northern_lights

; working title: sea changes near wallpaper city

        *= $801

        byte $0B, $08, $0A, $00, $9E, $34, $30, $39, $36, $00, $00, $00
chars
        byte 78, 77, 73, 75, 242, 66, 97, 72
txt
        byte 13, 5; color 
        text "E-SIRAMIS " ; 10b
        byte 31
        text "[KEY]"
        byte 154 ; reset to lt. blue

        * = $1000

; todo:
; cls + title

        ;lda #15; 15
        sta $d020
        sta $d021
        ldy #0
title
        lda txt,y
        jsr $ffd2
        cpy #20
        iny
        bne title
        
        lda #0    ; wait
        sta $c6
wait
        lda $c6
        beq wait
        jsr $e544 ; cls

loop
        lda #1; 1
        and $d012
offchar
        adc #78; 73,77
putchar 
        sta $0400
        inc putchar+1
        bne loop
        inc putchar+2
        ldy #8 ; end of screen mem
        cpy putchar+2
        bne loop
        lda #4 ; reset offset
        sta putchar+2
        ;
        ; todo: audio
        stx $d418        

pause   
        ;
        ; $d016 16/140 vs 140/16 ("diamonds")
        ;
        lda #140 ; 16, 31
        eor $d016    
        sta $d016
        ;
        ;
        lda #31 ; lda #140/16 <- glitch vs. asl
        eor $d016    
        sta $d016
        ;
        ; ~1 (~2) Hz screen update
        ;
        lda $a2
        and #63
        bne pause
        ;
        ; change pattern
        ;
        lda chars,x
        sta offchar+1
        inx
        txa
        and #7
        tax
        bne loop
        ;dec offchar+1 vs. lda chars,x sta offchar+1
        jmp loop