--- min_mon.asm.asl	2012-01-29 14:29:39.000000000 -0800
+++ min_mon.asm	2012-01-29 19:54:43.000000000 -0800
@@ -1,3 +1,4 @@
+	page	0
 
 ; minimal monitor for EhBASIC and 6502 simulator V1.05
 
@@ -5,6 +6,7 @@
 ; running [F6] then start the code with the RESET [CTRL][SHIFT]R. Just selecting RUN
 ; will do nothing, you'll still have to do a reset to run the code.
 
+	include	"bitfuncs.inc"		; required so that hi() and lo() work
 	include "basic.asm"
 
 ; put the IRQ and MNI code in RAM so that it can be changed
@@ -12,18 +14,14 @@
 IRQ_vec	= VEC_SV+2		; IRQ code vector
 NMI_vec	= IRQ_vec+$0A	; NMI code vector
 
-; setup for the 6502 simulator environment
-
-IO_AREA	= $F000		; set I/O area for this monitor
-
-ACIAsimwr	= IO_AREA+$01	; simulated ACIA write port
-ACIAsimrd	= IO_AREA+$04	; simulated ACIA read port
+sercsr	equ	$c000
+serdata	equ	$c001
 
 ; now the code. all this does is set up the vectors and interrupt code
 ; and wait for the user to select [C]old or [W]arm start. nothing else
 ; fits in less than 128 bytes
 
-	org	$FF80			; pretend this is in a 1/8K ROM
+	org	$b000
 
 ; reset vector points here
 
@@ -41,6 +39,12 @@
 	DEY				; decrement index/count
 	BNE	LAB_stlp		; loop if more to do
 
+serinit:
+	lda	#3		; code to reset ACIA
+	sta	sercsr
+	lda	#$15		; interrupts off, 8N1, div by 16
+	sta	sercsr
+
 ; now do the signon message, Y = $00 here
 
 LAB_signon
@@ -67,23 +71,31 @@
 LAB_dowarm
 	JMP	LAB_WARM		; do EhBASIC warm start
 
-; byte out to simulated ACIA
-
-ACIAout
-	STA	ACIAsimwr		; save byte to simulated ACIA
-	RTS
-
-; byte in from simulated ACIA
-
-ACIAin
-	LDA	ACIAsimrd		; get byte from simulated ACIA
-	BEQ	LAB_nobyw		; branch if no byte waiting
+output
+	pha				; save byte to be output
+outlp
+	lda	sercsr
+	and	#2			; check for transmit data reg empty
+	beq	outlp
+	pla
+	sta	serdata
+	cmp	#0			; N and Z flags should reflect char in A
+	rts
+
+input
+	lda	sercsr			; check for byte received
+	and	#1
+	beq	no_input
+
+	lda	serdata
+
+	sec				; set carry
+	rts
+
+no_input
+	clc				; clear carry (A already zero)
+	rts
 
-	SEC				; flag byte received
-	RTS
-
-LAB_nobyw
-	CLC				; flag no byte received
 no_load				; empty load vector for EhBASIC
 no_save				; empty save vector for EhBASIC
 	RTS
@@ -91,8 +103,8 @@
 ; vector tables
 
 LAB_vec
-	fdb	ACIAin		; byte in from simulated ACIA
-	fdb	ACIAout		; byte out to simulated ACIA
+	fdb	input		; input byte from serial port (non-blocking)
+	fdb	output		; output byte to serial port
 	fdb	no_load		; null load vector for EhBASIC
 	fdb	no_save		; null save vector for EhBASIC
 
@@ -123,12 +135,3 @@
 LAB_mess
 	fcb	$0D,$0A,"6502 EhBASIC [C]old/[W]arm ?",$00
 					; sign on string
-
-; system vectors
-
-	org	$FFFA
-
-	fdb	NMI_vec		; NMI vector
-	fdb	RES_vec		; RESET vector
-	fdb	IRQ_vec		; IRQ vector
-