3B series computers
AT&T/BELL FAMILY OF COMPUTERS
3B (ATT Computers); 3B20D; 3B21D; 3B2; 3B20C; AT&T 3B2; 3B Computers
The 3B series computers are a line of minicomputers produced from the late 1970s by AT&T Computer Systems' Western Electric subsidiary for use with the company's UNIX operating system. The line primarily consists of the models 3B20, 3B5, 3B15, 3B2, and 3B4000.