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@jedahan
Last active Aug 29, 2015
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.inesprg 2 ; 2x 16KB PRG code
.ineschr 1 ; 1x 8KB CHR data
.inesmap 0 ; mapper 0 = NROM, no bank swapping
.inesmir 1 ; background mirroring
;;;;;;;;;;;;;;;
.bank 2
.org $C000
RESET:
SEI ; disable IRQs
CLD ; disable decimal mode
LDX #$40
STX $4017 ; disable APU frame IRQ
LDX #$FF
TXS ; Set up stack
INX ; now X = 0
STX $2000 ; disable NMI
STX $2001 ; disable rendering
STX $4015 ; disable DMC IRQs
vblankwait1: ; First wait for vblank to make sure PPU is ready
BIT $2002
BPL vblankwait1
clrmem:
LDA #$00
STA $0000, x
STA $0100, x
STA $0300, x
STA $0400, x
STA $0500, x
STA $0600, x
STA $0700, x
LDA #$FE
STA $0200, x
INX
BNE clrmem
vblankwait2: ; Second wait for vblank, PPU is ready after this
BIT $2002
BPL vblankwait2
LoadPalettes:
LDA $2002 ; read PPU status to reset the high/low latch
LDA #$3F
STA $2006 ; write the high byte of $3F00 address
LDA #$00
STA $2006 ; write the low byte of $3F00 address
LDX #$00 ; start out at 0
LoadPalettesLoop:
LDA palette, x ; load data from address (palette + the value in x)
; 1st time through loop it will load palette+0
; 2nd time through loop it will load palette+1
; 3rd time through loop it will load palette+2
; etc
STA $2007 ; write to PPU
INX ; X = X + 1
CPX #$20 ; Compare X to hex $20, decimal 32 - copying 32 bytes = 4 sprites
BNE LoadPalettesLoop ; Branch to LoadPalettesLoop if compare was Not Equal to zero
; if compare was equal to 64, keep going down
LoadBackground:
LDA $2002 ; read PPU status to reset the high/low latch
LDA #$20
STA $2006 ; write the high byte ($20) of $2000 address
LDA #$00
STA $2006 ; write the low byte ($00) of $2000 address
LDX #$00 ; start out at 0
LoadBackgroundLoop:
LDA background, x ; load data from address (background + the value in x)
STA $2007 ; write to PPU
INX ; X++
BNE LoadBackgroundLoop ; Branch to LoadBackgroundLoop if compare was Not Equal to zero
; if compare was equal to 00, keep going down
LDX #$00 ; start out at 0
LoadBackgroundLoop2: ; Do this one more time for the next 256 bytes
LDA background+256, x
STA $2007
INX
BNE LoadBackgroundLoop2
LDX #$00
LoadBackgroundLoop3: ; Do this one more time for the next 256 bytes
LDA background+512, x
STA $2007
INX
BNE LoadBackgroundLoop3
LDX #$00
LoadBackgroundLoop4: ; Do this one more time for the next 256 bytes
LDA background+768, x
STA $2007
INX
BNE LoadBackgroundLoop4
LoadAttribute:
LDA $2002 ; read PPU status to reset the high/low latch
LDA #$23
STA $2006 ; write the high byte ($23) of $23C0 address
LDA #$C0
STA $2006 ; write the low byte ($C0) of $23C0 address
LDX #$00 ; start out at 0
LoadAttributeLoop:
LDA attribute, x ; load data from address (attribute + the value in x)
STA $2007 ; write to PPU
INX ; X = X + 1
CPX #$40 ; Compare X to hex $40, decimal 16*4 - copying 64 bytes
BNE LoadAttributeLoop ; Branch to LoadAttributeLoop if compare was Not Equal to zero
; if X was equal to 64, keep going down
LDA #%10010000 ; enable NMI, sprites from Pattern Table 0, background from Pattern Table 1
STA $2000
LDA #$00
STA $2005
LDA #$00
STA $2005
;;;;;;;;;;;;;; Here is our main loop. Beautiful.
Forever:
JMP Forever ;jump back to Forever, infinite loop
;;;;;;;;;;;;;; What to do in between frames?
NMI:
LDA #%10010000 ; enable NMI, sprites from Pattern Table 0, background from Pattern Table 1
STA $2000
LDA #%00011110 ; enable sprites, enable background, no clipping on left side
STA $2001
LDA #$00
STA $2003 ; set the low byte (00) of the RAM address
LDA #$02
STA $4014 ; set the high byte (02) of the RAM address, start the transfer
RTI ; return from interrupt
;;;;;;;;;;;;;; Setup nametables, attribute tables, palettes
.bank 3
.org $E000
palette:
.db $0F,$13,$23,$33, $0F,$44,$55,$66, $77,$88,$99,$AA, $0F,$78,$BD,$DE ;; background palette
.db $0F,$13,$23,$33, $0A,$44,$55,$66, $77,$88,$99,$AA, $0F,$78,$BD,$DE ;; sprite palette
background:
;; we put down 2 blank lines because NTSC is 240x224 instead of PALs 256x224
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0E,$0F
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $10,$11,$12,$13,$14,$15,$16,$17,$18,$19,$1A,$1B,$1C,$1D,$1E,$1F
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $20,$21,$22,$23,$24,$25,$26,$27,$28,$29,$2A,$2B,$2C,$2D,$2E,$2F
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $30,$31,$32,$33,$34,$35,$36,$37,$38,$39,$3A,$3B,$3C,$3D,$3E,$3F
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $40,$41,$42,$43,$44,$45,$46,$47,$48,$49,$4A,$4B,$4C,$4D,$4E,$4F
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $50,$51,$52,$53,$54,$55,$56,$57,$58,$59,$5A,$5B,$5C,$5D,$5E,$5F
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $60,$61,$62,$63,$64,$65,$66,$67,$68,$69,$6A,$6B,$6C,$6D,$6E,$6F
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $70,$71,$72,$73,$74,$75,$76,$77,$78,$79,$7A,$7B,$7C,$7D,$7E,$7F
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $70,$71,$72,$73,$74,$75,$76,$77,$78,$79,$7A,$7B,$7C,$7D,$7E,$7F
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $80,$81,$82,$83,$84,$85,$86,$87,$88,$89,$8A,$8B,$8C,$8D,$8E,$8F
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $90,$91,$92,$93,$94,$95,$96,$97,$98,$99,$9A,$9B,$9C,$9D,$9E,$9F
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $A0,$A1,$A2,$A3,$A4,$A5,$A6,$A7,$A8,$A9,$AA,$AB,$AC,$AD,$AE,$AF
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $B0,$B1,$B2,$B3,$B4,$B5,$B6,$B7,$B8,$B9,$BA,$BB,$BC,$BD,$BE,$BF
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $C0,$C1,$C2,$C3,$C4,$C5,$C6,$C7,$C8,$C9,$CA,$CB,$CC,$CD,$CE,$CF
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $D0,$D1,$D2,$D3,$D4,$D5,$D6,$D7,$D8,$D9,$DA,$DB,$DC,$DD,$DE,$DF
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $E0,$E1,$E2,$E3,$E4,$E5,$E6,$E7,$E8,$E9,$EA,$EB,$EC,$ED,$EE,$EF
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $F0,$F1,$F2,$F3,$F4,$F5,$F6,$F7,$F8,$F9,$FA,$FB,$FC,$FD,$FE,$FF
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
.db $00,$00,$00,$00,$00,$00,$00,$00
attribute: ; attribute table is $40
.db %00000000, %00000000, %00000000, %00000000, %00000000, %00000000, %00000000, %00000000
.db %00000000, %00000000, %00000000, %00000000, %00000000, %00000000, %00000000, %00000000
.db %00000000, %00000000, %00000000, %00000000, %00000000, %00000000, %00000000, %00000000
.db %00000000, %00000000, %00000000, %00000000, %00000000, %00000000, %00000000, %00000000
.db %00000000, %00000000, %00000000, %00000000, %00000000, %00000000, %00000000, %00000000
.db %00000000, %00000000, %00000000, %00000000, %00000000, %00000000, %00000000, %00000000
.db %00000000, %00000000, %00000000, %00000000, %00000000, %00000000, %00000000, %00000000
.db %00000000, %00000000, %00000000, %00000000, %00000000, %00000000, %00000000, %00000000
;;;;;;;;;;;;;; Set up interrupts
.org $FFFA ;first of the three vectors starts here
.dw NMI ;when an NMI happens (once per frame if enabled) jump to label NMI
.dw RESET ;when the processor first turns on or is reset, jump to label RESET
.dw 0 ;external interrupt IRQ is not used in this tutorial
;;;;;;;;;;;;;; Load graphics file to a new bank
.bank 4
.org $0000
.incbin "embassy.chr" ;includes 8KB graphics file
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