7.TERMINAL EMULATION

7. TERMINAL EMULATION


A video display terminal is basically a relatively dumb computer which is linked up to another computer (over a cable or modem link) and dis- plays what that computer sends to it. A mainframe or mini computer has a large amount of processing power and can drive a number of terminals at the same time.

There are many different terminal types. Each one follows its own codes for controlling how information is displayed on the screen. For example, there are sequences to clear the screen, move the cursor, scroll the display, and so on. Most terminals also have special keys which send special sequences back to the main computer.
Telix can emulate several terminals. While in terminal mode, you may change the terminal type Telix is currently emulating by pressing Alt- T. The default terminal can also be set in the 'Terminal settings' page of the Configuration Menu. Following are the choices Telix of- fers:

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7.1 TTY


A TTY (Teletype) terminal is very stupid. It basically displays all the values it receives, except for about 5 or 6 Control codes (such as Carriage Return), which move the cursor and ring the bell. Telix does not have any special key definitions for this terminal type.
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7.2 ANSI-BBS


This is a subset of the real ANSI terminal type defined by the Ameri- can National Standards Institute. Many BBS programs, when told to do so, can send sequences supported by this terminal to make screen dis- play more interesting and colorful. This emulation supports some known bugs in the DOS ANSI.SYS driver that are not part of the ANSI standard per se. The ANSI.KEY file contains definitions for the arrow keys, and is au- tomatically read when this terminal is selected. These definitions are supported by some full screen editors, for example.
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7.3 ANSI


This is the real ANSI terminal type defined by the American National Standards Institute. Many BBS programs, when told to do so, can send sequences supported by this terminal to make screen display more in- teresting and colorful. This conforms to the ANSI committee defini- tions of ANSI.
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7.4 VT102


The DEC VT102 terminal is one of the most popular (and most emulated) terminals in existence. It was developed by Digital Equipment Corpora- tion. The VT102 terminal has a large number of functions. Telix sup- ports all of these except for 132 column mode and double height mode. As well, Telix only emulates double width mode, by adding a space af- ter every character. Telix fully supports both normal and application cursor mode in VT em- ulation. The VT102 keyboard layout used by Telix is stored in the VT102.KEY file, which is automatically read by Telix when VT102 termi- nal emulation is selected. Once Telix has loaded this into memory, the definitions can be edited through the use of the Alt-K (Keyboard/macros) function.

The default keyboard layout is best suited for the (newer) 101-key style keyboards with separate arrow and numeric keypads, and functions keys across the top. In this layout, press F1 to F4 to simulate the VT's PF1 to PF4. With the NumLock key down, the PC's numeric keypad will simulate the VT's numeric keypad, while the arrow keys on the PC's numeric keypad (with the NumLock up) or the separate arrow keypad (at all times) will simulate the VT's arrow keys. Note that Telix will only recognize the separate arrow keypad if you turn on the 'Enhanced Keyboard' setting on the General Options screen of the Configuration Menu.
Another keyboard layout is available that is possibly better suited to older style keyboards with function keys on on the left side and no separate arrow keypad and numeric keypad. To make use of this alter- nate layout, while at the DOS prompt type: ren VT102.KEY VT102101.KEY ren VT102OLD.KEY VT102.KEY This layout is similar to one used by many comm programs, in which the normal function keys (F1-F10) represent the left side of the VT's nu- meric keypad, while the shifted function keys (Shift-F1 - Shift-F10) represent the right side, as follows: Telix function Keys DEC VT102 Keypad

PF1PF2PF3PF4PF1PF2PF3PF4
789-789-
456,456,
123123
0. ENTER0.ENTER

The arrow keys are also defined to send the proper sequences.

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7.5 VT52

The DEC VT52 is another relatively common terminal type, that is con- siderably simple than the VT102. Telix's key definitions for the VT52 are stored in the VT52.KEY file.

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This document was prepared by Alexandros Belsis