The Associated Press reports that the Justice Department is looking into allegations that IBM Corp. has abused its dominant position in the market for mainframe computers, the data-crunching heavy lifters of the computing world that IBM introduced in the 1960s. The accusations stem from claims by IBM rivals that they’ve been illegally frozen out of the mainframe market because of IBM’s refusal to allow its mainframe operating software to run on non-IBM computers. IBM doesn’t have many rivals anymore that make mainframe computers, but some smaller companies are trying to develop technologies that would allow the software to run on cheaper hardware. They allege that IBM, which used to license its mainframe software to competitors and for the back half of the last century operated under an antitrust agreement with the government, stopped doing so in recent years to choke off competition. "IBM will tell big customers that if you buy that other stuff, we’re not going to let that stuff talk to our stuff," said Ed Black, CEO of the Computer and Communications Industry Association. "That’s very unsatisfactory for the customer base."