O.C. EARNINGS

Datum Inc.: The Irvine maker of timing products said net income for the fourth quarter fell to $55,000, or 1 cent a share, from $992,000, or 23 cents a share, for the 1996 fourth quarter. Revenue declined 20% to $22.1 million from $27.5 million. Net income for the year climbed to $4.8 million, or 90 cents a share, from $2 million, or 46 cents a share, a year ago. Revenue rose 24% to $114.1 million from $91.9 million. The company attributed the fourth quarter declines to an order slowdown by two customers.