AST Research Inc is still having to turn to controlling shareholder Samsung Electronics Co for support. It says it has won a one-year extension of $200m bank credit guarantee agreement to December 31 1998. It has also finalized a new $200m two-year bank credit guarantee agreement with Samsung, which is providing guarantees for a total of $300m in bank credit for AST, effective December 13, rising to $400m on April 1 and continuing at that level to the end of next year. Samsung’s reward is another 500,000 shares of AST non-voting preferred.