<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE ANNUAL
REPORT ON FORM 10K FOR THE YEAR ENDED MARCH 31, 1999 AND IS QUALIFIED IN ITS
ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000

                                                  
<PERIOD-TYPE>                   YEAR                   YEAR
<FISCAL-YEAR-END>                          MAR-31-1998             MAR-31-1999
<PERIOD-START>                             APR-01-1997             APR-01-1998
<PERIOD-END>                               MAR-31-1998             MAR-31-1999
<CASH>                                           6,460                  13,530
<SECURITIES>                                    61,436                  73,010
<RECEIVABLES>                                   12,529                  19,452
<ALLOWANCES>                                       350                     177
<INVENTORY>                                      8,185                   9,813
<CURRENT-ASSETS>                                94,526                 125,020
<PP&E>                                          46,678                  58,708
<DEPRECIATION>                                  29,460                  35,580
<TOTAL-ASSETS>                                 112,834                 150,655
<CURRENT-LIABILITIES>                           17,109                  21,403
<BONDS>                                          4,091                   7,558
<PREFERRED-MANDATORY>                                0                       0
<PREFERRED>                                          0                       0
<COMMON>                                           225                     266
<OTHER-SE>                                      91,409                 121,428
<TOTAL-LIABILITY-AND-EQUITY>                   112,834                 150,655
<SALES>                                         76,618                 105,000
<TOTAL-REVENUES>                                76,618                 105,000
<CGS>                                           34,321                  37,937
<TOTAL-COSTS>                                   34,321                  37,937
<OTHER-EXPENSES>                                27,546                  43,147
<LOSS-PROVISION>                                   157                      50
<INTEREST-EXPENSE>                                 381                     542
<INCOME-PRETAX>                                 15,622                  27,366
<INCOME-TAX>                                       406                  10,233
<INCOME-CONTINUING>                             15,216                  17,133
<DISCONTINUED>                                       0                       0
<EXTRAORDINARY>                                      0                       0
<CHANGES>                                            0                       0
<NET-INCOME>                                    15,216                  17,133
<EPS-BASIC>                                     1.44                     .70
<EPS-DILUTED>                                      .75                     .62