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EMULATE.TXT
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1989-10-05
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Terminal Emulation
------------------
What is Emulation?
------------------
The emulation feature allows you to let your personal
computer act like, or emulate, a terminal such as the DEC
VT-100, the IBM 3101, or the Wyse 50.
For example, if a certain sequence received from the host
computer instructs a terminal to clear the screen, the
emulation feature will tell BitCom to clear the screen when
that same sequence is received.
If the host computer that you are connected to uses full
screen applications such as an accounting system or editor,
you may need to use the terminal emulation feature. Most
other systems such as CompuServe or Easylink display text
line by line. These types of systems do not need to use
emulation. If you are not sure whether emulation is needed
or not, check with the company or department running the
host computer.
Generally, you should not use emulation unless you are
specifically instructed to emulate a particular terminal.
An exception to this is many BBS's that use ANSI
color/graphics. If you have a graphics monitor and want to
take advantage of this, use the ANSI emulation file.
BitCom's emulation files are programmable. This means you
can change many options, keys or colors by editing a file
called the emulation file. The emulation file tells BitCom
what keys to use, what characters to filter, and how to
enable certain functions. The emulation file is a text
(ASCII) file, so you can edit or change it using any text
editor.
Included on the BitCom diskette are the following emulation
files.
ANSI.EMU for ANSI color/graphics support
VT100A.EMU for DEC VT-100 with ANSI support
VT100B.EMU for DEC VT-100 with ANSI and VT-52 support
3101.EMU for IBM 3101 terminal
WYSE50.EMU for Wyse 50 terminal
WYSE60.EMU for Wyse 60 terminal
TVI920.EMU for Televideo 920 terminal
TVI9XX.EMU for Televideo 900 series terminals
Keyboard mapping for these terminals is shown at the end of
this section.
2
Using Terminal Emulation
------------------------
To set up a phone number record to use terminal emulation,
follow the steps below.
1. From the Communications Selection Menu, press the up or
down arrow keys until the pointer is next to the record
requiring terminal emulation.
2. Press 'S' to Show More. This will take you to the
Communications Parameters Menu.
3. Highlight the 'Emulation' field' by pressing the up or
down arrow keys.
4. Type in the emulation file name, without the .EMU
filename extension. For example, to use the VT100A.EMU
file, you would type in VT100A.
5. If you are using an emulation file such as ANSI that
supports color/graphics, set the 'Input' and 'Output'
fields to No. To do this, press the up or down arrow
keys until the appropriate field is highlighted, then
the right or left arrow keys until 'No' is displayed in
the field.
6. If you are using an emulation file other than ANSI, you
also need to change the BitCom special keys that will
conflict with the function keys defined in the
emulation file. If you need to do this follow steps 7
through 10. If you do not need to do this, jump to
step 11.
7. Press the up or down arrow keys until the first special
key (Help) is highlighted.
8. Press <Esc>.
9. Press the new key value. You might want to use Alt-F1
or Shift-F1.
10. Repeat steps 7 through 10 for the Escape, Print, and
Snapshot keys.
11. Press <F2>. This will take you back to the
Communications Selection Menu.
12. When you connect with your host computer using this
record, the emulation file will be invoked
automatically. Your keyboard will simulate the
appropriate terminal that you have chosen to emulate.
3
How Terminal Emulation Works
----------------------------
Terminal emulation usually involves translating the commands
that are sent to and from the host computer, to the
functions that are defined by the terminal manufacturers.
These commands usually, but not always, start with the ASCII
code ESC (hexadecimal 1B), followed by a sequence of
characters. Therefore, this sequence is commonly known as
an escape sequence. The escape sequence definitions are
different from terminal to terminal.
For example, the DEC VT-100 uses a different escape sequence
than the IBM 3101. If you need more information about
particular escape sequences, consult the terminal
manufacturer's hardware reference manual.
Some terminals, such as the Televideo and the Wyse, use
control codes in addition to escape sequences. Control
codes are displayed in an emulation file as a hexadecimal
number, preceded by a dollar sign ( $ ).
If you are not familiar with programming concepts, we
suggest that you do not attempt to modify existing emulation
files by yourself.
Common Problems Using Terminal Emulation
----------------------------------------
When using terminal emulation, you may sometimes experience
one of the following problems.
**Problem**
When using emulation, the function keys do not work for
the application that is being used. For instance, instead
of <F1> acting like the Gold Key on a VT-100, it brings up
the BitCom Help Screen when pressed.
**Solution**
The BitCom special keys are conflicting with the
function keys that are defined in the emulation file.
Normally, BitCom will use F1 through F5. Change the BitCom
special keys on the Communications Parameters Menu for the
record that is using emulation. You may want to use Alt-F1
through Alt-F5, or Shift-F1 through Shift-F5.
**Problem**
The screen displays a set of strange characters