diff --git a/libsrc/apple2/crt0.s b/libsrc/apple2/crt0.s
index 106642d79..074e592ed 100644
--- a/libsrc/apple2/crt0.s
+++ b/libsrc/apple2/crt0.s
@@ -4,129 +4,168 @@
 ; This must be the *first* file on the linker command line
 ;
 
-	.export		_exit, __Exit
-	.import	   	initlib, donelib
-	.import	   	zerobss
-       	.import	       	__STARTUP_LOAD__, __BSS_LOAD__	; Linker generated
-	.import		callmain
+        .export		_exit, __Exit
+        .import		zerobss
+        .import	   	initlib, donelib
+        .import	   	callmain, callirq
+        .import	       	__STARTUP_LOAD__, __BSS_LOAD__	; Linker generated
+        .import	       	__INTERRUPTOR_COUNT__		; Linker generated
 
         .include        "zeropage.inc"
-	.include	"apple2.inc"
+        .include	"apple2.inc"
+        .include	"mli.inc"
 
 ; ------------------------------------------------------------------------
-; The executable header
 
-.segment	"EXEHDR"
+        .segment	"EXEHDR"
 
-       	.word  	__STARTUP_LOAD__                ; Start address
-       	.word  	__BSS_LOAD__ - __STARTUP_LOAD__	; Size
+        .addr		__STARTUP_LOAD__                ; Start address
+        .word		__BSS_LOAD__ - __STARTUP_LOAD__	; Size
 
 ; ------------------------------------------------------------------------
-; Place the startup code in a special segment.
 
-.segment       	"STARTUP"
+        .segment       	"STARTUP"
 
-; ProDOS TechRefMan, chapter 5.2.1:
-; "For maximum interrupt efficiency, a system program should not use more
-;  than the upper 3/4 of the stack."
+        ; ProDOS TechRefMan, chapter 5.2.1:
+        ; "For maximum interrupt efficiency, a system program should not
+        ;  use more than the upper 3/4 of the stack."
+        ldx	#$FF
+        txs	       		; Init stack pointer
 
-	ldx	#$FF
-	txs	       		; Init stack pointer
+        ; Delegate all further processing to keep STARTUP small
+        jsr	init
 
-; Save the zero page locations we need
+        ; Avoid re-entrance of donelib. This is also the _exit entry
+_exit:  ldx	#<__Exit
+        lda	#>__Exit
+        jsr	reset		; Setup RESET vector
 
-       	ldx	#zpspace-1
-:	lda	sp,x
-   	sta	zpsave,x
-	dex
-       	bpl	:-
+        ; Check for valid interrrupt vector table entry number
+        lda	intnum
+        beq	:+
 
-; Save the original RESET vector
+        ; Deallocate interrupt vector table entry
+        dec	params		; Adjust parameter count
+        jsr	ENTRY
+        .byte	$41		; Dealloc interrupt
+        .addr	params
 
-	ldx	#$02
-:	lda	SOFTEV,x
-	sta	rvsave,x
-	dex
-	bpl	:-
+        ; Call module destructors
+:       jsr	donelib
 
-; ProDOS TechRefMan, chapter 5.3.5:
-; "Your system program should place in the RESET vector the address of a
-;  routine that ... closes the files."
+        ; Restore the original RESET vector. This is also the __Exit entry
+__Exit: ldx	#$02
+:       lda	rvsave,x
+        sta	SOFTEV,x
+        dex
+        bpl	:-
 
-	ldx	#<_exit
-	lda	#>_exit
-	jsr	reset		; Setup RESET vector
-		
-; Clear the BSS data
+        ; Copy back the zero page stuff
+        ldx	#zpspace-1
+:       lda	zpsave,x
+        sta	sp,x
+        dex
+        bpl	:-
 
-	jsr	zerobss
+        ; ProDOS TechRefMan, chapter 5.2.1:
+        ; "System programs should set the stack pointer to $FF at the
+        ;  warm-start entry point."
+        ldx	#$FF
+        txs			; Re-init stack pointer
 
-; Setup the stack
-
-	lda    	HIMEM
-	sta	sp
-	lda	HIMEM+1
-       	sta	sp+1   	    	; Set argument stack ptr
-
-; Call module constructors
-
-	jsr	initlib
-
-; Push arguments and call main()
-
-	jsr	callmain
-
-; Avoid re-entrance of donelib. This is also the _exit entry
-
-_exit:	ldx	#<__Exit
-	lda	#>__Exit
-	jsr	reset		; Setup RESET vector
-
-; Call module destructors
-
-	jsr	donelib
-
-; Restore the original RESET vector. This is also the __Exit entry
-
-__Exit:	ldx	#$02
-:	lda	rvsave,x
-	sta	SOFTEV,x
-	dex
-	bpl	:-
-
-; Copy back the zero page stuff
-
-	ldx	#zpspace-1
-:	lda	zpsave,x
-	sta	sp,x
-	dex
-       	bpl	:-
-
-; ProDOS TechRefMan, chapter 5.2.1:
-; "System programs should set the stack pointer to $FF at the warm-start
-;  entry point."
-
-	ldx	#$FF
-	txs			; Re-init stack pointer
-
-; Back to DOS
-
-	jmp	DOSWARM
+        ; Back to DOS
+        jmp	DOSWARM
 
 ; ------------------------------------------------------------------------
-; Setup RESET vector
 
-reset:	stx	SOFTEV
-	sta	SOFTEV+1
-	eor	#$A5
-	sta	PWREDUP
-	rts
+        .segment       	"INIT"
+
+        ; Save the zero page locations we need
+init:   ldx	#zpspace-1
+:       lda	sp,x
+        sta	zpsave,x
+        dex
+        bpl	:-
+
+        ; Save the original RESET vector
+        ldx	#$02
+:       lda	SOFTEV,x
+        sta	rvsave,x
+        dex
+        bpl	:-
+
+        ; ProDOS TechRefMan, chapter 5.3.5:
+        ; "Your system program should place in the RESET vector the
+        ;  address of a routine that ... closes the files."
+        ldx	#<_exit
+        lda	#>_exit
+        jsr	reset		; Setup RESET vector
+
+        ; Clear the BSS data
+        jsr	zerobss
+
+        ; Setup the stack
+        lda    	HIMEM
+        sta	sp
+        lda	HIMEM+1
+        sta	sp+1   	    	; Set argument stack ptr
+
+        ; Call module constructors
+        jsr	initlib
+
+        ; Check for interruptors
+        lda     #<__INTERRUPTOR_COUNT__
+        beq	:+
+
+        ; Check for ProDOS
+        lda	ENTRY
+        cmp	#$4C		; Is MLI present? (JMP opcode)
+        bne	:+
+
+        ; Allocate interrupt vector table entry
+        jsr	ENTRY
+        .byte	$40		; Alloc interrupt
+        .addr	params
+
+        ; Push arguments and call main()
+:       jmp	callmain
 
 ; ------------------------------------------------------------------------
-; Data
 
-.data
+        .segment	"LOWCODE"
 
-zpsave:	.res	zpspace
+        ; ProDOS TechRefMan, chapter 6.2:
+        ; "Each installed routine must begin with a CLD instruction"
+intrpt: cld
 
-rvsave:	.res	3
+        ; Call interruptors
+        jsr	callirq
+
+        ; ProDOS TechRefMan, chapter 6.2:
+        ; "When the routine that can process the interrupt is called, it
+        ;  should ... return (via an RTS) with the carry flag clear."
+        clc
+        rts
+
+; ------------------------------------------------------------------------
+
+        .code
+
+        ; Setup RESET vector
+reset:  stx	SOFTEV
+        sta	SOFTEV+1
+        eor	#$A5
+        sta	PWREDUP
+        rts
+
+; ------------------------------------------------------------------------
+
+        .data
+
+zpsave: .res	zpspace
+
+rvsave: .res	3
+
+params: .byte	$02		; Parameter count
+intnum: .byte	$00		; Interrupt number
+        .addr	intrpt		; Interrupt handler