diff --git a/host/src/STARTUP.s b/host/src/STARTUP.s
index bff5f06..26eb5a2 100755
--- a/host/src/STARTUP.s
+++ b/host/src/STARTUP.s
@@ -1,6 +1,6 @@
 ;;; -*- Mode: asm; indent-tabs-mode: t; tab-width: 8 -*-
 
-.scope STARTUP
+.proc STARTUP
         ;; Settings positions
         CR1 = $d011; Graphic settings
         VIC_bank_settings = $DD00 ; Vic position
@@ -69,8 +69,7 @@
 
         ;; Disable maskeble interups (not all)
         SEI
-        ;; Set up bank switching.
-	;; Disable BASIC and KERNAL(sic) ROM, keep I/O
+        ;; Disable BASIC ROM mohahaha
 	;; https://www.c64-wiki.com/wiki/Bank_Switching
         LDA #%11111000
         AND $01
@@ -81,29 +80,36 @@
 
         ;;Disable non maskable interupts
         ;;https://codebase64.org/doku.php?id=base:nmi_lock_without_kernal
-        ;; write to $FFFA/$FFFB possible (and needed) if KERNAL ROM is disabled
+        ;; write to $FFFA/$FFFB possible (and needed) if BASIC ROM is disabled
 
         LDA #<NMI_routine
         STA $FFFA
         LDA #>NMI_routine
         STA $FFFB
-        LDA #$00  ;; stop Timer A
-        STA $DD0E
-        STA $DD04 ;; set Timer A to 0, after starting
-        STA $DD05 ;; NMI will occur immediately
-        LDA #$81
-        STA $DD0D ;; set Timer A as source for NMI
-        LDA #$01
-        STA $DD0E ;; start Timer A -> NMI
-        ;; from here on NMI is disabled
-
-	;; Set up IRQ for userprog transfer timer
 	LDA #<IRQ_routine
 	STA $FFFE
 	LDA #>IRQ_routine
 	STA $FFFF
-
+        LDA #%00101000  ;; stop Timer A
+        STA $DD0E
+        STA $DD04 ;; set Timer A to 0, after starting
+        STA $DD05 ;; NMI will occur immediately
+        LDA #$80
+        STA $DD0D ;; set Timer A as source for NMI
+        LDA #%00101000
+        STA $DD0E ;; start Timer A -> NMI
+        ;; from here on NMI is disabled
         JMP mainsetup
 NMI_routine:
-        RTI ;; exit interrupt not acknowledged
-.endscope
+	BIT $DD0D
+	LDA #%11111110
+	STA $DD0D
+	JMP STARTUP
+IRQ_routine:
+	PHA
+	BIT $DC0D
+	LDA #$00
+	STA $DC0D
+	PLA
+	RTI
+.endproc
diff --git a/host/src/mainloop.s b/host/src/mainloop.s
index 3aac8d7..c6a17bb 100644
--- a/host/src/mainloop.s
+++ b/host/src/mainloop.s
@@ -1,6 +1,5 @@
 ;;; -*- Mode: asm; indent-tabs-mode: t; tab-width: 8 -*-
-mainsetup:
-.scope mainsetup
+.proc mainsetup
  	USERPROG	=	$C000
 .repeat 4, I
  	ldy #$00
@@ -10,60 +9,20 @@ mainsetup:
  	dey
  	bne :-
 .endrep
+.endproc
 
-@waitstart: ;; Wait until joystick 2 has been pulled down to start the program
-	dec $d020
-
-	lda #%11111111
-	sta $dc02
-	lda #%00000000
-	sta $dc03
-
-	lda #%01111111
-	sta $dc00
-
-	lda $dc01
-	eor #$ff
-	beq @waitstart
-
-	lda #%00000000
-	sta $dc02
-
-endsetup:
-	DOWNLOAD_TIMER	=	$FFFF
+mainstart:
 	lda #$0d
 	sta $d020
 
-	;; Turn on CIA 1's Timer A as IRQ source Summary: Timer A counts down
-	;; for 0xFFFF cycles. When it finishes, an IRQ is sent to the
-	;; CPU. Once it's ready to receive it, the IRQ routine is called,
-	;; which checks if a userprog download is beginning. If it is, we
-	;; download and reset the unwind the stack. The transfer hardware has
-	;; a certain delay between the transfer command being sent and the
-	;; start of bits being sent. This duration must be some amount longer
-	;; than the timer's duration to account for variable execution time of
-	;; interrupt-free routines.
-
-	sei 			; let's be extra sure interrupts are disabled
-
-	lda #<DOWNLOAD_TIMER
-	sta $dc04		; Timer A's counter low byte
-	lda #>DOWNLOAD_TIMER
-	sta $dc05		; Likewise for high byte
-
-	lda #%10000001		; Send IRQ to CPU when Timer A is done
-	sta $dc0d
-
-	lda #%00011001		; Start Timer A, one-shot mode, cycle counting mode
-	sta $dc0e
+.scope mainloop
 
 	ldx #$00
 	stx FRAMECOUNT
 	inx
 	sta FIRSTTIME
-.endscope
 
-.proc mainloop
+ml:
 	USERPROG	=	$C000
 	RASTER		=	$D012
 
@@ -72,9 +31,19 @@ endsetup:
 	ora $01
 	sta $01
 
-	cli
+	jsr maybe_download_userprog
+	beq @nochange
+	ldx #$00
+	stx FRAMECOUNT
+	inx
+	sta FIRSTTIME
+@nochange:
 	jsr USERPROG
 
+	;; Bank out character ROM, I/O in
+	lda #%00000100
+	ora $01
+	sta $01
 @framewait:
 	ldy RASTER
 	cpy #$66
@@ -82,8 +51,8 @@ endsetup:
 	inc FRAMECOUNT
 	lda #$00
 	sta FIRSTTIME
-	jmp mainloop
-.endproc
+	jmp ml
+.endscope
 
 .proc time			; user-procedure
 	lda FRAMECOUNT
@@ -107,41 +76,7 @@ endsetup:
 	rts
 .endproc
 
-.proc reset_userprog
-	ldx #$00
-	stx FRAMECOUNT
-	inx
-	sta FIRSTTIME
-.endproc
 
 FRAMECOUNT:	.byte 0
 FIRSTTIME:	.byte 1
-
-IRQ_routine:
-	lda $dc0d		; Check CIA 1's status
-	beq @somethingelse
-	jsr maybe_download_userprog
-	beq @done
-	jsr reset_userprog
-
-	;; Reconstruct the stack to exit to toplevel
-	ldx #$00
-	txs
-	lda #<mainloop
-	pha
-	lda #>mainloop
-	pha
-	txa
-	pha
-
-	lda #%00011001		; Start Timer A, one-shot mode, cycle counting
-	sta $dc0e
-
-	rti
-
-@somethingelse:
-	;; TODO: Ack potential VIC-II IRQ
-@done:
-	lda #%00011001		; Start Timer A, one-shot mode, cycle counting
-	sta $dc0e
-	rti
+RESTORE_DEST:	.word mainsetup