1103 - NewComm and Unix

NewDeal Hot Tip 1103

Telecommunications

NewComm and Unix

If you're using a CGA system to log on to a Unix server and the prompt is always at the bottom of the screen, you are probably using 12 lines by 80 columns in NewComm. In order for things to be in sync, you need to tell Unix about your screen size. The appropriate command is "stty rows 12 columns 80". You probably need to do this every time you log on from a CGA system. In EGA, VGA, and HGC, you can use the normal 24x80 display. Even in these cases, however, you should make sure that Unix knows what your screen size is.

Another important thing is the terminal emulation. Make sure that the NewComm terminal type is the same as what Unix thinks you are using.

Unix and Backspace

NewComm doesn't send the DELETE (ASCII 127) character. Try the following solutions to make Unix accept BACKSPACE (ASCII 8) instead. At the Unix command line, enter:

stty erase "^H"

In GNU-Emacs:

Meta-X global-set-key "\C-h" 'backward-delete-char-untabify

If you absolutely must send a delete character, try this: Create a DELETE.TXT file containing just the delete character. (You'll have to use a DOS-based text editor to do it.) To send a delete, select "Type From Text File" on the File menu. In the dialog box, choose DELETE.TXT, this will send the delete.

VT100 Terminal Emulation and Unix

The problem:

Communicating with a Unix-based information system, both systems using VT100, ";7m" is displayed where the highlighted cursor should be.

Solution:

First, make sure that NewComm is set to VT100.

To move the cursor around, each manufacturer has a different set of control sequences. The DEC VT100 uses the ANSI-standard "ESC [ " sequences (i.e. the Unix end sends an ESC character, followed by a left bracket, followed by other characters that cause things like cursor movement and reverse video).

Try typing, at the Unix prompt, "echo $term", and if it says vt100, then NewComm should work with the VT100 setting.

Also try the command "stty -a" to show what Unix expects about your terminal. Here's an example:

% stty -a
speed 19200 baud, 24 rows, 80 columns
parenb -parodd cs7 -cstopb hupcl cread -clocal -crtscts
-ignbrk brkint ignpar -parmrk -inpck istrip -inlcr -igncr icrnl -iuclc
ixon -ixany -ixoff imaxbel
isig iexten icanon -xcase echo echoe echok -echonl -noflsh -tostop
echoctl -echoprt echoke
opost -olcuc onlcr -ocrnl -onocr -onlret -ofill -ofdel -tabs
erase kill werase rprnt flush lnext susp intr quit stop eof
^H  ^?  ^W  ^R  ^O  ^V  ^Z/  ^Y  ^C  ^\  ^S/  ^Q  ^D

Note the "cs7" (Character Size 7, vs. 5, 6, or 8; this is the number of "data bits" that NewComm should be set for) and also the "-parodd" (or it could say "evenp"), which means "not odd parity" which of course means "even parity".

These facts about stty are available via the Unix on-line manual. Just enter "man stty" at your Unix prompt. Also the "tset" command is useful for getting your terminal stuff set on the Unix end (man tset).

The VT100 emulation in NewComm may not properly support all Unix systems. For example, on one such system, the screen doesn't clear as expected when using the vi editor after dialing into an IBM RS6000 even though termenv is set to vt100.

The problem is most likely that the particular host is expecting different screen clear sequence than what NewComm expects or that the host uses some screen clear sequence that NewComm doesn't support. Since the screen clear action is supported by NewComm in general, it might be possible to modify the termcap file to achieve the expected results.

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Last Modified 2 Mar 1999