M29W640GB NUMONYX [Numonyx B.V], M29W640GB Datasheet - Page 79

• Manufacturer Part Number: M29W640GB
• Description: 64 Mbit (8Mb x8 or 4Mb x16, Page) 3V supply Flash memory
• Manufacturer: NUMONYX [Numonyx B.V]

M29W640GH, M29W640GL, M29W640GT, M29W640GB
Appendix C
C.1
C.2
The M29W640G has an extra block, the Extended Block, that can be accessed using a
dedicated command.
This Extended 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 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 factory 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
Bus Operations, BYTE = V
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 command
Table 10
Factory Locked Extended Block
In devices where the Extended Block is factory locked, the Security Identification Number is
written to the Extended Block address space (see
data) in the factory. The DQ7 bit is set to ‘1’ and the Extended Block cannot be unprotected.
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 protection of the Extended Block is not
reversible.
There are two ways of protecting the Extended Block:
●
●
Once the Extended Block is programmed and protected, the Exit Extended Block command
must be issued to exit the Extended Block mode and return the device to Read mode.
Issue the Enter Extended Block command to place the device in Extended Block mode,
then use the In-System Technique with RP either at V
In-System Technique
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,
to the corresponding flowcharts,
the technique).
and
Extended Memory Block
Table 11: Commands, 8-bit mode, BYTE = V
and to the corresponding flowcharts,
IL
and
and
Table 8: Bus Operations, BYTE = V
Section 4.3.2: Exit Extended Block
Figure 25
and
Table 36: Extended block address and
Section D.1: Programmer Technique
Figure
IL
IH
26, for a detailed explanation of
.
or at V
Figure 27
Extended Memory Block
ID
IH
(refer to
, for details of how to
command, and to
and
Section 4.3.1:
Figure
Section D.2:
”
in
Table 7:
28, for
79/90
and