MBM29DL32XTE/BE80/90
When reading the HiddenROM region, either change addresses or change CE pin from “H” to “L”. The same
procedure should be taken (changing addresses or CE pin from “H” to “L”) after the system issues the Exit
HiddenROM command sequence to read actual data of memory cell.
• HiddenROM Entry Command
MBM29DL32XTE/BE has 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 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 (8 KB ×8
sector) . 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/erase 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.
• HiddenROM Program Command
To program the data to the HiddenROM area, write the HiddenROM program command sequence during
HiddenROM mode. This command is same as the program 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 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 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.
• HiddenROM Protect Command
There are two methods to protect the HiddenROM area. One is to write the sector group protect setup command
(60h) , set the sector address in the HiddenROM area and (A6, A1, A0) = (0, 1, 0) , and write the sector group
protect command (60h) during the HiddenROM mode. The same command sequence could be used because
except that it is in the HiddenROM mode and that it does not apply high voltage to RESET pin, it is the same as
the extension sector group protect in the past. Please refer to “Function Explanation Extended Command (3)
Extended Sector Group Protection” for details of extension sector group protect setting.
The other is to apply high voltage (VID) to A9 and OE, set the sector address in the HiddenROM area and (A6,
A1, A0) = (0, 1, 0) , and apply the write pulse during the HiddenROM mode. To verify the protect circuit, apply
high voltage (VID) to A9, specify (A6, A1, A0) = (0, 1, 0) and the sector address in the HiddenROM area, and
read. When “1” appears to DQ0, the protect setting is completed. “0” will appear to DQ0 if it is not protected.
Please apply write pulse again. The same command sequence could be used for the above method because
other than the HiddenROM mode, it is the same as the sector group protect in the past. Please refer to “Function
Explanation Sector Group Protection” for details of sector group protect setting
Other sector group will be effected if the address other than the HiddenROM area is selected for the sector group
address, so please be careful. Once it is protected, protection can not be cancelled, so please pay closest
attention.
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