A device he have a great interest in

A group of friends challenged Mark, the brightest among them, to an escape room challenge (two rooms). They know Mark have a wide range of knowledge. But for this one they thought even the bright Mark would have a hard time figuring out the answer.

The instructions were following:

"You have 30 minutes to solve part one of the puzzle in the first room – if you can’t, too bad. If you manage to solve it however then ring the bell and we’ll unlock the door to the right of you. Enter the door, sit down at the table and solve part two of the puzzle. This time you’ll have 1 hour to solve it. If you figure out the answer, just shout it out loud and we’ll give you your reward. You have to answer correct on your first try though. Good luck!"

It didn’t take long before Mark solved part one, well before the 30 minutes. So he rang the bell. They unlocked the door and Mark entered the room, saw the table and briefly saw some large rectangular plate on it. But just within milliseconds after the door got closed behind him, the part one of the puzzle suddenly made sense.

Being Mark, he managed to figure it out of course and shouted the answer with great joy ("they really know me, these guys" he thought to himself) and got his reward. But it wasn’t too easy.

Can you tell me what Mark shouted?