System 75:Communications and Control Architecture
Leslie A. Baxter, P. R. Berkowitz, C. A. Buzzard, J. J. Horenkamp, F. E. Wyatt · AT&T Technical Journal · 1985
The System 75 office communication system uses a unique communications and control architecture that provides great flexibility and a minimum of overhead for small configurations while growing smoothly to larger line sizes. A distributed communication network provides 64 kb/s connectivity for both voice and data. It consists of a pair of time division multiplexed buses and intelligent port circuits. Flexible conferencing and gain adjustment are supported as an integral part of the network. The control complex supports an operating-system-based software structure.