American Telephone & Telegraph said it will...

American Telephone & Telegraph said it will make sure that its widely used Unix operating system, the internal traffic cop of computers, is readily available to all the computer hardware companies that want to use it. Some major computer companies had charged that AT&T; was playing favorites by giving early information about future versions of Unix to Sun Microsystems Inc., a Silicon Valley maker of engineering workstations that is a close partner of AT&T.;