Everyone's A Wally: Routine at E77A

E77A: Clear the inventory display, so new text can go on

Used by the routine at E41D.
E77A	PUSH HL	Store main registers.
E77B	PUSH BC
E77C	PUSH DE
E77D	LD IX,$81F8	Point IX at the screen offset table.
E781	LD C,$20	20 rows to update.
E783	LD L,(IX+$00)	Get the next screen address in HL.
E786	LD H,(IX+$01)	Get the next screen address in HL.
E789	LD B,$0F	0F columns per row to update.
E78B	LD (HL),$00	Clear all bits.
E78D	INC HL	Move to the next column.
E78E	DJNZ $E78B	Loop until all columns are done.
E790	INC IX	Move to the next position in the offset table.
E792	INC IX	Move to the next position in the offset table.
E794	DEC C	Loop until all rows are updated.
E795	JR NZ,$E783	Loop until all rows are updated.
E797	POP DE	Restore main registers and return.
E798	POP BC
E799	POP HL
E79A	RET