diff --git a/applecorn.po b/applecorn.po
index 1570116..b72f590 100644
Binary files a/applecorn.po and b/applecorn.po differ
diff --git a/mainmem.audio.s b/mainmem.audio.s
index d52f845..b2592e9 100644
--- a/mainmem.audio.s
+++ b/mainmem.audio.s
@@ -444,7 +444,7 @@ AUDIOISR    INC   SYSCLOCK+0                ; Increment system clock
             PLA                             ; Recover frequency
             STA   CURRPITCH,X               ; Store for pitch envelope
             PLY                             ; Recover amplitude
-            JSR   ENSQNOTE                  ; Start note playing
+            JSR   AUDIONOTE                 ; Start note playing
 :NEXT 	    DEX
             BPL   :L1                       ; Next audio queue
 
@@ -459,7 +459,7 @@ AUDIOISR    INC   SYSCLOCK+0                ; Increment system clock
 :NOENV      DEX
             BPL   :L2                       ; Next audio queue
             CLC
-            RTL
+            RTS
 :HOLDSET    JSR   REMAUDIO                  ; Dequeue amplitude/env (ignored)
             JSR   REMAUDIO                  ; Dequeue frequency (ignored)
             JSR   REMAUDIO                  ; Dequeue duration
@@ -471,7 +471,7 @@ AUDIOISR    INC   SYSCLOCK+0                ; Increment system clock
 :CNT        DB    $05                       ; Used to determine 20Hz cycles
 
 
-* Helper function for ENSQISR - called when no note playing
+* Helper function for AUDIOISR - called when no note playing
 * On entry: X is audio channel #
 NONOTE      LDA   CHANENV,X                 ; See if envelope is in effect
             CMP   #$FF
@@ -479,14 +479,14 @@ NONOTE      LDA   CHANENV,X                 ; See if envelope is in effect
             STZ   CURRAMP,X                 ; Next env will start at zero vol
             LDY   #$00                      ; Zero volume
             LDA   #$00                      ; Zero freq
-            JSR   ENSQNOTE                  ; Silence channel Y
+            JSR   AUDIONOTE                 ; Silence channel Y
             RTS
 :RELEASE    LDA   #3                        ; Phase 3 is release phase
             STA   AMPSECT,X                 ; Force release phase
             RTS
 
 
-* Helper function for ENSQISR
+* Helper function for AUDIOISR
 * On entry: X is audio channel #
 * On return: CS if there are <= 4 bytes in queue, CC otherwise
 * X is preserved
@@ -508,6 +508,30 @@ CHECK4BYTES PHX
             RTS
 
 
+* Configure an oscillator to play a note
+* On entry: X - oscillator number 0-3 , A - frequency, Y - amplitude
+* Preserves all registers
+AUDIONOTE
+            JMP  ENSQNOTE
+*            JMP  MOCKNOTE
+
+
+* Adjust frequency of  oscillator
+* On entry: X - oscillator number 0-3 , Y - frequency to set
+* Preserves X & Y
+AUDIOFREQ
+            JMP  ENSQFREQ
+*            JMP  MOCKFREQ
+
+
+* Adjust amplitude of  oscillator
+* On entry: X - oscillator number 0-3 , Y - amplitude to set
+* Preserves X & Y
+AUDIOAMP
+            JMP  ENSQAMP
+*            JMP  MOCKAMP
+
+
 * Handle envelope tick counter
 * On entry: X is audio channel #
 * On return: CS if this cycle is an envelope tick, CC otherwise.
@@ -618,7 +642,7 @@ UPDPITCH    STX   OSCNUM
             ADC   CURRPITCH,X               ; Add change to current
             STA   CURRPITCH,X               ; Update
             TAY
-            JSR   ENSQFREQ                  ; Update Ensoniq regs
+            JSR   AUDIOFREQ                 ; Update Ensoniq regs
             RTS
 
 
@@ -706,7 +730,7 @@ ADSRPHASE   STX   OSCNUM
 :CLAMP      LDA   :TARGET                   ; Recover target level
 :UPDATE     STA   CURRAMP,X                 ; Store updated amplitude
             TAY                             ; Tell the Ensoniq
-            JSR   ENSQAMP
+            JSR   AUDIOAMP
 :DONE       CLC                             ; CC to indicate phase continues
             RTS
 :TARGET     DB    $00
diff --git a/mainmem.ensq.s b/mainmem.ensq.s
index cb1407f..0ee9fbb 100644
--- a/mainmem.ensq.s
+++ b/mainmem.ensq.s
@@ -156,7 +156,8 @@ ENSQAMP     PHX
 
 * Ensoniq interrupt service routine - just calls generic audio ISR
 ENSQISR     CLD
-            JMP   AUDIOISR
+            JSR   AUDIOISR
+            RTL
 
 
 **
diff --git a/mainmem.init.s b/mainmem.init.s
index 15dfe40..d43ea49 100644
--- a/mainmem.init.s
+++ b/mainmem.init.s
@@ -37,5 +37,7 @@ RESETHW      SEC
              JSR   IDROUTINE         ; See if this is a GS
              BCS   :NOTGS
              JSR   ENSQINIT          ; Initialize Ensoniq
-:NOTGS       RTS
+:NOTGS
+*             JSR   MOCKINIT          ; Initialize Mockingboard (sl4)
+             RTS
 
diff --git a/mainmem.mock.s b/mainmem.mock.s
index dbc10ac..e922366 100644
--- a/mainmem.mock.s
+++ b/mainmem.mock.s
@@ -130,7 +130,11 @@ MOCKAMP     PHX
 
 * Mockingboard interrupt service routine - just calls generic audio ISR
 MOCKISR     CLD
-            JMP   AUDIOISR
+* TODO: Check whether interrupt is from Mockingboard or not
+            BIT    MOCK_6522_T1CL          ; Clear interrupt
+*            JSR   AUDIOISR
+            CLC                            ; CC indicates we serviced irq
+            RTS
 
 
 **