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