Imperial dungeon ships were introduced at the height of the Purge in an attempt to control Jedi Knights and other dangerous prisoners. Originally designed by the Mandalorians, the majority of the ships cells were devoted to common prisoners. Sections were partitioned off to allow for variable gravity, lighting, atmosphere and other factors - often prisoners were held under uncomfortable (such as heavier than normal gravity) conditions to keep them docile during the prisoner transfer. Other tactics of control included mild electric shocks (painful but causing no permanent damage), sirens and hallucinogenic gases.
Prisoners were guarded by droids along with normal organic guards (who were heavily armed and ordered to maintain order no matter what happened). Since the prisoners knew that disobedience meant death, there were few uprisings aboard the dungeon ships.
When it came to Jedi Knights, the prison ships were designed on the principle that the best way to keep a Jedi Knight under control was to keep him disoriented and preoccupied with survival. Traditional restraints were useless against those who could call upon the force. Super dense alloys lined each cell to prevent any physical escape and, it was (erroneously) hoped, to screen out any telepathy. Eventually the energy shields used on the Universal Energy Cages had to be installed around the perimeter of the cells to prevent the Jedi from using their abilities. Life support settings were set extremely low to force the Jedi into hibernating for the duration of the voyage.
To prevent prisoners from commandeering vessels, the dungeon ships lack a normal nav computer. The computer can only hold two sets of coordinates at any given time: the jump to the prisoner transfer planet and the final destination. If a jump ship had to make multiple jumps, it would have to get new jump coordinates at each stopover. The bridge is located at the bottom of the ship in a self contained and detachable command chamber equipped with emergency rations and a signal beacon.
Grand Admiral Danetta Pitta used the dungeon ships Angrix,
Apocahk, and Azgoghk to collect alien civilizations for use as slaves.