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Bottom view
Figure 4. ThinkPad T520, T520i, and W520 bottom view
1 SIM card slot
2 Battery
3 Docking connector 4 Memory-upgrade slot
5 Hard disk drive (HDD) or solid state drive
1 SIM card slot
If your computer has a wireless WAN feature, it may require a SIM (Subscriber Identication Module) card to
establish a wireless WAN (Wide Area Network) connections. Depending on the country of delivery, the SIM
card may be already installed in the SIM card slot.
2 Battery
Use your computer with battery power whenever ac power is unavailable.
By installing a second battery, available as an option, in the serial Ultrabay enhanced, you can extend the
operating time of the computer. You can also use Power Manager to adjust your power setting as needed.
For details, refer to the instructions in “Power Manager” on page 27
.
3 Docking connector
With a ThinkPad Port Replicator Series 3, ThinkPad Mini Dock Series 3, ThinkPad Mini Dock Plus Series 3,
or ThinkPad Mini Dock Plus Series 3 (170 W), you can extend the computer capabilities when you are in
your ofce or at home.
4 Memory-upgrade slot
You can increase the amount of memory in your computer by installing a memory module in the memory
bay. Memory modules are available as options.
Note: If your computer is a dual-core processor model, two Dummy DIMM cards are preinstalled and do
not replace the Dummy DIMM cards with SO-DIMMs. For details, refer to the instructions in “Increasing or
replacing memory (W520)” on page 139
.
10 User Guide