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VT100/UNIX -- Using the VT100 emulator with a Remote UNIX(R) System
              Running 'termcap'                                       84/05/16


  The  following are some tips for using the VT100 emulator when the remote host
  is a UNIX(R) system that has the termcap facility.

  Most users set the TERM and  TERMCAP  environment  variables  by  running  the
  'tset'  program in their .login or .profile startup files.  When logging in to
  a UNIX system through  the  VT100  emulator,  you  should  specify  that  your
  terminal  is  a  VT132,  which  is  a  VT100  with insert/delete character and
  insert/delete lines capabilities.  The only difference is that a real VT132 is
  always 24 lines by 80 columns, and the emulator will use  as  many  lines  and
  columns  as  will fit in the DM window.  However, you can automatically modify
  your TERMCAP variable at login time so that the li and co capabilities reflect
  the actual size of the emulator screen.  To do so,  place  the  following  two
  lines,  or  something  similar,  in  your  .login  file (this would need to be
  changed slightly for use in a .profile file):

      tset -s -I vt132 >tset1.$$; setsize <tset1.$$ >tset.$$
      source tset.$$; stty nl0; rm tset.$$ tset1.$$

  where setsize is the following C-shell script:

      #
      set size=`sz`
      set lines=$size[1]
      set columns=$size[2]
      sed -e "s/li#[0-9]*:/li#${lines}:/" -e "s/co#[0-9]*:/co#${columns}:/"

  and sz is a C program, shown below:

      #include <stdio.h>
      #include <sgtty.h>

      main()
      {
          FILE *fp;
          int fd, lines, columns;
          struct sgttyb otty, ntty;

          if ((fd = open("/dev/tty", 2)) < 0)
                  perror("open"), exit(1);
          if ((fp = fdopen(fd, "r")) == NULL)
                  perror("fdopen"), exit(2);
          if (gtty(fd, &otty) < 0)
                  perror("gtty"), exit(3);
          ntty = otty;
          ntty.sg_flags = (ntty.sg_flags & ~ECHO) | RAW;
          stty(fd, &ntty);
          write(fd, "\033[50n", 5);
          fscanf(fp, "\033[%d;%dS", &lines, &columns);
          stty(fd, &otty);
          printf("%d %d\n", lines, columns);
      }

  This program sends ESC[50n to the emulator.  This  is  a  non-standard  escape
  sequence,  in  response  to  which  the emulator sends back the current screen
  size, in the form ESC[nn;mmS, where nn is the number of lines, and mm  is  the
  number of columns.

  NOTE: In  order  for  programs such as 'vi' to work properly in windows larger
        than 24 lines, there is one change you must make to  the  termcap  entry
        for   VT100.      The   sf  (scroll  forward)  capability  is  given  as
        sf=30\E7\E[24H\ED\E8.  This works by saving the cursor (ESC  7),  moving
        to  the  bottom line (ESC[24H, which moves the cursor to the 24th line),
        doing an index operation (ESC D), and restoring the cursor (ESC 8).  The
        problem, of course, is that line 24 may not be the bottom  line.    This
        can  be  fixed  by  changing  the 24 to some very large number, say 200,
        since trying to move the cursor outside the bounds of the screen  always
        causes  it  to be placed at the edge of the screen.  Thus this change is
        safe to make, even when a real VT100 terminal is being used.