Code: Select all
; *** X816 SETTINGS ***
.mem 8 ; 8-bit memory mode
.index 8 ; 8-bit index mode
.opt on ; address optimize
.org $8000 ; replace dashes with load address MINUS $80
.incbin "nomryi.nsf" ; include NSF tune
.incbin "our.bkg" ; empty background first
.incbin "our.spr" ; our sprite pic data
Reset_Routine:
cld ; clear decimal flag
sei ; disable interrupts
lda #%00000000 ; disable vblank interrupts by clearing
sta $2000 ; the most significant bit of $2000
:****graphix!****
Start:
lda #%00001000 ; do the setup of PPU
sta $2000 ; that we
lda #%00011110 ; talked about
sta $2001 ; on a previous day
;supermario clouds code
lda #$3F ; NES background palette location
sta $2006
lda #$00
sta $2006
lda #$21 ;background [powder blue]
sta $2007
lda #$30 ;cloud inside [white]
sta $2007
lda #$11 ; highlight [blue]
sta $2007
lda #$0d ;outline [black]
sta $2007
;end supermario clouds code
waitblank: ; this is the wait for VBlank code from above
lda $2002 ; load A with value at location $2002
bpl waitblank ; if bit 7 is not set (not VBlank) keep checking
lda #$00 ; these lines tell $2003
sta $2003 ; to tell
lda #$00 ; $2004 to start
sta $2003 ; at $0000.
lda #100 ; load Y value
sta $2004 ; store Y value
lda #$00 ; tile number 0
sta $2004 ; store tile number
lda #$00 ; no special junk
sta $2004 ; store special junk
lda #100 ; load X value
sta $2004 ; store X value
; and yes, it MUST go in that order.
;****end graphix code****
; *** WAIT 2 VBLANKS ***
WaitV1:
lda $2002 ; give the PPU a little time to initialize
bpl WaitV1 ; by waiting for a vblank
WaitV2:
lda $2002 ; wait for a second vblank to be safe
bpl WaitV2 ; and now the PPU should be initialized
; *** CLEAR SOUND REGISTERS ***
lda #$00 ; clear all the sound registers by setting
ldx #$00 ; everything to 0 in the Clear_Sound loop
Clear_Sound:
sta $4000,x ; store accumulator at $4000 offset by x
inx ; increment x
cpx #$0F ; compare x to $0F
bne Clear_Sound ; branch back to Clear_Sound if x != $0F
lda #$10 ; load accumulator with $10
sta $4010 ; store accumulator in $4010
lda #$00 ; load accumulator with 0
sta $4011 ; clear these 3 registers that are
sta $4012 ; associated with the delta modulation
sta $4013 ; channel of the NES
; *** ENABLE SOUND CHANNELS ***
lda #%00001111 ; enable all sound channels except
sta $4015 ; the delta modulation channel
; *** RESET FRAME COUNTER AND CLOCK DIVIDER ***
lda #$C0 ; synchronize the sound playback routine
sta $4017 ; to the internal timing of the NES
; *** SET SONG # & PAL/NTSC SETTING ***
lda #$00 ; replace dashes with song number
ldx #$00 ; replace with $00 for NTSC or $01 for PAL
jsr $8000 ; replace dashes with init address
; *** ENABLE VBLANK NMI ***
lda #%10000000 ; enable vblank interrupts by setting the
sta $2000 ; most significant bit of $2000
Loop:
jmp Loop ; loop loop loop loop ...
NMI_Routine:
lda $2002 ; read $2002 to reset the vblank flag
lda #%00000000 ; clear the first PPU control register
sta $2000 ; writing 0 to it
lda #%10000000 ; reenable vblank interrupts by setting
sta $2000 ; the most significant bit of $2000
jsr $8003 ; replace dashes with play address
rti ; return from interrupt routine
IRQ_Routine:
rti ; return from interrupt routine
.pad $FFFA
.dw NMI_Routine ; setup the NMI vector at $FFFA
.dw Reset_Routine ; setup the Reset vector at $FFFC
.dw IRQ_Routine ; setup the IRQ vector at $FFFE
