The Damage Control computer relays information to the CIC on malfunctioning or damaged areas of the battlestar, presumably from various sensors throughout the ship. It also has access to radiation sensors in the event of nuclear attack to warn against dangerous radiation levels that could harm the crew. The DC computer's function can be compromised by a hostile force through places such as Aft Damage Control, as was threatened in "Valley of Darkness". If these locations are compromised, the computer's safeties can be overridden and various life-support controls, such as bulkheads and atmospheric controls, could be altered, venting the ship's air (and crew) into space.
Fire Control Computer
The Fire Control computer manages a battlestar's primary offensive weapons, the central flak turret and smaller port and starboard turrets along the length of each side of the ship. It is presumed that the Fire Control computers report to crewmembers responsible for the upkeep of ammunition on the guns when to reload an particular turret. The Fire Control computer can target individual bogeys with the flak turret guns, which, in tandem with the smaller turrets, make even Galactica, an old original battlestar from the first Cylon War, a formidable foe to encounter. Like the DC computer, there are control rooms on Galactica where the ship's computerized gun control can be overriden.
Aft Damage Control
The Aft Damage Control room presumably controls shipboard bulkheads, vents, and other life-sustaining aspects on Galactica. In the event of fire or other hazards, the room could be used to adjust controls that manage fires or prevent smoke and other toxins from permeating the remainder of the ship. It is likely that this room is used only if the command crew in CIC are dead or incapacitated, or unable to perform the D.C. task from CIC's Damage Control station
This computer likely manages secondary functions of the ship, such as communications. The mainframe likely provides extra calculating power for other ship tasks when required, and may also serve as the ship's library for tactical information. Of all the computers on Galactica, this computer is likely very resistant by design to infiltration since it controls communication traffic (and thus is accessible to Cylon external intrusion by wireless). The mainframe likely possesses a basic gateway, but, per Galactica's no-networks edict, it is typically unused.
The communications elements of the mainframe, while having digital controls, are analog instruments, which make them highly resistant to external Cylon electronic attack as they do not transfer digital signals. As with other battlestar systems, the mainframe hardware remains susceptible to internal Cylon electronic attacks (viruses and logic bombs that infect and transfer from other systems).