71 lines
2.3 KiB
ArmAsm
71 lines
2.3 KiB
ArmAsm
TTL 'lang. cd. irq, nmi, & reset'
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***********************************************************
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* This code is used when an IRQ happens while the RAM
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* at $D000-$FFFF is switched on (inside an MLI
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* call, for example) if we have the "new style"
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* monitor ROMs
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ORG $FF9B
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LanIrq PHA
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LDA Acc ;Save ($45)
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STA old45 ;Now put A-reg into loc $45
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PLA
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STA Acc
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PLA ;Get status register from stack
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PHA ; (and restore it!)
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AND #$10 ;Is it a break or interupt
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BNE lBreak ;Branch if break
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LDA $D000 ;Get bankID
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EOR #$D8 ;Is the system active? (CLD)
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BEQ SysActv ;Branch if it is
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LDA #$FF ;In $D000 bank 2
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SysActv STA IntBankID ;Update bank ID (=$00/$FF)
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STA afBank
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LDA #>aftIrq ;Push fake "RTI" vector
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PHA ; with IRQ disabled
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LDA #<aftIrq ;Set up return address
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PHA
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LDA #$04 ;Status reg w/int flag set
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PHA
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lBreak LDA #>ROMIrq ;Push ROM entry also
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PHA
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LDA #<ROMIrq
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PHA
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GoROM STA RDROM2 ;Switch to ROM (hits RTS immediately)
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lReset LDA rReset+1
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PHA ;Since reset, Acc can be destroyed
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LDA rReset
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PHA
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JMP GoROM
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rReset DA $FA62-1 ;Monitor reset-1
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*-------------------------------------------------
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fix45 STA IntAReg ;Preserve the Acc
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LDA old45
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STA Acc
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LDA LCBANK1
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LDA LCBANK1 ;Switch RAM in for write & read
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LDA afBank
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JMP IrqXit0
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* (Y)=0
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ZeroPfxPtrs STY NewPfxPtr ;Fix AppleTalk PFI bug
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STY PfixPtr ;Flag not an active prefix
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RTS
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*(A)=flag
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SetPfxPtrs STA NewPfxPtr
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STA PfixPtr
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RTS
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DA NMI
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DA lReset
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IrqVect DA LanIrq
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