A major new computer-systems joint venture may be afoot in japan. IBM-japan say that "Matsushit Electric industrial Co. and IBM have agreed to hold detailed discussions with the intention of establishing a joint-venture company. Its mission would be to develop and manufacture low-cost, high-volume information-processing products such as terminals, office-automation systems, and small business computer" Matsushita, less effusive, say that IBM's startement represents only the American firm's desire and that no agreement beyond the decision to hold discussions has yet been reached. Over the years, Matsushita has been a supplier to IBM of components and assemm=blies, including those for magnetic recording and the display for IBM's Displaywriter. what's IBM-japan is expected to start selling the spring