| Routines

FC57: Hide the play area

Used by the routines at 7866 and FB52. Hides the play area and clears the screen refresh buffer (SRB).
FC57 | LD HL,$5A7F | Set the attribute bytes for the top 20 rows of the screen to 9 (INK 1: PAPER 1)
FC5A | LD (HL),$09
FC5C | DEC HL
FC5D | BIT 3,H
FC5F | JR NZ,$FC5A
FC61 | LD HL,$7F5F | Set every byte in the SRB to 0
FC64 | LD (HL),$00
FC66 | DEC L
FC67 | JR NZ,$FC64
FC69 | RET |