A C64 example in assembly that moves a sprite up/down/left/right

MoveSprite.asm

;*************************************************
;* Create and move a simple sprite x,y           *
;*************************************************

		processor 6502
		org $1000
		
;helpful labels
CLEAR = $E544
GETIN  =  $FFE4
SCNKEY =  $FF9F

ENTER	= $C202
MOVE	= $C203
;sprite 0 setup
SPRITE0 = $7F8
COLOR0  = $D027
SP0X	= $D000
SP0Y	= $D001
MSBX	= $D010
SP0VAL	= $0340

ENABLE  = $D015
YEXPAND	= $D017
XEXPAND	= $D01D
		
		JSR CLEAR
		
		LDA #13
		STA ENTER
		
		LDA #$0D	;using block 13 for sprite0
		STA SPRITE0
		
		LDA #01		;enable sprite0
		STA ENABLE
		
		LDA #02		;use red for sprite0
		STA COLOR0
		
		LDX #0
		LDA #0
		
		;reset the spriteval data
CLEANUP	        STA SP0VAL,X
		INX
		CPX #63
		BNE CLEANUP
		
		;build the sprite
		LDX #0
BUILD	        LDA DATA,X
		STA SP0VAL,X
		INX
		CPX #63
		BNE BUILD
		
		;position
		LDA #0		;stick with x0-255
		STA MSBX
		
		;starting sprite location
		LDX #100
		LDY #70
		STX SP0X
		STY SP0Y
		
SCAN	        JSR SCNKEY	;get key
		JSR GETIN	;put key in A

START	        CMP #87		;W - up
		BEQ UP
		
		CMP #83		;S - down
		BEQ DOWN
		
		CMP #65		;A - left
		BEQ LEFT
		
		CMP #68		;D - right
		BEQ RIGHT
		
		CMP ENTER	;end if enter clicked
		BEQ END
		
		JMP SCAN
		
UP		LDY SP0Y
		DEY
		STY SP0Y
		JMP SCAN

DOWN	        LDY SP0Y
		INY
		STY SP0Y
		JMP SCAN

LEFT	        LDX SP0X
		DEX
		STX SP0X
		CPX #255
		BNE SCAN
		LDA #0
		STA MSBX
		JMP SCAN

RIGHT	        LDX SP0X
		INX
		STX SP0X
		CPX #255
		BNE SCAN
		LDA #1
		STA MSBX
		JMP SCAN

		;clean up at the end
END		JSR CLEAR
		LDA #0
		STA ENABLE
		RTS
		
		;define the sprite
DATA 	        .BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.BYTE 255,255,255
		.END