TeRMiNaL

What is means by terminal??

A computer terminal is an electronic or electromechanical hardware device that is used for entering data into, and displaying data from, a computer or a computing system. Early terminals were inexpensive devices but very slow compared to punch cards or paper tape for input, but as the technology improved and video displays were introduced, terminals pushed these older forms of interaction from the industry. A related development was timesharing systems, which evolved in parallel and made up for any inefficiencies of the user's typing ability with the ability to support multiple users on the same machine, each at their own terminal. The function of a terminal is confined to display and input of data; a device with significant local programmable data processing capability may be called a "smart terminal" or fat client. A terminal that depends on the host computer for its processing power is called a thin client. A personal computer can run software that emulates the function of a terminal, sometimes allowing concurrent use of local programs and access to a distant terminal host system. There are three different types, Dumb terminal, Smart terminal and Intelligent terminal.

• Dumb Terminal

The specific meaning of the term dumb terminal can vary depending on the context in which it is used. In the context of traditional computer terminals that communicate over a serial RS-232 connection, dumb terminals are those that can interpret a limited number of control codes (CR, LF, etc.) but do not have the ability to process special escape sequences that perform functions such as clearing a line, clearing the screen, or controlling cursor position. In this context dumb terminals are sometimes dubbed glass teletypes, for they essentially have the same limited functionality as does a mechanical teletype. This type of dumb terminal is still supported on modern Unix-like systems by setting the environment variable TERM to dumb. Smart or intelligent terminals are those that also have the ability to process escape sequences, in particular the VT52, VT100 or ANSI escape sequences. In the broader context that includes all forms of keyboard/screen computer communication devices, including personal computers, diskless workstations, network computers, thin clients, and X Terminals, the term dumb terminal is sometimes used to refer to any type of traditional computer terminal that communicates serially over a RS-232 connection that does not locally process data or execute user programs. The term dumb terminal sometimes also refers to public computer terminals that are limited to monochrome text-only capabilities, or to terminals that transmit each character as it is typed rather than waiting until it is polled by a host computer.


• Smart Terminal

A terminal that has enough computing capability to render graphics or to offload some kind of front-end processing from the computer it talks to. The development of workstations and personal computers has made this term and the product it describes semi-obsolescent, but one may still hear variants of the phrase act like a smart terminal used to describe the behavior of workstations or PCs with respect to programs that execute almost entirely out of a remote server's storage, using local devices as displays. Smart terminals have built-in logic for performing simple display operations, such as blinking and boldface. In contrast, a dumb terminal has no processing capabilities at all.

• Intelligent Terminal

This terminal that has a full processing capability. The terminal has a processing unit, primary voltage. It may or may not have local storage. Recently, most intelligent terminal have local disk. An intelligent terminal is actually a microcomputer with communications capabilities.