Network Computing Devices Inc, of Mountain View, California is making its first major diversification from its core X Window terminal business, by buying one of the backers of its system for including audio on its X terminal sustems. The company is Z-Code Software Corp, based in Novato, California, developer of the Z-Mail graphics-oriented electronic mail system. Network Computing will pay an initial $3.2m in cash and 1.7m new shares – $14.7m all told – for the company, and the pact calls for contingency payments of an additional $3.2m and 1.3m shares if financial objectives are met – for a total valuation of up to $26.4m.