Terminal emulation

Terminals are the hardware combinations of display device and keyboard with which users can interact with a main frame computer system.

Terminals frequently have little processing power within themselves, they are a means of controlling the processing power within the main frame.

There is no absolute standard by which terminals communicate with the main frames, and different main frame vendors develop their own communications protocols.

Terminal emulation is the name given to the process whereby a computer runs software which allows the computer to function as a specific type of terminal.

This means that display codes can be correctly decoded, and keyboard operations can be correctly coded and transmitted.

As there are different communications protocols used by terminals, a PC is usually programmed to behave as one specific type of terminal.

So the programme Terminal in Windows 3.11 allows a PC to be set to emulate one of three different systems, ie, TTY ( Generic ), DEC VT-100 ( ANSI ), or DEC VT-52.

Another communications software package, Procomm Plus, can emulate 34 different types of terminal.

The programme Hyper-Terminal in Windows 95 allows emulation out of TTY, ANSI, Minitel, Viewdata, VT 100, or VT 52.

It is obviously essential to have both ends of the transmission path expecting the same protocol, or else strange results will occur.

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