The graphics vector is called 'pstat'.  It is (currently) 13
integers long.  It contains:

pstat[CM]	Current Mode.  This word relates to the current
	    state of the plotting device.

pstat[X]	Current 'x' axix postion

pstat[Y]	Current 'y' axis postion

pstat[CCS]	Current charactor size. This is a charactor for the
	   current size.  Sizes are:
		0	Smallest
		1
		2
		3
		4	Largest.

pstat[CVT]	Current vector type.  This is a charactor for the
	    current type of vector that can be drawn. Types are:
		`	Straight line
		a	dotted	(...)
		b	dot-dashed (._._._.)
		c	short-dashed (_ _ _ _ _)
		d	long-dash (__ __ __ __)

pstat[CD]	Current plotting device.
		TEK = 1 = tektronics 4014
		HP = 0  = HP 7221A plotter

pstat[FD]	Current output file descriptor for plotter

pstat[DEBUG]	Debug mode flag.  1 = debug mode on.  Ends all
	    graphics mode commands with a return to ascii mode.

pstat[FILL]	Number of fill charactors to put in after a vector.

pstat[HPBS]	HP buffer start address.  This is a 512 byte buffer
		This buffer must be supplied by and HPBS must be set
		up by the end user before calling any plot routines.

pstat[HPBC]	HP buffer count.  Count of # of char. in the buffer.

pstat[HPBP]	HP buffer pointer.  *char into current (writing) place
		in the buffer

pstat[FDI]	File descriptor for reading the HP plotter.

