!source "constants.s" !source "basic-boot.s" +start_at $0900 sei ; no interrupts pls ldx #$00 ; Screen colours stx bdcol ldx #$08 stx bgcol jsr $e544 ; clear screen lda #> message ; print message pha lda #< message pha jsr print_string pla pla ;ldx #$01 ; start triangle wave ;ldy #$11 ;stx ch1_freq_hi ;sty ch1_freq_lo ;ldx #$11 ;stx ch1_ctl .loop inc bdcol lda inputb ; Scans the keyboard buffer cmp #$EF ; If user presses Space ($ef) then quit bne .loop ldx #$08 ; kill sound stx ch1_ctl rts print_string: tsx inx inx inx lda stack, x sta PSL + 1 inx lda stack, x sta PSL + 2 ldx #$00 PSL lda message, x cmp #$0 ; return on null terminator beq + sta screen + rowlen, x inx jmp PSL + rts message !scr "welcome to scat os", 0