The first generators were extremely primitive and had no control over the location of the realm. In fact, the first generator was only ever shown to work in theory. Later models, however, could not only join a realm to our universe at any point (a doorway was often used for this purpose) but could shape the landscape of the realm to any desired form within an area of the connection point of roughly the radius of the Earth.
Originally the realms were believed to be infinite, and the drive was named as such. A mathematician whose name is lost to us eventually disproved this, resulting in the renaming of the generator, but the region is so vast that no one has ever seen one of its edges. A large ship equipped for several generations of travel set out top find the edge of a realm connected to a moon of one of the planets in the Terra system, but which moon and even which planet has been forgotten and the ship has not been heard from since their departure, and since much of the system was destroyed by [Kingdom of Atholl]? forces at the end of the third phase of the Orbital Wars it is doubtful the generator holding the connection point open remains intact.
The realm generators were abandoned as a solution to the overpopulation problem when popular opinion turned against them after one of the generators malfunctioned stranding just over ten thousand new colonists without resources in a newly opened realm. Shortly after this event Pharmacon? bought all realm generator related patents for unknown reasons.
Finite realm generator technology was largely forgotten until Durviian scientists discovered its link to the teleportation ability of Barren Walkers. It is highly unlikely that the Durvii would have been able to reproduce such advanced technology from little more than the information of its existence in such a short time as they did, and it is ususlly supposed that either the Durvii Battalion raided the Pharmacon Reseach and Development building and stole the technology or that the Pharmacon corporation gave the technology to the Durvii in trade, though what the Durvii could have traded for it is uncertain.