Many hosts use the ASCII (American Standard Code for Information Interchange) character set to simplify communication with other computers; for example, a Digital VAX running VMS, almost all UNIX systems, and Macintosh or PC-DOS systems. You can use either VT102, VT100, VT220, Heath-19, or PC-ANSI emulation with these hosts; the VAX requires one of the VT emulators.
The buttons at the top and left side of the window provide a convenient method of sending frequently used commands to the host with the mouse. You can set the buttons to send a macro instead of the default VT100 control sequences by clicking on the button while holding the Option key down. You can also select text on the screen with the mouse to Copy, Paste, Append, or Print.
If the "Control Controls" dialog item "Show cursor-buttons at left of window" is enabled, the cursor is set to button numbers which appear when you move the cursor up and down the left margin of the window. By default, these send key sequences equivalent to the Keypad keys in VT100 Application mode. You can see the labels for the buttons when you click on the '?' control at the top left of the window.
If the "Control Controls" dialog item "Show status bar at top of window" is enabled, there are 11 buttons at the top of the emulator window which perform functions useful with hosts which use ASCII terminals.
To the right of the buttons are two counters; the left one shows the packets sent to the network, the right one shows the packets received.
Moving the mouse over a point on the terminal screen will draw a heavy underline beneath that character position; pressing the mouse button will cause dataComet to attempt to move the terminal cursor to the underlined position. (Cursor positioning can be disabled using the "!Ct" macro, or by setting the Single-click macro to an empty macro.) Please note that if you click again while the cursor is still moving, it will not move to the point you expect it to! If the cursor does not go to the proper position on the first mouse click, try it again; the presence of tabs in the text may cause incorrect positioning. When using the UNIX vi editor, you can use "vi cursor motion" to get around this problem, in addition to speeding the process up. ("vi cursor motion" does have a minor problem in that it does not handle wrapped lines properly.)
You can modify ASCII key mapping using options in the "Control Emulator" dialog; the default keymapping has:
On the Apple extended keyboard, there are additional function keys available at the top of the keyboard and in between the keyboard and keypad.
The "ins", "home", "end", "x->", "page up", and "page down" keys are mapped by default to perform the expected local Mac-like function (i.e, paging and character deletion). To send VT220 keys, hold down the Shift key while pressing the key. You can use the "Control keypad..." dialog to switch so that the keys send VT220 keys ordinarily and perform the local functions when shifted.
You can also use the "Control keypad..." dialog to control whether the keypad keys function as regular numeric keys or as "Application" keys which send special escape sequences; if you have problems using the keypad with an application, try using this dialog to switch the setting.
The keys at the top of the keypad are mapped to F1 - F4. The keys at the top of the keypad are mapped to F1 - F15 (shift to map F1 -> F13, F2 -> F14, etc., up to F8 -> F20). In VT100 mode the keys send the following sequences:
Resizing the terminal window when drivers don't support Telnet Window Size negotiation: If your host does not have the correct terminal size set after you change the window size, you need to issue the following commands (e.g., where you want to set the size of your window to 50 rows X 80 columns):
stty rows 50 columns 80
echo 'r'
The second command clears the screen and resets the terminal's scrolling region to the full size of the screen so all the rows specified will be used before scrolling occurs.
To get 8-bit connections: UNIX terminal drivers normally do not pass 8 bit characters. To enable proper handling of ISO-Latin or other character sets which have more than 128 characters, add the following lines to your .cshrc:
tty -s
if ($status == 0) stty cs8 -istrip -parenb
If you don't use csh, add equivalent code to your shell's start up file. (Note that it is necessary to check whether your standard I/O streams are connected to a terminal. Only then should you reconfigure the terminal driver.)
dataComet offers reliable performance with EMACS editor sessions. "Control-Option" sends a meta-character; "Control-Shift" sends a meta-control-character. You can also use the "Control Emulator" dialog item "Option is Meta Key" to set up the Option key to serve as a Meta Key (see description below) . Alternatively, you can set the eight bit of the character to make it a Meta key using the !CM macro, which you need to associate with a key using a key macro.
Note that "Substitute Comet-Font for characters > 127" needs to be OFF for PC-ANSI sessions to display the correct font consistently; if this is not the case, box characters will appear as odd characters. (This is ordinarily automatic, but may not be set correctly if you reconfigure a session as a PC-ANSI session after connecting as a VT100).
Use the Heath-19 emulator and turn on the "Use IBM menus and key mapping" option in the "Control Emulator..." dialog if you want to communicate with an IBM mainframe through the 7171 ASCII terminal adapter. This mode allows you to run programs such as the XEDIT full-screen editor as if you were using an IBM 3278 terminal. Buttons and menu items are provided which allow you to conveniently produce the commands the 7171 accepts as the equivalent of keys on the 3278 terminal. When the 7171 requests your terminal type, type in "C19". (The C19 definition must be loaded into the 7171 configuration for this to work correctly.)
dataComet provides an emulation of the IBM 3278 display terminal; it allows you to run programs such as FILELIST or the XEDIT full-screen editor just as if you were using an IBM 3278 terminal. Buttons and menu items are provided which allow the user to conveniently produce the commands produced by keys on the 3278 terminal.
Moving the mouse over a point on the terminal screen will draw a heavy underline beneath that character position; pressing the mouse button will move the terminal cursor to the underlined position. You can also select text on the screen with the mouse to Copy, Paste, Append, or Print. (Note that Paste aborts if the text runs past the end of the current field.)
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Key Assignments (see IBM menus also)
Key 3270 Action
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Return Enter
Shift-Return New Line
Enter Enter
Option-Enter PA2
Shift-Tab Back-Tab
Backspace Backspace, Delete
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The Backspace key changes its behavior when the 3270 emulator is put into "Insert" mode. Ordinarily it produces a Backspace-Space-Backspace, so that the text to the right of the cursor is left in its original position. When Insert mode is ON, the Backspace key will produce a Backspace-Delete, so that the text to the right of the cursor shifts to the left.
You can also use the Command, Shift, and Option keys to control which action you wish the Backspace to perform. When Command is held down while Backspace is pressed, the character to the right of the cursor is deleted, and the remaining text is shifted left. When the Option key is held down, the result is a Backspace-Delete, as is the case in Insert mode. When the Shift key is held down, the standard Backspace-Space-Backspace will be produced.
If the "Control Controls" dialog item "Show cursor-buttons at left of window" is enabled, the cursor is set to button numbers which appear when you move the cursor up and down the left margin of the window. By default, these send the PF keys from 1 through 24. You can see the labels for the buttons when you click on the '?' control at the top left of the window.
If the "Control Controls" dialog item "Show status bar at top of window" is enabled, there are 11 buttons at the top of the emulator window which (by default) perform actions available on 3270-type terminal keys. (See "2. Menus", "Using IBM menus" for a description of their functions.)
To the right of the buttons are two counters; the left one shows the packets sent to the network, the right one shows the packets received. If you are using Telnet, the counter on the left may appear reversed (white on black)--this indicates that MacTCP is resending the packet to the host.
A "HOST BUSY" indicator appears at the top of the screen when one the host system is busy processing your command; the host will not accept new commands from an Enter or PF key until the "HOST BUSY" indicator goes off.
IMPORTANT NOTE: You can enhance your communications efficiency when using the 3270 emulator by making sure that XEDIT has "SET FULLREAD OFF" in your PROFILE XEDIT file; XEDIT-based applications such as RICEMAIL may need to have this option turned off also to get optimal performance. FULLREAD mode causes an extra 2,000 bytes to be sent with every PF-keystroke in the Action menu, and can significantly degrade performance on slower networks such as LocalTalk.
