diff --git a/mocktest/speech.h b/mocktest/speech.h
index 4bc798e..d9d1263 100644
--- a/mocktest/speech.h
+++ b/mocktest/speech.h
@@ -13,10 +13,9 @@
 extern uint8_t *speechData;
 extern uint16_t speechLen;
 extern uint8_t speechBusy;
-extern uint16_t outptr;
-extern uint16_t endptr;
 
 extern void setupSpeech(void);
+extern void unsetupSpeech(void);
 
 
 #endif /* speech_h */
diff --git a/mocktest/speech.s b/mocktest/speech.s
index a8b388e..341ad82 100644
--- a/mocktest/speech.s
+++ b/mocktest/speech.s
@@ -7,139 +7,169 @@
 ;
 
 
-    .export _setupSpeech, _speechData, _speechLen, _speechBusy
-    .export _outptr, _endptr
-;    .interruptor speechIRQ
+    .export _setupSpeech, _unsetupSpeech
+    .export _speechData, _speechLen, _speechBusy
 
 
-OUTPTR  := $FB           ;START OF DATA POINTER
-IRQL    := $03FE         ;INTERRUPT VECTOR, LOW BYTE
-IRQH    := $03FF         ;INTERRUPT VECTOR, HIGH BYTE
-BASE    := $C440         ;FIRST SPEECH CHIP
-DURPHON := BASE          ;REGISTER 0 OF SPEECH CHIP
-INFLECT := BASE+$01      ;REGISTER 1 OF SPEECH CHIP
-RATEINF := BASE+$02      ;REGISTER 2 OF SPEECH CHIP
-CTTRAMP := BASE+$03      ;REGISTER 3 OF SPEECH CHIP
-FILFREQ := BASE+$04      ;REGISTER 4 OF SPEECH CHIP
+TMPPTR  := $FB           ; Temporary pointer used in interrupt handler
+IRQL    := $03FE         ; Interrupt vector, low byte
+IRQH    := $03FF         ; Interrupt vector, high byte
+BASE    := $C440         ; First speech chip
+DURPHON := BASE          ; Register 0 of speech chip
+INFLECT := BASE+$01      ; Register 1 of speech chip
+RATEINF := BASE+$02      ; Register 2 of speech chip
+CTTRAMP := BASE+$03      ; Register 3 of speech chip
+FILFREQ := BASE+$04      ; Register 4 of speech chip
 DDRB    := $C402
 DDRA    := $C403
-PCR     := $C48C         ;PERIPHERAL CONTROL REG-6522
-IFR     := $C48D         ;INTERRUPT FLAG REG-6522
+PCR     := $C48C         ; Peripheral control register, 6522
+IFR     := $C48D         ; Interrupt flag register, 6522
 IER     := $C48E
 
 
 .DATA
-speechIRQ:      .byte   $60, <_interr, >_interr   ; RTS plus two dummy bytes
 _speechData:    .byte   $00, $00
 _speechLen:     .byte   $00, $00
 _outptr:        .byte   $00, $00
 _endptr:        .byte   $00, $00
 _speechBusy:    .byte   $00
+_irqLandingPad: .byte   $4C, $00, $00
 
 
 .CODE
 
 .proc _setupSpeech
-    SEI             ;DISABLE INTERRUPTS
-    LDA #<_interr   ;SET INTERRUPT VECTOR
-    STA IRQL        ;TO POINT TO INTERRUPT
-    LDA #>_interr   ;SERVICE ROUTINE
-    STA IRQH
-;    LDA #$4C        ; JMP opcode
-;    STA speechIRQ
-    LDA #$00
-    STA DDRA
-    STA DDRB
+    sei                 ; Disable interrupts
 
-    LDA _speechData+1   ;GET HIGH ADDRESS OF DATA
-    STA OUTPTR+1        ;STORE IN WORK POINTER
-    LDA _speechData     ;GET LOW ADDRESS OF DATA
-    STA OUTPTR          ;STORE LOW BYTE
+    lda IRQL            ; Store the old interrupt vector
+    sta _irqLandingPad+1
+    lda IRQH
+    sta _irqLandingPad+2
 
-    LDA _speechLen+1    ;GET HIGH LENGTH BYTE
-    CLC
-    ADC _speechData+1   ;AND ADD TO BASE ADDRESS
-    STA _endptr+1       ;STORE END ADDRESS
-    LDA _speechLen      ;GET LOW LENGTH BYTE
-    CLC
-    ADC _speechData     ;AND ADD TO BASE ADDRESS
-    BCC @L2             ;CHECK FOR PAGE BOUNDARY
-    INC _endptr+1
+    lda #<_interr       ; Set interrupt vector
+    sta IRQL            ; to point to interrupt
+    lda #>_interr       ; service routine
+    sta IRQH
+    lda #$00
+    sta DDRA
+    sta DDRB
+
+    lda _speechData+1   ; Get high address of data
+    sta _outptr+1       ; Store in work pointer
+    lda _speechData     ; Get low address of data
+    sta _outptr         ; Store low byte
+
+    lda _speechLen+1    ; Get high length byte
+    clc
+    adc _speechData+1   ; And add to base address
+    sta _endptr+1       ; Store end address
+    lda _speechLen      ; Get low length byte
+    clc
+    adc _speechData     ; And add to base address
+    bcc @L2             ; Check for page boundary
+    inc _endptr+1
 @L2:
-    STA _endptr         ;STORE END ADDRESS
+    sta _endptr         ; Store end address
 
-    LDA #$FF            ;SET BUSY FLAG
-    STA _speechBusy     ;AND SET PERIPHERAL CONTROL
-    LDA #$0C            ;REGISTER TO RECOGNIZE
-    STA PCR             ;SIGNAL FROM SPEECH CHIP
-    LDA #$80            ;RAISE CTRL BIT IN REGISTER 3
-    STA CTTRAMP
-    LDA #$C0            ;SET TRANSITIONED INFLECTION
-    STA DURPHON         ;MODE IN REGISTER 0
-    LDA #$70            ;LOWER CTRL BIT
-    STA CTTRAMP
-    LDA #$82            ;ENABLE 6522 INTERRUPTS
-    STA IER
-    CLI                 ;CLEAR INTERRUPT MASK
-    RTS                 ;RETURN TO CALLER
+    lda #$FF            ; Set busy flag
+    sta _speechBusy     ; And set peripheral control
+    lda #$0C            ; Register to recognize
+    sta PCR             ; Signal from speech chip
+    lda #$80            ; Raise control bit in register 3
+    sta CTTRAMP
+    lda #$C0            ; Set transitioned inflection
+    sta DURPHON         ; Mode in register 0
+    lda #$70            ; Lower control bit
+    sta CTTRAMP
+    lda #$82            ; Enable 6522 interrupts
+    sta IER
+    cli                 ; Clear interrupt mask
+    rts                 ; Return to caller
+.endproc
+
+
+.proc _unsetupSpeech
+    sei                 ; Restore the old interrupt vector
+    lda _irqLandingPad+1
+    sta IRQL
+    lda _irqLandingPad+2
+    sta IRQH
+    cli
+    rts
 .endproc
 
 
 .proc _interr
-    PHA
-    TXA             ;SAVE REGISTERS
-    PHA
-    TYA
-    PHA
-    LDA IFR
-    BPL @L2
-    LDA #$02        ;CLEAR INTERRUPT FLAG
-    STA IFR
-    LDY #$00        ;INIT REGISTERS
-    LDX #$04
-    LDA OUTPTR+1
-    CMP _endptr+1
-    BCC @L1
-    BNE @L5
-    LDA OUTPTR      ;CHECK FOR END OF DATA FILE
-    CMP _endptr
-    BCC @L1         ;IF NOT THEN CONTINUE
+    pha                 ; Save accumulator
+    lda IFR
+    bmi @L4             ; If we have 6522 interrupt jump to L4
+    pla                 ; Otherwise restore the accumulator
+    jmp _irqLandingPad  ; And jump to the old interrupt handler
+@L4:
+    txa                 ; Save other registers
+    pha
+    tya
+    pha
+    lda #$02            ; Clear interrupt flag
+    sta IFR
+    ldy #$00            ; Init registers
+    ldx #$04
+    lda _outptr+1
+    cmp _endptr+1
+    bcc @L1
+    bne @L5
+    lda _outptr         ; Check for end of data file
+    cmp _endptr
+    bcc @L1             ; If not, then continue
 @L5:
-    LDA #$00        ;IF END, TURN EVERYTHING OFF
-    STA DURPHON     ;STORE PAUSE PHONEME
-    LDA #$70        ;ZERO AMPLITUDE
-    STA CTTRAMP
-    LDA #$00        ;CLEAR BUSY FLAG
-    STA _speechBusy
-    LDA #$02        ;CLEAR INTERRUPT ENABLE
-    STA IER         ;IN 6522
-    LDA #$FF
-    STA DDRA
-    LDA #$07
-    STA DDRB
+    lda #$00            ; If end, turn everything off
+    sta DURPHON         ; Store pause phoneme
+    lda #$70            ; Zero amplitude
+    sta CTTRAMP
+    lda #$00            ; Clear busy flag
+    sta _speechBusy
+    lda #$02            ; Clear interrupt enable
+    sta IER             ; In 6522
+    lda #$FF
+    sta DDRA
+    lda #$07
+    sta DDRB
 @L2:
-    LDA OUTPTR
-    STA _outptr
-    LDA OUTPTR+1
-    STA _outptr+1
-    PLA             ;RESTORE REGISTERS
-    TAY
-    PLA
-    TAX
-    PLA
-    RTI             ;RETURN FROM INTERRUPT
+    pla                 ; Restore registers
+    tay
+    pla
+    tax
+    pla
+    rti                 ; Return from interrupt
 
 @L1:
-    LDA (OUTPTR),Y  ;GET DATA
-    STA BASE,X      ;STORE IN SPEECH CHIP
-    INC OUTPTR      ;NEXT DATA
-    BNE @L3
-    INC OUTPTR+1
+    lda TMPPTR          ; Save the value in the tmp pointer
+    pha
+    lda TMPPTR+1
+    pha
+    lda _outptr         ; Move the _outptr into the tmp pointer
+    sta TMPPTR
+    lda _outptr+1
+    sta TMPPTR+1
+@L6:
+    lda (TMPPTR),Y      ; Get data
+    sta BASE,X          ; Store in speech chip
+    inc TMPPTR          ; Next data
+    bne @L3
+    inc TMPPTR+1
 
 @L3:
-    DEX             ;NEXT REGISTER
-    CPX #$FF        ;LAST REGISTER?
-    BNE @L1         ;NO, CONTINUE
-    BEQ @L2         ;YES, RETURN
+    dex                 ; Next register
+    cpx #$FF            ; Last register?
+    bne @L6             ; No, then continue
+    lda TMPPTR          ; We are done, move tmp pointer to _outptr
+    sta _outptr
+    lda TMPPTR+1
+    sta _outptr+1
+    pla                 ; Restore the tmp pointer
+    sta TMPPTR+1
+    pla
+    sta TMPPTR
+    jmp @L2             ; Finish the interrupt handler
 .endproc
 
diff --git a/mocktest/speech_api.c b/mocktest/speech_api.c
index 9ab78cb..bdcb0d4 100644
--- a/mocktest/speech_api.c
+++ b/mocktest/speech_api.c
@@ -15,15 +15,6 @@
 
 bool speechIsBusy(void)
 {
-    static uint16_t old_outptr = 0;
-    if (old_outptr == 0) {
-        printf("endptr=%x\n", endptr);
-    }
-    if (old_outptr != outptr) {
-        old_outptr = outptr;
-        printf("%x ", old_outptr);
-    }
-    //printf("busy=0x%x, outptr=0x%x, endptr=0x%x\n", speechBusy, outptr, endptr);
     return (speechBusy != 0);
 }