Figure 12
Sector Unprotect Algorithm
Start
Protect All Sectors
Verify 98403/98406
Device Code
PLSCNT = 1
Set Up Sector Address
Unprotected Mode
(A5 = VIH, A9 = VIL)
Set OE = VID OR VSP
WE = VSP
Activate CE Pulse
Time Out 5 mS
Set OE = VIL, WE = VIH
A6 = VIH, A9 = VID OR VSP
Setup Sector Address SA0
Set A1, A0 = 1, 0
CE = VIL
Read Data
From Device
Increment
Sector Address
Notes:
SA0 = Sector Address for initial sector
SA7 = Sector Address for last sector
Please refer to Table 2 for details
Aeroflex Circuit Technology
No
Data = 00H
?
Yes
No
Sector
Address = SA7
?
Yes
Remove VID OR VSP from A9
Sector Unprotect
Completed
16
A
Increment
PLSCNT
No
PLSCNT = 1000
?
Yes
Device Failure
SCD1665 REV B 6/29/01 Plainview NY (516) 694-6700