Exhibit 10(d)
                      FIRST AMENDMENT TO 2000 AMENDED AND
                       RESTATED CREDIT FACILITY AGREEMENT


      THIS FIRST  AMENDMENT,  dated as of the 14th day of August,  2000, to that
certain 2000 Amended and Restated  Credit  Facility  Agreement  dated as of July
28, 2000,  between FLEET NATIONAL BANK, a national  banking  association with an
office at One East Avenue,  Rochester,  New York 14638,  and DETECTION  SYSTEMS,
INC., a New York  corporation  with offices at 130 Perinton  Parkway,  Fairport,
New York 14450 ("Borrower") (the "Agreement").

      The parties hereby agree as follows:
      .     Except  as  expressly  amended  hereby,  the  Agreement  is  in  all
respects  ratified  and  confirmed,   and  all  of  the  terms,  provisions  and
conditions  thereof  shall be and  remain  in full  force and  effect,  and this
Amendment and all of its terms,  provisions  and  conditions  shall be deemed to
be a part of the Agreement.

      .     Section 1.1 of the  Agreement is amended by replacing  the following
term in its entirety:

                  "Fixed  Charges"  shall mean for the  applicable  period,  (i)
                        Interest Expense,       and  (ii)   principal  or  other
                        payments  due with  respect  to Debt  which are  Current
                        Liabilities.

      .     Section 9.2 of the  Agreement  is amended in its entirety to read as
follows:

                  9.2   Loans  and  Investments.  Loans  and  Investments.  Make
      any loan or advance  to, or any  investment  of any kind in,  any  person,
      firm, joint venture,  corporation or other entity  whatsoever,  except (i)
      short-term   investments   in   certificates   of  deposit  of   financial
      institutions  and  similar  investments  made in the  ordinary  course  of
      business,  (ii) to the extent  permitted by this  Agreement,  to or in any
      Subsidiary,  provided however,  that aggregate  investments and/or capital
      contributions  by the Borrower and its Domestic  Subsidiaries in or to the
      Foreign  Subsidiaries  (taken  as  a  whole)  shall  in  no  event  exceed
      $1,000,000  per year,  and (iii)  provided  that  Borrower  remains at all
      times in  compliance  with each of the  financial  covenants  set forth in
      Article 10 hereof,  payment of up to (A)  $10,000,000 in the aggregate for
      repurchases of common stock of Detection  Systems,  Inc.  between April 1,
      1999  and  March  31,  2000,  and  (B)  $1,500,000  in the  aggregate  for
      repurchases of common stock of Detection  Systems,  Inc.  following  March
      31, 2000.

      .     Section  10.2 of the  Agreement  is amended in its  entirety to read
as follows:

                  10.2   Minimum  Fixed  Charge  Coverage.  Maintain  a ratio of
      (a)  EBITDA  minus   Distributions,   minus  provision  for  taxes,  minus
      capital  expenditures  not funded by Funded Debt or out of additional paid
      in capital,  to (b) Fixed  Charges,  calculated  for the quarter ending on
      the  measurement  date  plus  the  fewer  of  either  (i) the  last  three
      preceding   quarters,   or  (ii)  the  number  of   quarters   except  the
      measurement  date quarter  that have ended after March 31, 1998,  as shown
      on the quarterly  financial  statements  provided to the Bank, of at least
      1.5 to 1.0 for the quarter ending June 30, 1998 and thereafter.


      .     Section  10.4 of the  Agreement  is amended in its  entirety to read
as follows:

                  10.4   Minimum   Tangible   Net  Worth.   Maintain  a  minimum
Tangible Net Worth equal to at least  ninety-five  percent (95%) of Tangible Net
Worth of the  Borrower  as of March 31,  2000 plus,  in each  succeeding  fiscal
quarter,  an amount equal to seventy-five  percent (75%) of net operating income
for all periods  following  March 31, 2000 plus one  hundred  percent  (100%) of
the net  proceeds  from  any sale of stock  or  other  equity  interests  in the
Borrower  for all periods  following  March 31, 2000 as shown on each  quarterly
financial statement provided to the Bank.

      .     Borrower  hereby  confirms  the  accuracy  of and  remakes as of the
date hereof all of its  representations,  warranties and covenants  contained in
the Agreement.

      .     Borrower  confirms  that as of the  date  hereof,  there  exists  no
condition  or  event  that  constitutes  (or  that  would  after  expiration  of
applicable  grace or cure periods  constitute)  an Event of Default as described
in Article 12 of the  Agreement,  except for events or  conditions  that will no
longer constitute Events of Default upon the effective date of this Amendment.

      .     As of the  date  hereof,  the  Borrower  has no  defenses,  offsets,
claims or  counterclaims  with  respect  to its  obligations  arising  under the
Agreement or this Amendment and all related documents and instruments.

      .     Borrower  agrees to pay any and all  costs  incurred  in  connection
with preparation for closing,  the closing,  and post-closing  items relating to
this Amendment  including  without  limitation the legal fees and  disbursements
of Bank's counsel.

      .     This  Amendment,  together with all of the rights and obligations of
the parties  hereto,  shall be  construed,  governed and enforced in  accordance
with the laws of the State of New York.

      IN WITNESS  WHEREOF,  the parties have executed this Amendment on the date
first above written.

FLEET NATIONAL BANK                       DETECTION SYSTEMS, INC.


By:_______________________________        By: ______________________________
  Martin K. Birmingham                        Christopher P. Gerace
  Vice President                              Vice President