<TABLE> <S> <C>

<PAGE>

<ARTICLE> 5
<RESTATED>

<S>                             <C>                     <C>                     <C>
<PERIOD-TYPE>                   9-MOS                   6-MOS                   3-MOS
<FISCAL-YEAR-END>                          DEC-31-1997             DEC-31-1997             DEC-31-1997
<PERIOD-START>                             JAN-01-1997             JAN-01-1997             JAN-01-1997
<PERIOD-END>                               SEP-30-1997             JUN-30-1997             MAR-31-1997
<CASH>                                       5,773,708               3,798,047               2,258,127
<SECURITIES>                                13,170,052              12,188,550              12,283,828
<RECEIVABLES>                                4,844,971               5,599,555               5,716,607
<ALLOWANCES>                                    61,955                  97,347                 191,041
<INVENTORY>                                  4,242,795               3,655,870               4,087,630
<CURRENT-ASSETS>                            30,126,904              26,617,581              25,459,713
<PP&E>                                      10,711,276              10,143,900              10,094,903
<DEPRECIATION>                               5,120,507               4,667,518               4,364,546
<TOTAL-ASSETS>                              40,801,997              37,386,162              36,336,084
<CURRENT-LIABILITIES>                        7,416,740               6,728,563               7,343,124
<BONDS>                                              0                       0                       0
<PREFERRED-MANDATORY>                                0                       0                       0
<PREFERRED>                                          0                       0                       0
<COMMON>                                         6,976                   6,919                   6,870
<OTHER-SE>                                  32,364,342              29,864,859              27,963,291
<TOTAL-LIABILITY-AND-EQUITY>                40,801,997              37,386,162              36,336,084
<SALES>                                     33,979,349              23,169,609              11,712,148
<TOTAL-REVENUES>                            33,979,349              23,169,609              11,712,148
<CGS>                                       15,888,890              11,003,380               5,813,580
<TOTAL-COSTS>                               26,533,697              18,090,485               9,274,730
<OTHER-EXPENSES>                                29,930                  36,868                   5,226
<LOSS-PROVISION>                                     0                       0                       0
<INTEREST-EXPENSE>                             139,750                  98,392                  52,368
<INCOME-PRETAX>                              7,759,864               5,262,460               2,567,188
<INCOME-TAX>                                 2,743,400               1,894,300                 924,000
<INCOME-CONTINUING>                          5,016,464               3,368,160               1,643,188
<DISCONTINUED>                                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0
<CHANGES>                                            0                       0                       0
<NET-INCOME>                                 5,016,464               3,368,160               1,643,188
<EPS-PRIMARY>                                     0.73<F1>                    0.49<F1>                    0.24<F1>
<EPS-DILUTED>                                     0.65<F2>                    0.44<F2>                    0.21<F2>
<FN>
<F1>EPS - Basic Per SFAS No. 128
<F2>EPS - Diluted SFAS No. 128
</FN>


</TABLE>