optcompo

optcompo38.s

; Build _without_ BASIC header
;
        * = $2e0
start:
        lda #$92
next_basic_line:
next_char:
        ldx #$A0
adr:    stx $7c0
adr2:   stx $7c0+39
        inc adr + 1
        dec adr2 + 1
        dec 213
stop:   bmi stop

roller: 
        sec 
        tax
        bmi skip
        asl $d020-$49,x
        jsr $e8ec 
        clc 
skip:
        rol 
        bne next_char
        .word start

optcompo43.s

; Build _without_ BASIC header
;
        * = $801
        .word next_basic_line
        lda #$92
        .byte $9e
next_basic_line:
        .byte "2049"
next_char:
        ldx #$A0
adr:    stx $7c0
adr2:   stx $7c0+39
        inc adr + 1
        dec adr2 + 1
        dec 213
stop:   bmi stop

roller:
        sec
        tax
        bmi skip
        asl $d020-$49,x
        jsr $e8ec
        clc
skip:
        rol
        bne next_char

optcompo53.s

; Build with standard basic header
;
        sta $d020
        sta $d021
next_char:
        lda #$A0
adr:    sta $7c0
adr2:   sta $7c0+39

        inc adr + 1
        dec adr2 + 1
        dec 213
stop:   bmi stop

        lda roller
        rol

        rol roller
        bcc next_char
        jsr $e8ea
        beq next_char

roller: .byte %01101101

optcompo71.s

; Build with standard basic header
;
ptr = 251
roller = 253
yreg1 = 254
yreg2 = 255
xreg = 250

        sta $d020
        sta $d021
        sta yreg1
        lda #<$7c0
        sta ptr
        lda #>$7c0
        sta ptr + 1

        ldx #40
        stx xreg
        dex
        stx yreg2
        lda #$6d
        sta roller
next_char:
        lda #$A0
        ldy yreg1
        sta (ptr),y
        ldy yreg2
        sta (ptr),y
        dec xreg
stop:   beq stop

        inc yreg1
        dec yreg2

        lda roller
        rol
        rol roller
        bcc next_char
        jsr $e8ea
        beq next_char

optcompo75.s

; Build with standard basic header
;
ptr = 200
roller = 202

        jsr $e544
        ldx #0
        ldy #0
restart:
        stx $d020
        stx $d021
        stx ptr
        lda #>$400
        sta ptr + 1

        ldx #40
        lda #$6d
        sta roller
next_char:
        lda #$A0
        sta (ptr),y
        dex
stop:   bne go_on

        lda #$88    ; DEY
        sta opcode
        ldy #39
        bne restart
go_on:
opcode: iny
        lda roller
        rol
        rol roller
        bcc next_char
        lda ptr
        adc #39
        sta ptr
        bcc next_char
        inc ptr + 1
        bne next_char