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    .inesprg    1   ; One 16k prg bank
    .ineschr    0   ; One 8k  chr bank
    .inesmir    1   ; Vertical map mirroring
    .inesmap    0   ; Use mapper 0

    .bank 0
    .org  $C000

reset:
	lda #$1F        ; Make all sound channels active, stolen from NESASM's JUNKDEMO...
        sta $4015
        lda #$0F        ; See NES Document for register values and meaning
        sta $4000       ; Square 1
        sta $4004       ; Square 2
        sta $4008       ; Triangle 
        lda #$00        ; See NES Document for register values and meaning
        sta $4001       ; Square 1
        sta $4005       ; Square 2
        sta $4009       ; Triangle
	ldx #$4F	;<Little tune, i think...
	ldy #$A8		;...>
	lda #$00	;<Get the joysticks ready, i think...
	sta $4016	;...
	lda #$01	;...
	sta $4016	;>
	jsr cjs		;Calls cjs (Check JoyStick)

cjs:
	sta $4016	;Reads A (?)
	bne lol		;If the result isn't zero jumps to lol (?)

lol:
	stx $4006       ; Stolen from JUNKDEMO again.
        sty $4007
        rts

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    .bank 0
    .org  $8000

	.dw		nmi_stuph
	.dw		reset
	.dw             irq


nmi_stuph:
	sta $4016	;Reads A (?)
	bne lol		;If the result isn't zero jumps to lol (?)

irq:
	rti
	
reset:
	lda #$1F        ; Make all sound channels active, stolen from NESASM's JUNKDEMO...
        sta $4015
        lda #$0F        ; See NES Document for register values and meaning
        sta $4000       ; Square 1
        sta $4004       ; Square 2
        sta $4008       ; Triangle 
        lda #$00        ; See NES Document for register values and meaning
        sta $4001       ; Square 1
        sta $4005       ; Square 2
        sta $4009       ; Triangle
	ldx #$4F	;<Little tune, i think...
	ldy #$A8		;...>
	lda #$00	;<Get the joysticks ready, i think...
	sta $4016	;...
	lda #$01	;...
	sta $4016	;>

lol:
	stx $4006       ; Stolen from JUNKDEMO again.
        sty $4007
        rts

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 .bank 0
 .org $8000

;your code

 .bank 3
 .org $fffa
 .dw  nmi
 .dw  reset
 .dw  0

Code: Select all

    .bank 0
    .org  $8000

	
reset:

	lda #$00	;<Get the joysticks ready, i think...
	sta $4016	;...
	lda #$01	;...
	sta $4016	;>


	.bank 3
	.org $fffa
	.dw		nmi_stuph
	.dw		reset
	.dw             0

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    .inesprg    2
    .ineschr    1
    .inesmir    0
    .inesmap    0

    .bank 0
    .org $8000

PPU_CTRL		equ $2000
PPU_MASK		equ $2001
PPU_STATUS		equ $2002
PPU_SCROLL		equ $2005
PPU_ADDR		equ $2006
PPU_DATA		equ $2007
PPU_FRAMECNT	equ $4017
DMC_FREQ		equ $4010
CTRL_PORT1		equ $4016

FRAME_CNT		equ $ff


reset

;init hardware

    sei
    ldx #$40
    stx PPU_FRAMECNT
    ldx #$ff
    txs
    inx
    stx PPU_MASK
    stx DMC_FREQ
	lda #%10000000
    sta PPU_CTRL

	jsr waitVBlank

;clear ram content

    txa
clearRAM
    sta $000,x
    sta $100,x
    sta $200,x
    sta $300,x
    sta $400,x
    sta $500,x
    sta $600,x
    sta $700,x
    inx
    bne clearRAM

;clear vram too

clearVRAM
	lda #$00
	sta PPU_ADDR
	sta PPU_ADDR
	ldx #$00
.1
	ldy #$40
.2
	sta PPU_DATA
	iny
	bne .2
	inx
	bne .1

	jsr waitNMI
	lda #%00011110	;enable display
	sta PPU_MASK

mainLoop

	;do anything you want here
	
	jmp mainLoop
	


waitVBlank
    bit PPU_STATUS
.1
    bit PPU_STATUS
    bpl .1
	rts

	
	
waitNMI
	lda FRAME_CNT
.1
	cmp FRAME_CNT
	beq .1
	rts

	
	
nmi
    rti

    .org  $fffa
    .dw   nmi
    .dw   reset
	.dw   0

	.bank 4
	.incbin "patterns.chr"

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	lda #$20	;Set PPU Pointer to start drawing tiles at $20E8
	sta $2006
	pha		;Push High byte onto stack
	lda #$E8
	sta $2006
	pha		;Push Low byte onto stack

	ldx #0		;Save tile ID in X, start with tile 0
	ldy #$10	;Y is a counter, counting down from 16 to 0 for each row
			;of tiles being displayed
DisplayCHR:
	stx $2007  	;Place tile on the screen at PPU Pointer's location.
			;PPU Pointer will go up by 1 automatically.
	inx		;Move onto the next tile number
	dey		;Count down until row is done being drawn
	bne DisplayCHR	;Go back to the start of the loop
			

	clc		;Clear Carry flag
	pla		;Pull saved PPU Pointer low byte from stack
	adc #$20	;Add 32 to get the PPU Pointer address of the next tile row
	tay		;Save this value in Y temporarily
	pla		;Pull saved PPU Pointer high byte from stack
	adc #0		;Add nothing (will add 1 if the low byte wrapped past 0 when adding 32)
	pha		;Push back onto the stack for later use
	sta $2006	;Set PPU Pointer to the new value (Previous value of entire pointer + 32)
	tya		;Transfer saved low value from Y into A to write to $2006
	sta $2006
	pha		;And push back onto stack
	ldy #$10	;Load Y with 16 to count 16 tiles for the next row of tiles
	cpx #0		;Only if X is not 0, in which case all tiles have been drawn.
	bne DisplayCHR	;Otherwise, move onto next row.