diff --git a/host/mainloop.s b/host/mainloop.s
new file mode 100644
index 0000000..65854b1
--- /dev/null
+++ b/host/mainloop.s
@@ -0,0 +1,45 @@
+;;; -*- Mode: asm; indent-tabs-mode: t; tab-width: 8 -*-
+.scope mainsetup
+	USERPROG	=	$C000
+	.repeat 4, I
+	ldy #$00
+:
+	lda batch_userprog+(I*256),Y
+	sta USERPROG+(I*256),Y
+	dey
+	bne :-
+	.endrep
+.endscope
+
+.scope mainloop
+ml:
+	USERPROG	=	$C000
+	RASTER		=	$D012
+	;; Currently no code for fetching new programs, since we're testing with
+	;; batch compiled version of the whole to begin with.
+
+	;; Bank in character ROM
+	lda #%11111011
+	and $01
+	sta $01
+
+	jsr USERPROG
+
+	;; Bank out character ROM, I/O in
+	lda #%00000100
+	ora $01
+	sta $01
+@framewait:
+	ldy RASTER
+	cpy #$66
+	beq @framewait
+	inc FRAMECOUNT
+	jmp ml
+.endscope
+
+.proc time			; user-procedure
+	lda FRAMECOUNT
+	rts
+.endproc
+
+FRAMECOUNT:	.byte 0