diff --git a/Source/HBIOS/Config/RCZ80_kio.asm b/Source/HBIOS/Config/RCZ80_kio.asm
index d4cbea78..f096c73d 100644
--- a/Source/HBIOS/Config/RCZ80_kio.asm
+++ b/Source/HBIOS/Config/RCZ80_kio.asm
@@ -40,6 +40,8 @@ SIOENABLE	.SET	TRUE		; SIO: ENABLE ZILOG SIO SERIAL DRIVER (SIO.ASM)
 SIOCNT		.SET	1		; SIO: NUMBER OF CHIPS TO DETECT (1-2), 2 CHANNELS PER CHIP
 SIO0MODE	.SET	SIOMODE_EZZ80	; SIO 0: CHIP TYPE: SIOMODE_[RC|SMB|ZP|EZZ80]
 SIO0BASE	.SET	KIOBASE+$08	; SIO 0: REGISTERS BASE ADR
+SIO0ACLK	.SET	1843200		; SIO 0A: OSC FREQ IN HZ, ZP=2457600/4915200, RC/SMB=7372800
+SIO0BCLK	.SET	1843200		; SIO 0B: OSC FREQ IN HZ, ZP=2457600/4915200, RC/SMB=7372800
 ;
 FDENABLE	.SET	FALSE		; FD: ENABLE FLOPPY DISK DRIVER (FD.ASM)
 FDMODE		.SET	FDMODE_RCWDC	; FD: DRIVER MODE: FDMODE_[DIO|ZETA|DIDE|N8|DIO3]
diff --git a/Source/HBIOS/cfg_ezz80.asm b/Source/HBIOS/cfg_ezz80.asm
index 256b8b40..692524c5 100644
--- a/Source/HBIOS/cfg_ezz80.asm
+++ b/Source/HBIOS/cfg_ezz80.asm
@@ -45,6 +45,7 @@ CTCBASE		.EQU	$88		; CTC BASE I/O ADDRESS
 ;
 DIAGENABLE	.EQU	FALSE		; ENABLES OUTPUT TO 8 BIT LED DIAGNOSTIC PORT
 DIAGPORT	.EQU	$00		; DIAGNOSTIC PORT ADDRESS
+DIAGDISKIO	.EQU	TRUE		; ENABLES DISK I/O ACTIVITY ON DIAGNOSTIC LEDS
 ;
 DSKYENABLE	.EQU	FALSE		; ENABLES DSKY (DO NOT COMBINE WITH PPIDE)
 ;
diff --git a/Source/HBIOS/cfg_master.asm b/Source/HBIOS/cfg_master.asm
index 11f11006..add48b40 100644
--- a/Source/HBIOS/cfg_master.asm
+++ b/Source/HBIOS/cfg_master.asm
@@ -63,6 +63,7 @@ CTCBASE		.EQU	$20		; CTC BASE I/O ADDRESS
 ;
 DIAGENABLE	.EQU	FALSE		; ENABLES OUTPUT TO 8 BIT LED DIAGNOSTIC PORT
 DIAGPORT	.EQU	$00		; DIAGNOSTIC PORT ADDRESS
+DIAGDISKIO	.EQU	TRUE		; ENABLES DISK I/O ACTIVITY ON DIAGNOSTIC LEDS
 ;
 DSKYENABLE	.EQU	FALSE		; ENABLES DSKY (DO NOT COMBINE WITH PPIDE)
 ;
diff --git a/Source/HBIOS/cfg_mk4.asm b/Source/HBIOS/cfg_mk4.asm
index 1b374069..8f2cceb4 100644
--- a/Source/HBIOS/cfg_mk4.asm
+++ b/Source/HBIOS/cfg_mk4.asm
@@ -49,6 +49,7 @@ CTCENABLE	.EQU	FALSE		; ENABLE ZILOG CTC SUPPORT
 ;
 DIAGENABLE	.EQU	FALSE		; ENABLES OUTPUT TO 8 BIT LED DIAGNOSTIC PORT
 DIAGPORT	.EQU	$00		; DIAGNOSTIC PORT ADDRESS
+DIAGDISKIO	.EQU	TRUE		; ENABLES DISK I/O ACTIVITY ON DIAGNOSTIC LEDS
 ;
 DSKYENABLE	.EQU	FALSE		; ENABLES DSKY (DO NOT COMBINE WITH PPIDE)
 ;
diff --git a/Source/HBIOS/cfg_n8.asm b/Source/HBIOS/cfg_n8.asm
index 3dacdd9b..5ff655bb 100644
--- a/Source/HBIOS/cfg_n8.asm
+++ b/Source/HBIOS/cfg_n8.asm
@@ -52,6 +52,7 @@ CTCENABLE	.EQU	FALSE		; ENABLE ZILOG CTC SUPPORT
 ;
 DIAGENABLE	.EQU	FALSE		; ENABLES OUTPUT TO 8 BIT LED DIAGNOSTIC PORT
 DIAGPORT	.EQU	$00		; DIAGNOSTIC PORT ADDRESS
+DIAGDISKIO	.EQU	TRUE		; ENABLES DISK I/O ACTIVITY ON DIAGNOSTIC LEDS
 ;
 DSKYENABLE	.EQU	FALSE		; ENABLES DSKY (DO NOT COMBINE WITH PPIDE)
 ;
diff --git a/Source/HBIOS/cfg_rcz180.asm b/Source/HBIOS/cfg_rcz180.asm
index ddcd94d3..dc009336 100644
--- a/Source/HBIOS/cfg_rcz180.asm
+++ b/Source/HBIOS/cfg_rcz180.asm
@@ -49,6 +49,7 @@ CTCENABLE	.EQU	FALSE		; ENABLE ZILOG CTC SUPPORT
 ;
 DIAGENABLE	.EQU	TRUE		; ENABLES OUTPUT TO 8 BIT LED DIAGNOSTIC PORT
 DIAGPORT	.EQU	$00		; DIAGNOSTIC PORT ADDRESS
+DIAGDISKIO	.EQU	TRUE		; ENABLES DISK I/O ACTIVITY ON DIAGNOSTIC LEDS
 ;
 DSKYENABLE	.EQU	FALSE		; ENABLES DSKY (DO NOT COMBINE WITH PPIDE)
 ;
diff --git a/Source/HBIOS/cfg_rcz80.asm b/Source/HBIOS/cfg_rcz80.asm
index 9bcc308c..5361832e 100644
--- a/Source/HBIOS/cfg_rcz80.asm
+++ b/Source/HBIOS/cfg_rcz80.asm
@@ -44,6 +44,7 @@ CTCBASE		.EQU	$88		; CTC BASE I/O ADDRESS
 ;
 DIAGENABLE	.EQU	TRUE		; ENABLES OUTPUT TO 8 BIT LED DIAGNOSTIC PORT
 DIAGPORT	.EQU	$00		; DIAGNOSTIC PORT ADDRESS
+DIAGDISKIO	.EQU	TRUE		; ENABLES DISK I/O ACTIVITY ON DIAGNOSTIC LEDS
 ;
 DSKYENABLE	.EQU	FALSE		; ENABLES DSKY (DO NOT COMBINE WITH PPIDE)
 ;
diff --git a/Source/HBIOS/cfg_sbc.asm b/Source/HBIOS/cfg_sbc.asm
index 8e7fa1dd..ded8a6e0 100644
--- a/Source/HBIOS/cfg_sbc.asm
+++ b/Source/HBIOS/cfg_sbc.asm
@@ -41,6 +41,7 @@ CTCENABLE	.EQU	FALSE		; ENABLE ZILOG CTC SUPPORT
 ;
 DIAGENABLE	.EQU	FALSE		; ENABLES OUTPUT TO 8 BIT LED DIAGNOSTIC PORT
 DIAGPORT	.EQU	$00		; DIAGNOSTIC PORT ADDRESS
+DIAGDISKIO	.EQU	TRUE		; ENABLES DISK I/O ACTIVITY ON DIAGNOSTIC LEDS
 ;
 DSKYENABLE	.EQU	FALSE		; ENABLES DSKY (DO NOT COMBINE WITH PPIDE)
 ;
diff --git a/Source/HBIOS/cfg_sc126.asm b/Source/HBIOS/cfg_sc126.asm
index a853fa45..10d18e74 100644
--- a/Source/HBIOS/cfg_sc126.asm
+++ b/Source/HBIOS/cfg_sc126.asm
@@ -44,6 +44,7 @@ CTCENABLE	.EQU	FALSE		; ENABLE ZILOG CTC SUPPORT
 ;
 DIAGENABLE	.EQU	TRUE		; ENABLES OUTPUT TO 8 BIT LED DIAGNOSTIC PORT
 DIAGPORT	.EQU	$0D		; DIAGNOSTIC PORT ADDRESS
+DIAGDISKIO	.EQU	TRUE		; ENABLES DISK I/O ACTIVITY ON DIAGNOSTIC LEDS
 ;
 DSKYENABLE	.EQU	FALSE		; ENABLES DSKY (DO NOT COMBINE WITH PPIDE)
 ;
diff --git a/Source/HBIOS/cfg_zeta.asm b/Source/HBIOS/cfg_zeta.asm
index 1a791066..f32ee166 100644
--- a/Source/HBIOS/cfg_zeta.asm
+++ b/Source/HBIOS/cfg_zeta.asm
@@ -41,6 +41,7 @@ CTCENABLE	.EQU	FALSE		; ENABLE ZILOG CTC SUPPORT
 ;
 DIAGENABLE	.EQU	FALSE		; ENABLES OUTPUT TO 8 BIT LED DIAGNOSTIC PORT
 DIAGPORT	.EQU	$00		; DIAGNOSTIC PORT ADDRESS
+DIAGDISKIO	.EQU	TRUE		; ENABLES DISK I/O ACTIVITY ON DIAGNOSTIC LEDS
 ;
 DSKYENABLE	.EQU	FALSE		; ENABLES DSKY (DO NOT COMBINE WITH PPIDE)
 ;
diff --git a/Source/HBIOS/cfg_zeta2.asm b/Source/HBIOS/cfg_zeta2.asm
index 175ce240..40ea8bd2 100644
--- a/Source/HBIOS/cfg_zeta2.asm
+++ b/Source/HBIOS/cfg_zeta2.asm
@@ -45,6 +45,7 @@ CTCBASE		.EQU	$20		; CTC BASE I/O ADDRESS
 ;
 DIAGENABLE	.EQU	FALSE		; ENABLES OUTPUT TO 8 BIT LED DIAGNOSTIC PORT
 DIAGPORT	.EQU	$00		; DIAGNOSTIC PORT ADDRESS
+DIAGDISKIO	.EQU	TRUE		; ENABLES DISK I/O ACTIVITY ON DIAGNOSTIC LEDS
 ;
 DSKYENABLE	.EQU	FALSE		; ENABLES DSKY (DO NOT COMBINE WITH PPIDE)
 ;
diff --git a/Source/HBIOS/hbios.asm b/Source/HBIOS/hbios.asm
index 7be689d8..4f36da3f 100644
--- a/Source/HBIOS/hbios.asm
+++ b/Source/HBIOS/hbios.asm
@@ -995,7 +995,7 @@ HB_CPU1:
 #IF (KIOENABLE)
 	LD	A,%11111001	; RESET ALL DEVICES, SET DAISYCHAIN
 	OUT	(KIOBASE+$0E),A	; DO IT
-	CALL	DLY64		; WAIT A BIT FOR RESET TO COMPLETE
+	;CALL	DLY64		; WAIT A BIT FOR RESET TO COMPLETE
 #ENDIF  
 ;
 ; SETUP INTERRUPT VECTORS, AS APPROPRIATE
@@ -1158,7 +1158,7 @@ HB_CPU1:
 ;
 ; FOR NOW, THIS IS SPECIFICALLY FOR A CTC TO DRIVE AN SIO
 ; AT 1:1 USING CTC CHANNELS A & B.  IN OTHER WORDS, IT JUST
-; PASSES THE INCOMING TRIGGER OUT AT 1:1.  NO INTERRUPTS.
+; PASSES THE INCOMING TRIGGER OUT AT 1:1.
 ;
   #IF (CTCENABLE == TRUE)
 ;
@@ -1206,7 +1206,7 @@ HB_CPU1:
 	LD	A,0
 	OUT	(CTCA),A		; SETUP CTC BASE INT VECTOR
 ;
-	; CTCC IS SLAVED (WIRED) TO TO CTCD TO ACT AS A PRESCALER
+	; CTCC IS SLAVED (WIRED) TO CTCD TO ACT AS A PRESCALER
 	; CONFIGURE CHANNEL D FOR 50HZ PERIODIC INTERRUPTS
 	; CTC CLK = 1,843,200HZ
 	; CTCC TIME CONSTANT = 256
@@ -1280,7 +1280,7 @@ HB_CPU1:
 	LD	DE,(CPUOSC / 2) / 1000
 ;
 #IF (Z180_CLKDIV >= 1)
-	LD	(HB_CPUTYPE),A	; CPU TYPE
+	LD	A,(HB_CPUTYPE)	; GET CPU TYPE
 	CP	2		; Z8S180 REV K OR BETTER?
 	JR	C,HB_CPU2	; IF NOT, NOT POSSIBLE!
 	; SET CLOCK DIVIDE TO 1 RESULTING IN FULL XTAL SPEED
@@ -1949,19 +1949,36 @@ DIO_TBL		.FILL	DIO_SIZ,0	; SPACE FOR ENTRIES
 ;
 ; TOS=READ FN ADR
 ; HL=BUF ADR
-; C=SEC COUNT
+; E=SEC COUNT
 ; D=BUF BANK ID
 ;	
 HB_DSKREAD:
+;
+	; THE ACTUAL SECTOR READ FUNCTION ADDRESS IS ON TOS, SAVE IT
+	EX	(SP),HL			; SAVE HL TO TOS, HL := READ FN ADR
+	LD	(HB_DSKFNADR),HL	; IMBED IN CALL OP BELOW
+	POP	HL			; RECOVER HL
+;
+#IF (DIAGENABLE)
+	; SAVE DISK UNIT NUMBER BIT MASK
+	LD	A,C			; GET DISK UNIT NUMBER
+	LD	B,A			; PUT IN B FOR LOOP COUNTER
+	INC	B			; LOOP ONE EXTRA TIME TO HANDLE UNIT=0
+	XOR	A			; START WITH ACCUM ZERO
+	SCF				; ... AND CF SET
+HB_DSKREAD0:
+	RLA				; ROTATE BIT
+	DJNZ	HB_DSKREAD0		; ... UNTIL IN PROPER LOCATION
+	LD	(HB_DSKBIT),A		; SAVE IT FOR DIAGNOSTICS
+#ENDIF
 ;
 #IF 1
-	; CHECK TO SEE IF INTER-BANK I/O NEEDED.  IF NOT
-	; WE JUST ABORT BACK TO DISK DRIVER TO HANDLE.
+	; CHECK TO SEE IF INTER-BANK I/O NEEDED.
 	BIT	7,H			; TGT BUF IN UPPER 32K?
-	RET	NZ			; IF SO, NOTHING TO DO
+	JP	NZ,HB_DSKIO		; IF SO, NON-BANKED
 	LD	A,D			; GET TGT BANK
 	CP	BID_BIOS		; BIOS BANK?
-	RET	Z			; IF SO, NOTHING TO DO
+	JP	Z,HB_DSKIO		; IF SO, NON-BANKED
 #ENDIF
 ;
 #IF 1
@@ -1975,23 +1992,16 @@ HB_DSKREAD:
 	LD	(HB_IOBUF),HL
 	LD	A,D
 	LD	(HB_IOBNK),A
-;
-	; SETUP READ FN ADR
-	POP	HL			; READ FN ADR IS AT TOS
-	LD	(HB_DSKREADFN),HL	; IMBED IN CALL OP BELOW
 ;
 	; SETUP READ AND LOOP COUNT
 	LD	B,E			; SEC LOOP COUNTER
 	LD	C,0			; SEC COMPLETE COUNTER
 ;
 HB_DSKREAD1:
+	LD	HL,HB_WRKBUF		; USE WORK BUF REAL I/O
+;
 	; CALL READ FN
-	PUSH	BC			; SAVE COUNTERS
-	LD	E,1			; ONE SECTOR
-	LD	HL,HB_WRKBUF		; USE WORK BUF FOR DATA
-HB_DSKREADFN	.EQU	$+1
-	CALL	PANIC			; READ ONE SECTOR
-	POP	BC			; RESTORE COUNTERS
+	CALL	HB_DSKFN		; READ ONE SECTOR
 ;
 	; IF FAIL, RETURN ERR
 	JR	NZ,HB_DSKREADX		; BAIL OUT ON ERROR
@@ -2016,9 +2026,7 @@ HB_DSKREADFN	.EQU	$+1
 ;
 HB_DSKREADX:
 	LD	HL,(HB_IOBUF)		; NEXT BUF ADR
-	LD	E,C			; READ COUNT TO E
-	OR	A			; SET RESULT FLAGS
-	RET				; DONE
+	JR	HB_DSKIOX		; DONE
 ;
 ;==================================================================================================
 ; DISK WRITE HELPER
@@ -2029,19 +2037,36 @@ HB_DSKREADX:
 ;
 ; TOS=WRITE FN ADR
 ; HL=BUF ADR
-; C=SEC COUNT
+; E=SEC COUNT
 ; D=BUF BANK ID
 ;	
 HB_DSKWRITE:
+;
+	; THE ACTUAL SECTOR READ FUNCTION ADDRESS IS ON TOS, SAVE IT
+	EX	(SP),HL			; SAVE HL TO TOS, HL := READ FN ADR
+	LD	(HB_DSKFNADR),HL	; IMBED IN CALL OP BELOW
+	POP	HL			; RECOVER HL
+;
+#IF (DIAGENABLE)
+	; SAVE DISK UNIT NUMBER BIT MASK
+	LD	A,C			; GET DISK UNIT NUMBER
+	LD	B,A			; PUT IN B FOR LOOP COUNTER
+	INC	B			; LOOP ONE EXTRA TIME TO HANDLE UNIT=0
+	XOR	A			; START WITH ACCUM ZERO
+	SCF				; ... AND CF SET
+HB_DSKWRITE0:
+	RLA				; ROTATE BIT
+	DJNZ	HB_DSKWRITE0		; ... UNTIL IN PROPER LOCATION
+	LD	(HB_DSKBIT),A		; SAVE IT FOR DIAGNOSTICS
+#ENDIF
 ;
 #IF 1
-	; CHECK TO SEE IF INTER-BANK I/O NEEDED.  IF NOT
-	; WE JUST ABORT BACK TO DISK DRIVER TO HANDLE.
+	; CHECK TO SEE IF INTER-BANK I/O NEEDED.
 	BIT	7,H			; TGT BUF IN UPPER 32K?
-	RET	NZ			; IF SO, NOTHING TO DO
+	JP	NZ,HB_DSKIO		; IF SO, NON-BANKED
 	LD	A,D			; GET TGT BANK
 	CP	BID_BIOS		; BIOS BANK?
-	RET	Z			; IF SO, NOTHING TO DO
+	JP	Z,HB_DSKIO		; IF SO, NON-BANKED
 #ENDIF
 ;
 #IF 1
@@ -2055,10 +2080,6 @@ HB_DSKWRITE:
 	LD	(HB_IOBUF),HL
 	LD	A,D
 	LD	(HB_IOBNK),A
-;
-	; SETUP WRITE FN ADR
-	POP	HL			; WRITE FN ADR IS AT TOS
-	LD	(HB_DSKWRITEFN),HL	; IMBED IN CALL OP BELOW
 ;
 	; SETUP WRITE AND LOOP COUNT
 	LD	B,E			; SEC LOOP COUNTER
@@ -2079,12 +2100,8 @@ HB_DSKWRITE1:
 	POP	BC			; RESTORE COUNTERS
 ;
 	; CALL WRITE FN
-	PUSH	BC			; SAVE COUNTERS
-	LD	E,1			; ONE SECTOR
-	LD	HL,HB_WRKBUF		; USE WORK BUF FOR DATA
-HB_DSKWRITEFN	.EQU	$+1
-	CALL	PANIC			; READ ONE SECTOR
-	POP	BC			; RESTORE COUNTERS
+	LD	HL,HB_WRKBUF		; WRITE FROM WORK BUFFER
+	CALL	HB_DSKFN		; WRITE ONE SECTOR
 ;
 	; IF FAIL, RETURN ERR
 	JR	NZ,HB_DSKWRITEX		; BAIL OUT ON ERROR
@@ -2096,12 +2113,53 @@ HB_DSKWRITEFN	.EQU	$+1
 ;
 HB_DSKWRITEX:
 	LD	HL,(HB_IOBUF)		; NEXT BUF ADR
+	JR	HB_DSKIOX		; DONE
+;
+;==================================================================================================
+; NON-BANKED DISK READ/WRITE
+;==================================================================================================
+;
+HB_DSKIO:
+;
+	; SETUP LOOP COUNT
+	LD	B,E			; SEC LOOP COUNTER
+	LD	C,0			; SEC COMPLETE COUNTER
+;
+HB_DSKIO1:
+	; CALL READ/WRITE FN
+	CALL	HB_DSKFN		; READ/WRITE ONE SECTOR
+;
+	; IF FAIL, RETURN ERR
+	JR	NZ,HB_DSKIOX		; BAIL OUT ON ERROR
+;
+	; INC SECTOR COUNT
+	INC	C			; BUMP SEC READ/WRITE COUNT
+	DJNZ	HB_DSKIO1		; LOOP AS NEEDED
+	XOR	A			; SIGNAL SUCCESS
+;
+HB_DSKIOX:
 	LD	E,C			; WRITE COUNT TO E
 	OR	A			; SET RESULT FLAGS
 	RET				; DONE
 ;
-HB_IOBUF	.DW	0
-HB_IOBNK	.DB	0
+HB_DSKFN:
+	PUSH	BC			; SAVE COUNTERS
+#IF (DIAGENABLE & DIAGDISKIO)
+	LD	A,(HB_DSKBIT)		; LOAD UNIT DISK BIT MASK
+	OUT	(DIAGPORT),A		; DISPLAY ON DIAG LEDS
+#ENDIF
+	LD	E,1			; ONE SECTOR
+HB_DSKFNADR	.EQU	$+1
+	CALL	PANIC			; READ ONE SECTOR
+#IF (DIAGENABLE & DIAGDISKIO)
+	DIAG(0)				; CLEAR DIAG LEDS
+#ENDIF
+	POP	BC			; RESTORE COUNTERS
+	RET				; RETURN
+;
+HB_DSKBIT	.DB	0		; ACTIVE DISK UNIT
+HB_IOBUF	.DW	0		; CURRENT IO BUFFER ADR
+HB_IOBNK	.DB	0		; CURRENT IO BUFFER BANK ID
 ;
 ;==================================================================================================
 ;   REAL TIME CLOCK DEVICE DISPATCHER
@@ -2723,10 +2781,12 @@ HB_DISPCALL:
 	JR	NC,HB_DISPERR		; HANDLE FN NUM OUT OF RANGE ERROR
 
 	; BUMP IY TO ACTUAL XXX_TBL ENTRY FOR INCOMING UNIT INDEX
+	PUSH	BC			; SAVE BC
 	LD	B,0			; MSB IS ALWAYS ZERO
 	RLC	C			; MULTIPLY UNIT INDEX
 	RLC	C			; ... BY 4 FOR TABLE ENTRY OFFSET
 	ADD	IY,BC			; SET IY TO ENTRY ADDRESS
+	POP	BC			; RESTORE BC
 
 	; DERIVE DRIVER FUNC ADR TO CALL
 	PUSH	HL			; SAVE INCOMING HL
diff --git a/Source/HBIOS/romldr.asm b/Source/HBIOS/romldr.asm
index 0e1d9dec..cd62a3bd 100644
--- a/Source/HBIOS/romldr.asm
+++ b/Source/HBIOS/romldr.asm
@@ -211,6 +211,12 @@ SEL:
 	CALL	CST		; CHECK CONSOLE INPUT
 	OR	A		; ZERO?
 	JR	Z,SEL1		; IF NOT, CONTINUE
+#IF (BIOS == BIOS_WBW)
+  #IF (DIAGENABLE)
+	XOR	A		; ZERO ACCUM
+	OUT	(DIAGPORT),A	; CLEAR DIAG LEDS
+  #ENDIF
+#ENDIF
 	CALL	CINUC		; GET THE KEY
 	CALL	COUT		; ECHO KEY
 	JR	MATS		; AND HANDLE IT
@@ -221,6 +227,12 @@ SEL1:
 	CALL	DSKY_STAT	; CHECK DSKY INPUT
 	OR	A		; TEST FOR ZERO
 	JR	Z,SEL2		; IF ZERO, NO KEY PRESSED
+#IF (BIOS == BIOS_WBW)
+  #IF (DIAGENABLE)
+	XOR	A		; ZERO ACCUM
+	OUT	(DIAGPORT),A	; CLEAR DIAG LEDS
+  #ENDIF
+#ENDIF
 	CALL	DSKY_GETKEY	; GET PENDING KEY PRESS
 	JR	MATK		; AND HANDLE IT
 #ENDIF
@@ -237,6 +249,12 @@ SEL2:
 	OR	C
 	JP	NZ,SEL3
 ;
+#IF (BIOS == BIOS_WBW)
+  #IF (DIAGENABLE)
+	XOR	A		; ZERO ACCUM
+	OUT	(DIAGPORT),A	; CLEAR DIAG LEDS
+  #ENDIF
+#ENDIF
 	LD	A,BOOT_DEFAULT	; TIMEOUT EXPIRED,
 	JR	MATS		; PERFORM DEFAULT BOOT ACTION
 #ENDIF