples: IBM AS-400, ATM Interfaces.

Not dependent on knowledge of commands.

Menus restrict choices and layouts may confuse users.

A mouse-driven, icon-based, and user-friendly interface consisting of one or more screens with windows. Examples: Windows 11, macOS X.

Easier to use, does not require knowledge of commands, interaction via mouse or keyboard.

Much harder to implement compared to CLI, needs powerful video graphics capability, and heavy memory utilisation to run many programs.