diff --git a/Source/HBIOS/hbios.asm b/Source/HBIOS/hbios.asm
index 1adc2014..241f5c92 100644
--- a/Source/HBIOS/hbios.asm
+++ b/Source/HBIOS/hbios.asm
@@ -1101,14 +1101,14 @@ HB_START:
 ;
 #IFDEF APPBOOT
   #IF (MEMMGR == MM_Z280)
-	LD	A,%00000001
+	LD	A,DIAG_01
 	OUT	(DIAGPORT),A
 	LD	DE,Z280_BOOTERR
 	LD	C,9
-	LD	A,%00000010
+	LD	A,DIAG_02
 	OUT	(DIAGPORT),A
 	CALL	$0005
-	LD	A,%00001000
+	LD	A,DIAG_04
 	OUT	(DIAGPORT),A
 	RET
 ;
@@ -1137,7 +1137,7 @@ Z280_BOOTERR	.TEXT	"\r\n\r\n*** Application mode boot not supported under Z280 n
 #ENDIF
 ;
 #IF (DIAGENABLE)
-	LD	A,%00000001
+	LD	A,DIAG_01
 	OUT	(DIAGPORT),A
 #ENDIF
 #IF (LEDENABLE)
@@ -1247,7 +1247,7 @@ Z280_INITZ:
 	LD	A,Z180_BASE
 	OUT0	($3F),A		; AT RESET, ICR IS AT $3F
 
-	DIAG(%00000010)
+	DIAG(DIAG_02)
 
 	; DISABLE REFRESH
 	XOR	A
@@ -1342,7 +1342,7 @@ Z280_INITZ:
 ; IS PERFORMED NEXT.
 ;
 #IF (DIAGENABLE)
-	LD	A,%00000011
+	LD	A,DIAG_02
 	OUT	(DIAGPORT),A
 #ENDIF
 ;
@@ -1670,7 +1670,7 @@ HB_START1:				; BNKCALL ARRIVES HERE, BUT NOW RUNNING IN RAM BANK
 	LD	SP,HBX_LOC - 2		; RESET STACK
 ;
 	; NOTIFY THAT WE MADE THE TRANSITION!
-	DIAG(%00000111)
+	DIAG(DIAG_03)
 	LED(%00000010)
 ;
 	; SET THE IN-RAM FLAG
@@ -1797,7 +1797,7 @@ SAVE_REC_M:
   #ENDIF
 #ENDIF
 ;
-	DIAG(%00001111)
+	DIAG(DIAG_04)
 ;
 #IF (WBWDEBUG == USEMIO)		; BUFFER OUTPUT UNTIL
 	CALL	MIO_INIT		; WE GET TO BOOT MESSAGE
@@ -1886,7 +1886,7 @@ HB_CPU1:
 ;
 #ENDIF
 ;
-	DIAG(%00011111)
+	DIAG(DIAG_05)
 ;
 ; INIT OSCILLATOR SPEED FROM CONFIG
 ;
@@ -2178,7 +2178,7 @@ Z280_TC	.EQU	CPUOSC / 4 / 50 / 2	; TIME CONSTANT
 	LD	A,$FF			; FILL WITH $FF
 	CALL	FILL			; DO IT
 ;
-	DIAG(%00111111)
+	DIAG(DIAG_06)
 ;
 #IF FALSE
 ;
@@ -2234,7 +2234,7 @@ NOT_REC_M0:
 ;
 #ENDIF
 ;
-	DIAG(%01111111)
+	DIAG(DIAG_07)
 	LED(%00000011)
 ;
 ;
@@ -2322,7 +2322,7 @@ NXTMIO:	LD	A,(HL)
 #ENDIF
 NOT_REC_M2:
 ;
-	DIAG(%11111111)
+	DIAG(DIAG_08)
 ;
 ; IO PORT SCAN
 ;
@@ -3504,7 +3504,7 @@ HB_DSKFN:
 HB_DSKFNADR	.EQU	$+1
 	CALL	PANIC			; READ ONE SECTOR
 #IF (DIAGENABLE & DIAGDISKIO)
-	DIAG(0)				; CLEAR DIAG LEDS
+	DIAG(DIAG00)				; CLEAR DIAG LEDS
 #ENDIF
 #IF (LEDENABLE & LEDDISKIO)
 	LED($00)
diff --git a/Source/HBIOS/hbios.inc b/Source/HBIOS/hbios.inc
index d5e69636..1931e1db 100644
--- a/Source/HBIOS/hbios.inc
+++ b/Source/HBIOS/hbios.inc
@@ -156,6 +156,111 @@ ERR_TIMEOUT		.EQU	-11	; DEVICE TIMEOUT
 ERR_BADCFG		.EQU	-12	; INVALID CONFIGURATION
 ERR_INTERNAL		.EQU	-13	; INTERNAL ERROR
 ;
+; HBIOS DIAG OPTIONS
+;
+DIAG_PROG	.EQU	0		; PROGRESS BAR
+DIAG_STEP	.EQU	1		; STEP BAR
+DIAG_ASCII	.EQU	2		; 8-BIT ASCII 30H - 39H
+DIAG_BINARY	.EQU	3		; BINARY 00H - 09H
+DIAG_7SEG	.EQU	4		; 7-SEGMENT
+DIAG_FLASH	.EQU	5		; FLASH
+DIAG_TRIG	.EQU	6		; TRIGGER
+;
+DIAG_DISP	.EQU	DIAG_PROG	; DEFAULT
+;
+#IF (DIAG_DISP == DIAG_PROG)
+DIAG_00 .EQU 00000000B	
+DIAG_01 .EQU 00000001B 
+DIAG_02 .EQU 00000011B 
+DIAG_03 .EQU 00000111B 
+DIAG_04 .EQU 00001111B 
+DIAG_05 .EQU 00011111B 
+DIAG_06 .EQU 01111111B 
+DIAG_07 .EQU 11111111B 
+DIAG_08 .EQU 11111111B 
+DIAG_09 .EQU 11111111B   
+#ENDIF
+;
+#IF (DIAG_DISP == DIAG_STEP)
+DIAG_00 .EQU 00000000B	
+DIAG_01 .EQU 00000001B 
+DIAG_02 .EQU 00000010B 
+DIAG_03 .EQU 00000100B 
+DIAG_04 .EQU 00001000B 
+DIAG_05 .EQU 00010000B 
+DIAG_06 .EQU 00100000B 
+DIAG_07 .EQU 01000000B 
+DIAG_08 .EQU 10000000B
+DIAG_09 .EQU 11111111B
+#ENDIF
+;
+#IF (DIAG_DISP == DIAG_ASCII)
+DIAG_00 .EQU '0'	
+DIAG_01 .EQU '1'
+DIAG_02 .EQU '2' 
+DIAG_03 .EQU '3' 
+DIAG_04 .EQU '4'
+DIAG_05 .EQU '5'
+DIAG_06 .EQU '6' 
+DIAG_07 .EQU '7'
+DIAG_08 .EQU '8' 
+DIAG_09 .EQU '9' 
+#ENDIF
+;
+#IF (DIAG_DISP == DIAG_BINARY)
+DIAG_00 .EQU 0	
+DIAG_01 .EQU 1
+DIAG_02 .EQU 2
+DIAG_03 .EQU 3
+DIAG_04 .EQU 4
+DIAG_05 .EQU 5
+DIAG_06 .EQU 6
+DIAG_07 .EQU 7
+DIAG_08 .EQU 8
+DIAG_09 .EQU 9 
+#ENDIF
+;
+#IF (DIAG_DISP == DIAG_7SEG)
+;             abcdefg
+DIAG_00 .EQU 00000000B ; BLANK
+DIAG_01 .EQU 01111110B ; 0
+DIAG_02 .EQU 00110000B ; 1
+DIAG_03 .EQU 01101101B ; 2
+DIAG_04 .EQU 01111001B ; 3 
+DIAG_05 .EQU 00110011B ; 4
+DIAG_06 .EQU 01011011B ; 5
+DIAG_07 .EQU 00011111B ; 6 
+DIAG_08 .EQU 01110000B ; 7
+DIAG_09 .EQU 01111111B ; 8
+DIAG_10 .EQU 01110011B ; 9
+#ENDIF
+;
+#IF (DIAG_DISP == DIAG_FLASH)
+DIAG_00 .EQU 00000000B ; OFF	
+DIAG_01 .EQU 11111111B ; ON
+DIAG_02 .EQU 00000000B ; OFF	
+DIAG_03 .EQU 11111111B ; ON
+DIAG_04 .EQU 00000000B ; OFF	
+DIAG_05 .EQU 11111111B ; ON
+DIAG_06 .EQU 00000000B ; OFF	
+DIAG_07 .EQU 11111111B ; ON
+DIAG_08 .EQU 00000000B ; OFF	
+DIAG_09 .EQU 11111111B ; ON 
+#ENDIF
+;
+#IF (DIAG_DISP == DIAG_TRIG)
+DIAG_00 .EQU 11111111B ; ON	
+DIAG_01 .EQU 11111111B ; ON
+DIAG_02 .EQU 11111111B ; ON
+DIAG_03 .EQU 11111111B ; ON
+DIAG_04 .EQU 11111111B ; ON
+DIAG_05 .EQU 11111111B ; ON
+DIAG_06 .EQU 11111111B ; ON
+DIAG_07 .EQU 11111111B ; ON
+DIAG_08 .EQU 11111111B ; ON
+DIAG_09 .EQU 11111111B ; ON 
+#ENDIF
+;
 ; MEDIA ID VALUES
 ;
 MID_NONE	.EQU	0