Jumping screen

[Guy Harris]

>Our SUN 3/60 consoles have a nasty habit of scrolling in a jump fashion -
>i.e. when you get to the bottom, the screen scrolls about 20 lines.  This
>is really annoying when using man.  The only way we have found to stop
>this is a fastboot.  Any help?

>From CONSOLE(4S):

     ESC[#r      Set scrolling (SUNSCRL)
          Takes one parameter, #  (default  0).   Sets  to  #  an
          internal  register  which determines how many lines the
          screen scrolls up when a  line-feed  function  is  per-
          formed with the cursor on the bottom line.  A parameter
          of 2 or 3 introduces a small amount of ``jump'' when  a
          scroll  occurs.   A  parameter  of 34 clears the screen
          rather than scrolling.  The initial  setting  is  1  on
          reset.

          A parameter of zero initiates ``wrap mode'' instead  of
          scrolling.   In  wrap mode, if a linefeed occurs on the
          bottom line, the cursor  goes  to  the  same  character
          position  in  the  top  line  of  the screen.  When any
          linefeed occurs, the line that the cursor moves  to  is
          cleared.   This  means  that  no scrolling ever occurs.
          `ESC [ 1 r' exits back to scroll mode.

          For more information, see the description of the  Line-
          feed (CTRL-J) control function above.

If you get any behavior from the console that you can't seem to fix except
by rebooting, check out CONSOLE(4S)'s "SUNxxx" escape sequences - you may
have just put the console PROM code into some funny mode with such an
escape sequence.  (Note that the SUNSCRL escape sequence is has the same
final character as the DEC escape sequence to set the scrolling region -
Sun consoles are *!NOT!* VT100s, so don't run software on them that thinks
they are!  The <ESC>[xxxr sequence is in the range of "private" escap
sequences specified by X3.64, so while both the VT100 and Sun console
claim to be X3.64 conformant, they can still have those sequences do
different things.  It might have been nice had the Sun console been
VT100-compatible, but what's done is done....)

The earlier problem with the screen going into white-on-black mode was
probably similar - there are escape sequences for that as well.