snake6502/src/multicolor.asm

		processor 6502

multicolor SUBROUTINE

; Prepare data struct for MultiColor mode
; ----------------------------------------------------------------------
multicolorInit:
	; Tell VIC-II to use:
	; - screen text memory at	$400	= $400 * 1
	; - characters ROM at		$2000	= $400 * 8
	lda #$18
	sta $d018

	rts

; Activate multicolor mode
; ----------------------------------------------------------------------
multicolorOn:
	; Set colors
	lda #$0
	sta $d021	; 00 is black
	lda #$a
	sta $d022	; 01 is gray
	lda #$d
	sta $d023	; 10 is green
				; and of course
				; 11 is the colour specified in color RAM

	lda $d016
	ora #$10
	sta $d016

	rts

; Deactivate multicolor mode
; ----------------------------------------------------------------------
multicolorOff:
	lda $d016
	and #$ef
	sta $d016
	rts