GRAPHICS CAPABILITY FOR OS/8 FORTRAN IV

	GENERAL PURPOSE GRAPHICS REQUIRES SEVERAL CAPABILITIES.
THE MOST IMPORTANT IS A ROUTINE WHICH WILL MOVE A PLOTTER PEN IN A
STRAIGHT LINE WITH THE PEN RAISED OR LOWERED.  IN THEORY THIS WOULD
ALLOW ANY PLOT TO BE DRAWN.  IN ACTUAL FACT HOWEVER, AT LEAST ONE
MORE ROUTINE IS REQUIRED.  THIS DRAWS CHARACTERS REPRESENTING 6 BIT
ASCII VALUES.  USEFUL ADDITIONAL FEATURES ALLOW ROTATION OF THE
CHARACTERS, COMBINATION OF A SERIES OF CHARACTERS AS A STRING, AND
AUTOMATIC SCALING OF THE PLOTTED DATA.
	FOUR FILES ARE INCLUDED IN THIS PACKAGE.  TWO OF THEM ARE
PEN MOVE ROUTINES WHICH ARE WRITTEN IN RALF CODE.  THE OTHER TWO ARE
CHARACTER ROUTINES AND ARE WRITTEN IN FORTRAN.  PLEASE NOTE THAT
THESE ROUTINES REQUIRE OS/8 FORTRAN IV AND WILL NOT RUN UNDER THE
OLDER RTPS FORTRAN IV.
	FOLLOWING IS A DESCRIPTION OF EACH OF THE FOUR FILES:


	1)  DPLOT.RA

	THIS FILE PROVIDES FORTRAN CALLABLE SUBROUTINES TO MOVE THE
PEN ON AN INCREMENTAL PLOTTER CONTROLLED BY AN XY12 OR VP8/I INTERFACE.
THE CALLS ARE SIMILAR TO THOSE PROVIDED IN FORLIB.RL TO DRAW ON THE
PDP-12 OR LAB-8E SCOPE.  THERE ARE FOUR ENTRY POINTS INTO THIS FILE:

	A) CALL INITDP
	THIS INITIALIZES THE SOFTWARE BY PLACING THE PROPER ROUTINES
ON THE INTERUPT AND IDLE QUEUES.

	B) CALL DSCALE(XMIN,YMIN,XMAX,YMAX)
	THIS INITIALIZES THE SCALE FACTORS FOR AUTOMATIC SCALING.
THE PARAMETER VALUES DEFINE THE LIMITS IN USER COORDINATES FOR AN
8.5X11 INCH PAGE.

	C) CALL DPLOT(N,X,Y,PEN)
	X, Y, AND PEN ARE ARRAYS OF DIMENSION N.  THEY DEFINE A SERIES
OF N PEN MOVE COMMANDS WHERE PEN CAN TAKE ON THE FOLLOWING VALUES.
	PEN<0:	INITIALIZE CURRENT LOCATION TO (0,0)
	PEN=0:	DRAW LINE
	PEN=1:	MOVE PEN WITHOUT DRAWING LINE.

	D) CALL DPWAIT
	WAIT FOR PLOTTER BUFFER TO EMPTY AND PLOTTER TO BECOME IDLE.
SINCE THE PLOTTER COMMANDS ARE BUFFERED, THIS CALL IS NECESSARY BEFORE
RETURNING TO OS/8.



	2)  FPLOT.RA

	THIS FILE IS INTERCHANGEABLE WITH DPLOT.RA.  THE DIFFERENCE
IS THAT THE PLOTTER COMMANDS, PASSED AS ARGUMENTS IN CALLS TO DPLOT,
ARE BUFFERED TO AN UNFORMATTED FILE ON LOGICAL UNIT 9.  THE COMMANDS
ARE PACKED, THREE SIGNED 12 BIT NUMBERS TO A 36 BIT FLOATING POINT WORD.
THE ORDER IS X, Y, PEN.  THERE ARE 85 COMMANDS PER BLOCK.  THE CALL
TO DPWAIT WILL FILL THE LAST BLOCK OF THE FILE WITH EOF CHARACTERS.
	NOTE THAT THIS FORMAT IS THAT WHICH IS EXPECTED BY PLOTVS.
(PLOTVS.SV WAS SUBMITTED TO DECUS EARLIER).



	3)  PLCHAR.FT

	THIS FILE PROVIDES CHARACTER PLOTTING CAPABILITY.  THE CHARACTER
VALUES ARE THOSE FOR 6 BIT ASCII AND WILL ALWAYS BE TAKEN MODULO 64.

	CALL PLCHAR(X,Y,WIDTH,HEIGHT,ROTATE,VAL)

	(X,Y) IS THE COORDINATE PAIR WHERE THE CHARACTER WILL BE DRAWN.
	(WIDTH,HEIGHT) DESCRIBES THE SIZE OF THE CHARACTER.
	ROTATE IS ROTATION OF THE CHARACTER IN DEGREES.
	VAL IS THE 6 BIT ASCII VALUE OF THE CHARACTER (0-63).



	4)  PLSTR.FT

	THIS FILE PROVIDES CHARACTER STRING PLOTTING BY REPETATIVELY
CALLING PLCHAR.

	CALL PLSTR(X,Y,WIDTH,HEIGHT,ROTATE,STRING)

	(X,Y) COORDINATES OF THE FIRST CHARACTER OF THE STRING
	(WIDTH,HEIGHT) SIZE OF EACH CHARACTER
	ROTATE IS THE ROTATION FOR EACH CHARACTER AND ALSO THE STRING
	STRING IS A STRING OF 6 BIT VALUES, PACKED SIX PER WORD USING CPUT.