QVT - A DEC VT220 Terminal Emulator
QVT is a public-domain program that performs 100% emulation of the
Digital Equipment VT220 data terminal. The version provided here is free, and
it supports full VT220 emulation, and additionally includes a facility for
capturing the incoming data stream and saving it to disk.
NOT included in the present version are facilities for uploading files,
both text and binary, for downloading binary files, for capturing screen images
to disk, and for performing auto-dial and auto-logon operations. The complete
version of QVT - including all of these features - may be purchased from the
author for the price of $30.00. Orders may be directed to the following ad-
P.O. Box 221
Penfield, NY 14526
Instructions For QVT
Before running QVT, it is recommended that you select a location on your hard
disk which can serve as a permanent residence for the program. Having done so,
you should create an environment variable as follows:
QVT will consult this environment variable when attempting to open the various
overlays and data files which it uses in the course of normal operation. If you
do NOT create the environment variable 'VT_DIR', QVT will look for its files in
the current directory. If the overlay file QVT.000 cannot be located, the prog-
ram will terminate immediately.
In addition to the above, users of composite monochrome monitors may wish to
issue the DOS command 'MODE BW80' before beginning execution of QVT. This will
cause QVT to suppress the use of color; if you are in the CO80 mode at the time
that QVT is loaded, color will be used at various points, and these colors will
detract from the readability of the display when viewed on a composite monitor.
Having prepared the environment, you may then begin executing the program by
entering the command 'QVT' at the DOS prompt. A brief hello screen will be
displayed, after which you will be placed directly into communication mode.
The FIRST time that you run the program, a message will appear on-screen to
the effect that the file 'DEFAULT.VT' is being created. This is the file that
QVT uses to configure itself at startup time; if no such is file can be loc-
ated, the built-in defaults are used. These defaults are:
1200 baud, 8 bits, 1 stop bit, no parity.
These settings may be changed at any time, and if the defaults are not appro-
priate for your requirements, a new DEFAULT.VT file may be created for storing
the desired default settings.
Configuring QVT Communication Parameters
QVT is supplied with a reasonable set of default communications settings. If
necessary, these may be changed by performing the following procedure:
1. Press to invoke the Configuration Menu
2. Use the Up and Down Arrow keys to select the parameter that you wish to
3. When the correct parameter is highlighted, press to bring up the
options menu for that parameter. The selection bar will be located at the
currently effective value for the selected parameter.
4. Use the Up and Down arrow keys to select the desired value. When the correct
value is highlighted, press to make your selection and return to the Config
Menu. If you decide not to make a new selection, press to return to the
Config Menu without changing the current setting.
5. When you have completed your Configuration selections, there are three ways
to exit from the Config Menu:
* To use the new settings and save them to disk, select 'Save Settings'. If
this option is selected, you will be prompted for a filename to use for the
new configuration. The file will be placed in the directory named by the
environment variable 'VT_DIR' (see discussion above).
* To use the new settings WITHOUT saving them to disk, select 'Use Settings'.
You will be returned to communications mode under the new settings, but these
settings will be lost upon program exit.
* To discard all changes and return to communications mode under the old
settings, press .
Configuring QVT Terminal Parameters
QVT is a VT220 emulator, and as such provides the various 'SETUP' options
which are available on the actual terminal. To view and/or change the current
values of these options, select the option 'Terminal Modes' from the Config
Menu (see above). You will be presented with a display of all of the current
values. To change a setting, first use the Arrow keys to move the cursor to
the desired option, then press the spacebar to step through the available
settings, stopping when the desired setting is displayed.
To return to the Config Menu, press .
NOTE 1: All changes to terminal options take effect immediately, NOT when
the Terminal Modes menu is exited. In this sense, this menu differs from the
various menus which are used to modify communications setting.
NOTE 2: The terminal options displayed on this menu are subject to change by
software running on the host system. Therefore, don't be surprised if you see
changes in these values even though you have made none yourself.
Other QVT Commands
As noted in the opening paragraphs of this document, much of the extended
functionality of QVT has been disabled in the present version. However, the
following commands remain essential:
1. To capture the incoming data stream to a disk file, press . This
will open a capture buffer which will capture all received data, up to avail-
able memory. To save the contents of this buffer to disk, press a
second time, at which point you will be prompted for a filename. You may either
enter a regular DOS filename to save the buffer, or a bare carriage return. In
the latter case, the buffer will NOT be saved at the present time, and you may
either continue capturing, or discard the present buffer without saving it.
If you enter a valid filename, QVT will first check to see if such a file
already exists; if so, you will be queried as to whether or not you wish to
2. To display the current keyboard mapping, press . The mapping of
the IBM numeric keypad will change depending on the state of the NumLock key.
If NumLock is OFF, the arrow keys function as cursor keys; with NumLock off,
the arrow keys produce the appropriate numbers.
Since the IBM keyboard differs substantially from the DEC keyboard, some rather
torturous re-mapping must be performed in order to retain full support for all
the keys on the VT220. The precise mapping employed by QVT may be seen by using
the command, but the following is worth mentioning here:
* The cursor keys are duplicated on the lower portion of the Function Key key-
pad; the cursor keys are emulated by the keys F6, F7, F8, and F10. This makes
certain that the four cursor keys are always available in an unshifted form,
even if NumLock has been turned on.
* The word-processing keys such as "Find", "InsertHere", and so on are also
placed on the lower portion of the Function Key keypad; the keys F6 through
F10 - when used in conjunction with the key - will emulate the six
word processing keys.
* The top-row function keys F1 through F20 are emulated by using the
key together with the keys '1' through '10' and 'Q' through 'P' across the
top of the keyboard. This formula preserves at least preserves the physical
layout of the DEC keys. As mentioned above, there simply aren't enough keys
on the PC keyboard to perform a completely comfortable re-mapping of the DEC
It is recommend that when using EDT, that the NumLock state be turned on. Unless
NumLock is enabled, you will be required to use the key in order to ob-
tain the EDT commands which are bound to the keys '2', '4', '6', and '8'.
Another EDT note: the ',' key - used for deleting characters - has been assigned
to the '*/PrtSc' key.
3. As mentioned above in the section on configuration, you may save your set-
tings to a disk file. In order to use these stored settings at a later date,
use the command to load a config file. You will be prompted for the
name of the config file, and if the named file cannot be located, the current
settings will remain in effect.
4. To quit from QVT and force a modem disconnect, press .
5. To suspend your QVT session and temporarily return to DOS, press .
You may perform any DOS operations in the normal manner, then return to your
session by re-starting QVT. NOTE: This command involves an actual return to
DOS, not the starting up of COMMAND.COM as a child process. You therefore
have all of your system memory available.
Enjoy! And remember, if you want the complete version of QVT with full file-
transfer and Auto-Dial capability, send a $30 check to the address at the top
of this document.
BONUS! For no additional charge, the full SOURCE CODE for QVT is available to
purchasers of the complete version. Simply indicate on your order that you want