%N tvrzscr %F $MIR/src/subs/tv.for
%D Reads the current channel, zoom, and scroll registers.
%P jm
%: tv, display
%B
        subroutine TvRZScr(chan,mag,xscr,yscr)

        implicit none
        integer chan,mag,xscr,yscr

  Read TV registers.

  Output:
    chan       The current channel being displayed.  If the current
               device is not capable of returning these values, chan
               is set to -1.
    mag        The current magnification.
    xscr       X scroll register (upper left relative).
    yscr       Y scroll register (upper left relative).
