Control Data Corp, still selling what it can where it can, has received a little relief with the news that the bank waiver under which it has been operating since mid-April has now been extended until June 30 to allow the company and its banks to complete negotiations on a new credit arrangement. The waiver has also been amended to increase the limit on direct credit borrowing to $50m from the previous limit of $30m, and the company says the negotiations for a new credit arrangement have been constructive and it expects to reach final agreement this month. The new credit arrangement would enable it to meet cash needs arising from the discontinuance of its ETA Systems Computer operations, the streamlining of its Cyber mainframe business and a reduction in its corporate staff, leaving enough over for its working capital requirements.