diff --git a/Source/HBIOS/md.asm b/Source/HBIOS/md.asm
index 5675df72..8c17032f 100644
--- a/Source/HBIOS/md.asm
+++ b/Source/HBIOS/md.asm
@@ -27,6 +27,7 @@ MD_AFSH		.EQU	%00111000	; FLASH ATTRIBUTE
 ;
 MD_FDBG		.EQU	0		; FLASH DEBUG CODE
 MD_FVBS		.EQU	1		; FLASH VERBOSE OUTPUT
+MD_FVAR		.EQU	1		; FLASH VERIFY AFTER WRITE
 ;
 ; DEVICE CONFIG TABLE (RAM DEVICE FIRST TO MAKE IT ALWAYS FIRST DRIVE)
 ;
@@ -54,7 +55,7 @@ MD_CFGTBL:
 ;
 MD_INIT:
 #IF (MDFFENABLE)
-	CALL	MD_FINIT			; PROBE FLASH CAPABILITY
+	CALL	MD_FINIT		; PROBE FLASH CAPABILITY
 #ENDIF
 
 	CALL	NEWLINE			; FORMATTING
@@ -316,7 +317,7 @@ MD_RDSECF:				; CALLED FROM MD_RW
 ;
 	LD	IX,MD_F4KBUF		; SET DESTINATION ADDRESS
 	LD	BC,MD_FREAD_R		; PUT ROUTINE TO CALL
-	CALL	FF_FNCALL		; EXECUTE: READ 4K SECTOR
+	CALL	MD_FNCALL		; EXECUTE: READ 4K SECTOR
 ;
 MD_SECM:
 	LD	A,(IY+MD_LBA+0)		; GET SECTOR WITHIN 4K BLOCK
@@ -377,11 +378,11 @@ MD_WRSECF:				; CALLED FROM MD_RW
 ;
 	LD	IX,MD_F4KBUF		; SET DESTINATION ADDRESS
 	LD	BC,MD_FREAD_R		; PUT ROUTINE TO CALL
-	CALL	FF_FNCALL		; EXECUTE: READ 4K SECTOR
+	CALL	MD_FNCALL		; EXECUTE: READ 4K SECTOR
 ;
 MD_SECM1:				; DESIRED SECTOR IS IN BUFFER
 	LD	BC,MD_FERAS_R		; PUT ROUTINE TO CALL
-	CALL	FF_FNCALL		; EXECUTE: ERASE 4K SECTOR
+	CALL	MD_FNCALL		; EXECUTE: ERASE 4K SECTOR
 	OR	A
 	RET	NZ			; RETURN IF ERROR
 ;
@@ -409,9 +410,28 @@ MD_SECM1:				; DESIRED SECTOR IS IN BUFFER
 ;
 	LD	IX,MD_F4KBUF		; SET SOURCE ADDRESS
 	LD	BC,MD_FWRIT_R		; PUT ROUTINE TO CALL
-	CALL	FF_FNCALL		; EXECUTE: WRITE 4K SECTOR
+	CALL	MD_FNCALL		; EXECUTE: WRITE 4K SECTOR
 ;
-	XOR	A
+	XOR	A			; PRESUME SUCCESS STATUS
+;
+#IF (MD_FVAR==1)
+	LD	IX,MD_F4KBUF		; SET SOURCE ADDRESS
+	LD	BC,MD_FVERI_R		; PUT ROUTINE TO CALL
+	CALL	MD_FNCALL		; EXECUTE: VERIFY 4K SECTOR
+;
+	OR	A
+	RET	Z			; RETURN IF SUCCESSFUL
+;
+	LD	IX,MD_F4KBUF		; SET SOURCE ADDRESS		; RETRY
+	LD	BC,MD_FWRIT_R		; PUT ROUTINE TO CALL		; WRITE
+	CALL	MD_FNCALL		; EXECUTE: WRITE 4K SECTOR	; ONCE
+;
+	LD	IX,MD_F4KBUF		; SET SOURCE ADDRESS		; VERIFY
+	LD	BC,MD_FVERI_R		; PUT ROUTINE TO CALL		; AGAIN
+	CALL	MD_FNCALL		; EXECUTE: VERIFY 4K SECTOR
+;
+	OR	A			; SET FINAL STATUS AFTER RETRY
+#ENDIF
 ;
 	RET
 ;
@@ -610,8 +630,7 @@ MDSTR_LEN	.TEXT	"LEN=$"
 ;	AND THE FLASH CHIP IS SWITCHED INTO THE LOWER BANK.
 ;
 ;	EACH FLASH ROUTINE MUST FIT INTO TO THE HBX_BUF, INCLUDING IT'S LOCAL STACK WHICH
-;	IS REQUIRED FOR CALLING THE BANK SWITCH ROUTINES. IN SOME CASES THIS MEANS
-;	OVERLAYING THE STACK ON THE INITIALIZATION CODE.
+;	IS REQUIRED FOR CALLING THE BANK SWITCH ROUTINES. 
 ;
 ;	INSPIRED BY WILL SOWERBUTTS FLASH4 UTILITY - https://github.com/willsowerbutts/flash4/
 ;
@@ -636,7 +655,7 @@ MD_FINIT:
 #ENDIF
 	LD	B,A			; NUMBER OF DEVICES TO PROBE
 	LD	C,$00			; START ADDRESS IS 0000:0000 IN DE:HL
-FF_PROBE:
+MD_PROBE:
 	LD	D,$00			; SET ADDRESS IN DE:HL
 	LD	E,C			;
 	LD	H,D			; WE INCREASE E BY $08
@@ -652,7 +671,7 @@ FF_PROBE:
 	CALL	COUT
 #ENDIF
 	LD	BC,MD_FIDENT_R		; PUT ROUTINE TO CALL
-	CALL	FF_FNCALL		; EXECUTE: IDENTIFY FLASH CHIP
+	CALL	MD_FNCALL		; EXECUTE: IDENTIFY FLASH CHIP
 
 	PUSH	HL
 	LD	HL,MD_TGTDEV		; IF WE MATCH WITH
@@ -672,7 +691,7 @@ FF_PROBE:
 	ADD	A,$08			; TO NEXT DEVICE
 	LD	C,A
 ;
-	DJNZ	FF_PROBE		; ALWAYS AT LEAST ONE DEVICE
+	DJNZ	MD_PROBE		; ALWAYS AT LEAST ONE DEVICE
 
 #IF (MD_FVBS==1)
 	CALL	PRTSTRD
@@ -705,21 +724,21 @@ MD_LAND:
 ;
 	LD	HL,MD_TABLE		; SEARCH THROUGH THE FLASH
 	LD	DE,MD_T_CNT		; TABLE TO FIND A MATCH
-FF_NXT1:LD	A,(HL)
+MD_NXT1:LD	A,(HL)
 	CP	B
-	JR	NZ,FF_NXT0		; FIRST BYTE DOES NOT MATCH
+	JR	NZ,MD_NXT0		; FIRST BYTE DOES NOT MATCH
 ;
 	INC	HL		
 	LD	A,(HL)
 	CP	C
 	DEC	HL
-	JR	NZ,FF_NXT0		; SECOND BYTE DOES NOT MATCH
+	JR	NZ,MD_NXT0		; SECOND BYTE DOES NOT MATCH
 ;
 	INC	HL
 	INC	HL
 	JR	FF_NXT2			; MATCH SO EXIT
 ;
-FF_NXT0:PUSH	BC			; WE DIDN'T MATCH SO POINT
+MD_NXT0:PUSH	BC			; WE DIDN'T MATCH SO POINT
 	LD	BC,MD_T_SZ		; TO THE NEXT TABLE ENTRY
 	ADD	HL,BC
 	POP	BC
@@ -727,7 +746,7 @@ FF_NXT0:PUSH	BC			; WE DIDN'T MATCH SO POINT
 	LD	A,D			; CHECK IF WE REACHED THE
 	OR	E			; END OF THE TABLE
 	DEC	DE
-	JR	NZ,FF_NXT1		; NOT AT END YET
+	JR	NZ,MD_NXT1		; NOT AT END YET
 ;
 	LD	HL,MD_FFMSGUNK		; WE REACHED THE END WITHOUT A MATCH
 ;
@@ -754,7 +773,12 @@ FF_NXT2:
 ;   ON ENTRY DE:HL POINTS TO A 32 BIT MEMORY ADDRESS.
 ;            IX    POINTS TO WHERE TO SAVE DATA
 ;   ON EXIT  A     NO STATUS IS RETURNED
-
+;
+;  MD_VERI_R - VERIFY FLASH SECTOR
+;   ON ENTRY DE:HL POINTS TO A 32 BIT MEMORY ADDRESS.
+;            IX    POINTS TO DATA TO COMPARE.
+;   ON EXIT  A     RETURNS STATUS 0=SUCCESS NZ=FAIL
+;
 ;  MD_FWRIT_R - WRITE FLASH SECTOR   
 ;   ON ENTRY DE:HL POINTS TO A 32 BIT MEMORY ADDRESS.
 ;            IX    POINTS TO DATA TO BE WRITTEN
@@ -767,17 +791,17 @@ FF_NXT2:
 ;  RETURN WITH ID CODE.
 ;======================================================================
 ;
-FF_FNCALL:	
+MD_FNCALL:	
 	PUSH	HL			; USING HBX_BUF FOR CODE AREA
 	PUSH	DE
 	PUSH	BC
-	CALL	FF_CALCA		; GET BANK AND SECTOR DATA IN BC
+	CALL	MD_CALCA		; GET BANK AND SECTOR DATA IN BC
 ;
 	POP	HL			; GET ROUTINE TO CALL
 	PUSH	BC
 ;
 	LD	DE,HBX_BUF		; EXECUTE / START ADDRESS
-	LD	BC,HBX_BUFSIZ		; MAX. CODE SIZE POSSIBLE
+	LD	BC,MD_CSIZE		; CODE SIZE. MAXIMUM 64 BYTES
 	LDIR				; COPY OUR RELOCATABLE CODE TO THE BUFFER
 ;
 	LD	D,B			; PRESET DE TO ZERO TO REDUCE
@@ -789,8 +813,14 @@ FF_FNCALL:
 	CALL	PRTHEXWORD
 #ENDIF
 ;
+	LD	HL,MD_FNRET		; ADDRESS RELOCATABLE CODE TO RETURN TO
 	HB_DI
-	CALL	HBX_BUF			; EXECUTE RELOCATED CODE
+	LD	(FF_SAVSTK),SP		; SAVE CURRENT STACK
+	LD	SP,(HBX_BUF_END-2	; SETUP A NEW HIMEM STACK AT END OF HX_BUF
+	EX	(SP),HL			; BEHIND CODE WITH RETURN ADDRESS PREPOPULATED
+	JP	HBX_BUF			; EXECUTE RELOCATED CODE
+MD_FNRET:
+	LD	SP,(FF_SAVSTK)		; RESTORE STACK
 	HB_EI
 ;
 #IF (MD_FDBG==1)
@@ -808,6 +838,8 @@ FF_FNCALL:
 	POP	HL
 	RET				; RETURN TO MD_READF, MD_WRITEF
 ;
+FF_SAVSTK	.DW	0
+;
 ;======================================================================
 ; CALCULATE BANK AND ADDRESS DATA FROM MEMORY ADDRESS
 ;
@@ -823,7 +855,7 @@ FF_FNCALL:
 ; XXXXXXXXXXXXBBBB BXXXXXXXXXXXXXXX < B = BANK
 ;======================================================================
 ;
-FF_CALCA:
+MD_CALCA:
 ;
 #IF (MD_FDBG==1)
 	CALL	PC_SPACE	; DISPLAY SECTOR
@@ -849,7 +881,7 @@ FF_CALCA:
 ;
 	LD	A,(HB_CURBNK)	; WE ARE STARTING IN HB_CURBNK
 ;
-	RET
+	RET			; RETURN TO MD_FNRET
 ;
 ;======================================================================
 ; FLASH IDENTIFY
@@ -866,9 +898,6 @@ FF_CALCA:
 ;======================================================================
 ;
 MD_FIDENT_R:				; THIS CODE GETS RELOCATED TO HIGH MEMORY
-;
-	LD	(HBX_BUF+MD_FIST-MD_FIDENT_R),SP		; SAVE STACK
-	LD	SP,HBX_BUF + (MD_FIST-MD_FIDENT_R)		; SETUP TEMP STACK
 ;
 	PUSH	AF			; SAVE CURRENT BANK
 ;
@@ -889,12 +918,8 @@ MD_FIDENT_R:				; THIS CODE GETS RELOCATED TO HIGH MEMORY
 	POP	AF			; RETURN TO ORIGINAL BANK
 	CALL	HBX_BNKSEL		; WHICH IS OUR RAM BIOS COPY
 ;
-	LD	SP,(HBX_BUF + (MD_FIST-MD_FIDENT_R))		; RESTORE STACK
+	RET				; RETURN TO MD_FNRET
 ;
-	RET
-;
-	.FILL	8,0			; STACK SPACE
-MD_FIST	.DW	0			; SAVE STACK
 MD_I_SZ	.EQU	$-MD_FIDENT_R		; SIZE OF RELOCATABLE CODE BUFFER REQUIRED
 ;
 ;======================================================================
@@ -912,29 +937,19 @@ MD_I_SZ	.EQU	$-MD_FIDENT_R		; SIZE OF RELOCATABLE CODE BUFFER REQUIRED
 ;
 MD_FERAS_R:				; THIS CODE GETS RELOCATED TO HIGH MEMORY
 ;
-MD_FEST	.EQU	$+2			; SAVE STACK
-;
-	LD	HL,$5555				; COMMAND		; LOCAL STACK
-	LD	DE,$2AAA				; PRELOAD		; LOCAL STACK
-	LD	(HBX_BUF+MD_FEST-MD_FERAS_R),SP		; SAVE STACK		; LOCAL STACK
-	LD	SP,HBX_BUF + (MD_FERAS_S-MD_FERAS_R)	; SETUP TEMP STACK	; LOCAL STACK
-;
-MD_FERAS_S
 	PUSH	AF			; SAVE CURRENT BANK
 	LD	A,B			; SELECT BANK
 	CALL	HBX_BNKSEL		; TO PROGRAM
 ;
-
-	LD	A,L			; LD	($5555),A		; COMMAND
-	LD	(HL),E			; LD	A,$55			; SETUP
-	LD	(DE),A			; LD	($2AAA),A
-	LD	(HL),$80		; LD	A,$80
-	LD	(HL),E			; LD	($5555),A
-	LD	(DE),A			; LD	A,$AA
-					; LD	($5555),A
-					; LD	A,$55
-					; LD	($2AAA),A
-
+	LD	HL,$5555		; LD	($5555),A
+	LD	DE,$2AAA		; LD	A,$55	
+	LD	A,L			; LD	($2AAA),A		
+	LD	(HL),E			; LD	A,$80		
+	LD	(DE),A			; LD	($5555),A		
+	LD	(HL),$80		; LD	A,$AA		
+	LD	(HL),E			; LD	($5555),A		
+	LD	(DE),A			; LD	A,$55		
+;					; LD	($2AAA),A		
 	LD	H,C			; SECTOR 
 	LD	L,$00			; ADDRESS
 ;
@@ -966,9 +981,7 @@ MD_WT5:	LD	C,L			; SET SUCCESS STATUS
 MD_WT6:	POP	AF			; RETURN TO ORIGINAL BANK
 	CALL	HBX_BNKSEL		; WHICH IS OUR RAM BIOS COPY
 ;
-	LD	SP,(HBX_BUF + (MD_FEST-MD_FERAS_R))		; RESTORE STACK
-;
-	RET
+	RET				; RETURN TO MD_FNRET
 ;
 MD_S_SZ	.EQU	$-MD_FERAS_R		; SIZE OF RELOCATABLE CODE BUFFER REQUIRED
 ;
@@ -990,11 +1003,8 @@ MD_S_SZ	.EQU	$-MD_FERAS_R		; SIZE OF RELOCATABLE CODE BUFFER REQUIRED
 ;
 MD_FREAD_R:				; THIS CODE GETS RELOCATED TO HIGH MEMORY
 ;
-	LD	H,C			; SECTOR				; LOCAL STACK
-	LD	L,D			; ADDRESS				; LOCAL	STACK
-	LD	(HBX_BUF+MD_FRST-MD_FREAD_R),SP		; SAVE STACK		; LOCAL STACK
-	LD	SP,HBX_BUF + (MD_FRD_S-MD_FREAD_R)	; SETUP TEMP STACK	; LOCAL STACK
-MD_FRD_S:
+	LD	H,C			; SECTOR
+	LD	L,D			; ADDRESS
 ;
 	PUSH	AF			; SAVE CURRENT BANK
 ;
@@ -1018,14 +1028,65 @@ MD_FRD1:
 	POP	AF			; RETURN TO ORIGINAL BANK
 	CALL	HBX_BNKSEL		; WHICH IS OUR RAM BIOS COPY
 ;
-	LD	SP,(HBX_BUF+MD_FRST-MD_FREAD_R)		; RESTORE STACK
-;
-	RET
+	RET				; RETURN TO MD_FNRET
 ;
-MD_FRST	.DW	0			; SAVE STACK
 MD_R_SZ	.EQU	$-MD_FREAD_R		; SIZE OF RELOCATABLE CODE BUFFER REQUIRED
 ;
 ;======================================================================
+; FLASH VERIFY SECTOR. 
+;
+;  SELECT THE APPROPRIATE BANK / ADDRESS
+;  VERIFY SECTOR OF 4096 BYTES, BYTE AT A TIME
+;  SELECT SOURCE BANK,  READ DATA,
+;	   SELECT DESTINATION BANK, COMPARE DATA
+;          DESTINATION BANK IS ALWAYS CURRENT BANK
+;
+; ON ENTRY BC CONTAINS BANK AND SECTOR DATA
+;          DE = 0000 BYTE COUNT
+;          IX POINTS TO DATA TO BE VERIFIED
+;          A  CONTAINS CURRENT BANK 
+; ON EXIT  NO STATUS RETURNED
+;======================================================================
+;
+MD_FVERI_R:				; THIS CODE GETS RELOCATED TO HIGH MEMORY
+;
+	LD	H,C			; SECTOR
+	LD	L,D			; ADDRESS
+;
+	PUSH	AF			; SAVE CURRENT BANK
+;
+MD_FVE1:	
+	LD	A,B			; SELECT BANK
+	CALL	HBX_BNKSEL		; TO READ
+	LD	C,(HL)			; READ BYTE
+;
+	POP	AF
+	PUSH	AF			; SELECT BANK
+	CALL	HBX_BNKSEL		; TO WRITE
+;
+	LD	A,C
+	SUB	(IX+0)			; COMPARE BYTE
+	LD	C,A			; SET NON ZERO STATUS
+	JR	NZ,MD_FVE2		; EXIT IF MISMATCH
+;
+	INC	HL			; NEXT SOURCE LOCATION
+	INC	IX			; NEXT DESTINATION LOCATION
+;
+	INC	DE			; CONTINUE READING UNTIL
+	BIT	4,D			; WE HAVE DONE ONE SECTOR
+	JR	Z,MD_FVE1
+;
+	LD	C,E			; SET SUCCESS STATUS = 0
+;
+MD_FVE2:
+	POP	AF			; RETURN TO ORIGINAL BANK
+	CALL	HBX_BNKSEL		; WHICH IS OUR RAM BIOS COPY
+;
+	RET				; RETURN TO MD_FNRET
+;
+MD_V_SZ	.EQU	$-MD_FVERI_R		; SIZE OF RELOCATABLE CODE BUFFER REQUIRED
+;
+;======================================================================
 ; FLASH WRITE SECTOR. 
 ;
 ;  SELECT THE APPROPRIATE BANK / ADDRESS
@@ -1043,13 +1104,8 @@ MD_R_SZ	.EQU	$-MD_FREAD_R		; SIZE OF RELOCATABLE CODE BUFFER REQUIRED
 ;
 MD_FWRIT_R:				; THIS CODE GETS RELOCATED TO HIGH MEMORY
 ;
-MD_FWST	.EQU	$+2			; SAVE STACK
-;
-	LD	H,C			; SECTOR				; LOCAL STACK
-	LD	L,D			; ADDRESS				; LOCAL STACK
-	LD	(HBX_BUF+MD_FWST-MD_FWRIT_R),SP		; SAVE STACK		; LOCAL STACK
-	LD	SP, HBX_BUF+(MD_FWRIT_S-MD_FWRIT_R)	; SETUP TEMP STACK	; LOCAL STACK
-MD_FWRIT_S:
+	LD	H,C			; SECTOR
+	LD	L,D			; ADDRESS
 ;
 	PUSH	AF			; SAVE CURRENT BANK
 ;
@@ -1089,8 +1145,6 @@ MD_FW7:	LD	A,(HL)			; FROM THE SAME FLASH ADDRESS.
 ;
 	POP	AF			; RETURN TO ORIGINAL BANK
 	CALL	HBX_BNKSEL		; WHICH IS OUR RAM BIOS COPY
-;
-	LD	SP,(HBX_BUF+MD_FWST-MD_FWRIT_R)		; RESTORE STACK
 ;
 	RET
 ;
@@ -1156,6 +1210,10 @@ MD_FFSEN	.DB	00h		; FLASH FILES SYSTEM ENABLE
 		.ECHO	"MD_FREAD_R "
 		.ECHO	MD_R_SZ
 		.ECHO	"\n"
+;
+		.ECHO	"MD_VERI_R "
+		.ECHO	MD_V_SZ
+		.ECHO	"\n"
 ;
 		.ECHO	"MD_FERAS_R "
 		.ECHO	MD_S_SZ
@@ -1180,6 +1238,9 @@ MD_CSIZE	.SET	MD_I_SZ
 #IF (MD_R_SZ>MD_CSIZE)
 MD_CSIZE	.SET	MD_R_SZ
 #ENDIF
+#IF (MD_V_SZ>MD_CSIZE)
+MD_CSIZE	.SET	MD_V_SZ
+#ENDIF
 ;
 #IF (MD_CSIZE>HBX_BUFSIZ)
 		.ECHO	"Warning: Flash code exceeds available space by "