IBM has locked up design and manufacture of the new Personal System/2 so effectively that the obvious pickings for add-on makers are decidedly slim – but one unfilled hole is the lack of a tape back-up subsystem. Those big disk drives on the new boxes will take a deal of backing up, and Computer Systems News has evidence that there is likely to be very big OEM business for one or two manufacturers from IBM. The paper reports that the company has sent requests for information on 5.25 and 3.5 form factor quarter inch tape drives with the mention of up to 200,000 units. Replies were due in on Friday, and companies that have received the requests include Cipher Data Products, Archive Corp, the Wangtek arm of Rexon Inc, Mountain Computer Corp and Alloy Computer Products. It is believed to be the third time that IBM has tested the water on the 3.5 tape drive situation, but this time, a solicitation for bids is likely to follow soon.