diff --git a/applecorn.po b/applecorn.po
index 6a20974..c84f0d3 100644
Binary files a/applecorn.po and b/applecorn.po differ
diff --git a/auxmem.init.s b/auxmem.init.s
index c193116..3e43e3b 100644
--- a/auxmem.init.s
+++ b/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 2022-11-21'
+HELLO       ASC   'Applecorn MOS 2022-11-22'
             DB    $00             ; Unify MOS messages
 * TO DO: Move into RAM
 GSSPEED     DB    $00             ; $80 if GS is fast, $00 for slow
diff --git a/mainmem.audio.s b/mainmem.audio.s
index f2e2cca..26e59d0 100644
--- a/mainmem.audio.s
+++ b/mainmem.audio.s
@@ -510,6 +510,13 @@ CHECK4BYTES PHX
             RTS
 
 
+* Stop the sound device (no more interrupts)
+AUDIOSTOP   LDA  AUDIOCARD
+            BEQ  :MOCK
+            JMP  ENSQSTOP
+:MOCK       JMP  MOCKSTOP
+
+
 * Configure an oscillator to play a note
 * On entry: X - oscillator number 0-3 , A - frequency, Y - amplitude
 * Preserves all registers
@@ -525,8 +532,7 @@ AUDIONOTE   PHA
 * Adjust frequency of  oscillator
 * On entry: X - oscillator number 0-3 , Y - frequency to set
 * Preserves X & Y
-AUDIOFREQ
-            LDA   AUDIOCARD
+AUDIOFREQ   LDA   AUDIOCARD
             BEQ   :MOCK
             JMP  ENSQFREQ
 :MOCK       JMP  MOCKFREQ
@@ -535,8 +541,7 @@ AUDIOFREQ
 * Adjust amplitude of  oscillator
 * On entry: X - oscillator number 0-3 , Y - amplitude to set
 * Preserves X & Y
-AUDIOAMP
-            LDA   AUDIOCARD
+AUDIOAMP    LDA   AUDIOCARD
             BEQ   :MOCK
             JMP  ENSQAMP
 :MOCK       JMP  MOCKAMP
diff --git a/mainmem.ensq.s b/mainmem.ensq.s
index 197f8ba..c05b7a6 100644
--- a/mainmem.ensq.s
+++ b/mainmem.ensq.s
@@ -69,6 +69,14 @@ ENSQSILENT  LDY   #$00                      ; Amplitude
             RTS
 
 
+* Stop Ensoniq interrupt
+ENSQSTOP    JSR   ENSQSILENT
+            LDX   #$A4                      ; Control register for osc #4
+            LDY   #$00                      ; Free run, no IRQ, start
+            JSR   ENSQWRTDOC
+            RTS
+
+
 * Configure an Ensoniq oscillator to play a note
 * On entry: X - oscillator number 0-3 , A - frequency, Y - amplitude
 * Preserves all registers
diff --git a/mainmem.fsequ.s b/mainmem.fsequ.s
index c1c4f13..fd6595a 100644
--- a/mainmem.fsequ.s
+++ b/mainmem.fsequ.s
@@ -38,6 +38,7 @@ FBEND       EQU   FILEBLK+14  ; End address for SAVE
 
 * ProDOS MLI command numbers
 ALLOCCMD    EQU   $40
+DEALLOCCMD  EQU   $41
 QUITCMD     EQU   $65
 GTIMECMD    EQU   $82
 CREATCMD    EQU   $C0
diff --git a/mainmem.lists.s b/mainmem.lists.s
index c7a0b76..9156741 100644
--- a/mainmem.lists.s
+++ b/mainmem.lists.s
@@ -114,3 +114,6 @@ ALLOCPL     HEX   02          ; Number of parameters
             DB    $00         ; Interrupt number returned here
             DW    $0000       ; Pointer to ISR
 
+DEALLOCPL   HEX   01          ; Number of parameters
+            DB    $01         ; Interrupt number
+
diff --git a/mainmem.mock.s b/mainmem.mock.s
index 30cea38..3093b3a 100644
--- a/mainmem.mock.s
+++ b/mainmem.mock.s
@@ -71,9 +71,9 @@ MOCKINIT    LDA   #$FF                      ; All VIA pins output
             SEI
             LDA   #$40                      ; Configure VIA interrupt
             STA   MOCK_6522_ACR
-            LDA   #$7F
+            LDA   #$7F                      ; Clear all bits
             STA   MOCK_6522_IER
-            LDA   #$C0
+            LDA   #$C0                      ; Set bit 6
             STA   MOCK_6522_IFR
             STA   MOCK_6522_IER
             LDA   #$F4                      ; $27F4 => 100Hz
@@ -94,6 +94,18 @@ MOCKSILENT  LDX  #13                        ; Clear all 14 AY-3 regs
             RTS
 
 
+* Stop Mockingboard interrupt
+MOCKSTOP    JSR   MOCKSILENT
+            LDA   #$7F                      ; Clear all bits
+            STA   MOCK_6522_IER
+            LDA   ALLOCPL+1                 ; Interrupt number
+            STA   DEALLOCPL+1
+            JSR   MLI                       ; Deallocate ISR
+            DB    DEALLOCCMD
+            DW    DEALLOCPL
+            RTS
+
+
 * Configure a Mockingboard oscillator to play a note
 * On entry: X - oscillator number 0-3, A - frequency, Y - amplitude
 * Preserves all registers
diff --git a/mainmem.svc.s b/mainmem.svc.s
index efc2306..987e136 100644
--- a/mainmem.svc.s
+++ b/mainmem.svc.s
@@ -939,7 +939,8 @@ CHKNOTFND     CMP   #$44               ; Convert ProDOS 'not found'
 
 
 * Quit to ProDOS
-QUIT          INC   PWRDUP             ; Invalidate powerup byte
+QUIT          JSR   AUDIOSTOP          ; Shut down audio, dereg ISR
+              INC   PWRDUP             ; Invalidate powerup byte
               STA   PAGE1              ; PAGE2 off
               STA   CLRALTCHAR         ; Alt font off
               JSR   MLI