256Mb, 512Mb, 1Gb, 2Gb: 3V Embedded Parallel NOR Flash
Protection Operations
NONVOLATILE PROTECTION BIT LOCK BIT Commands
After the ENTER NONVOLATILE PROTECTION BIT LOCK BIT COMMAND SET (50h)
command has been issued, the commands that allow the nonvolatile protection bit lock
bit to be set can be issued to the device.
The PROGRAM NONVOLATILE PROTECTION BIT LOCK BIT (A0h) command is used to
set the nonvolatile protection bit lock bit to 0, thus locking the nonvolatile protection
bits and preventing them from being modified.
The READ NONVOLATILE PROTECTION BIT LOCK BIT STATUS command is used to
read the status of the nonvolatile protection bit lock bit.
VOLATILE PROTECTION Commands
After the ENTER VOLATILE PROTECTION COMMAND SET (E0h) command has been
issued, commands related to the volatile protection mode can be issued to the device.
The PROGRAM VOLATILE PROTECTION BIT (A0h) command individually sets a vola-
tile protection bit to 0 for a given block. If the nonvolatile protection bit for the same
block is set, the block is locked regardless of the value of the volatile protection bit. (See
the Block Protection Status table.)
The status of a volatile protection bit for a given block can be read by issuing a READ
VOLATILE PROTECTION BIT STATUS command along with the block address.
The CLEAR VOLATILE PROTECTION BIT (A0h) command individually clears (sets to 1)
the volatile protection bit for a given block. If the nonvolatile protection bit for the same
block is set, the block is locked regardless of the value of the volatile protection bit. (See
the Block Protection Status table.)
EXTENDED MEMORY BLOCK Commands
The device has one extra 128-word extended memory block that can be accessed only
by the ENTER EXTENDED MEMORY BLOCK (88h) command. The extended memory
block is 128 words (x16) or 256 bytes (x8). It is used as a security block to provide a per-
manent 128-bit security identification number or to store additional information. The
device can be shipped with the extended memory block prelocked permanently by Mi-
cron, including the 128-bit security identification number. Or, the device can be ship-
ped with the extended memory block unlocked, enabling customers to permanently
program and lock it. (See Lock Register, the AUTO SELECT command, and the Block
Protection table.)
Table 15: Extended Memory Block Address and Data
Address
x16
Data
x8
Micron prelocked
Customer Lockable
000000h–00000Fh 000000h–000007h
000010h–0000FFh 000008h–00007Fh
Secure ID number
Determined by customer
Secure ID number
Determined by customer
Protected and
unavailable
After the ENTER EXTENDED MEMORY BLOCK command has been issued, the device
enters the extended memory block mode. All bus READ or PROGRAM operations are
conducted on the extended memory block, and the extended memory block is ad-
PDF: 09005aef849b4b09
m29ew_256mb_2gb.pdf - Rev. B 8/12 EN
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43
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