100 REM HEARTS DEMO 2
110 READ A: REM READ CALL ADDRESS
120 PRINT "READY FOR SOME HEARTS?"
130 GET K$:IF K$="" GOTO 130
140 FOR I=0 TO 4
150 POKE 255, 83:SYS A
160 FOR D=0 TO 300:NEXT D
170 POKE 255,211:SYS A
180 FOR D=0 TO 300:NEXT D
190 NEXT I
200 POKE 255,32:SYS A
210 PRINT "THIS WAS FUN!"
220 DATA {ASMSTART}

;routine to fill the screen with char in $ff
       lda $ff ;unused zeropage addr
       ldx #0
loop:  sta $8000,x
       sta $8100,x
       sta $8200,x
       sta $8300,x
       dex
       bne loop
       rts