Counterintuitively, a button on i-286 through i-486 processor systems which when activated slowed the CPU clock.

https://en.wikipedia.org/wiki/Turbo_button

It had a Turbo button and we made sure it was always on. As to what it did, none of us really knew. But it was on, and there was a problem if it was off. So even if it wasn't connected to anything inside the beige tower it still made things better.

If the turbo button is off, the PC is clocked to run slower. Video:

https://www.youtube.com/watch?v=p2q02Bxtqds

Maybe it worked like the Magic Switch:

http://catb.org/jargon/html/magic-story.html

The NEC V20 and other 8088 compatibles could run at 8 or 10 MHz as opposed to the standard 4.77 MHz. I guess it had one of those.

Most likely, they were running a terminal emulator on the XT, and dialed in to a multiuser Unix system running lynx.