M29W320ET, M29W320EB
APPENDIX C. EXTENDED MEMORY BLOCK
The M29W320E has an extra block, the Extended
Block, that can be accessed using a dedicated
command.
This Extended Block is 32 KWords in x16 mode
and 64 KBytes in x8 mode. It is used as a security
block (to provide a permanent security identifica-
tion number) or to store additional information.
Factory Locked Extended Block
In devices where the Extended Block is factory
locked, the Security Identification Number is writ-
ten to the Extended Block address space (see Ta-
ble 28., Extended Block Address and Data) in the
factory. The DQ7 bit is set to ‘1’ and the Extended
Block cannot be unprotected.
The Extended Block is either Factory Locked or
Customer Lockable, its status is indicated by bit
DQ7. This bit is permanently set to either ‘1’ or ‘0’
at the factory and cannot be changed. When set to
‘1’, it indicates that the device is factory locked and
the Extended Block is protected. When set to ‘0’, it
indicates that the device is customer lockable and
the Extended Block is unprotected. Bit DQ7 being
permanently locked to either ‘1’ or ‘0’ is another
security feature which ensures that a customer
lockable device cannot be used instead of a facto-
ry locked one.
Bit DQ7 is the most significant bit in the Extended
Block Verify Code and a specific procedure must
be followed to read it. See “Extended Memory
Block Verify Code” in Table 2. and Table 3., Bus
Operations, BYTE = VIL and Bus Operations,
BYTE = VIH, respectively, for details of how to read
bit DQ7.
The Extended Block can only be accessed when
the device is in Extended Block mode. For details
of how the Extended Block mode is entered and
exited, refer to the Enter Extended Block Com-
mand and Exit Extended Block Command para-
graphs, and to Table 4. and Table 5., “Commands,
16-bit mode, BYTE = VIH” and “Commands, 8-bit
mode, BYTE = VIL”, respectively.
Customer Lockable Extended Block
A device where the Extended Block is customer
lockable is delivered with the DQ7 bit set to ‘0’ and
the Extended Block unprotected. It is up to the
customer to program and protect the Extended
Block but care must be taken because the protec-
tion of the Extended Block is not reversible.
There are two ways of protecting the Extended
Block:
■
Issue the Enter Extended Block command to
place the device in Extended Block mode,
then use the In-System Technique with RP
either at VIH or at VID (refer to APPENDIX D.,
In-System Technique and to the
corresponding flowcharts, Figure 22. and
Figure 23., for a detailed explanation of the
technique).
■
Issue the Enter Extended Block command to
place the device in Extended Block mode,
then use the Programmer Technique (refer to
APPENDIX D., Programmer Technique and to
the corresponding flowcharts, Figure 20. and
Figure 21., for a detailed explanation of the
technique).
Once the Extended Block is programmed and pro-
tected, the Exit Extended Block command must be
issued to exit the Extended Block mode and return
the device to Read mode.
Table 28. Extended Block Address and Data
(1)
Data
Address
Device
x8
x16
Factory Locked
Customer Lockable
Security Identification
Number
3F0000h-3F000Fh
3F0010h-3FFFFFh
000000h-00000Fh
000010h-00FFFFh
1F8000h-1F8007h
1F8008h-1FFFFFh
000000h-000007h
000008h-007FFFh
Determined by
Customer
M29W320ET
M29W320EB
Unavailable
Security Identification
Number
Determined by
Customer
Unavailable
Note: 1. See Table 20. and Table 21., Top and Bottom Boot Block Addresses.
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STMICROELECTRONICS [ ST ]
