diff --git a/Source/HBIOS/hbios.asm b/Source/HBIOS/hbios.asm
index db40c88e..c73dff3a 100644
--- a/Source/HBIOS/hbios.asm
+++ b/Source/HBIOS/hbios.asm
@@ -598,28 +598,6 @@ INT_IM1:
 ;	JR	HBX_INT			; GO TO ROUTING CODE
 ;  #ENDIF
 ;;
-;#IF (PIO_ZP)
-;INT_ZP0:	; PIO INTERRUPT HANDLER
-;	PUSH	HL			; SAVE HL
-;	LD	HL,PIO0INT		; HL := PIO INT HANDLER IN BIOS BANK
-;	JR	HBX_INT			; GO TO ROUTING CODE
-;INT_ZP1
-;	PUSH	HL			; SAVE HL
-;	LD	HL,PIO1INT		; HL := PIO INT HANDLER IN BIOS BANK
-;	JR	HBX_INT			; GO TO ROUTING CODE
-;#ENDIF
-;;
-;#IF (PIO_4P)
-;INT_4P0:	; PIO INTERRUPT HANDLER
-;	PUSH	HL			; SAVE HL
-;	LD	HL,PIO2INT		; HL := PIO INT HANDLER IN BIOS BANK
-;	JR	HBX_INT			; GO TO ROUTING CODE
-;INT_4P1:
-;	PUSH	HL			; SAVE HL
-;	LD	HL,PIO3INT		; HL := PIO INT HANDLER IN BIOS BANK
-;	JR	HBX_INT			; GO TO ROUTING CODE
-;#ENDIF
-;;
 ;#ENDIF
 ;
 #IF (INTMODE > 0)
@@ -967,6 +945,20 @@ HB_START1:				; BNKCALL ARRIVES HERE, BUT NOW RUNNING IN RAM BANK
 	LD	HL,MSG_HBVER
 	CALL	DSKY_SHOWSEG
 #ENDIF
+
+#IF	(WBWDEBUG=USEMIO)		; BUFFER OUTPUT UNTIL
+	CALL	MIO_INIT		; WE GET TO BOOT MESSAGE
+#ENDIF
+;
+; TEST DEBUG ***************************************************************************************
+;
+	PRTS("DEBUG-IVT$")
+	LD	DE,HB_IVT
+	CALL	DUMP_BUFFER
+	CALL	NEWLINE
+;
+; TEST DEBUG ***************************************************************************************
+;
 ;
 ; DISCOVER CPU TYPE
 ;
@@ -1039,6 +1031,14 @@ HB_CPU1:
 ;
 ; PRE-CONSOLE INITIALIZATION
 ;
+
+; TEST DEBUG ***************************************************************************************
+;
+	CALL	NEWLINE
+	CALL	REGDMP
+;
+; TEST DEBUG ***************************************************************************************
+;
 #IF (ASCIENABLE)
 	CALL	ASCI_PREINIT
 #ENDIF
@@ -1054,15 +1054,48 @@ HB_CPU1:
 #IF (PIO_4P | PIO_ZP)
 	CALL	PIO_PREINIT
 #ENDIF
+; TEST DEBUG ***************************************************************************************
+;
+	CALL	NEWLINE
+	CALL	REGDMP
+;
+; TEST DEBUG ***************************************************************************************
 ;
 	DIAG(%01111111)
 ;
-; PRIOR TO THIS POINT, CONSOLE I/O WAS DIRECTED TO HARDWARE (XIO.ASM).
+; PRIOR TO THIS POINT, CONSOLE I/O WAS NOT AVAILABLE UNLESS DIRECTED TO DEBUG OUTPUT I.E. XIO
 ; NOW THAT HBIOS IS READY, SET THE CONSOLE UNIT TO ACTIVATE CONSOLE I/O
 ; VIA HBIOS.
 ;
 	XOR	A			; INITIALLY, FIRST SERIAL UNIT IS CONSOLE
 	LD	(CB_CONDEV),A		; SAVE IT, ACTIVATES CONSOLE ON HBIOS
+
+#IF	(WBWDEBUG=USEMIO)		; OUTPUT ANY CACHED DEBUG TEXT
+	LD	HL,MIOOUTPTR
+	LD	E,(HL)
+	INC	HL
+	LD	D,(HL)
+	INC	HL
+NXTMIO:	LD	A,(HL)
+	CALL	COUT
+	INC	HL
+	LD	A,L
+	CP	E
+	JR	NZ,NXTMIO
+	LD	A,H
+	CP	D
+	JR	NZ,NXTMIO
+;	CALL	WRITESTR		; WRITESTR WILL WORK WILL ONLY PRINT UP TO FIRST $
+#ENDIF
+;
+; TEST DEBUG ***************************************************************************************
+;
+	CALL	NEWLINE2
+	PRTS("DEBUG+IVT$")
+	LD	DE,HB_IVT
+	CALL	DUMP_BUFFER
+;
+; TEST DEBUG ***************************************************************************************
 ;
 ; ANNOUNCE HBIOS
 ;
@@ -2728,7 +2761,13 @@ SIZ_PIO		.EQU	$ - ORG_PIO
 #INCLUDE "time.asm"
 #INCLUDE "bcd.asm"
 #INCLUDE "decode.asm"
-;#INCLUDE "xio.asm"
+;
+#IF	WBWDEBUG=USEXIO
+#INCLUDE "xio.asm"
+#ENDIF
+#IF	WBWDEBUG=USEMIO
+#INCLUDE "mio.asm"
+#ENDIF
 ;
 #IF (DSKYENABLE)
 #DEFINE	DSKY_KBD
@@ -3511,7 +3550,7 @@ COUT:
 	LD	E,A			; TEMPORARILY STASH OUTPUT CHAR IN E
 	LD	A,(CB_CONDEV)		; GET CONSOLE UNIT BYTE
 	CP	$FF			; TEST FOR $FF (HBIOS NOT READY)
-	JR	Z,COUT1			; IF NOT READY, USE XIO
+	JR	Z,COUT1			; IF NOT READY, TRY DEBUG OUTPUT
 ;
 	; USE HBIOS
 	LD	C,A			; CONSOLE UNIT TO C
@@ -3520,9 +3559,15 @@ COUT:
 	JR	COUT2			; CONTINUE
 ;
 COUT1:
-	;; USE XIO
-	;LD	A,E			; GET OUTPUT CHAR BACK TO ACCUM
-	;CALL	XIO_OUTC		; OUTPUT VIA XIO
+;	
+#IF	WBWDEBUG=USEXIO
+	LD	A,E			; GET OUTPUT CHAR BACK TO ACCUM
+	CALL	XIO_OUTC		; OUTPUT VIA XIO
+#ENDIF
+#IF	WBWDEBUG=USEMIO
+	LD	A,E
+	CALL	MIO_OUTC		; OUTPUT VIA MIO
+#ENDIF
 ;
 COUT2:
 	; RESTORE ALL REGISTERS
@@ -3542,7 +3587,7 @@ CIN:
 ;
 	LD	A,(CB_CONDEV)		; GET CONSOLE UNIT BYTE
 	CP	$FF			; TEST FOR $FF (HBIOS NOT READY)
-	JR	Z,CIN1			; IF NOT READY, USE XIO
+	JR	Z,CIN1			; IF NOT READY, TRY DEBUG INPUT
 ;
 	; USE HBIOS
 	LD	C,A			; CONSOLE UNIT TO C
@@ -3552,8 +3597,13 @@ CIN:
 	JR	CIN2			; CONTINUE
 ;
 CIN1:
-	;; USE XIO
-	;CALL	XIO_INC			; GET CHAR
+;
+#IF	WBWDEBUG=USEXIO
+	CALL	XIO_INC			; GET CHAR
+#ENDIF
+#IF	WBWDEBUG=USEMIO
+	CALL	MIO_INC			; GET CHAR
+#ENDIF
 ;
 CIN2:
 ;
@@ -3573,7 +3623,7 @@ CST:
 ;
 	LD	A,(CB_CONDEV)		; GET CONSOLE UNIT BYTE
 	CP	$FF			; TEST FOR $FF (HBIOS NOT READY)
-	JR	Z,CST1			; IF NOT READY, USE XIO
+	JR	Z,CST1			; IIF NOT READY, TRY DEBUG DEBUG STATUS
 ;
 	; USE HBIOS
 	LD	C,A			; CONSOLE UNIT TO C
@@ -3582,8 +3632,13 @@ CST:
 	JR	CST2			; CONTINUE
 ;
 CST1:
-	;; USE XIO
-	;CALL	XIO_IST			; GET STATUS
+;
+#IF	WBWDEBUG=USEXIO
+	CALL	XIO_IST			; GET STATUS
+#ENDIF
+#IF	WBWDEBUG=USEMIO
+	CALL	MIO_IST			; GET STATUS
+#ENDIF
 ;
 CST2:
 	; RESTORE REGISTERS (AF IS OUTPUT)
diff --git a/Source/HBIOS/mio.asm b/Source/HBIOS/mio.asm
new file mode 100644
index 00000000..850a6195
--- /dev/null
+++ b/Source/HBIOS/mio.asm
@@ -0,0 +1,49 @@
+;___MIO________________________________________________________________________________________________________________
+;
+; MEMORY MAPPED I/O
+;
+;   PROVIDES AN INTERFACE TO BUFFER OUTPUT FROM PRE-INITIALIZATION 
+;   FUNCTIONS PRIOR TO OTHER OUTPUT METHODS BEING AVAILABLE
+;______________________________________________________________________________________________________________________
+;
+; $ CODE NOT STRICTLY REQUIRED.
+;
+MIOOUTPTR	.EQU	BNKTOP
+;
+MIO_INIT:				; MINIMAL INIT
+	PUSH	HL
+	LD	HL,MIOOUTPTR+2
+	LD	(MIOOUTPTR),HL
+	LD	(HL),'$'
+	POP	HL
+	RET
+;
+MIO_OUTC:	; OUTPUT BYTE IN A
+	PUSH	HL
+	PUSH	DE
+	LD	HL,MIOOUTPTR
+	LD	E,(HL)
+	INC	HL
+	LD	D,(HL)
+	LD	H,D
+	LD	L,E
+	LD	(HL),A
+	INC	HL
+	LD	(MIOOUTPTR),HL
+	LD	(HL),'$'
+	POP	DE
+	POP	HL
+	RET
+;
+; NOT USED AT THE MOMENT
+;
+MIO_INC:	; INPUT BYTE TO A
+	LD	A,'$'
+	RET
+;
+;
+MIO_IST:	; INPUT STATUS TO A (NUM CHARS WAITING)
+	LD	A,1
+	OR	A
+	RET				; DONE
+;
\ No newline at end of file
diff --git a/Source/HBIOS/std.asm b/Source/HBIOS/std.asm
index 77f9404c..e7822b92 100644
--- a/Source/HBIOS/std.asm
+++ b/Source/HBIOS/std.asm
@@ -27,6 +27,13 @@
 FALSE		.EQU 	0
 TRUE		.EQU 	~FALSE
 ;
+; DEBUGGNG OPTIONS
+;
+USENONE		.EQU	0		; NO DEBUG
+USEXIO		.EQU	1		; BASIC SERIAL DRIVER
+USEMIO		.EQU	2		; MEMORY BUFFER DRIVER
+WBWDEBUG	.EQU	USENONE
+;
 ; PRIMARY HARDWARE PLATFORMS
 ;
 PLT_SBC		.EQU	1		; SBC ECB Z80 SBC