/FOCAL FUNCTION FXY(X,Y)   -JVZ

/THIS FUNCTION USES THE STANDARD VC8-E POINT-PLOT INTERFACE
/TO PROVIDE ANALOG SIGNALS ON THE X- AND Y-AXES AND A PULSE
/ON THE Z-AXIS.  THE FUNCTION MAY BE CALLED WITH EITHER ONE
/OR TWO ARGUMENTS.  IF Y IS OMITTED, ONLY THE X VALUE WILL
/BE CHANGED.   THE RANGE OF THE ARGUMENTS IS -512 TO +511.

/SYSTEM SYMBOLS:

	DISD=6052
	DILX=6053
	DILY=6054
	DIXY=6055
	FIXTAB

/FOCAL SYMBOLS:

	FIELD 1
	CHAR=66
	END=134
	EVAL=1613
	FIXIT=4453
	FNEW=3224
	FNTABF=355
	FNTABL=2155
	MCOM=72
	PUSHJ=4540
	RETURN=5536

	*END
	STVAR

	*FNTABF+22
	FXY		/ENTRY POINT
	*FNTABL+22
	"X^2+"Y		/CODE FOR 'FXY'

	*FNEW
FXY,	FIXIT		/CHANGE X TO AN INTEGER
	DILX		/LOAD X AXIS CONVERTER
	CLA
	TAD CHAR
	TAD MCOM
	SZA CLA		/ARE THERE TWO ARGUMENTS?
	JMP .+5		/NO
	PUSHJ		/YES
	    EVAL-1	/EVALUATE THE NEXT ONE
	FIXIT		/CHANGE Y TO AN INTEGER
	DILY		/LOAD Y AXIS CONVERTER
	DISD		/WAIT A WHILE
	JMP .-1
	DIXY		/BRIGHTEN THINGS UP
	RETURN
STVAR=.;$