Lenovo NVS-4200M, 42825BU, 4242X04, 42421A0 Bottom view, SIM card slot, Battery, Docking connector

Bottom view

Figure 4. ThinkPad T520, T520i, and W520 bottom view

	SIM card slot		Battery
1		2
	Docking connector		Memory-upgrade slot
3		4
	Hard disk drive (HDD) or solid state drive
5

1

SIM card slot

If your computer has a wireless WAN feature, it may require a SIM (Subscriber Identification 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 office 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.

10User Guide