Page 93
                                                            Exhibit 10(iii)A(10)



Don W. Hubble
October 18, 1996
                            October 18, 1996



Don W. Hubble
2621 Winslow Drive
Atlanta, Georgia   30305


         Re:      Amendment of Stock Option Agreements


Dear Don:

          In connection  with your  termination of employment,  and as confirmed
and  evidenced  by this letter  agreement,  the terms of certain  stock  options
previously granted to you were amended by action taken by the Executive Resource
and Nominating Committee of NSI's Board of Directors (the "Committee") on August
2, 1996, and ratified by the Board of Directors on September 18, 1996.

          The  following  installments  of  employee  stock  options,  which had
previously  been granted to you and which would otherwise have vested and become
exercisable  after this date, have been accelerated so that they are immediately
exercisable on this date:

                                                                 Number of
                       Option Grant Date                Shares In Installments

                      September 15, 1993                            3,750
                      September 21, 1994                            4,011
                      September 21, 1994                            8,489
                      September 20, 1995                            3,252
                      September 20, 1995                           15,498
                                                                   35,000

          In addition,  the Committee amended the expiration provisions of those
options for 35,000  shares and options for 42,756  shares which were  previously
granted to you and were already exercisable  according to their original vesting
schedules.  Pursuant to the  amendment,  said options for 77,756  shares  remain
exercisable through October 31, 1998, notwithstanding your resignation effective
today.


Page 94
                                                            Exhibit 10(iii)A(10)

          Your  Incentive  Stock  Option  Agreement  dated  September  15, 1993,
Incentive Stock Option  Agreement dated September 21, 1994,  Nonqualified  Stock
Option  Agreement  dated September 21, 1994,  Incentive  Stock Option  Agreement
dated September 20, 1995 and Nonqualified Stock Option Agreement dated September
20, 1995 (the "Stock Option  Agreements")  are each hereby amended in accordance
with this letter.

          Please  acknowledge  your  acceptance of this letter by signing in the
space  provided  below and returning  the executed  letter to me. A duplicate is
enclosed for you to retain with your copies of the Stock Option Agreements.

                                           Very truly yours,


                                           /s/ James S. Balloun


                                           James S. Balloun
                                           Chairman and Chief Executive Officer

JSB:sdh
Enclosures

Accepted and agreed to as of the
18th day of October, 1996:



/s/ Don W. Hubble   
Don W. Hubble