NAME   
        VBeamPos -- Get vertical beam position at this instant.

   SYNOPSIS
        pos = VBeamPos()
         d0

        long vbeampos( void );

   FUNCTION
        Get the vertical beam position from the hardware.

   INPUTS
        none

   RESULT
        interrogates hardware for beam position and returns value.
        valid results in are the range of 0-511.
        Because of multitasking, the actual value returned may have
        no use. If you are the highest priority task then the value
        returned should be close, within 1 line.

   BUGS

   SEE ALSO