32 lines
770 B
NASM
32 lines
770 B
NASM
;;
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;; Output the string 'Hello, World!'
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;;
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.alias iobase $8800
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.alias iostatus [iobase + 1]
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.alias iocmd [iobase + 2]
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.alias ioctrl [iobase + 3]
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.org $0300
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start: cli
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lda #$0b
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sta iocmd ; Set command status
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lda #$1a
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sta ioctrl ; 0 stop bits, 8 bit word, 2400 baud
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init: ldx #$00 ; Initialize index
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loop: lda iostatus
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and #$10 ; Is the tx register empty?
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beq loop ; No, wait for it to empty
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lda string,x ; Otherwise, load the string pointer
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beq init ; If the char is 0, re-init
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sta iobase ; Otherwise, transmit
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inx ; Increment string pointer.
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jmp loop ; Repeat write.
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string: .byte "Hello, 6502 world! ", 0
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