at&t computer systems is the generic name for american telephone & telegraph's unsuccessful attempt to compete in the computer business. in return for divesting the local bell operating companies (baby bells), at&t was allowed to have an unregulated division to sell computer hardware and software. prior to the divestiture of the bell system on january 1, 1984, the bell labs processor division had developed the 3b20d ("d" for duplex); the commercial simplex version 3b20s, which competed with the dec vax for internal bell system usage; the world's first 32-bit microprocessor, the bellmac 32a; and, using this microprocessor, the 3b5 and 3b15 computers for billing and telecom switching control applications. ==divestiture== after divestiture, january 1, 1984, american telephone & telegraph was required to put its computer business into a fully separated subsidiary called at&t information systems (attis, without the ampersand or hyphen). software was developed in new jersey locations (murray hill, summit, holmdel, and piscataway), and software, hardware, and system solutions were developed in naperville and lisle, il. after a couple years of court hearings, at&t was allowed to pull the business back into the mainstream corporate organization, and it was renamed at&t data systems group, consisting of 3 divisions: computer, terminals (the teletype corporation of skokie, il), and printers. in 1991, the at&t data systems group, with the three divisions was announced to the public. in 1992 the terminals division (teletype corporation) was sold to memorex-telex, and the printer division, which had only bought oem equipment from genicom, was phased out. by the mid-1990s, this left only at&t computer systems. at&t computer systems (abbreviated at&t-cs) was the home of the unix system v operating system, originally developed in the bell labs research division. the important system v interface definition (svid) was written, attempting to standardize the various flavors of unix, and define the official interfaces which made up a unix operating system. in 1988, at&t announced its intent to buy up to a 20% stake in sun microsystems, a company then most well known for making high-end unix workstations.{{cite news | first = burgess | last = john | title = at&t to buy stake in sun microsystems | url = http://pqasb.pqarchiver.com/washingtonpost_historical/access/406816581.html?dids=406816581:406816581&fmt=abs&fmts=abs:ft&date=jan+07%2c+1988&author=john+burgess+washington+post+staff+writer&pub=the+washington+post | work = the washington post | date= 1988-01-07 | accessdate = 2007-01-23 | quote = american telephone & telegraph co. announced yesterday that it will buy up to a 20 percent stake in sun mic
AT&T Telecommunications_companies_of_the_United_States