With the big disk drive design and manufacturing operations of Memorex under its belt, Unisys Corp has no need of an interest in the Control Data-managed rival, Magnetic Peripherals Inc, and has persuaded the revitalised Minneapolis company to buy the stake. Control Data signed a letter of intent to buy the 13% Unisys stake on undisclosed terms in a move that will take its stake up to 80%. Honeywell Information Systems holds 14% and Bull SA 6%. Unisys acquired the stake through Sperry, which pitched its withering ISI big disk manufacturer into Magnetic Peripherals in exchange for a 13% holding four years ago. Unisys has agreed to remain a customer for disk drives manufactured by Magnetic Peripherals Inc for at least another two years following the sale.