Evalla was a citizen of the domed city of P3X-289, in the episode, 7.05 "Revisions".
Evalla was married to Pallan, one of the technicians who maintained the computer system which controlled the dome which harbored the survivors of a world which nearly killed themselves with over industrialization by poisoning their air and water. She and her husband entertained Carter and Daniel during their over-night stay on the planet and it was then that Evalla explained to Daniel about the archives of her world being accessible through a computer device called "the link". This link was worn on the user's temple and connected them directly to the same computer system which controlled the domed city.
Carter discouraged Daniel from using the link device for fear that it would not be compatible with his physiology. This precaution turned out to be warrented when it was discovered that the computer was sending people to the toxic wasteland outside the dome in order to control the population because the dome could not be maintained at its current size due to depleting energy derived from geo-thermal vents. Because the computer controlled the link, it was able to erase any memory of the people it sent out of the dome, perhaps to keep the population from panicking, but we are never really given the opportunity to delve into the intelligence, artificial or otherwise, of the actual computer system.
Evalla had shown Daniel the old archival records and he was able to discover the original population of the domed city. As it turns out, over one hundred thousand people originally chartered the domed city over four hundred years ago, but when SG-1 visited, there were only 1374 people inhabiting the dome. One of them, a councilwoman, left the dome while SG-1 was there, and then Evalla was instructed to leave, placing the population at 1372 when SG-1 discovered what was happening.
Unfortunately, Pallan's memory of his wife was erased and only Daniel or Carter could tell him of her.
--DeeKayP 20:10, 15 Aug 2004 (PDT)