M29W128FL View Datasheet(PDF) - Numonyx -> Micron
Part Name
Description
MFG CO.
'M29W128FL' PDF : 78 Pages View PDF
M29W128FH, M29W128FL
Appendix C Extended Memory Block
Extended Memory Block
The M29W128F has an extra block, the Extended Memory Block, that can be accessed
using a dedicated command. This Extended Memory Block is 128 Words in x16 mode and
256 Bytes in x8 mode. It is used as a security block (to provide a permanent security
identification number) or to store additional information.
The Extended Memory 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
Memory Block is protected. When set to ‘0’, it indicates that the device is customer lockable
and the Extended Memory 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 factory locked one.
Bit DQ7 is the most significant bit in the Extended Memory Block Verify Indicator and a
specific procedure must be followed to read it. See Verify Extended Memory Block
Protection Indicator in Table 4: Block Protection, 8-bit mode and Table 7: Block Protection,
16-bit mode, for details of how to read bit DQ7.
The Extended Memory Block can only be accessed when the device is in Extended Memory
Block mode. For details of how the Extended Block mode is entered and exited, refer to the
Section 5.3.1: Enter Extended Memory Block command and Section 5.3.2: Exit Extended
Block command, and to Table 13 and Table 9.
C.1
Factory Locked Extended Memory Block
In devices where the Extended Memory Block is factory locked, the Security Identification
Number is written to the Extended Memory Block address space (see Table 35: Extended
Memory Block Address and Data) in the factory. The DQ7 bit is set to ‘1’ and the Extended
Memory Block cannot be unprotected.
67/78
Share Link: 
