Our patient tonight is the NVRAM (real-time clock, serial number, and preferences) chip from a Sun Microsystems Ultra 80 workstation. The little plastic carrier around it serves to make it hard to plug in backwards and easy to remove.
For reasons unfathomable to anyone with common sense, Sun decided to store the system serial number on a battery-backed chip, as opposed to permanently setting it somewhere (in a serial EEPROM, perhaps). So, when your computer gets old enough to outlive the battery, you can't get on the network anymore. These chips are obsolete and sell at about $16/ea and will have significantly reduced battery life because they're all old.
Fortunately, the battery in there is a plain old 3V lithium cell, so we can replace it. Let's dive in!