1 Exhibit 11.1 ISOCOR STATEMENT OF COMPUTATION OF SHARES USED IN PER SHARE COMPUTATION (IN THOUSANDS) Three months ended Nine months ended ------------------------- ------------------------- September September September September 30, 1997 30, 1996 30, 1997 30, 1996 --------- --------- --------- --------- Computation of shares used in net income (loss) per share: Weighted average common shares outstanding ................................ 9,429 9,271 9,405 6,789 Common equivalent shares attributable to stock options (treasury stock method) ...... 1,181 1,158 Common equivalent shares attributable to redeemable preferred stock.................. ----- ------ ----- ----- Shares used in per share calculation ........ 9,429 10,452 9,405 7,947 ===== ====== ===== ===== 1