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23 lines
809 B
Plaintext
23 lines
809 B
Plaintext
;Atari 2600 Initialization Code - C02 Assembly Language File
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;Based on Batari Basic Initialization Code
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START: SEI ;Disable Interrupts
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CLD ;Disable Decimal Modes
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LDY #0 ;Set Y-Index to $00
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LDA $D0 ;If Location $D0
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CMP #$2C ; Does Not Contain $2C
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BNE IS2600 ;And
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LDA $D1 ; Location $D1
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CMP #$A9 ; Does Not Contain $D1
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BNE IS2600 ;Then
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DEY ; Set Y-Index to $FF
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IS2600: LDX #0 ;
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TXA ;
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CLRMEM: INX ;Clear TIA Registers and RAM
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TXS ; by Cycling Through All Stack Locations
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PHA ; and Pushing 0
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BNE CLRMEM ; which leaves Stack Pointer at $FF
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TYA ;Copy 2600 Flag to Accumulator
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JMP MAIN
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