Embedded Files
;;--- CODE START ---;;
.inesprg 1
.inesmap 0
.inesmir 1
.ineschr 1
.bank 1
.org $FFFA
.dw 0 ; no VBlank
.dw Start ; address to execute on reset
.dw 0 ; no whatever
.bank 0
.org $0000
X_Pos .db 20 ; a X position for our sprite, start at 20
Y_Pos .db 20 ; a Y position for our sprite, start at 20
.org $8000 ; code starts at $8000 or $C000
Start:
lda #%00001000 ;
sta $2000 ;
lda #%00011110 ; Our typical PPU Setup code.
sta $2001 ;
ldx #$00 ; clear X ;; start of pallete loading code
lda #$3F ; have $2006 tell
sta $2006 ; $2007 to start
lda #$00 ; at $3F00 (pallete).
sta $2006
loadpal: ; this is a freaky loop
lda tilepal, x ; that gives 32 numbers
sta $2007 ; to $2007, ending when
inx ; X is 32, meaning we
cpx #32 ; are done.
bne loadpal ; if X isn't =32, goto "loadpal:" line.
;; end of pallete loading code
infinite: ; a label to start our infinite loop
waitblank:
lda $2002 ; these 3 lines wait for VBlank, this loop will actually miss VBlank
bpl waitblank ; alot, in a later Day, I'll give a better way.
lda #$00 ; these lines tell $2003
sta $2003 ; to tell
lda #$00 ; $2004 to start
sta $2003 ; at $0000.
;sprite 1
lda Y_Pos ; 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 X_Pos ; load X value
sta $2004 ; store X value
; and yes, it MUST go in that order.
;sprite2
lda Y_Pos ; load Y value
sta $2004 ; store Y value
lda #$01 ; tile number 1
sta $2004 ; store tile number
lda #$00 ; no special junk
sta $2004 ; store special junk
lda X_Pos ; load X value
adc #$7
sta $2004 ; store X value
; and yes, it MUST go in that order.
;sprite3
lda Y_Pos ; load Y value
adc #$7
sta $2004 ; store Y value
lda #16 ; tile number 1
sta $2004 ; store tile number
lda #$00 ; no special junk
sta $2004 ; store special junk
lda X_Pos ; load X value
sta $2004 ; store X value
; and yes, it MUST go in that order.
;sprite4
lda Y_Pos ; load Y value
adc #$7
sta $2004 ; store Y value
lda #17 ; tile number 1
sta $2004 ; store tile number
lda #$00 ; no special junk
sta $2004 ; store special junk
lda X_Pos ; load X value
adc #$7
sta $2004 ; store X value
; and yes, it MUST go in that order.
lda #$01 ; these
sta $4016 ; lines
lda #$00 ; setup/strobe the
sta $4016 ; keypad.
lda $4016 ; load Abutton Status ; note that whatever we ain't interested
lda $4016 ; load Bbutton Status ; in we just load so it'll go to the next one.
lda $4016 ; load Select button status
lda $4016 ; load Start button status
lda $4016 ; load UP button status
and #1 ; AND status with #1
bne UPKEYdown ; for some reason (not gonna reveal yet), need to use NotEquals
;with ANDs. So it'll jump (branch) if key was down.
lda $4016 ; load DOWN button status
and #1 ; AND status with #1
bne DOWNKEYdown
lda $4016 ; load LEFT button status
and #1 ; AND status with #1
bne LEFTKEYdown
lda $4016 ; load RIGHT button status
and #1 ; AND status with #1
bne RIGHTKEYdown
jmp NOTHINGdown ; if nothing was down, we just jump (no check for conditions)
; down past the rest of everything.
UPKEYdown:
lda Y_Pos ; load A with Y position
sbc #1 ; subtract 1 from A. Only can do math on A register. SBC (Subtract with Borrow)
sta Y_Pos ; store back to memory
jmp NOTHINGdown ; jump over the rest of the handling code.
DOWNKEYdown:
lda Y_Pos
adc #1 ; add 1 to A. ADC (Add with Carry)((to A register))
sta Y_Pos
jmp NOTHINGdown ; jump over the rest of handling code.
LEFTKEYdown:
lda X_Pos
sbc #1
sta X_Pos
jmp NOTHINGdown
;the left and right handling code does the same as UP and Down except.. well.. with
; left and right. :)
RIGHTKEYdown:
lda X_Pos
adc #1
sta X_Pos
; don't need to jump to NOTHINGdown, it's right below. Saved several bytes of
; PRG-Bank space! :)
NOTHINGdown:
jmp infinite
tilepal: .incbin "our.pal" ; a label for our pallete data
.bank 2
.org $0000
.incbin "sprite.bkg"
.incbin "sprite.spr"
;;--- END OF CODE FILE ---;;
WhatsApp Video 2022-08-28 at 8.54.52 AM.mp4Page updated
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