Bug fix to Mockingboard ISR. Works now!

applecorn.s

@@ -85,6 +85,8 @@ CLR80VID    EQU   $C00C
 SET80VID    EQU   $C00D
 CLRALTCHAR  EQU   $C00E
 SETALTCHAR  EQU   $C00F
+RDRAMRD     EQU   $C013
+RDRAMWR     EQU   $C014
 
 KBDSTRB     EQU   $C010
 RDVBL       EQU   $C019

auxmem.init.s

@@ -290,7 +290,7 @@ BYTE00      BEQ   BYTE00A         ; OSBYTE 0,0 - generate error
             RTS                   ; %000x1xxx host type, 'A'pple
 BYTE00A     BRK
             DB    $F7
-HELLO       ASC   'Applecorn MOS 2022-11-09'
+HELLO       ASC   'Applecorn MOS 2022-11-20'
             DB    $00             ; Unify MOS messages
 * TO DO: Move into RAM
 GSSPEED     DB    $00             ; $80 if GS is fast, $00 for slow

auxmem.misc.s

@@ -380,12 +380,17 @@ GSBRKAUX    >>>   IENTAUX          ; IENTAUX does not do CLI
 IRQBRKHDLR  PHA
 * Mustn't enable IRQs within the IRQ handler
 * Do not use WRTMAIN/WRTAUX macros
+            LDA   RDRAMRD          ; Record softswitch state
+            STA   $90
+            LDA   RDRAMWR
+            STA   $91
+
             STA   WRMAINRAM        ; Write to main memory
             STA   $45              ; $45=A for ProDOS IRQ handlers
             STA   WRCARDRAM        ; Write to aux memory
+            STA   RDCARDRAM        ; Read from aux memory
 
-            TXA
-            PHA
+            PHX
             CLD
             TSX
             LDA   $103,X           ; Get PSW from stack
@@ -405,17 +410,31 @@ IRQBRKHDLR  PHA
             JSR   SERVICEX
             LDX   BYTEVARBASE+$FC  ; Get current language
             JSR   ROMSELECT        ; Bring it into memory
-            PLA
-            TAX
+            PLX
             PLA
             CLI
             JMP   (BRKV)           ; Pass on to BRK handler
 
-:IRQ        >>>   XF2MAIN,A2IRQ    ; Bounce to Apple IRQ handler
+:IRQ        PHY
+            >>>   XF2MAIN,A2IRQ    ; Bounce to Apple IRQ handler
 IRQBRKRET
             >>>   IENTAUX          ; IENTAUX does not do CLI
-            PLA                    ; TODO: Pass on to IRQ1V
-            TAX
+
+            PLY
+            LDA   $90              ; Restore state of RAMRD
+            BMI   :S1
+            STA   RDMAINRAM
+            BRA   :S2
+:S1         STA   RDCARDRAM
+
+:S2         LDA   $91              ; Restore state of RAMWRT
+            BMI   :S3
+            STA   WRMAINRAM
+            BRA   :S4
+:S3         STA   WRCARDRAM
+
+:S4                                ; TODO: Pass on to IRQ1V
+            PLX
             PLA
 NULLRTI     RTI