Langdon walked with Sophie down a series of corridors, past several large rooms filled with blinking mainframe computers.
Gettum typed in a few words: LONDON, KNIGHT, POPE As she clicked the SEARCH button, she could feel the hum of the massive mainframe downstairs scanning data at a rate of 500 MB/sec.
There are no more uses of "mainframe" in the book.
Show samples from other sources
Instead, she says the pellet is a tracking device, hooked into the base’s mainframe.
Rick Yancey -- The 5th Wave
They’d been tiptoeing around each other since she’d returned home from the lab two days before, Adri trying to remind Cinder of her superiority by ordering her to defrag their apartment’s entire mainframe and update all the software that they didn’t even use anymore, while at the same time lurking around as if she were—almost, kind of—ashamed of what she’d done to Cinder.