<TABLE> <S> <C>

<ARTICLE> 5
<MULTIPLIER> 1000
       
<S>                             <C>                     <C>                     <C>                                        
<PERIOD-TYPE>                   3-MOS                   3-MOS                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-1998             DEC-31-1997             DEC-31-1997   
<PERIOD-END>                               SEP-30-1998             SEP-30-1997             SEP-30-1997 
<CASH>                                           68164                   73557                   73557
<SECURITIES>                                    246079                  158404                  158404 
<RECEIVABLES>                                    78850                   45628                   45628
<ALLOWANCES>                                      1218                    1206                    1206
<INVENTORY>                                       7554                    5404                    5404
<CURRENT-ASSETS>                                405656                  231143                  231143
<PP&E>                                          109629                   83681                   83681
<DEPRECIATION>                                   65950                   54114                   54114
<TOTAL-ASSETS>                                  472693                  327099                  327099
<CURRENT-LIABILITIES>                            69175                   48343                   48343
<BONDS>                                              0                       0                       0
<PREFERRED-MANDATORY>                                0                       0                       0
<PREFERRED>                                          0                       0                       0
<COMMON>                                         32599                   22045                   22045
<OTHER-SE>                                      294042                  236118                  236118
<TOTAL-LIABILITY-AND-EQUITY>                    472693                  327099                  327099
<SALES>                                          99715                   71306                  189719
<TOTAL-REVENUES>                                 99715                   71306                  189719
<CGS>                                            73490                   52360                  141825
<TOTAL-COSTS>                                    77477                   56450                  153421
<OTHER-EXPENSES>                                     0                       0                       0
<LOSS-PROVISION>                                   588                     310                     925
<INTEREST-EXPENSE>                                1063                     299                     496
<INCOME-PRETAX>                                  25617                   17856                   43964
<INCOME-TAX>                                      8908                    6264                   16234
<INCOME-CONTINUING>                              16709                   11592                   27730
<DISCONTINUED>                                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0
<CHANGES>                                            0                       0                       0
<NET-INCOME>                                     16709                   11592                   27730
<EPS-PRIMARY>                                     0.17                    0.12                    0.29
<EPS-DILUTED>                                     0.17                    0.12                    0.28
        

</TABLE>