43 lines
898 B
Plaintext
43 lines
898 B
Plaintext
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include "cartheader.dasm"
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; program start
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Temp equ $03
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Start
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jsr $FF81 ; CINT (clear screen)
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sei ; turn off interrupts
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ldy #0
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sty $d020 ; reset border color
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Loop
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lda Message,y ; load message byte
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beq EOM ; 0 = end of string
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clc
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adc #$c0 ; + 192
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sta $400+41,y ; store to screen
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iny
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bne Loop ; next character
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EOM
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Wait1
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lda $d011
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bmi Wait1 ; wait for line < 256
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Wait2
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lda $d012 ; get current scanline
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Wait3
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cmp $d012
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beq Wait3 ; wait for scanline to change
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lsr
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lsr
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clc
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adc Temp
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sta $d020 ; set border color
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lda $d011 ; get status bits
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bpl Wait2 ; repeat until line >= 256
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sty $d020 ; reset border color
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dec Temp ; scroll colors
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jmp Wait1 ; endless loop
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Message
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; PETSCII - http://sta.c64.org/cbm64pet.html
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byte "HELLO`WORLDa"
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byte 0
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