[Letterhead of Physician Support Systems appears here]


Contact:  Jan McClure (NDC)                        For Immediate Release
          (404) 728-2363                           ---------------------
                         
          David S. Geller (PHSS)
          (717) 653-5350


                           NATIONAL DATA CORPORATION
                 AND PHYSICIAN SUPPORT SYSTEMS, INC. ANNOUNCE
              AGREEMENT ON EXCHANGE RATIO IN PENDING TRANSACTION


ATLANTA, December 10, 1997 - National Data Corporation (NYSE: NDC) and Physician
Support Systems, Inc. (NASDAQ: PHSS) announced today that the two companies have
reached an agreement regarding the exchange ratio in the pending merger of PHSS
with NDC.

     On October 14, 1997, the companies announced a merger in which PHSS would
be merged into a subsidiary of NDC in a stock-for-stock transaction, with the
final exchange ratio to be determined based on the average closing price of NDC
common stock beginning on and including November 13, 1997 through and including
December 5, 1997 (the "Average Closing Price").  The actual Average Closing
Price as calculated under the merger agreement is $35.7969.

     Since the Average Closing Price is less than $36.782, the merger agreement
provides that the exchange ratio will be adjusted to equal that fraction of a
share of NDC common stock obtained by dividing $16.00 by the Average Closing
Price.  However, the merger agreement also provides that NDC has the right to
terminate the merger agreement unless PHSS agrees to maintain the exchange ratio
at 0.435.

     NDC has exercised its right to terminate the merger agreement subject to
PHSS' agreement to the 0.435 exchange ratio.  The Board of Directors of PHSS has
agreed to maintain the exchange ratio at 0.435.  The merger is presently
scheduled to close Friday, December 19, 1997.

     Robert A. Yellowlees, NDC's chairman and CEO, commenting on the
announcement stated, "We have felt from the beginning that the excellent
business that Peter Gilson and his team have built provides a very strong fit
with NDC . . . and NDC

 
with PHSS.  We expect that our plans to capitalize on the synergies of the two
companies will be rewarding for our mutual shareholders, customers and
employees."

     National Data Corporation is a leading provider of information services and
systems for the health care and payment systems markets.

     PHSS is one of the leading providers of business and financial management
services to physicians and hospitals in 29 states.


                                    #  #  #


     When used in this report, press releases and elsewhere by management or the
Company from time to time, the words "believes," "anticipates," "expects" and
similar expressions are intended to identify forward-looking statements
concerning the Company's operations, economic performance and financial
condition, including in particular, the likelihood of the Company's success in
developing and expanding its business.  These statements are based on a number
of assumptions and estimates which are inherently subject to significant
uncertainties and contingencies, many of which are beyond the control of the
Company, and reflect future business decisions and conditions which are subject
to change.  A variety of factors could cause actual results to differ materially
from those anticipated in the Company's forward-looking statements, some of
which include competition in the market for the Company's services, continued
expansion of the Company's processing and payment systems markets, successfully
completing and integrating acquisitions in existing and new markets and other
risk factors that are discussed from time to time in the Company's Securities
and Exchange Commission ("SEC") reports and other filings.  Readers are
cautioned not to place undue reliance on these forward-looking statements, which
speak only as of the date hereof.  The Company undertakes no obligations to
publicly release the results of any revisions to these forward-looking
statements that may be made to reflect events or circumstances after the date
hereof, or thereof, as the case may be, or to reflect the occurrence of
unanticipated events.