The Apple Cluster Controller maintains an interface between an IBM host and
the Apple Computer by emulating IBM 3278-2 terminal functions and 3287-1
printer functions. The Controller comes in two flavors:
1. SNA/SDLC, which emulates an IBM 3274 or IBM 3276 Control Unit/Display
Station, and
2. BSC (bisynchronous), which emulates an IBM 3271 Control Unit.
The cluster controller does not support low and high intensity displays;
otherwise, the terminal and printer functions are completely emulated.