NES/joypad - Sample is best!

開発環境

• Windows 10 Home (64bit)
• ASM6

sample.chr
https://jsfiddle.net/zr3o07uq/

joypad.asm

;asm6 joypad.asm joypad.nes
 
joypad	= $00
 
	; iNES header
	db	"NES", $1a
	db	$01	; PRG-ROM
	db	$01	; CHR-ROM
	db	$00	; mapper / mirroring
	dsb	9, $00
 
	base	$c000
Reset:
	lda	#$00
	sta	$2000	; PPU制御レジスタ1
	sta	$2001	; PPU制御レジスタ2
 
	; パレットテーブル $3f00-3f1f
	lda	#$3f
	sta	$2006	; VRAMアドレスレジスタ
	lda	#$00
	sta	$2006
	ldx	#$00
	ldy	#$10
-
	lda	palette, x
	sta	$2007	; VRAMアクセスレジスタ
	inx
	dey
	bne	-
 
	lda	#$08
	sta	$2000	; PPU制御レジスタ1
	lda	#$0e
	sta	$2001	; PPU制御レジスタ2
loop:
-
	lda	$2002	; PPUステータスレジスタ
	bmi	-
-
	lda	$2002	; PPUステータスレジスタ
	bpl	-
 
	lda	#$01
	sta	$4016	; ジョイパッド1レジスタ
	lda	#$00
	sta	$4016
 
	lda	#$01
	sta	joypad
	ldy	#$08
-
	lda	$4016
	and	#$01
	asl	joypad
	ora	joypad
	sta	joypad
	dey
	bne	-
 
	; ネームテーブル $2000-$23bf
	lda	#$21
	sta	$2006	; VRAMアドレスレジスタ
	lda	#$f0
	sta	$2006
	lda	joypad
	sta	$2007	; VRAMアクセスレジスタ
 
	lda	#$00
	sta	$2005	; スクロールレジスタ
	sta	$2005
	jmp	loop
 
palette:
	db	$0f, $28, $01, $28
	db	$00, $00, $00, $00
	db	$00, $00, $00, $00
	db	$00, $00, $00, $00
 
	org	$fffa
	dw	0	; NMI VBlank
	dw	Reset
	dw	0	; IRQ/BRK
 
	incbin	"joypad.chr"