Retaining serial numbers

This section includes the following descriptions:

•“Restoring the serial number of the system unit” on page 54

•“Retaining the UUID” on page 54

•“Reading or writing the ECA information” on page 55

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 LENOVO ThinkPad Hardware Maintenance Diskette Version 1.76 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:

• 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 LENOVO ThinkPad Hardware Maintenance Diskette Version 1.76 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.

If the MTM and Product ID numbers differ from each other on the rear label, use what is shown for the Product ID field. See example below:

MTM on rear label:

TTTT-CTO S/N SSSSSSS

Product ID on rear label:

TTTT-MMM (Use this number when setting 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.

54Hardware Maintenance Manual

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Lenovo L421, L520, L420 manual Retaining serial numbers, Restoring the serial number of the system unit, Retaining the Uuid
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L420, L520, L421 specifications

The Lenovo L421, L520, and L420 are part of Lenovo's ThinkPad series, which is known for its reliability, durability, and performance. These models are designed primarily for business professionals and students, providing a blend of functionality and portability tailored for everyday computing.

The Lenovo L421 is equipped with the second-generation Intel Core processors, which enhance its performance and efficiency. It features a 14-inch LED backlit display, offering sharp visuals and sufficient screen real estate for multitasking. The L421 also sports a spill-resistant keyboard, ensuring that accidental spills do not affect the device's functionality. This model supports up to 8GB of RAM and incorporates various connectivity options, including USB 3.0 ports, HDMI, and an SD card reader, which makes it versatile for various peripherals.

The L520 is another solid offering from Lenovo, featuring a slightly larger 15.6-inch display for increased productivity. It shares many characteristics with the L421, such as the use of Intel’s second-generation processors. The L520 also emphasizes security with features like a fingerprint reader and a Trusted Platform Module (TPM) for data encryption, appealing to businesses that require stringent security measures. Its ExpressCard and docking station compatibility add flexibility, allowing users to tailor their setups according to their needs.

The L420, like its siblings, comes with an emphasis on performance and utility. With a 14-inch HD display, it offers vibrant visuals. The L420 also benefits from Lenovo's legendary keyboard design, which ensures a comfortable typing experience. This model is geared for users who require a balance between performance and portability without compromising on essential features. The same Intel Core processors and security features are incorporated, ensuring a reliable experience for professional applications.

All three models feature Lenovo's innovative Power Management technology, which optimizes battery life, allowing users to work longer hours without needing to recharge. Additionally, they are built with robust materials that ensure longevity, making them suitable for both office and on-the-go environments.

Overall, the Lenovo L421, L420, and L520 exemplify the ThinkPad series' commitment to performance, security, and durability, making them excellent choices for anyone looking for reliable laptops for professional use.
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