diff --git a/c64/aliases/,aliases_hardware.s b/c64/aliases/,aliases_hardware.s
index ee6ceddb..b9622844 100644
--- a/c64/aliases/,aliases_hardware.s
+++ b/c64/aliases/,aliases_hardware.s
@@ -28,7 +28,7 @@
 	.alias VIC_SP7Y       $D00F
 
 	.alias VIC_MSIGX      $D010
-	.alias VIC_SCROLLY    $D011
+	.alias VIC_SCROLY     $D011
 	.alias VIC_RASTER     $D012
 	.alias VIC_LPENX      $D013
 	.alias VIC_LPENY      $D014
diff --git a/c64/aliases/,aliases_rom_basic.s b/c64/aliases/,aliases_rom_basic.s
index e69de29b..ff6c46dc 100644
--- a/c64/aliases/,aliases_rom_basic.s
+++ b/c64/aliases/,aliases_rom_basic.s
@@ -0,0 +1,5 @@
+
+	;; BASIC startup vector
+	
+	.alias IBASIC_COLD_START     $A000
+	.alias IBASIC_WARM_START     $A002
diff --git a/c64/basic/,target_generic/,hooks_generic.s b/c64/basic/,target_generic/,hooks_generic.s
index 186b29d0..92860379 100644
--- a/c64/basic/,target_generic/,hooks_generic.s
+++ b/c64/basic/,target_generic/,hooks_generic.s
@@ -4,6 +4,6 @@
 
 .macro TARGET_HOOK_BANNER
 
-	.byte $05, "  OPEN ROMS, ", $00
+	.byte "  OPEN ROMS, ", $00
 
 .macend
diff --git a/c64/basic/,target_ultimate64/,hooks_ultimate64.s b/c64/basic/,target_ultimate64/,hooks_ultimate64.s
index 519d07e9..9ae05e35 100644
--- a/c64/basic/,target_ultimate64/,hooks_ultimate64.s
+++ b/c64/basic/,target_ultimate64/,hooks_ultimate64.s
@@ -4,6 +4,6 @@
 
 .macro TARGET_HOOK_BANNER
 
-	.byte $05, "  OPEN ROMS FOR ULTIMATE 64", $0D, $0D, "  ", $00
+	.byte "  OPEN ROMS FOR ULTIMATE 64", $0D, $0D, "  ", $00
 
 .macend
diff --git a/c64/kernal/cint.s b/c64/kernal/cint.s
index 973def0d..25c31472 100644
--- a/c64/kernal/cint.s
+++ b/c64/kernal/cint.s
@@ -10,6 +10,9 @@
 
 
 cint:
+
+cint_brk: ; entry for BRK and STOP+RESTORE - XXX, where should it start?
+
 	jsr setup_vicii
 	
 	;; Initialise cursor blink flags  (Compute's Mapping the 64 p215)
@@ -34,8 +37,8 @@ cint:
 	stx key_first_repeat_delay
 
 	;; Set current colour for text (Compute's Mapping the 64 p215)
-	ldx #$0e  		; light blue by default
-	stx $0286
+	ldx #$01     ; default is light blue ($0E), but we use a different one
+	stx text_colour
 
 	;; Set maximum keyboard buffer size (Compute's Mapping the 64 p215)
 	ldx #10
diff --git a/c64/kernal/e544.clear_screen.s b/c64/kernal/e544.clear_screen.s
index 6b1d41fc..431c571e 100644
--- a/c64/kernal/e544.clear_screen.s
+++ b/c64/kernal/e544.clear_screen.s
@@ -1,21 +1,20 @@
 	;; Clear screen and initialise line link table
 	;; (Compute's Mapping the 64 p215-216)
 
-clear_screen:	
-	
+clear_screen:
+
 	;; Clear line link table 
 	;; (Compute's Mapping the 64 p215)
 
 	lda #$00
 	ldy #24
-clearscreen_l1:	
+clearscreen_l1:
 	sta screen_line_link_table,y
 	dey
 	bpl clearscreen_l1
 
 	;; Y now = #$FF
 
-	
 	;; Clear screen RAM.
 	;; We should do this at HIBASE, which annoyingly
 	;; is no ZP, so we need to make a vector
diff --git a/c64/kernal/e5a0.setup_vicii.s b/c64/kernal/e5a0.setup_vicii.s
index 671bfadf..d2483a45 100644
--- a/c64/kernal/e5a0.setup_vicii.s
+++ b/c64/kernal/e5a0.setup_vicii.s
@@ -1,19 +1,20 @@
 
-setup_vicii:	
+setup_vicii:
+
 	;; Set up default IO values (Compute's Mapping the 64 p215)
-	lda #$1b    		; Enable text mode
-	sta $d011
-	lda #$c8		; 40 column etc
-	sta $d016
+	lda #$1B    ; Enable text mode
+	sta VIC_SCROLY
+	lda #$C8    ; 40 column etc
+	sta VIC_SCROLX
 
 	;; Compute's Mapping the 64, p156
 	;; We use a different colour scheme of white text on all blue
 	lda #$06
-	sta $D020
-	sta $D021
+	sta VIC_EXTCOL
+	sta VIC_BGCOL0
 
-	;; Turn off sprites
-	;; (observed hanging around after running programs and resetting)
+	;; Turn off sprites (observed hanging around after running programs and resetting)
 	lda #$00
-	sta $D015	
-	
+	sta VIC_SPENA
+
+	;;FALLTROUGH
diff --git a/c64/kernal/interrupts/ea31.default_irq_handler.s b/c64/kernal/interrupts/ea31.default_irq_handler.s
index e37991f1..ab74f1c8 100644
--- a/c64/kernal/interrupts/ea31.default_irq_handler.s
+++ b/c64/kernal/interrupts/ea31.default_irq_handler.s
@@ -1,3 +1,4 @@
+
 default_irq_handler:	
 
 	jsr blink_cursor
diff --git a/c64/kernal/ea31.interop b/c64/kernal/interrupts/ea31.interop
similarity index 100%
rename from c64/kernal/ea31.interop
rename to c64/kernal/interrupts/ea31.interop
diff --git a/c64/kernal/ea7e.s b/c64/kernal/interrupts/ea7e.ack_cia1_return_from_interrupt.s
similarity index 100%
rename from c64/kernal/ea7e.s
rename to c64/kernal/interrupts/ea7e.ack_cia1_return_from_interrupt.s
diff --git a/c64/kernal/ea81.s b/c64/kernal/interrupts/ea81.return_from_interrupt.s
similarity index 100%
rename from c64/kernal/ea81.s
rename to c64/kernal/interrupts/ea81.return_from_interrupt.s
diff --git a/c64/kernal/interrupts/fe47.default_nmi_handler.s b/c64/kernal/interrupts/fe47.default_nmi_handler.s
index be183b26..fac6d0a7 100644
--- a/c64/kernal/interrupts/fe47.default_nmi_handler.s
+++ b/c64/kernal/interrupts/fe47.default_nmi_handler.s
@@ -1,7 +1,11 @@
 
 default_nmi_handler:
 
-	;; XXX provide real implementation
+	;; XXX implement according to Compute's Mapping the Commodore 64, page 74
+
+	;; XXX check if the source was RESTORE key, quit if it wasn't (no RS-232 support)
+	;; XXX if cartridge present, enter it through warm start vector
+	;; XXX if stop pressed, go to default_brk_handler
 
 	inc $D020
 	rti
diff --git a/c64/kernal/fe47.interop b/c64/kernal/interrupts/fe47.interop
similarity index 100%
rename from c64/kernal/fe47.interop
rename to c64/kernal/interrupts/fe47.interop
diff --git a/c64/kernal/interrupts/fe66.default_brk_handler.s b/c64/kernal/interrupts/fe66.default_brk_handler.s
index 54232eeb..230be89d 100644
--- a/c64/kernal/interrupts/fe66.default_brk_handler.s
+++ b/c64/kernal/interrupts/fe66.default_brk_handler.s
@@ -1,6 +1,11 @@
+
 default_brk_handler:
 
-	;; XXX implement this!
+	;; Implemented according to Compute's Mapping the Commodore 64, pages 73-74
+
+	jsr JRESTOR
+	jsr JIOINIT
+	jsr CINT_BRK
+
+	jmp (IBASIC_WARM_START)
 
-	;; Acknowledge CIA interrupt and return
-	jmp clear_cia1_interrupt_flag_and_return_from_interrupt
diff --git a/c64/kernal/fe66.interop b/c64/kernal/interrupts/fe66.interop
similarity index 100%
rename from c64/kernal/fe66.interop
rename to c64/kernal/interrupts/fe66.interop
diff --git a/c64/kernal/interrupts/irq_handler.s b/c64/kernal/interrupts/irq_handler.s
index 82bbaac7..74d1eb78 100644
--- a/c64/kernal/interrupts/irq_handler.s
+++ b/c64/kernal/interrupts/irq_handler.s
@@ -1,3 +1,4 @@
+
 irq_handler:
 	;; The IRQ is a commonly messed with thing on the C64,
 	;; so we need to handle entry points that are commonly
@@ -7,17 +8,18 @@ irq_handler:
 	;; $EA81 - https://www.lemon64.com/forum/viewtopic.php?t=2112&sid=6ea01982b26da69783120a7923ca46fb
 	;; Also the $0314 vector is widely used (e.g., https://www.lemon64.com/forum/viewtopic.php?t=2112&sid=6ea01982b26da69783120a7923ca46fb)
 
-	;; Save registers
-	;; Sequence according to Compute's Mapping the 64 p73
+	;; Save registers, sequence according to Compute's Mapping the Commodore 64, page 73
 	pha
 	txa
 	pha
 	tya
 	pha
 
-	;; Call interrupt routine
-	;; (but only if initialised)
+	;; Call interrupt routine (only if initialised)
 	lda CINV
 	ora CINV+1
-	beq default_irq_handler
+	bne +
 	jmp (CINV)
+*
+	;; Vector not initialized - call default interrupt routine
+	jmp default_irq_handler
diff --git a/c64/kernal/interrupts/nmi_handler.s b/c64/kernal/interrupts/nmi_handler.s
index 652070f1..220ec401 100644
--- a/c64/kernal/interrupts/nmi_handler.s
+++ b/c64/kernal/interrupts/nmi_handler.s
@@ -1,5 +1,7 @@
 
 nmi_handler:
 
+	;; XXX provide real implementation
+
 	jmp (NMINV)