The Hobbit (v1.0): Routine at 8BE9

8BE9: Start a picture: clear the picture area

Reads the picture's first two bytes: the border colour, which is set straight away, and the attribute for the picture area. The top two thirds of the screen ($4000-$4FFF) are cleared, and the 512 attributes of that area are filled with the picture's colour. If Bilbo is in the dark (954D), the border and attributes are set to black instead, and the drawing is abandoned: the return address is discarded and the routine jumps to the end of 8985.
8BE9	CALL $954D	Is Bilbo in the dark? (carry set if so)
8BEC	EX AF,AF'	Keep the answer in the alternate AF
8BED	LD A,(IY+$00)	A = the border colour (first byte of the picture)
8BF0	INC IY
8BF2	EX AF,AF'
8BF3	JR NC,$8BF8	Not dark: keep it
8BF5	EX AF,AF'	Dark: black border
8BF6	XOR A
8BF7	EX AF,AF'
8BF8	EX AF,AF'
8BF9	OUT ($FE),A	Set the border
8BFB	PUSH HL
8BFC	PUSH DE
8BFD	PUSH BC
8BFE	LD HL,$4000	Clear the top two thirds of the screen ($4000-$4FFF)
8C01	LD DE,$4001
8C04	LD BC,$0FFF
8C07	LD (HL),$00
8C09	LDIR
8C0B	LD HL,$5800	512 attributes from $5800
8C0E	LD DE,$5801
8C11	LD BC,$01FF
8C14	LD A,(IY+$00)	A = the picture's colours (second byte)
8C17	INC IY
8C19	EX AF,AF'
8C1A	JR NC,$8C1F	Not dark: keep them
8C1C	EX AF,AF'	Dark: black on black
8C1D	XOR A
8C1E	EX AF,AF'
8C1F	EX AF,AF'
8C20	LD (HL),A	Fill the attributes
8C21	LDIR
8C23	POP BC
8C24	POP DE
8C25	POP HL
8C26	EX AF,AF'	Not dark?
8C27	RET NC	Then return and draw the picture
8C28	POP HL	Dark: discard the return address...
8C29	JP $8A47	...and skip the drawing altogether