IBM put a lot of work into a detailed corporate design aesthetic. Itis described in detail in the book "The Interface: IBM and the Transformation of Corporate Design". The design principles were developed by Edgar Kaufmann, Jr (whose father owned Frank Lloyd Wright's Fallingwater), and they were developed by Eliot Noyes, a notable industrial designer.

Some design concepts in the computers were recessed pedestals for a feeling of floating and lightness, the concealment of most of the circuitry, expressing the "inherent drama" of computers, the carefully controlled color scheme, and modern materials for the cabinets. The tape drives in particular were wildly successful at expressing the "inherent drama" of computing, to the point that spinning tape drives became a movie cliche .

It probably falls under the broad umbrella of Mid-Century Modern, but if you mean the machinery more specifically, i don't know. It's a little too grounded to be atompunk or streamline moderne, and a little too early to be cassette futurism.