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v “Retaining the UUID”
v “Reading or writing the ECA information”
Restoring the serial number of the system unit
When the computer was manufactured, the EEPROM on the system board was
loaded with the serial numbers of the system and all major components. These
numbers need to remain the same throughout the life of the computer.
If you replace the system board, you must restore the serial number of the system
unit to its original value.
Before replacing the system board, save the original serial number by doing the
following:
1. Install the ThinkPad Hardware Maintenance Diskette Version 1.73 or later, and
restart the computer.
2. From the main menu, select 1. Set System Identification.
3. Select 2. Read S/N data from EEPROM.
The serial number of each device in your computer is displayed; the serial number
of the system unit is listed as follows:
v 20: Serial number
Write down that number.
Note: The serial number of the system unit is also written on the label attached to
the bottom of the computer.
After you have replaced the system board, restore the serial number by doing the
following:
1. Install the ThinkPad Hardware Maintenance Diskette Version 1.73 or later and
restart the computer.
2. From the main menu, select 1. Set System Identification.
3. Select 1. Add S/N data from EEPROM.
Follow the instructions on the screen.
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 as follows:
1. Install the ThinkPad Hardware Maintenance Diskette Version 1.73 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 is not
overwritten.
Reading or writing the ECA information
Information on Engineering Change Announcements (ECA) are stored in the
EEPROM of the system board. The electronic storage of this information simplifies
the procedure to check if the ECA has been previously applied to a machine. The
machine does not need to be disassembled to check for the ECA application.
FRU replacement notices
ThinkPad Z61t 53