John Titsworth, credited with having saved Control Data Corp’s mainframe division after having built up the company’s OEM peripherals business to a leadership position in the mid-1970s, has moved in to become president and chief executive of Priam Corp, San Jose, California. He takes over from Joe Booker, who resigned from Priam effective yesterday. Another industry veteran, Don Massaro, who was a leading light at Xerox Office Systems, remains chairman of Priam. After turning Control Data around, Titsworth joined Xerox Corp as group vice president for all systems and peripheral businesses and in May 1980, he was promoted to executive vice president and elected to the Xerox board of directors. He left Xerox in 1983 to become a general partner with the Regional Financial Enterprises, venture capital firm, but clearly felt the call of the experience of hands-on running of a leading edge computer peripherals manufacturer.