Character User Interface (CUI)

Character User Interface (CUI) is a kind of user interface that uses only alphanumeric characters and pseudographics for input-output and presentation of information.

It is characterized by a low demand for I/O hardware resources (in particular, memory) and high information display speed. CUI appeared at one of the initial stages of computer technology development.

The disadvantage of this type of interface is the limited visual media, due to the restricted number of characters included in the font provided by the equipment.

Programs with a text interface can implement a window interface, which is particularly facilitated by the use of pseudo-graphic symbols.

CUI Features

In the simplest mode, the character interface uses only the command-line, but many programs use interactive elements to create a more user-friendly visualisation.

The character interface implements all the basic elements - menus, buttons, switches, checkboxes, drop-down lists, scroll bars and so on.
Many programs implemented a well-developed window system, which was facilitated by libraries like CScape, D-Flat, Turbo Vision and many others. Some had interchangeable themes (for example, DOS Navigator) and supported various interactive devices such as a mouse, joystick, light pen.
At the software level, console programs use standard input-output devices (stdin, stdout, stderr) to enter and display information, although they can open other files, network connections and perform other actions available in the operating environment. Displaying printed characters in stdout and stderr results in the appearance of these characters on the output device and their receipt by the user.

Console programs for some operating systems, especially UNIX, are usually able to work on an advanced user interface functionality. To simplify the writing of such programs, the ncurses library is widely used.