diff --git a/bin/kernal b/bin/kernal
index b992407f..b169ad25 100644
Binary files a/bin/kernal and b/bin/kernal differ
diff --git a/c64/kernal/acptr.s b/c64/kernal/acptr.s
index d9ac012f..b6fd88be 100644
--- a/c64/kernal/acptr.s
+++ b/c64/kernal/acptr.s
@@ -1,3 +1,12 @@
-; Function defined on pp272-273 of C64 Programmers Reference Guide
+
+;;
+;; Official Kernal routine, described in:
+;;
+;; - [RG64] C64 Programmer's Reference Guide   - page 274
+;; - [CM64] Compute's Mapping the Commodore 64 - page 224/225
+;;
+;; CPU registers that has to be preserved (see [RG64]): .Y
+;;
+
 acptr:
 	rts
diff --git a/c64/kernal/chkin.s b/c64/kernal/chkin.s
index ffa509d7..f48b8b5e 100644
--- a/c64/kernal/chkin.s
+++ b/c64/kernal/chkin.s
@@ -1,4 +1,12 @@
-; Function defined on pp272-273 of C64 Programmers Reference Guide
+
+;;
+;; Official Kernal routine, described in:
+;;
+;; - [RG64] C64 Programmer's Reference Guide   - page 275
+;; - [CM64] Compute's Mapping the Commodore 64 - page 229
+;;
+;; CPU registers that has to be preserved (see [RG64]): .Y
+;;
 
 chkin:
 
diff --git a/c64/kernal/chkout.s b/c64/kernal/chkout.s
index 36b5a683..0f1f2e58 100644
--- a/c64/kernal/chkout.s
+++ b/c64/kernal/chkout.s
@@ -1,4 +1,12 @@
-; Function defined on pp272-273 of C64 Programmers Reference Guide
+
+;;
+;; Official Kernal routine, described in:
+;;
+;; - [RG64] C64 Programmer's Reference Guide   - page 276
+;; - [CM64] Compute's Mapping the Commodore 64 - page 229
+;;
+;; CPU registers that has to be preserved (see [RG64]): .Y
+;;
 
 chkout:
 
diff --git a/c64/kernal/chrin.s b/c64/kernal/chrin.s
index c60c5040..761c7c79 100644
--- a/c64/kernal/chrin.s
+++ b/c64/kernal/chrin.s
@@ -1,5 +1,14 @@
-				; Function defined on pp272-273 of C64 Programmers Reference Guide
-	;; Compute's Mapping the 64, p228
+
+;;
+;; 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
+;;
+
+
 	;;  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.
diff --git a/c64/kernal/chrout.s b/c64/kernal/chrout.s
index 02503fa7..926a9391 100644
--- a/c64/kernal/chrout.s
+++ b/c64/kernal/chrout.s
@@ -1,4 +1,14 @@
-; Function defined on pp272-273 of C64 Programmers Reference Guide
+
+;;
+;; Official Kernal routine, described in:
+;;
+;; - [RG64] C64 Programmer's Reference Guide   - page 278/279
+;; - [CM64] Compute's Mapping the Commodore 64 - page 228
+;;
+;; CPU registers that has to be preserved (see [RG64]): .Y
+;;
+
+
 chrout:
 	;; Crude implementation of character output	
 
diff --git a/c64/kernal/cint.s b/c64/kernal/cint.s
index bf760279..7dd92f46 100644
--- a/c64/kernal/cint.s
+++ b/c64/kernal/cint.s
@@ -1,5 +1,14 @@
-	;; Function defined on pp272-273 of C64 Programmers Reference Guide 
-	;; Compute's Mapping the 64 p215
+
+;;
+;; Official Kernal routine, described in:
+;;
+;; - [RG64] C64 Programmer's Reference Guide   - page 280
+;; - [CM64] Compute's Mapping the Commodore 64 - page 242
+;;
+;; CPU registers that has to be preserved (see [RG64]): none
+;;
+
+
 cint:
 	jsr setup_vicii
 	
diff --git a/c64/kernal/fda3.ioinit.s b/c64/kernal/fda3.ioinit.s
index 2cadb1bc..fd579b03 100644
--- a/c64/kernal/fda3.ioinit.s
+++ b/c64/kernal/fda3.ioinit.s
@@ -1,4 +1,13 @@
-; Function defined on pp272-273 of C64 Programmers Reference Guide
+
+;;
+;; Official Kernal routine, described in:
+;;
+;; - [RG64] C64 Programmer's Reference Guide   - page 285
+;; - [CM64] Compute's Mapping the Commodore 64 - page 238
+;;
+;; CPU registers that has to be preserved (see [RG64]): none
+;;
+
 ioinit:
 
 	; Set $00/$01 port mode and value
diff --git a/c64/kernal/iec_turnaround_to_listen.s b/c64/kernal/iec_turnaround_to_listen.s
index 964ef0ed..b1d0f576 100644
--- a/c64/kernal/iec_turnaround_to_listen.s
+++ b/c64/kernal/iec_turnaround_to_listen.s
@@ -4,6 +4,10 @@
 
 iec_turnaround_to_listen:
 
+	;; Timing is critical here - execute on disabled IRQs
+	php
+	sei
+
 	;; Pull DATA, release CLK and ATN (we are not sending commands)
 	jsr iec_pull_data_release_atn_clk
 
@@ -17,11 +21,13 @@ iec_turnaround_to_listen:
 	bne -
 
 	;; Timeout
+	plp
 	sec
 	rts
 
 	;; CLK is pulled by the device, OK
-*	
+*
+	plp
 	clc
 	rts
 
diff --git a/c64/kernal/iec_turnaround_to_talk.s b/c64/kernal/iec_turnaround_to_talk.s
index c8cc9b47..c24639d2 100644
--- a/c64/kernal/iec_turnaround_to_talk.s
+++ b/c64/kernal/iec_turnaround_to_talk.s
@@ -4,6 +4,10 @@
 
 iec_turnaround_to_talk:
 
+	;; Timing is critical here - execute on disabled IRQs
+	php
+	sei
+
 	;; First make sure both CLK, DATA and ATN are released at our side
 	jsr iec_release_atn
 	jsr iec_release_clk_data
@@ -14,5 +18,6 @@ iec_turnaround_to_talk:
 	;; Pull CLK line, it should be held by talker
 	jsr iec_pull_clk_release_data
 
+	plp
 	clc
 	rts
diff --git a/c64/kernal/ramtas.s b/c64/kernal/ramtas.s
index 45de1315..e54f7bd2 100644
--- a/c64/kernal/ramtas.s
+++ b/c64/kernal/ramtas.s
@@ -1,4 +1,13 @@
-; Function defined on pp272-273 of C64 Programmers Reference Guide
+
+;;
+;; Official Kernal routine, described in:
+;;
+;; - [RG64] C64 Programmer's Reference Guide   - page 291
+;; - [CM64] Compute's Mapping the Commodore 64 - page 237
+;;
+;; CPU registers that has to be preserved (see [RG64]): none
+;;
+
 ramtas:
 	; C64 Programmer's Reference guide p291:
 	; Clear $0000-$0101, $0200-$03ff
diff --git a/c64/kernal/vector.s b/c64/kernal/vector.s
index 027bf14a..4a086198 100644
--- a/c64/kernal/vector.s
+++ b/c64/kernal/vector.s
@@ -1,4 +1,12 @@
-; Functions defined on pp272-273 of C64 Programmers Reference Guide
+
+;;
+;; Official Kernal routine, described in:
+;;
+;; - [RG64] C64 Programmer's Reference Guide   - page 293 (RESTOR), 304 (VECTOR)
+;; - [CM64] Compute's Mapping the Commodore 64 - page 237
+;;
+;; CPU registers that has to be preserved (see [RG64]): none
+;;
 
 restor: