<ARTICLE>5

                                                                                                     
<PERIOD-TYPE>                                                                3-MOS            3-MOS            12-MOS
<FISCAL-YEAR-END>                                                            Dec-31-1996      Dec-31-1996      Dec-31-1996
<PERIOD-END>                                                                 Jun-30-1997      Sep-30-1997      Dec-31-1997
<CASH>                                                                             5,188            9,636           37,225
<SECURITIES>                                                                      34,097           26,215           17,921
<RECEIVABLES>                                                                          0                0                0
<ALLOWANCES>                                                                           0                0                0
<INVENTORY>                                                                            0                0                0
<CURRENT-ASSETS>                                                                  40,438           36,818           55,639
<PP&E>                                                                            29,348           30,283           30,478
<DEPRECIATION>                                                                    24,581           25,370           25,914
<TOTAL-ASSETS>                                                                    49,780           46,306           64,776
<CURRENT-LIABILITIES>                                                              8,398            9,360            8,763
<BONDS>                                                                                0                0                0
<COMMON>                                                                              20               20               20
<PREFERRED-MANDATORY>                                                                  0                0                0
<PREFERRED>                                                                            0                0                0
<OTHER-SE>                                                                        26,755           22,401           31,220
<TOTAL-LIABILITY-AND-EQUITY>                                                      49,780           46,306           64,776
<SALES>                                                                                0                0                0
<TOTAL-REVENUES>                                                                     674              125           18,383
<CGS>                                                                                  0                0                0
<TOTAL-COSTS>                                                                          0                0                0
<OTHER-EXPENSES>                                                                   9,048            8,478           35,552
<LOSS-PROVISION>                                                                       0                0                0
<INTEREST-EXPENSE>                                                                   252              282            1,101
<INCOME-PRETAX>                                                                   (8,014)          (8,140)         (15,765)
<INCOME-TAX>                                                                           0                0                0
<INCOME-CONTINUING>                                                               (8,014)          (8,140)         (15,765)
<DISCONTINUED>                                                                         0                0                0
<EXTRAORDINARY>                                                                        0                0                0
<CHANGES>                                                                              0                0                0
<NET-INCOME>                                                                      (8,014)          (8,140)         (15,765)
<EPS-BASIC>                                                                        (0.20)           (0.21)           (0.44)
<EPS-DILUTED>                                                                      (0.20)           (0.21)           (0.44)