diff --git a/Source/HBIOS/flashfs.asm b/Source/HBIOS/flashfs.asm
index a0b20e4e..ca84d870 100644
--- a/Source/HBIOS/flashfs.asm
+++ b/Source/HBIOS/flashfs.asm
@@ -4,6 +4,7 @@
 ;
 ;	26 SEP 2020 - CHIP IDENTIFICATION IMPLMENTED -- PHIL SUMMERS
 ;		    - CHIP ERASE IMPLEMENTED
+;	23 OCT 2020 - SECTOR ERASE IMPLEMENTED
 ;==================================================================================================
 ;
 ;	UPPER RAM BANK IS ALWAYS AVAILABLE REGARDLESS OF MEMORY BANK SELECTION. HBX_BNKSEL AND
@@ -62,7 +63,7 @@ FF_NXT1:LD	A,(HL)
 	JR	FF_NXT2			; MATCH SO EXIT
 ;
 FF_NXT0:PUSH	BC			; WE DIDN'T MATCH SO POINT
-	LD	BC,17			; TO THE NEXT TABLE ENTRY
+	LD	BC,FF_T_SZ		; TO THE NEXT TABLE ENTRY
 	ADD	HL,BC
 	POP	BC
 ;
@@ -75,8 +76,6 @@ FF_NXT0:PUSH	BC			; WE DIDN'T MATCH SO POINT
 ;
 FF_NXT2:CALL	PRTSTR			; AFTER SEARCH DISPLAY THE RESULT
 ;
-	CALL	FF_EINIT		; ERASE TEST
-
 	XOR	A			; INIT SUCCEEDED
 	RET
 ;
@@ -189,6 +188,7 @@ FF_WT2:	LD	C,(HL)			; IF TOGGLE BIT (BIT 6)
 	BIT	6,A			; IF THEY ARE THEN OPERATION WAS COMPLETED					
 	JR	Z,FF_WT1		; OTHERWISE ERASE OPERATION FAILED OR TIMED OUT.
 ;
+	LD	(HL),$F0		; WRITE DEVICE RESET
 	LD	C,$FF			; SET FAIL STATUS
 	JR	FF_WT3
 ;
@@ -202,11 +202,42 @@ FF_WT3:	LD	A,B			; RETURN TO ORIGINAL BANK
 FF_E_SZ	.EQU	$-FF_ERASE
 ;
 ;======================================================================
-; ERASE FLASH SECTOR.
+; ERASE FLASH SECTOR (1MB LIMIT)
+; ON ENTRY DE:HL contains 32 bit memory address.
+; The sector number is bits 19-12 i.e there are 256 sectors per 1024K
+; The erase sector command must be written to the lowest 32K of each chip.
+; The bank number is bits 19-15 i.e. there are up to 32 for 1024K
+;
+; DDDDDDDDEEEEEEEE HHHHHHHHLLLLLLLL
+; 3322222222221111 1111110000000000
+; 1098765432109876 5432109876543210
+; XXXXXXXXXXXXSSSS SSSSXXXXXXXXXXXX < SECTOR = ADDRESS / 4096 - 0-256
+; XXXXXXXXXXXXBBBB BXXXXXXXXXXXXXXX < BANK  = ADDRESS / 32768
+
 ;======================================================================
 ;
-;
 FF_SINIT:
+	CALL	PC_SPACE	; DISPLAY FULL
+	EX	DE,HL
+	CALL	PRTHEXWORDHL	; SECTOR ADDRESS DE:HL
+	EX	DE,HL
+	CALL	PRTHEXWORDHL
+	CALL	PC_SPACE	; DISPLAY SECTOR
+;
+	LD	A,E		; BOTTOM PORTION OF SECTOR
+	AND	$0F		; ADDRESS THAT GETS WRITTEN
+	RLC	H		; WITH ERASE COMMAND BYTE
+	RLA			; A15 GETS MASKED OFF AND
+	LD	B,A		; ADDED TO BANK SELECT
+;
+	LD	A,H		; TOP SECTION OF SECTOR
+	RRA			; ADDRESS THAT GETS WRITTEN				; REG C SET
+	AND	$70		; TO BANK SELECT PORT
+	LD	C,A
+;
+	PUSH	BC
+	POP	IY
+;
 	LD	(FF_STACK),SP		; SAVE STACK
 	LD	HL,(FF_STACK)
 ;
@@ -217,23 +248,18 @@ FF_SINIT:
 ;
 	PUSH	HL			; SAVE THE EXECUTE ADDRESS
 	EX	DE,HL			; PUT EXECUTE / START ADDRESS IN DE
-	LD	HL,FF_ERASE		; COPY OUR RELOCATABLE
+	LD	HL,FF_SERASE		; COPY OUR RELOCATABLE
 	LDIR				; CODE TO THE BUFFER
+	POP	HL			; CALL OUR RELOCATABLE CODE
 ;
-	LD	A,(HB_CURBNK)		; WE ARE STARTING IN HB_CURBNK
-	LD	B,A			; WHICH IS THE RAM COPY OF THE BIOS
-;
-;	SELECT THE CORRECT ROM BANK
-;
-	LD	A,BID_BOOT		; BID_BOOT IS ROM BANK 0
+	LD	A,(HB_CURBNK)		; WE ARE STARTING IN HB_CURBNK	
 ;
-	POP	HL			; CALL OUR RELOCATABLE CODE
-	CALL	JPHL
+	CALL	JPHL			; CALL FF_SERASE
 ;
 	LD	HL,(FF_STACK)		; RESTORE ORIGINAL 
 	LD	SP,HL			; STACK POSITION
 ;
-	XOR	A
+	LD	A,C			; STATUS
 	RET
 ;
 ;======================================================================
@@ -241,14 +267,17 @@ FF_SINIT:
 ; IT SWITCHES THE REQUIRED BANK TO THE BOTTOM OF CHIP ADDRESS RANGE.
 ; RETURNS THE BOTTOM BANK TO INITIAL STATE. ERASE SECTOR COMMAND IS ISSUED TO
 ; THE FLASH CHIP AND THEN TOGGLE BIT IS MONITORED FOR COMPLETION.
-; ON ENTRY HL CONTAINS THE SECTOR TO ERASE.
+; ON ENTRY B CONTAINS THE START BANK WHICH WE RETURN TO AT THE END
+;	   C CONTAINS THE TOP SECTION OF SECTOR WHICH SELECTS THE BANK.
 ;======================================================================
 ;
 FF_SERASE:
 	HB_DI
-	CALL	HBX_BNKSEL		; SELECT ROM BANK 0
+	PUSH	AF
+	LD	A,0
+	CALL	HBX_BNKSEL		; SELECT ROM BANK FROM A
 ;
-	LD	A,$AA			; SET CHIP ERASE
+	LD	A,$AA			; SET SECTOR  ERASE
 	LD	($5555),A
 ;
 	LD	A,$55
@@ -263,11 +292,41 @@ FF_SERASE:
 	LD	A,$55
 	LD	($2AAA),A
 ;
+	LD	A,B
+	CALL	HBX_BNKSEL		; SELECT ROM BANK FROM A	
+;
+	LD	H,C
+	LD	L,$00
 	LD	A,$30			; SECTOR ADDRESS
 	LD	(HL),A
 ;
-	LD	A,B			; RETURN TO ORIGINAL BANK
+	LD	A,0
+	CALL	HBX_BNKSEL		; SELECT ROM BANK FROM A
+;
+	LD	HL,$5555		; DO TWO SUCCESSIVE READS 
+	LD	A,(HL)			; FROM THE SAME FLASH ADDRESS. 
+FF_WT4:	LD	C,(HL)			; IF TOGGLE BIT (BIT 6) 
+	XOR	C			; IS THE SAME ON BOTH READS
+	BIT	6,A			; THEN ERASE IS COMPLETE SO EXIT.
+	JR	Z,FF_WT5		; Z TRUE IF BIT 6=0 I.E. "NO TOGGLE" WAS DETECTED. 
+;
+	LD	A,C			; OPERATION IS NOT COMPLETE. CHECK TIMEOUT BIT (BIT 5).
+	BIT	5,C			; IF NO TIMEOUT YET THEN LOOP BACK AND KEEP CHECKING TOGGLE STATUS
+	JR	Z,FF_WT4		; IF BIT 5=0 THEN RETRY; NZ TRUE IF BIT 5=1
+;
+	LD	A,(HL)			; WE GOT A TIMOUT. RECHECK TOGGLE BIT IN CASE WE DID COMPLETE 
+	XOR	(HL)			; THE OPERATION. DO TWO SUCCESSIVE READS. ARE THEY THE SAME?
+	BIT	6,A			; IF THEY ARE THEN OPERATION WAS COMPLETED					
+	JR	Z,FF_WT5		; OTHERWISE ERASE OPERATION FAILED OR TIMED OUT.
+;
+	LD	(HL),$F0		; WRITE DEVICE RESET
+	LD	C,$FF			; SET FAIL STATUS
+	JR	FF_WT6
+;
+FF_WT5:	LD	C,0			; SET SUCCESS STATUS
+FF_WT6:	POP	AF			; RETURN TO ORIGINAL BANK
 	CALL	HBX_BNKSEL		; WHICH IS OUR RAM BIOS COPY
+
 	HB_EI
 ;
 	RET
@@ -277,40 +336,42 @@ FF_S_SZ	.EQU	$-FF_SERASE
 ;	FLASH STYLE
 ;
 ST_NORMAL	.EQU	0
-ST_ERASE_CHIP	.EQU	1
+ST_ERASE_CHIP	.EQU	1	; SECTOR BASED ERASE NOT SUPPORTED
 ST_PROGRAM_SECT	.EQU	2
 ;
 ; FLASH CHIP MACRO
 ;
-#DEFINE	FF_CHIP(FFROMID,FFROMNM,FFROMSS,FFROMMD) 	\
+#DEFINE	FF_CHIP(FFROMID,FFROMNM,FFROMSS,FFROMSC,FFROMMD)\
 #DEFCONT ;						\
 #DEFCONT	.DW	FFROMID				\
 #DEFCONT	.DB	FFROMNM				\
 #DEFCONT	.DW	FFROMSS				\
-#DEFCONT	.DW	FFROMMD				\
+#DEFCONT	.DW	FFROMSC				\
+#DEFCONT	.DB	FFROMMD				\
 #DEFCONT ;
 ;
 ; FLASH CHIP LIST
 ;
 FF_TABLE:
-FF_CHIP(00120H,"29F010$    ",128,ST_NORMAL)
-FF_CHIP(001A4H,"29F040$    ",512,ST_NORMAL)
-FF_CHIP(01F04H,"AT49F001NT$",1024,ST_ERASE_CHIP)
-FF_CHIP(01F05H,"AT49F001N$ ",1024,ST_ERASE_CHIP)
-FF_CHIP(01F07H,"AT49F002N$ ",2048,ST_ERASE_CHIP)
-FF_CHIP(01F08H,"AT49F002NT$",2048,ST_ERASE_CHIP)
-FF_CHIP(01F13H,"AT49F040$  ",4096,ST_ERASE_CHIP)
-FF_CHIP(01F5DH,"AT29C512$  ",1,ST_PROGRAM_SECT)
-FF_CHIP(01FA4H,"AT29C040$  ",2,ST_PROGRAM_SECT)
-FF_CHIP(01FD5H,"AT29C010$  ",1,ST_PROGRAM_SECT)
-FF_CHIP(01FDAH,"AT29C020$  ",2,ST_PROGRAM_SECT)
-FF_CHIP(02020H,"M29F010$   ",128,ST_PROGRAM_SECT)
-FF_CHIP(020E2H,"M29F040$   ",512,ST_NORMAL)
-FF_CHIP(0BFB5H,"39F010$    ",32,ST_NORMAL)
-FF_CHIP(0BFB6H,"39F020$    ",32,ST_NORMAL)
-FF_CHIP(0BFB7H,"39F040$    ",32,ST_NORMAL)
-FF_CHIP(0C2A4H,"MX29F040$  ",512,ST_NORMAL)
-;
-FF_T_CNT	.EQU	($-FF_TABLE) / 17
+FF_CHIP(00120H,"29F010$    ",128,8,ST_NORMAL)
+FF_CHIP(001A4H,"29F040$    ",512,8,ST_NORMAL)
+FF_CHIP(01F04H,"AT49F001NT$",1024,1,ST_ERASE_CHIP)
+FF_CHIP(01F05H,"AT49F001N$ ",1024,1,ST_ERASE_CHIP)
+FF_CHIP(01F07H,"AT49F002N$ ",2048,1,ST_ERASE_CHIP)
+FF_CHIP(01F08H,"AT49F002NT$",2048,1,ST_ERASE_CHIP)
+FF_CHIP(01F13H,"AT49F040$  ",4096,1,ST_ERASE_CHIP)
+FF_CHIP(01F5DH,"AT29C512$  ",1,512,ST_PROGRAM_SECT)
+FF_CHIP(01FA4H,"AT29C040$  ",2,2048,ST_PROGRAM_SECT)
+FF_CHIP(01FD5H,"AT29C010$  ",1,1024,ST_PROGRAM_SECT)
+FF_CHIP(01FDAH,"AT29C020$  ",2,1024,ST_PROGRAM_SECT)
+FF_CHIP(02020H,"M29F010$   ",128,8,ST_PROGRAM_SECT)
+FF_CHIP(020E2H,"M29F040$   ",512,8,ST_NORMAL)
+FF_CHIP(0BFB5H,"39F010$    ",32,32,ST_NORMAL)
+FF_CHIP(0BFB6H,"39F020$    ",32,64,ST_NORMAL)
+FF_CHIP(0BFB7H,"39F040$    ",32,128,ST_NORMAL)
+FF_CHIP(0C2A4H,"MX29F040$  ",512,8,ST_NORMAL)
+;
+FF_T_CNT	.EQU	17
+FF_T_SZ		.EQU	($-FF_TABLE) / FF_T_CNT
 FF_UNKNOWN	.DB	"UNKNOWN$"
 FF_STACK:	.DW	0