"The IBM 2250 Display Unit Model 3 is a cathode-ray tube (CRT) display console which can be attached to a System/360 via the IBM 2840 Display Control Model 2."

This is information extracted from:
IBM System/360 Component Description
IBM 2250 Display Unit Model 3
IBM 3840 Display Control Unit Model 2

A27-2721-0, 1967


Note that the 2250-4 (1130 attached) had a significantly different set of mode orders than those described here.

Documents subject to revision.