The central data core is a glowing, mushroom-shaped device, which can be controlled by a console standing in front of it. The data core serves as a back-up hard drive for the Asurans and through it, The base-code of the nanites can be manipulated. Thus, a new program or a virus can be uploaded into the race, forcing them to follow new directives.
10,000 years ago, after the Lanteans were defeated by the Wraith, the Asurans attacked the Wraith due to a command programmed into their base-code. When the Wraith discovered the data core, they uploaded a virus to shut down the attack code and end the Asuran assault. This was accomplished by Guide and the members of his hive ship. (SGA: "Consort")
In 2007, Atlantis 1 was able to sneak into Asuras undetected to steal a much needed Zero Point Module. Rodney McKay was able to discover the core and its purpose through Elizabeth Weir and her recently reactivated nanites. McKay managed to instruct Sheppard and Ronon on how to upload the command to attack the Wraith via the data core, and the Asurans quickly launched a renewed assault on the Wraith. (SGA: "Lifeline")
During the Battle of Asuras, McKay, Ronon and a team of Marines are beamed to the data core by the Apollo so McKay can use it to take control of the Asuran power grid. After the power grid is destroyed, McKay is able to use the core to increase the mass of the Replicator Godzilla so it sinks to the planet's core and causes it to explode. The team is then beamed out by the Daedalus before the explosion. (SGA: "Be All My Sins Remember'd")