mirror of https://github.com/cc65/cc65.git
40 lines
1.2 KiB
PHP
40 lines
1.2 KiB
PHP
;-----------------------------------------------------------
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; Y2K FIX by Alan Davis, Dennis Debro, and Ronen Habot
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;-----------------------------------------------------------
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Y2K LDY #$00 ; Copy BIOS opening screen to RAM
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LDA #$FD
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STA TEMPH
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LDA #$58 ; Assume 2 port system
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LDX $FD32
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CPX #$E8 ; Is this a 4 port?
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BNE Y2K0 ; Jump if not
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LDA #$42 ; Yes, 4 port system
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Y2K0 STA TEMPL
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Y2K1 LDA (TEMPL),Y
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STA $0600,Y
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INY
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BNE Y2K1
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LDY #$50
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INC TEMPH
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Y2K2 LDA (TEMPL),Y
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STA $0700,Y
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DEY
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BPL Y2K2
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LDA #$D4 ; Point to copyright string
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STA $0724
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LDA #$BF
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STA $0725
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LDX #$0B ; Store NOP's @ end
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LDA #$EA
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Y2K3 STA $0732,X
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DEX
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BPL Y2K3
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LDA #$60 ; Store RTS opcode @ end
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STA $0750
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JSR $0600 ; Show title screen
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LDY #<$0600 ; Clear RAM from $0600-$3FFF
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STY $80
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LDA #>$0600
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STA $81
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JMP CLRRAM
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