A vagabond by the name of Cheversly got caught in a strong duststorm and battened down behind the silo as a wind break. After the sands settled, a small vent revealed an entrance to the tower. A vagabond has nothing better to do with his ample free time, so her entered and became the first Si-Mas, or Silo Master, when he discovered the inside to be an immaculately preserved chute of color-coded switches with a single chair in the center.
Again, being a piece of dirty wind living wind trash, Cheversly mounted in the single chair, noting his rump to fit almost eerily comfortably, and immediately a HUD green screen projected itself in front of him, as a number of metallic straps shot out and bolted him to the place. Tubes quickly dug in through his side, into his kidney and stomach. Cheversly yowled, but his massive pain subsided moments after when powerful anesthetics kicked in. Scared and sweating, Cheversely waited in a dim light until a flicker, then a beam of light opened the full view of the shaft before him. It extended high into the sky and well below ground. From Cherevsly's life energy, the machine came to life and now his life was in the machine.
After an hour or so of terror-filled panic, calling out to a mother he had long forgotten, he calmed down (with the help of powerful neural agents being administered) and figured he might as well try reading, which he still had some small grasp on, and see if there was an off button to get out.
After perusing the manuals in the HUD, he decided to stay. He felt the minimal reading skill elevating quickly, almost unnaturally, as he sorted through operating logs, instruction screens, and data records.
It was then Cheversly grasped what he had gotten into: he was the first to uncover a fully-functional silo, one of the massive totems of power distribution from the world before the Whump.
He decided to put his crash course to the test and flip one of the ancient technologies to life again. Only 16 of the original 400 observation cams were functioning, so he chose one nearby and called up the dusty image to his HUD. The green landscape of barren waste showed before him. Two ohbochos were striding along in the distance. He flipped the switch associated with the area. Immediately, a vapor of green gas exploded from the ground, detonating the landscape, and the ohbochos were nowhere to be found.
He repeated this experiment with a number of other switches, witnessing the results through the remaining sentry viewers. One turned lights on from beneath the ground, so that the sand itself lit up like daytime in the night. Another made hundreds of little robots spawn from nowhere in the dirt and mercilessly slaughter a kennel of bandits around a fire. Three more did nothing. When he flipped another, he wasn't sure what happened, but the camera's view began shaking and the image blacked out.
Over the days and weeks that followed, Cheversly learned the mechanisms of control and realized his silo was only one on a grid, of which there were many more at some time long ago.
From then, he began to rewire and reconstruct his grid. Cheversly's intervention led to the surfacing of tech left over from the old world that has been sold and stolen, repurposed and remade across the Ava.
Cheversly has long since passed on, and the next curious person who entered found themselves strapped to a chair and took his place, falling in line with the work done before, methodically and without resistance. It was then the pattern was clear. You became the silo. This gave rise to the Si-Mas, silo masters who have given themselves up to the tech of the old world's consciousness. People who do so are known as Techs.