diff --git a/libsrc/plus4/Makefile b/libsrc/plus4/Makefile
index a503225af..8dc900462 100644
--- a/libsrc/plus4/Makefile
+++ b/libsrc/plus4/Makefile
@@ -19,8 +19,29 @@ OBJS =	_scrsize.o	\
 	conio.o		\
 	cputc.o		\
 	crt0.o		\
+        kacptr.o        \
+        kbasin.o        \
 	kbhit.o		\
-        kernal.o        \
+        kbsout.o        \
+        kchkin.o        \
+        kciout.o        \
+        kckout.o        \
+        kclall.o        \
+        kclose.o        \
+        kclrch.o        \
+        kiobase.o       \
+        klisten.o       \
+        kload.o         \
+        kopen.o         \
+        krdtim.o        \
+        kreadst.o       \
+        ksave.o         \
+        ksetlfs.o       \
+        ksetnam.o       \
+        ksettim.s       \
+        ktalk.o         \
+        kunlsn.o        \
+        kuntlk.o        \
         randomize.o     \
 	readjoy.o	\
 	tgi_mode_table.o
diff --git a/libsrc/plus4/cgetc.s b/libsrc/plus4/cgetc.s
index c48676745..0bcd6013a 100644
--- a/libsrc/plus4/cgetc.s
+++ b/libsrc/plus4/cgetc.s
@@ -9,9 +9,10 @@
 
        	.include	"plus4.inc"
 
-
 ; --------------------------------------------------------------------------
 
+.segment        "LOWMEM"        ; Accesses the ROM - must go into low mem
+
 _cgetc:	lda	KEY_COUNT 	; Get number of characters
        	ora	FKEY_COUNT	; Or with number of function key chars
        	bne	L2	  	; Jump if there are already chars waiting
@@ -44,7 +45,9 @@ L1:    	lda	KEY_COUNT
        	sta	TED_CURSLO	; Cursor off
        	sta	TED_CURSHI
 
-L2:    	jsr    	KBDREAD	       	; Read char and return in A
+L2:    	sta     ENABLE_ROM      ; Bank in the ROM
+        jsr    	KBDREAD	       	; Read char and return in A (ROM routine)
+        sta     ENABLE_RAM      ; Reenable the RAM
        	ldx	#0
        	rts
 
@@ -56,6 +59,8 @@ L2:    	jsr    	KBDREAD	       	; Read char and return in A
 	.constructor	initkbd
 	.destructor	donekbd
 
+.code                           ; Can go into the normal code segment
+
 .proc	initkbd
 
      	ldy	#15
@@ -68,13 +73,17 @@ L2:    	jsr    	KBDREAD	       	; Read char and return in A
 .endproc
 
 
+.segment        "LOWMEM"        ; Accesses the ROM - must go into low mem
+
 .proc	donekbd
 
      	ldx    	#$39		; Copy the original function keys
+        sta     ENABLE_ROM      ; Bank in the ROM
 @L1:  	lda    	FKEY_ORIG,x
      	sta    	FKEY_SPACE,x
      	dex
      	bpl    	@L1
+        sta     ENABLE_RAM      ; Bank out the ROM
      	rts
 
 .endproc
diff --git a/libsrc/plus4/clrscr.s b/libsrc/plus4/clrscr.s
index 4b6c48355..6641c336b 100644
--- a/libsrc/plus4/clrscr.s
+++ b/libsrc/plus4/clrscr.s
@@ -8,7 +8,16 @@
 
 	.include	"plus4.inc"
 
-_clrscr	= CLRSCR
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   _clrscr
+        sta     ENABLE_ROM              ; Enable the ROM
+        jsr     CLRSCR                  ; Call the ROM routine
+        sta     ENABLE_RAM              ; Switch back to RAM
+        rts                             ; Return to caller
+.endproc
+
+
 
 
 
diff --git a/libsrc/plus4/crt0.s b/libsrc/plus4/crt0.s
index 9c8b66fea..503d086d5 100644
--- a/libsrc/plus4/crt0.s
+++ b/libsrc/plus4/crt0.s
@@ -7,61 +7,71 @@
 	.export		_exit
 	.import		initlib, donelib
 	.import	     	push0, _main, zerobss
-        .import         MEMTOP, RESTOR, BSOUT, CLRCH
+	.import	       	__IRQFUNC_TABLE__, __IRQFUNC_COUNT__
 
         .include        "zeropage.inc"
 	.include	"plus4.inc"
 
 
 ; ------------------------------------------------------------------------
-; BASIC header with a SYS call
+; Place the startup code in a special segment to cope with the quirks of
+; plus/4 banking.
 
-.code
+.segment       	"STARTUP"
 
-	.org	$0FFF
         .word   Head            ; Load address
 Head:   .word   @Next
         .word   1000            ; Line number
         .byte   $9E,"4109"	; SYS 4109
         .byte   $00             ; End of BASIC line
 @Next:  .word   0               ; BASIC end marker
-	.reloc
 
 ; ------------------------------------------------------------------------
 ; Actual code
 
+        sei                     ; No interrupts since we're banking out the ROM
+        sta     ENABLE_RAM
        	ldx   	#zpspace-1
 L1:	lda	sp,x
    	sta	zpsave,x	; save the zero page locations we need
 	dex
        	bpl	L1
+        sta     ENABLE_ROM
+        cli
 
 ; Close open files
 
-	jsr	CLRCH
+	jsr	$FFCC           ; CLRCH
 
 ; Switch to second charset
 
 	lda	#14
-	jsr	BSOUT
+	jsr	$FFD2           ; BSOUT
+
+; Setup the IRQ vector in the banked RAM and switch off the ROM
+
+        sei                     ; No ints, handler not yet in place
+        sta     ENABLE_RAM
+        lda     #<IRQ
+        sta     $FFFE           ; Install interrupt handler
+        lda     #>IRQ
+        sta     $FFFF
+        cli                     ; Allow interrupts
 
 ; Clear the BSS data
 
 	jsr	zerobss
 
-; Save system stuff and setup the stack
+; Save system stuff and setup the stack. The stack starts at the top of the
+; usable RAM.
 
        	tsx
        	stx    	spsave       	; save system stk ptr
 
-	sec
-	jsr	MEMTOP		; Get top memory
-	cpy	#$80  		; We can only use the low 32K :-(
-	bcc	MemOk
-	ldy	#$80
-	ldx	#$00
-MemOk:	stx	sp
-      	sty	sp+1  		; set argument stack ptr
+        lda     #<$FD00
+        sta     sp
+        lda     #>$FD00
+        sta     sp+1
 
 ; Call module constructors
 
@@ -92,11 +102,41 @@ L2:	lda	zpsave,x
 	dex
        	bpl	L2
 
-; Reset changed vectors
+; Enable the ROM, reset changed vectors and return to BASIC
 
-	jmp	RESTOR
+        sta     ENABLE_ROM
+	jmp	$FF8A           ; RESTOR
 
 
+; ------------------------------------------------------------------------
+; IRQ handler
+
+.segment        "LOWCODE"
+
+IRQ:    pha
+        txa
+        pha
+        tsx                     ; Get the stack pointer
+        lda     $0103,x         ; Get the saved status register
+        tax
+        lda     #>irqret        ; Push new return address
+        pha
+        lda     #<irqret
+        pha
+        txa
+        pha
+        sta     ENABLE_ROM      ; Switch to ROM
+        jmp     ($FFFE)         ; Jump to kernal irq handler
+
+irqret: sta     ENABLE_RAM      ; Switch back to RAM
+        pla
+        tax
+        pla
+        rti
+
+; ------------------------------------------------------------------------
+; Data
+
 .data
 zpsave:	.res	zpspace
 
diff --git a/libsrc/plus4/kacptr.s b/libsrc/plus4/kacptr.s
new file mode 100644
index 000000000..75a43c224
--- /dev/null
+++ b/libsrc/plus4/kacptr.s
@@ -0,0 +1,20 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; ACPTR replacement function
+;
+
+        .export         ACPTR
+
+        .include        "plus4.inc"
+
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   ACPTR
+        sta     ENABLE_ROM              ; Enable the ROM
+        jsr     $FFA5                   ; Call the ROM routine
+        sta     ENABLE_RAM              ; Switch back to RAM
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/kbasin.s b/libsrc/plus4/kbasin.s
new file mode 100644
index 000000000..507043866
--- /dev/null
+++ b/libsrc/plus4/kbasin.s
@@ -0,0 +1,20 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; BASIN replacement function
+;
+             
+        .export         BASIN
+
+        .include        "plus4.inc"
+
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   BASIN
+        sta     ENABLE_ROM              ; Enable the ROM
+        jsr     $FFCF                   ; Call the ROM routine
+        sta     ENABLE_RAM              ; Switch back to RAM
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/kbsout.s b/libsrc/plus4/kbsout.s
new file mode 100644
index 000000000..a86a334b2
--- /dev/null
+++ b/libsrc/plus4/kbsout.s
@@ -0,0 +1,20 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; BSOUT replacement function
+;
+
+        .export         BSOUT
+
+        .include        "plus4.inc"
+
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   BSOUT
+        sta     ENABLE_ROM              ; Enable the ROM
+        jsr     $FFD2                   ; Call the ROM routine
+        sta     ENABLE_RAM              ; Switch back to RAM
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/kchkin.s b/libsrc/plus4/kchkin.s
new file mode 100644
index 000000000..139e5122f
--- /dev/null
+++ b/libsrc/plus4/kchkin.s
@@ -0,0 +1,20 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; CHKIN replacement function
+;
+
+        .export         CHKIN
+
+        .include        "plus4.inc"
+
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   CHKIN
+        sta     ENABLE_ROM              ; Enable the ROM
+        jsr     $FFC6                   ; Call the ROM routine
+        sta     ENABLE_RAM              ; Switch back to RAM
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/kciout.s b/libsrc/plus4/kciout.s
new file mode 100644
index 000000000..5f9f08beb
--- /dev/null
+++ b/libsrc/plus4/kciout.s
@@ -0,0 +1,20 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; CIOUT replacement function
+;
+
+        .export         CIOUT
+
+        .include        "plus4.inc"
+
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   CIOUT
+        sta     ENABLE_ROM              ; Enable the ROM
+        jsr     $FFA8                   ; Call the ROM routine
+        sta     ENABLE_RAM              ; Switch back to RAM
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/kckout.s b/libsrc/plus4/kckout.s
new file mode 100644
index 000000000..a1d38f37a
--- /dev/null
+++ b/libsrc/plus4/kckout.s
@@ -0,0 +1,20 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; CKOUT replacement function
+;
+
+        .export         CKOUT
+
+        .include        "plus4.inc"
+
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   CKOUT
+        sta     ENABLE_ROM              ; Enable the ROM
+        jsr     $FFC9                   ; Call the ROM routine
+        sta     ENABLE_RAM              ; Switch back to RAM
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/kclall.s b/libsrc/plus4/kclall.s
new file mode 100644
index 000000000..eb00661ee
--- /dev/null
+++ b/libsrc/plus4/kclall.s
@@ -0,0 +1,20 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; CLALL replacement function
+;
+
+        .export         CLALL
+
+        .include        "plus4.inc"
+
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   CLALL
+        sta     ENABLE_ROM              ; Enable the ROM
+        jsr     $FFE7                   ; Call the ROM routine
+        sta     ENABLE_RAM              ; Switch back to RAM
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/kclose.s b/libsrc/plus4/kclose.s
new file mode 100644
index 000000000..f5f100ca6
--- /dev/null
+++ b/libsrc/plus4/kclose.s
@@ -0,0 +1,20 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; CLOSE replacement function
+;
+
+        .export         CLOSE
+
+        .include        "plus4.inc"
+
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   CLOSE
+        sta     ENABLE_ROM              ; Enable the ROM
+        jsr     $FFC3                   ; Call the ROM routine
+        sta     ENABLE_RAM              ; Switch back to RAM
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/kclrch.s b/libsrc/plus4/kclrch.s
new file mode 100644
index 000000000..b36c04488
--- /dev/null
+++ b/libsrc/plus4/kclrch.s
@@ -0,0 +1,20 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; CLRCH replacement function
+;
+
+        .export         CLRCH
+
+        .include        "plus4.inc"
+
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   CLRCH
+        sta     ENABLE_ROM              ; Enable the ROM
+        jsr     $FFCC                   ; Call the ROM routine
+        sta     ENABLE_RAM              ; Switch back to RAM
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/kernal.s b/libsrc/plus4/kernal.s
deleted file mode 100644
index 78914c084..000000000
--- a/libsrc/plus4/kernal.s
+++ /dev/null
@@ -1,90 +0,0 @@
-;
-; Ullrich von Bassewitz, 19.11.2002
-;
-; Plus/4 kernal functions
-;
-
-        .export         CINT
-        .export         IOINIT
-        .export         RAMTAS
-        .export         RESTOR
-        .export         VECTOR
-        .export         SETMSG
-        .export         SECOND
-        .export         TKSA
-        .export         MEMTOP
-        .export         MEMBOT
-        .export         SCNKEY
-        .export         SETTMO
-        .export         ACPTR
-        .export         CIOUT
-        .export         UNTLK
-        .export         UNLSN
-        .export         LISTEN
-        .export         TALK
-        .export         READST
-        .export         SETLFS
-        .export         SETNAM
-        .export         OPEN
-        .export         CLOSE
-        .export         CHKIN
-        .export         CKOUT
-        .export         CLRCH
-        .export         BASIN
-        .export         BSOUT
-        .export         LOAD
-        .export         SAVE
-        .export         SETTIM
-        .export         RDTIM
-        .export         STOP
-        .export         GETIN
-        .export         CLALL
-        .export         UDTIM
-        .export         SCREEN
-        .export         PLOT
-        .export         IOBASE
-
-
-;-----------------------------------------------------------------------------
-; All functions are available in the kernal jump table
-
-CINT		= $FF81
-IOINIT		= $FF84
-RAMTAS		= $FF87
-RESTOR		= $FF8A
-VECTOR		= $FF8D
-SETMSG		= $FF90
-SECOND		= $FF93
-TKSA		= $FF96
-MEMTOP		= $FF99
-MEMBOT		= $FF9C
-SCNKEY		= $FF9F
-SETTMO		= $FFA2
-ACPTR		= $FFA5
-CIOUT		= $FFA8
-UNTLK		= $FFAB
-UNLSN		= $FFAE
-LISTEN		= $FFB1
-TALK		= $FFB4
-READST		= $FFB7
-SETLFS		= $FFBA
-SETNAM		= $FFBD
-OPEN		= $FFC0
-CLOSE		= $FFC3
-CHKIN		= $FFC6
-CKOUT		= $FFC9
-CLRCH		= $FFCC
-BASIN		= $FFCF
-BSOUT		= $FFD2
-LOAD		= $FFD5
-SAVE		= $FFD8
-SETTIM		= $FFDB
-RDTIM		= $FFDE
-STOP		= $FFE1
-GETIN		= $FFE4
-CLALL		= $FFE7
-UDTIM		= $FFEA
-SCREEN		= $FFED
-PLOT		= $FFF0
-IOBASE		= $FFF3
-
diff --git a/libsrc/plus4/kiobase.s b/libsrc/plus4/kiobase.s
new file mode 100644
index 000000000..de00517d4
--- /dev/null
+++ b/libsrc/plus4/kiobase.s
@@ -0,0 +1,20 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; IOBASE replacement function
+;
+
+        .export         IOBASE
+
+        .include        "plus4.inc"
+
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   IOBASE
+        sta     ENABLE_ROM              ; Enable the ROM
+        jsr     $FFF3                   ; Call the ROM routine
+        sta     ENABLE_RAM              ; Switch back to RAM
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/klisten.s b/libsrc/plus4/klisten.s
new file mode 100644
index 000000000..06a4609a6
--- /dev/null
+++ b/libsrc/plus4/klisten.s
@@ -0,0 +1,20 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; LISTEN replacement function
+;
+
+        .export         LISTEN
+
+        .include        "plus4.inc"
+
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   LISTEN
+        sta     ENABLE_ROM              ; Enable the ROM
+        jsr     $FFB1                   ; Call the ROM routine
+        sta     ENABLE_RAM              ; Switch back to RAM
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/kload.s b/libsrc/plus4/kload.s
new file mode 100644
index 000000000..c2b62dd5c
--- /dev/null
+++ b/libsrc/plus4/kload.s
@@ -0,0 +1,20 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; LOAD replacement function
+;
+
+        .export         LOAD
+
+        .include        "plus4.inc"
+
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   LOAD
+        sta     ENABLE_ROM              ; Enable the ROM
+        jsr     $FFD5                   ; Call the ROM routine
+        sta     ENABLE_RAM              ; Switch back to RAM
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/kopen.s b/libsrc/plus4/kopen.s
new file mode 100644
index 000000000..b7e4b1c50
--- /dev/null
+++ b/libsrc/plus4/kopen.s
@@ -0,0 +1,20 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; OPEN replacement function
+;
+
+        .export         OPEN
+
+        .include        "plus4.inc"
+
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   OPEN
+        sta     ENABLE_ROM              ; Enable the ROM
+        jsr     $FFC0                   ; Call the ROM routine
+        sta     ENABLE_RAM              ; Switch back to RAM
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/krdtim.s b/libsrc/plus4/krdtim.s
new file mode 100644
index 000000000..99fb74f18
--- /dev/null
+++ b/libsrc/plus4/krdtim.s
@@ -0,0 +1,22 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; RDTIM replacement function
+;
+
+        .export         RDTIM
+
+        .include        "plus4.inc"
+
+; Read the clock from the zero page to avoid banking in the ROM
+
+.proc   RDTIM
+        sei                             ; No interrupts
+        lda     TIME+2
+        ldx     TIME+1
+        ldy     TIME                    ; Read the time
+        cli                             ; Allow interrupts
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/kreadst.s b/libsrc/plus4/kreadst.s
new file mode 100644
index 000000000..afebbc884
--- /dev/null
+++ b/libsrc/plus4/kreadst.s
@@ -0,0 +1,18 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; READST replacement function
+;
+
+        .export         READST
+
+        .include        "plus4.inc"
+
+; Read the status byte from the zero page instead of banking in the ROM
+
+.proc   READST
+        lda     ST                      ; Load status
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/ksave.s b/libsrc/plus4/ksave.s
new file mode 100644
index 000000000..0e691829e
--- /dev/null
+++ b/libsrc/plus4/ksave.s
@@ -0,0 +1,20 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; SAVE replacement function
+;
+
+        .export         SAVE
+
+        .include        "plus4.inc"
+
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   SAVE
+        sta     ENABLE_ROM              ; Enable the ROM
+        jsr     $FFD8                   ; Call the ROM routine
+        sta     ENABLE_RAM              ; Switch back to RAM
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/ksetlfs.s b/libsrc/plus4/ksetlfs.s
new file mode 100644
index 000000000..6ad7f34bc
--- /dev/null
+++ b/libsrc/plus4/ksetlfs.s
@@ -0,0 +1,20 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; SETLFS replacement function
+;
+
+        .export         SETLFS
+
+        .include        "plus4.inc"
+
+; Write directly to the zero page to avoid banking in the ROM
+
+.proc   SETLFS
+        sta     LFN
+        stx     DEVNUM
+        sty     SECADR
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/ksetnam.s b/libsrc/plus4/ksetnam.s
new file mode 100644
index 000000000..1d1297cdf
--- /dev/null
+++ b/libsrc/plus4/ksetnam.s
@@ -0,0 +1,62 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; SETNAM replacement function
+;
+
+        .export         SETNAM
+
+        .include        "plus4.inc"
+
+; This function is special in that the name must reside in low memory,
+; otherwise it is not accessible by the ROM code.
+
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   SETNAM
+
+; Limit the length of the name and store it into the zero page
+
+        cmp     #16+1
+        bcc     @L1
+        lda     #16                     ; Use a maximum of 16 chars
+@L1:    sta     FNAM_LEN
+
+; Check if we have to copy the name to low memory
+
+        cmp     #$00                    ; Length zero?
+        beq     @L3                     ; Yes: Copying not needed
+        cpy     #$00                    ; Is the name in low memory?
+        bpl     @L3                     ; Yes: Copying not needed
+
+; Store the length and the pointer to the name
+
+        stx     TMPPTR
+        sty     TMPPTR+1                ; Store pointer to name in TMPPTR
+
+; Copy the given name into DOS_FN1
+
+        ldy     #$00
+@L2:    lda     (TMPPTR),y
+        sta     DOS_FN1,y
+        iny
+        cpy     FNAM_LEN
+        bne     @L2
+
+; Load the new parameters for the low memory buffer
+
+        ldx     #<DOS_FN1
+        ldy     #>DOS_FN1
+
+; Instead of banking in the ROM, store the values directly into the zeropage
+
+@L3:    stx     FNAM_ADR
+        sty     FNAM_ADR+1
+
+; Return to caller
+
+        rts
+
+.endproc
+
+
diff --git a/libsrc/plus4/ksettim.s b/libsrc/plus4/ksettim.s
new file mode 100644
index 000000000..b3c59836a
--- /dev/null
+++ b/libsrc/plus4/ksettim.s
@@ -0,0 +1,22 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; SETTIM replacement function
+;
+
+        .export         SETTIM
+
+        .include        "plus4.inc"
+
+; Set the clock by writing directly to zero page to avoid banking in the ROM
+
+.proc   SETTIM
+        sei                             ; No interrupts
+        sta     TIME+2
+        stx     TIME+1
+        sty     TIME                    ; Set the time
+        cli                             ; Allow interrupts
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/ktalk.s b/libsrc/plus4/ktalk.s
new file mode 100644
index 000000000..bad693bfe
--- /dev/null
+++ b/libsrc/plus4/ktalk.s
@@ -0,0 +1,20 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; TALK replacement function
+;
+
+        .export         TALK
+
+        .include        "plus4.inc"
+
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   TALK
+        sta     ENABLE_ROM              ; Enable the ROM
+        jsr     $FFB4                   ; Call the ROM routine
+        sta     ENABLE_RAM              ; Switch back to RAM
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/kunlsn.s b/libsrc/plus4/kunlsn.s
new file mode 100644
index 000000000..486bb969b
--- /dev/null
+++ b/libsrc/plus4/kunlsn.s
@@ -0,0 +1,20 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; UNLSN replacement function
+;
+
+        .export         UNLSN
+
+        .include        "plus4.inc"
+
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   UNLSN
+        sta     ENABLE_ROM              ; Enable the ROM
+        jsr     $FFAE                   ; Call the ROM routine
+        sta     ENABLE_RAM              ; Switch back to RAM
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/kuntlk.s b/libsrc/plus4/kuntlk.s
new file mode 100644
index 000000000..52a5633d8
--- /dev/null
+++ b/libsrc/plus4/kuntlk.s
@@ -0,0 +1,20 @@
+;
+; Ullrich von Bassewitz, 22.11.2002
+;
+; UNTLK replacement function
+;
+
+        .export         UNTLK
+
+        .include        "plus4.inc"
+
+.segment        "LOWCODE"               ; Must go into low memory
+
+.proc   UNTLK
+        sta     ENABLE_ROM              ; Enable the ROM
+        jsr     $FFAB                   ; Call the ROM routine
+        sta     ENABLE_RAM              ; Switch back to RAM
+        rts                             ; Return to caller
+.endproc
+
+
diff --git a/libsrc/plus4/plus4.inc b/libsrc/plus4/plus4.inc
index 259fc7540..680a9611a 100644
--- a/libsrc/plus4/plus4.inc
+++ b/libsrc/plus4/plus4.inc
@@ -6,18 +6,22 @@
 ; ---------------------------------------------------------------------------
 ; Zero page, Commodore stuff
 
+TMPPTR          = $22           ; Temporary ptr used by BASIC
 ST   		= $90	     	; IEC status byte
-
 TIME            = $A3           ; 60HZ clock
 FNAM_LEN       	= $AB	     	; Length of filename
+LFN             = $AC           ; Logical file number
 SECADR		= $AD	     	; Secondary address
 DEVNUM		= $AE	     	; Device number
+FNAM_ADR        = $AF           ; Pointer to filename for OPEN
 KEY_COUNT      	= $EF 	     	; Number of keys in input buffer
 CURS_X		= $CA  		; Cursor column
 CURS_Y		= $CD  		; Cursor row
 SCREEN_PTR	= $C8  		; Pointer to current char in text screen
 CRAM_PTR	= $EA  		; Pointer to current char in color RAM
 
+DOS_FN1         = $25E          ; DOS filename buffer #1
+DOS_FN1LEN      = $26E          ; DOS filename length #1
 CHARCOLOR       = $53B
 FKEY_COUNT	= $55D		; Characters for function key
 FKEY_SPACE	= $55F		; Function key definitions
@@ -63,5 +67,10 @@ TED_HPOS	= $FF1E
 TED_ROMSEL	= $FF3E
 TED_RAMSEL	= $FF3F
 
+; ---------------------------------------------------------------------------
+; RAM/ROM selection addresses
+
+ENABLE_ROM      = $FF3E
+ENABLE_RAM      = $FF3F