diff --git a/c64/kernal/f157.chrin.jmp.s b/c64/kernal/f157.chrin.jmp.s
deleted file mode 100644
index b1b7c234..00000000
--- a/c64/kernal/f157.chrin.jmp.s
+++ /dev/null
@@ -1,6 +0,0 @@
-
-// Our implementation is longer than the original one,
-// placing it here would cause a collision with CHROUT
-
-CHRIN:
-    jmp chrin_real
diff --git a/c64/kernal/iec/chrin_iec.s b/c64/kernal/iec/chrin_iec.s
new file mode 100644
index 00000000..f293fa0c
--- /dev/null
+++ b/c64/kernal/iec/chrin_iec.s
@@ -0,0 +1,10 @@
+
+//
+// IEC part of the CHRIN routine
+//
+
+
+chrin_iec:
+
+	// XXX is this really all?
+	jmp JACPTR // carry will be set accordingly
diff --git a/c64/kernal/iostack/f157.chrin.s b/c64/kernal/iostack/f157.chrin.s
new file mode 100644
index 00000000..6ab21bfa
--- /dev/null
+++ b/c64/kernal/iostack/f157.chrin.s
@@ -0,0 +1,48 @@
+
+//
+// Official Kernal routine, described in:
+//
+// - [RG64] C64 Programmer's Reference Guide   - page 277/278
+// - [CM64] Compute's Mapping the Commodore 64 - page 228
+//
+// CPU registers that has to be preserved (see [RG64]): .Y
+//
+
+// XXX keyboard part currently does not preserve register Y, to be fixed!
+
+// Reads a byte of input, unless from keyboard.
+// If from keyboard, then it gets a whole line of input, and returns the first char.
+// Repeated calls after that read out the successive bytes of the line of input.
+
+
+CHRIN:
+
+	// Determine the device number
+	lda DFLTN
+
+	// Try $00 - keyboard
+	beq_far chrin_keyboard
+
+	// XXX Try $03 - screen
+	// cmp #$03
+	// beq_far chrin_screen
+
+#if HAS_RS232
+
+	// Try $02 - RS-232
+	cmp #$02
+	beq_far chrin_rs232
+
+#endif // HAS_RS232
+
+#if CONFIG_IEC
+
+	// Try IEC devices
+	jsr iec_check_devnum_oc
+	bcc_far chrin_iec
+
+#endif // CONFIG_IEC
+
+	// Not a supported device
+
+	jmp lvs_device_not_found_error
diff --git a/c64/kernal/f157.interop b/c64/kernal/iostack/f157.interop
similarity index 100%
rename from c64/kernal/f157.interop
rename to c64/kernal/iostack/f157.interop
diff --git a/c64/kernal/chrin_real.s b/c64/kernal/keyboard/chrin_keyboard.s
similarity index 71%
rename from c64/kernal/chrin_real.s
rename to c64/kernal/keyboard/chrin_keyboard.s
index f744920c..b91245a7 100644
--- a/c64/kernal/chrin_real.s
+++ b/c64/kernal/keyboard/chrin_keyboard.s
@@ -1,49 +1,8 @@
 
 //
-// Official Kernal routine, described in:
-//
-// - [RG64] C64 Programmer's Reference Guide   - page 277/278
-// - [CM64] Compute's Mapping the Commodore 64 - page 228
-//
-// CPU registers that has to be preserved (see [RG64]): .Y
+// Keyboard part of the CHRIN routine
 //
 
-// XXX keyboard part currently does not preserve register Y, to be fixed!
-// XXX try to make chrin_real unnecessary (try to fit this into original location)
-
-// Reads a byte of input, unless from keyboard.
-// If from keyboard, then it gets a whole line of input, and returns the first char.
-// Repeated calls after that read out the successive bytes of the line of input.
-
-chrin_real:
-
-	// Determine the device number
-	lda DFLTN
-
-	beq chrin_keyboard // #$00 - keyboard
-	// XXX add screen support
-
-#if CONFIG_IEC
-
-	jsr iec_check_devnum_oc
-	bcc chrin_iec
-	jmp lvs_device_not_found_error // not a supported device
-
-chrin_iec:
-
-	jsr JACPTR
-	bcs chrin_done_fail
-	// FALLTROUGH
-
-#endif // CONFIG_IEC
-
-chrin_done:
-	clc // indicate success
-	rts
-
-chrin_done_fail:
-	sec // indicate failure
-	rts
 
 chrin_keyboard:
 
diff --git a/c64/kernal/rs232/chkin_rs232.s b/c64/kernal/rs232/chkin_rs232.s
index 6cc6d002..b2cc4086 100644
--- a/c64/kernal/rs232/chkin_rs232.s
+++ b/c64/kernal/rs232/chkin_rs232.s
@@ -3,6 +3,8 @@
 // RS-232 part of the CHKIN routine
 //
 
+// XXX connect to I/O stack
+
 
 #if HAS_RS232
 
diff --git a/c64/kernal/rs232/chrout_rs232.s b/c64/kernal/rs232/chrout_rs232.s
index 9c3af02f..4617bc1a 100644
--- a/c64/kernal/rs232/chrout_rs232.s
+++ b/c64/kernal/rs232/chrout_rs232.s
@@ -3,6 +3,8 @@
 // RS-232 part of the CHROUT routine
 //
 
+// XXX connect to I/O stack
+
 
 #if HAS_RS232
 
diff --git a/c64/kernal/rs232/ckout_rs232.s b/c64/kernal/rs232/ckout_rs232.s
index 66d4b3e7..cefe35a7 100644
--- a/c64/kernal/rs232/ckout_rs232.s
+++ b/c64/kernal/rs232/ckout_rs232.s
@@ -3,6 +3,8 @@
 // RS-232 part of the CKOUT routine
 //
 
+// XXX connect to I/O stack
+
 
 #if HAS_RS232
 
diff --git a/c64/kernal/rs232/close_rs232.s b/c64/kernal/rs232/close_rs232.s
index 3871fe04..95e5959e 100644
--- a/c64/kernal/rs232/close_rs232.s
+++ b/c64/kernal/rs232/close_rs232.s
@@ -3,6 +3,8 @@
 // RS-232 part of the CLOSE routine
 //
 
+// XXX connect to I/O stack
+
 
 #if HAS_RS232
 
diff --git a/c64/kernal/rs232/getin_rs232.s b/c64/kernal/rs232/getin_rs232.s
index 17215ead..fd062e3a 100644
--- a/c64/kernal/rs232/getin_rs232.s
+++ b/c64/kernal/rs232/getin_rs232.s
@@ -3,6 +3,8 @@
 // RS-232 part of the GETIN routine
 //
 
+// XXX connect to I/O stack
+
 
 #if HAS_RS232
 
diff --git a/c64/kernal/rs232/open_rs232.s b/c64/kernal/rs232/open_rs232.s
index c347ec70..b864cdc0 100644
--- a/c64/kernal/rs232/open_rs232.s
+++ b/c64/kernal/rs232/open_rs232.s
@@ -3,6 +3,8 @@
 // RS-232 part of the OPEN routine
 //
 
+// XXX connect to I/O stack
+
 
 #if HAS_RS232