IBM THINKPAD X121E, Hardware Maintenance Manual

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MTM on the rear label:
TTTT-CTO S/N SSSSSSS
Product ID on the rear label:
TTTT-MMM (Use this number when setting the serial number)
In the example, the Serial Number to be input is “1STTTTMMMSSSSSSS”.
Retaining the UUID
The Universally Unique Identifier (UUID) is a 128-bit number uniquely assigned to your computer at
production and stored in the EEPROM of your system board. The algorithm that generates the number is
designed to provide unique IDs until the year A.D. 3400. No two computers in the world have the same
number.
When you replace the system board, you must set the UUID on the new system board by doing the following:
1. Install the LENOVO ThinkPad Hardware Maintenance Diskette Version 1.76 or later, and restart the
computer.
2. From the main menu, select 4. Assign UUID . A new UUID is created and written. If a valid UUID
already exists, it will not be overwritten.
Reading or writing the ECA information
Information on Engineering Change Announcements (ECA) is stored in the EEPROM of the system board.
The electronic storage of this information simplifies the procedure to check if an engineering change has
been previously applied to a computer.
To check what engineering changes have been previously applied to the machine, use the ECA information
read/write function on the LENOVO ThinkPad Hardware Maintenance Diskette Version 1.76 or later.
1. Insert the LENOVO ThinkPad Hardware Maintenance Diskette Version 1.76 or later, and restart the
computer.
2. From the main menu, select 6. Set ECA Information .
3. To read the ECA information, select 2. Read ECA/rework number from EEPROM and follow the
instruction.
4. To read the box build date, select 5. Read box build date from EEPROM , and follow the instructions
on the computer.
After an engineering change is applied to the machine, the EEPROM must be updated. Use the LENOVO
ThinkPad Hardware Maintenance Diskette Version 1.76 or later to update the EEPROM.
Note: Only the ECA number is stored in the EEPROM. The machine type of the ECA is assumed to be the
same as the machine type of the machine that had the engineering change applied to it.
1. Insert the LENOVO ThinkPad Hardware Maintenance Diskette Version 1.76 or later, and restart the
computer.
2. From the main menu, select 6. Set ECA Information .
3. To write ECA information, select 1. Write ECA/rework number from EEPROM , and follow the
instruction.
4. To write box build date, select 4. Write box build date from EEPROM , and follow the instruction on
the screen.
If the system board is being replaced, try to read the ECA information from the old system board and transfer
the information to the new system board. If the system board is inoperable, this will not be possible.
Chapter 7
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FRU replacement notices
47