diff --git a/Makefile b/Makefile
index fde56031..62da0476 100644
--- a/Makefile
+++ b/Makefile
@@ -431,7 +431,7 @@ build/padding_64_KB:
 
 $(TARGET_M65_x) $(TARGET_M65_x_PXL): $(SEG_LIST_M65) build/padding_64_KB build/chargen_openroms.rom build/chargen_openroms.patched build/chargen_pxlfont.rom build/chargen_pxlfont.patched
 	@echo
-	cat $(DIR_M65)/dos.seg_1       >> $(TARGET_M65_x)
+	cat $(DIR_M65)/dos.seg_1        > $(TARGET_M65_x)
 	cat $(DIR_M65)/kernal.seg_1    >> $(TARGET_M65_x)
 	cat $(DIR_M65)/basic.seg_1     >> $(TARGET_M65_x)
 	cat $(DIR_M65)/basic.seg_0     >> $(TARGET_M65_x)
@@ -440,7 +440,7 @@ $(TARGET_M65_x) $(TARGET_M65_x_PXL): $(SEG_LIST_M65) build/padding_64_KB build/c
 	cat $(DIR_M65)/kernal.seg_0    >> $(TARGET_M65_x)
 	cat build/padding_64_KB                 >> $(TARGET_M65_x)
 	@echo
-	cat $(DIR_M65)/dos.seg_1       >> $(TARGET_M65_x_PXL)
+	cat $(DIR_M65)/dos.seg_1        > $(TARGET_M65_x_PXL)
 	cat $(DIR_M65)/kernal.seg_1    >> $(TARGET_M65_x_PXL)
 	cat $(DIR_M65)/basic.seg_1     >> $(TARGET_M65_x_PXL)
 	cat $(DIR_M65)/basic.seg_0     >> $(TARGET_M65_x_PXL)
diff --git a/src/dos_m65/dos_vectable.s b/src/dos_m65/4000.dos_vectable.s
similarity index 100%
rename from src/dos_m65/dos_vectable.s
rename to src/dos_m65/4000.dos_vectable.s
diff --git a/src/kernal/board_m65/mega65_map_helpers.s b/src/kernal/board_m65/mega65_map_helpers.s
index 0009100f..2353b70e 100644
--- a/src/kernal/board_m65/mega65_map_helpers.s
+++ b/src/kernal/board_m65/mega65_map_helpers.s
@@ -6,8 +6,10 @@
 //
 
 // Available memory maps:
-// - NORMAL   - nothing mapped in
-// - KERNAL_1 - for calling KERNAL_1 segment code
+// - NORMAL            - nothing mapped in
+// - KERNAL_1          - for calling KERNAL_1 segment code
+// - DOS_1             - for swiching to DOS context
+// - NORMAL_from_DOS_1 - for switching bact from DOS context
 
 
 map_NORMAL:
@@ -19,6 +21,11 @@ map_NORMAL:
 	phz
 
 	lda #$00
+
+	// FALLTROUGH
+
+map_NORMAL_common:
+
 	tax
 	tay
 	taz
@@ -30,6 +37,10 @@ map_end:
 	map
 	eom
 
+	// FALLTROUGH
+
+map_end_no_eom:
+
 	plz
 	ply
 	plx
@@ -53,4 +64,37 @@ map_KERNAL_1:
 
 	ldx #$42    // 0x4000 <- map 8KB from 0x20000
 
-	bne map_end
+	jmp_8 map_end
+
+map_DOS_1:
+
+	php
+	pha
+	phx
+	phy
+	phz
+
+	lda #$C0
+	tab                      // from now on, zeropage starts from $C000
+
+	ldy #$00
+	taz #$81                 // 0xC000 <- map 8KB (4KB useable) from $10000
+
+	tya
+	ldx #$C2                 // 0x4000 <- map 16KB from 0x20000
+
+	map
+	jmp_8 map_end_no_eom     // no EOM, we do not want interrupts within DOS!
+
+map_NORMAL_from_DOS_1:
+
+	php
+	pha
+	phx
+	phy
+	phz
+
+	lda #$00
+	tba
+
+	jmp_8 map_NORMAL_common
diff --git a/src/kernal/iec_fast/dos_m65.s b/src/kernal/iec_fast/dos_m65.s
deleted file mode 100644
index 3d08c6b5..00000000
--- a/src/kernal/iec_fast/dos_m65.s
+++ /dev/null
@@ -1,19 +0,0 @@
-// #LAYOUT# M65 KERNAL_0 #TAKE
-// #LAYOUT# *   *        #IGNORE
-
-//
-// MEGA65 pseudo-IEC internal DOS support
-//
-
-.label VDOS_INIT    = $4000
-.label VDOS_HASUNIT = $4002
-.label VDOS_ACPTR   = $4004
-.label VDOS_CIOUT   = $4006
-.label VDOS_LISTEN  = $4008
-.label VDOS_SECOND  = $400A
-.label VDOS_TALK    = $400C
-.label VDOS_TKSA    = $400E
-.label VDOS_UNTLK   = $4010
-.label VDOS_UNLSN   = $4012
-
-// XXX implement support
diff --git a/src/kernal/iec_fast/m65dos_bridge.s b/src/kernal/iec_fast/m65dos_bridge.s
new file mode 100644
index 00000000..b429353a
--- /dev/null
+++ b/src/kernal/iec_fast/m65dos_bridge.s
@@ -0,0 +1,84 @@
+// #LAYOUT# M65 KERNAL_0 #TAKE
+// #LAYOUT# *   *        #IGNORE
+
+//
+// MEGA65 pseudo-IEC internal DOS support
+//
+
+
+.label VDOS_INIT    = $4000
+.label VDOS_HASUNIT = $4002
+.label VDOS_ACPTR   = $4004
+.label VDOS_CIOUT   = $4006
+.label VDOS_LISTEN  = $4008
+.label VDOS_SECOND  = $400A
+.label VDOS_TALK    = $400C
+.label VDOS_TKSA    = $400E
+.label VDOS_UNTLK   = $4010
+.label VDOS_UNLSN   = $4012
+
+
+// XXX connect this to core IEC implementation
+
+
+m65dos_init:
+
+	jsr map_DOS_1
+	jsr_ind VDOS_INIT
+	jmp_8 !+
+
+m65dos_hasunit:
+
+	jsr map_DOS_1
+	jsr_ind VDOS_HASUNIT
+	jmp_8 !+
+
+m65dos_acptr:
+
+	jsr map_DOS_1
+	jsr_ind VDOS_ACPTR
+!:
+	jmp map_NORMAL_from_DOS_1          // try to make ACPTR slightly faster
+
+m65dos_ciout:
+
+	jsr map_DOS_1
+	jsr_ind VDOS_CIOUT
+!:
+	jmp map_NORMAL_from_DOS_1          // try to make CIOUT slightly faster
+
+m65dos_listen:
+
+	jsr map_DOS_1
+	jsr_ind VDOS_LISTEN
+	jmp_8 !-
+
+m65dos_second:
+
+	jsr map_DOS_1
+	jsr_ind VDOS_SECOND
+	jmp_8 !-
+
+m65dos_talk:
+
+	jsr map_DOS_1
+	jsr_ind VDOS_TALK
+	jmp_8 !-
+
+m65dos_tksa:
+
+	jsr map_DOS_1
+	jsr_ind VDOS_TKSA
+	jmp_8 !-
+
+m65dos_untlk:
+
+	jsr map_DOS_1
+	jsr_ind VDOS_UNTLK
+	jmp_8 !-
+
+m65dos_unlsn:
+
+	jsr map_DOS_1
+	jsr_ind VDOS_UNLSN
+	jmp_8 !-