Joe,

This is a primitive disassembly of the ROM 03 interrupt handler
firmware.  You need to fix this up to look like the ROM 01 version
I have in SIM.ASM.

MasterIntHandler clc                    (E1/0010 JMPs here, FF/BC6C)
         xce
         LONG  I,M
         php
         phb
         Assume B=00E1
         pea   $E1E1
         plb
         sta   |ASave                   ($108)
         lda   SHADOW                   shadow register
         sta   |ShadSave                ($119)
         ora   #$8000
         and   #$9F3E
         sta   SHADOW                   shadow register
         stx   |XSave                   ($10a)
         sty   |YSave                   ($10c)
         tdc
         sta   |DPSave                  ($110)
         lda   #$0000
         tcd
         SHORT I,M
         bcc   NotSure                  ; check emulation mode
         lda   $04,s
         and   #$10
         adc   #$70
NotSure  bvs   hmm2
         lda   #$03
         sta   SCCAREG                  SCC channel A cmd register
         lda   SCCAREG                  SCC channel A cmd register
         bit   |ATlkFlag
         beq   SerInt2
         pha
         and   #$07
         bne   ChanB
         lda   SCCADATA                 SCC channel A data register
         sta   |SerIntData
         lda   SCCADATA                 SCC channel A data register
         sta   |SerIntData+1
         jsl   >IRQ_ATalk
         bra   Next
ChanB    lda   SCCBDATA                 SCC channel B data register
         sta   |SerIntData
         lda   SCCBDATA                 SCC channel B data register
         sta   |SerIntData+1
         jsl   >IRQ_ATalk
Next     lda   >$010101
         sta   |EmulStakSave
         lda   #$00
         ror   a
         sta   |$E10101
         pla
         bra   Next2
SerInt2  pha
         lda   >$010101
         sta   |EmulStakSave
         stz   |$E10101
         jsl   >$E1021C                 MIDI?
         pla
         bcc   $BD0C
         clc
Next2    pha
         and   |SerFlag
         beq   NoSerial
         jsl   >IRQ_Serial
         ror   |$E10101
         pla
         lda   |$E10101
         bne   NoMoreSer
         LONG  I,M
         plb
         jmp   Exit
NoSerial pla
         bne   $BD07
NoMoreSer clv
hmm2     lda   >$010101
         sta   |EmulStakSave
         LONG  I,M
         ....