A2osX/ProDOS.FX/ProDOS.S.IRQ.txt
2019-10-19 20:35:30 +02:00

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NEW
AUTO 3,1
*--------------------------------------
* this routine handles interrupts and is coded to reach 'lreset' precisely at
* address $FFCB (ROM rts opcode) for rom switching to function.
* $2D9B-2DFF moved to $FF9B-FFFF
*--------------------------------------
OLDROM.IRQV
* pha
* lda accsav
* sta oldacc
* pla
* sta accsav
* pla get status register from stack
* pha and put it back.
* and #$10 is it a break or interrupt?
* bne H2DC2 branch if break.
* lda $D000 get ram bankid (LC1 = $D8, LC2=$EE)
* eor #$D8 is the system active? ($D8)
* beq sysactv branch if it is
* lda #$FF
*sysactv sta bankid
* sta afbank
* lda /aftirq setup return address
* pha
* lda #aftirq
* pha
* lda #$04 status reg with interrupt flag set
* pha
*H2DC2 lda /romirq setup ROM re-entry
* pha
* lda #romirq
* pha
.LIST ON
IRQ.FREE1 .EQ $ffc8-*
.LIST OFF
.BS IRQ.FREE1
gorom sta RROMBNK2 hits ROM rts at $FFCB
* 'lreset' address must = $FFCB for rom switch i/o to work
lreset lda /resetv-1
pha
lda #resetv-1
pha
jmp gorom
*rreset .DA resetv-1 rts to resetv
*fix45 sta p8areg A register savearea
* lda oldacc
* sta accsav
* lda RRAMWRAMBNK1 read/write RAM bank 1
* lda RRAMWRAMBNK1
* lda afbank
* jmp irqxit0
stypfx sty newpfxptr fix appletalk PFI bug
sty preflag prefix flag
rts
stapfx sta newpfxptr
sta preflag
rts
.LIST ON
IRQ.FREE2 .EQ $fffa-*
.LIST OFF
.BS IRQ.FREE2
.DA nmivect nmi handler
.DA lreset reset handler
irqv .DA * PATCHED with ROM vector by LDR
.LIST OFF
*--------------------------------------
MAN
SAVE USR/SRC/PRODOS.FX/PRODOS.S.IRQ
LOAD USR/SRC/PRODOS.FX/PRODOS.S
ASM