123456789101112131415161718192021222324 |
- *= $0801 "Basic Upstart"
- BasicUpstart(start) // 10 sys$0810
- *= $0810 "Program"
- start: ldx #$00
- stx $d020 // Border color register
- stx $d021 // Background color
- clear: lda #$20 // spacebar screen code
- sta $0400,x // fill four areas of screen with 256 spacebar characters
- sta $0500,x
- sta $0600,x
- sta $06e8,x
- lda #$00 // set foreground to black in Color Ram
- sta $d800,x
- sta $d900,x
- sta $da00,x
- sta $dae8,x
- inx
- bne clear // bne = branch on not equal
- // did x turn to zero already?
- // if yes -> stop loop
- // if no -> continue loop
- rts
|