INT FF - PCIBM PC/FORTH - GRAPHICS API(Application Program[ming] Interface) The defined set of calls which a program may make to interact with or request services of the operating system or environment under which it is running.  Because the inputs and outputs of the calls are well-defined, a program using the API can continue using the identical calls even if the internal organization of the program providing the API changes.
	BX = function number
	    0001h function REDRAW
	    0002h function !PEL
	    0003h function @PEL
	    0004h function LINE
	    0005h function ARC
	    0006h function @BLOCK
	    0007h function !BLOCK
	    0008h function FLOOD
	DS:SI -> FORTH program counter
	SS:BP -> FORTH parameter stack
	SS:SP -> FORTH return stack
	details of parameters not available
Return:	AX,BX,CX,DX,ES,DI may be destroyed
Note:	these functions all display an error message if the graphics routines
	  are not resident