MBM29DL16XTE/BE70/90
• HiddenROM Region
The HiddenROM 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 HiddenROM region is protected, any further
modification of that region is impossible. This ensures the security of the ESN once the product is shipped to
the field.
The HiddenROM region is 64 Kbytes in length and is stored at the same address of the 8 KB ×8 sectors. The
MBM29DL16XTE occupies the address of the byte mode 1F0000h to 1FFFFFh (word mode 0F8000h to
0FFFFFh) and the MBM29DL16XBE type occupies the address of the byte mode 000000h to 00FFFFh (word
mode000000hto007FFFh). AfterthesystemhaswrittentheEnterHiddenROMcommandsequence, thesystem
may read the HiddenROM 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 HiddenROM region. This
mode of operation continues until the system issues the Exit HiddenROM 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.
• HiddenROM Entry Command
MBM29DL16XTE/BE have a HiddenROM 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.
HiddenROM area is 64 Kbyte and in the same address area of 8 KB sectors. The address of top boot is 1F0000h
to 1FFFFFh at byte mode (0F8000h to 0FFFFFh 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 (8 KB ×
8 sectors). Therefore, write the HiddenROM entry command sequence to enter the HiddenROM area. It is called
as HiddenROM mode when the HiddenROM area appears.
Sector other than the boot block area could be read during HiddenROM mode. Read/program/earse of the
HiddenROM area is possible during HiddenROM mode. Write the HiddenROM reset command sequence to exit
the HiddenROM mode. The bank address of the HiddenROM should be set on the third cycle of this reset
command sequence.
In case of MBM29DL161TE/BE, whose Bank 1 size is 0.5 Mbit, the simultaneous operation cannot execute
multi-function mode between the HiddenROM area and Bank 2 Region.
• HiddenROM Program Command
To program the data to the HiddenROM area, write the HiddenROM program command sequence during
HiddenROMmode. Thiscommandisthesameastheprogramcommandinthepastexcepttowritethecommand
during HiddenROM mode. Therefore the detection of completion method is the same as in the past, using the
DQ7 data poling, DQ6 toggle bit and RY/BY pin. Need to pay attention to the address to be programmed. If the
address other than the HiddenROM area is selected to program, the data of the address will be changed.
• HiddenROM Erase Command
To erase the HiddenROM area, write the HiddenROM erase command sequence during HiddenROM mode.
This command is the same as the sector erase command in the past except to write the command during
HiddenROM mode. Therefore the detection of completion method is the same as in the past, using the DQ7 data
poling, DQ6 toggle bit and RY/BY pin. Need to pay attention to the sector address to be erased. If the sector
address other than the HiddenROM area is selected, the data of the sector will be changed.
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SPANSION [ SPANSION ]
