

A video display terminal is basically a dumb computer which is linked up to
another computer (over a cable or modem link) and displays what that computer
sends to it. A mainframe or minicomputer 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 that 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 imitate several terminals. While in terminal mode, you may change
the terminal type Telix is currently emulating (imitating) 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 offers:


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.


ANSI-BBS: This is a subset of 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 interesting and colorful.

          The ANSI.KEY file contains definitions for the arrow keys, and is
          automatically read when this terminal is selected. These definitions
          are supported by some full screen editors, for example.


VT102:    The DEC VT102 terminal is one of the most popular (and most emulat-
          ed) terminals in existence. It was developed by Digital Equipment
          Corporation. The VT102 terminal has a large number of functions.
          Telix supports all of these except for 132 column mode and double
          height mode. As well, Telix only emulates double width mode, by
          adding a space after every character.

          Telix fully supports both normal and application cursor mode in VT
          emulation. The VT102 keyboard layout used by Telix is stored in the
          VT102.KEY file, which is automatically read by Telix when VT102
          terminal 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 layout is one used by many
          comm programs, in which the normal function keys (F1-F10) represent
          the left side of the VT's numeric keypad, while the shifted function
          keys (Shift-F1 - Shift-F10) represent the right side, as follows:


              Telix function Keys                  DEC VT102 Keypad
          
           F1  - F10     SF1  - SF10
          
          ЪДДДДї ЪДДДДї  ЪДДДДї ЪДДДДї       ЪДДДДї ЪДДДДї ЪДДДДї ЪДДДДї
          іPF1 і іPF2 і  іPF3 і іPF4 і       іPF1 і іPF2 і іPF3 і іPF4 і
          АДДДДЩ АДДДДЩ  АДДДДЩ АДДДДЩ       АДДДДЩ АДДДДЩ АДДДДЩ АДДДДЩ
          ЪДДДДї ЪДДДДї  ЪДДДДї ЪДДДДї       ЪДДДДї ЪДДДДї ЪДДДДї ЪДДДДї
          і 7  і і 8  і  і 9  і і -  і       і 7  і і 8  і і 9  і і -  і
          АДДДДЩ АДДДДЩ  АДДДДЩ АДДДДЩ       АДДДДЩ АДДДДЩ АДДДДЩ АДДДДЩ
          ЪДДДДї ЪДДДДї  ЪДДДДї ЪДДДДї       ЪДДДДї ЪДДДДї ЪДДДДї ЪДДДДї
          і 4  і і 5  і  і 6  і і ,  і       і 4  і і 5  і і 6  і і ,  і
          АДДДДЩ АДДДДЩ  АДДДДЩ АДДДДЩ       АДДДДЩ АДДДДЩ АДДДДЩ АДДДДЩ
          ЪДДДДї ЪДДДДї  ЪДДДДї ЪДДДДї       ЪДДДДї ЪДДДДї ЪДДДДї ЪДДДДї
          і 1  і і 2  і  і 3  і і E  і       і 1  і і 2  і і 3  і і E  і
          АДДДДЩ АДДДДЩ  АДДДДЩ і    і       АДДДДЩ АДДДДЩ АДДДДЩ і N  і
          ЪДДДДДДДДДДДї  ЪДДДДї і T  і       ЪДДДДДДДДДДДї ЪДДДДї і T  і
          і     0     і  і .  і і R  і       і     0     і і .  і і R  і
          АДДДДДДДДДДДЩ  АДДДДЩ АДДДДЩ       АДДДДДДДДДДДЩ АДДДДЩ АДДДДЩ
          
          The arrow keys are also defined to send the proper sequences.


VT102:    There is also an alternate VT102 keyboard layout available, which
cont'd    may be more suitable to some users, and is much more useful on newer
          (101) enhanced keyboard. It is in the file, VT102ALT.KEY. Instead of
          using all the function keys to send out the codes generated by the
          VT's numeric keypad, this keypad will send the proper codes from the
          PC's numeric keypad when the Num-Lock key is depressed (F1 to F4
          represent the VT's PF1 to PF4). This layout is especially handy for
          users with the enhanced 101 key keyboard with the separate cursor
          key and numeric keypads, and functions keys across the top. To make
          use of the alternate layout, while at the DOS prompt type:

                          ren VT102.KEY VT102OLD.KEY 
                          ren VT102ALT.KEY VT102.KEY


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