MBM29DL32XTE Fujitsu Microelectronics, Inc., MBM29DL32XTE Datasheet - Page 42

• Manufacturer Part Number: MBM29DL32XTE
• Description: Flash Memory 32m 4m X 8/2m X 16 Bit Dual Operation
• Manufacturer: Fujitsu Microelectronics, Inc.

MBM29DL32XTE/BE
-80/90/12
• Hidden ROM (Hi-ROM) Region
The Hi-ROM feature provides a Flash memory region that the system may access through a new command
sequence. This is primarily intended for customers who wish to use an Electronic Serial Number (ESN) in the
device with the ESN protected against modification. Once the Hi-ROM region is protected, any further modifi-
cation of that region is impossible. This ensures the security of the ESN once the product is shipped to the field.
The Hi-ROM region is 64K bytes in length and is stored at the same address of the 8KB 8 sectors. The
MBM29DL32XTE occupies the address of the byte mode 3F0000h to 3FFFFFh (word mode 1F8000h to
1FFFFFh) and the MBM29DL32XBE type occupies the address of the byte mode 000000h to 00FFFFh (word
mode 000000h to 007FFFh). After the system has written the Enter Hi-ROM command sequence, the system
may read the Hi-ROM region by using the addresses normally occupied by the boot sectors. That is, the device
sends all commands that would normally be sent to the boot sectors to the Hi-ROM region. This mode of operation
continues until the system issues the Exit Hi-ROM command sequence, or until power is removed from the
device. On power-up, or following a hardware reset, the device reverts to sending commands to the boot sectors.
• Hidden ROM (Hi-ROM) Entry Command
MBM29DL32XTE/BE has a Hidden ROM area with One Time Protect function. This area is to enter the security
code and to unable the change of the code once set. Program/erase is possible in this area until it is protected.
However, once it is protected, it is impossible to unprotect, so please use this with caution.
Hidden ROM area is 64K Byte and in the same address area of 8KB sector. The address of top boot is 3F0000h
to 3FFFFFh at byte mode (1F8000h to 1FFFFFh at word mode) and the bottom boot is 000000h to 00FFFFh
at byte mode (000000h to 007FFFh at word mode). These areas are normally the boot block area (8KB 8
sector). Therefore, write the Hidden ROM entry command sequence to enter the Hidden ROM area. It is called
as Hidden ROM mode when the Hidden ROM area appears.
Sector other than the boot block area could be read during Hidden ROM mode. Read/program/erase of the
Hidden ROM area is possible during Hidden ROM mode. Write the Hidden ROM reset command sequence to
exit the Hidden ROM mode. The bank address of the Hidden ROM should be set on the third cycle of this reset
command sequence.
In case of MBM29DL321TE/BE, whose Bank 1 size is 0.5 Mbit, the simultaneous operation cannot execute
multi-function mode between the Hidden ROM area and Bank 2 Region.
• Hidden ROM (Hi-ROM) Program Command
To program the data to the Hidden ROM area, write the Hidden ROM program command sequence during Hidden
ROM mode. This command is same as the program command in the past except to write the command during
Hidden ROM mode. Therefore the detection of completion method is the same as in the past, using the DQ
7
data poling, DQ
toggle bit and RY/BY pin. Need to pay attention to the address to be programmed. If the address
6
other than the Hidden ROM area is selected to program, the data of the address will be changed.
• Hidden ROM (Hi-ROM) Erase Command
To erase the Hidden ROM area, write the Hidden ROM erase command sequence during Hidden ROM mode.
This command is same as the sector erase command in the past except to write the command during Hidden
ROM mode. Therefore the detection of completion method is the same as in the past, using the DQ
data poling,
7
DQ
toggle bit and RY/BY pin. Need to pay attention to the sector address to be erased. If the sector address
6
other than the Hidden ROM area is selected, the data of the sector will be changed.
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