![](http://datasheet.mmic.net.cn/170000/S71PL191HB0BFI100_datasheet_9723326/S71PL191HB0BFI100_117.png)
May 7, 2004 S29JL064HA1
S29JL064H
21
Pre l i m i n a r y
SecSi (Secured Silicon) Sector
Flash Memory Region
The SecSi (Secured Silicon) Sector feature provides a Flash memory region that
enables permanent part identification through an Electronic Serial Number
(ESN). The SecSi Sector is 256 bytes in length, and uses a SecSi Sector Indicator
Bit (DQ7) to indicate whether or not the SecSi Sector is locked when shipped from
the factory. This bit is permanently set at the factory and cannot be changed,
which prevents cloning of a factory locked part. This ensures the security of the
ESN once the product is shipped to the field.
The product is available with the SecSi Sector either factory locked or customer
lockable. The factory-locked version is always protected when shipped from the
factory, and has the SecSi (Secured Silicon) Sector Indicator Bit permanently set
to a “1.” The customer-lockable version is shipped with the SecSi Sector unpro-
tected, allowing customers to utilize the that sector in any manner they choose.
The customer-lockable version has the SecSi (Secured Silicon) Sector Indicator
Bit permanently set to a “0.” Thus, the SecSi Sector Indicator Bit prevents cus-
tomer-lockable devices from being used to replace devices that are factory
locked. The SecSi Customer Indicator Bit (DQ6) is permanently set to 1 if the part
has been customer locked, permanently set to 0 if the part has been factory
locked, and is 0 if customer lockable.
The system accesses the SecSi Sector Secure through a command sequence (see
has written the Enter SecSi Sector command sequence, it may read the SecSi
Sector by using the addresses normally occupied by the boot sectors. This mode
of operation continues until the system issues the Exit SecSi Sector command se-
quence, or until power is removed from the device. On power-up, or following a
hardware reset, the device reverts to sending commands to the first 256 bytes of
Sector 0. Note that the ACC function and unlock bypass modes are not available
when the SecSi Sector is enabled.
Factory Locked: SecSi Sector Programmed and Protected At the Factory
In a factory locked device, the SecSi Sector is protected when the device is
shipped from the factory. The SecSi Sector cannot be modified in any way. The
device is preprogrammed with both a random number and a secure ESN. The 8-
word random number is at addresses 000000h–000007h in word mode (or
000000h–00000Fh in byte mode). The secure ESN is programmed in the next 8
words at addresses 000008h–00000Fh (or 000010h–00001Fh in byte mode). The
device is available preprogrammed with one of the following:
A random, secure ESN only
Customer code through Spansion programming services
Both a random, secure ESN and customer code through Spansion program-
ming services
Contact an your local sales office for details on using Spansion programming
services.
Customer Lockable: SecSi Sector NOT Programmed or Protected At the Factory
If the security feature is not required, the SecSi Sector can be treated as an ad-
ditional Flash memory space. The SecSi Sector can be read any number of times,
but can be programmed and locked only once. Note that the accelerated pro-
gramming (ACC) and unlock bypass functions are not available when
programming the SecSi Sector.