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 6c0e6036..4f36da3f 100644
--- a/Source/HBIOS/hbios.asm
+++ b/Source/HBIOS/hbios.asm
@@ -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
@@ -1588,7 +1588,6 @@ HB_SPDTST:
 #ENDIF
 ;
 INITSYS3:
-	DIAG(0)
 ;
 	CALL	PRTSUM			; PRINT UNIT/DEVICE SUMMARY TABLE
 ;
@@ -2145,14 +2144,16 @@ HB_DSKIOX:
 ;
 HB_DSKFN:
 	PUSH	BC			; SAVE COUNTERS
-#IF (DIAGENABLE)
+#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
-	DIAG(0)				; CLEAR DIAG DISPLAY
+#IF (DIAGENABLE & DIAGDISKIO)
+	DIAG(0)				; CLEAR DIAG LEDS
+#ENDIF
 	POP	BC			; RESTORE COUNTERS
 	RET				; RETURN
 ;
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