Document:

PNC Bank, N.A.
1600 Market Street
Philadelphia, PA 19103
215 585 5000 Tel

February 3, 2000                                                        PNC BANK

Peter W. Knipe
Vice President and Chief Financial Officer
STV GROUP, INCORPORATED
205 West Welsh Drive
Douglassville, Pennsylvania 19518

Re:      $12,000,000 Committed Line of Credit

Dear Pete:

         We are pleased to inform you that PNC Bank,  National  Association (the
"Bank"),  has approved your request for a committed  line of credit (the "Loan")
to STV Group,  Incorporated and STV Incorporated and its subsidiaries  listed on
the attached Schedule A (individually and collectively, the "Borrower"). We look
forward  to this  opportunity  to help  you  meet  the  financing  needs of your
business.  All the details  regarding  your Loan are  outlined in the  following
sections of this  letter.  If these terms are  satisfactory,  please  follow the
instructions for proceeding with your Loan provided at the end of this letter.

1. Facility and Use of Proceeds.  This is a committed  revolving  line of credit
under which the  Borrower  may  request  and the Bank,  subject to the terms and
conditions of this letter,  will make advances to the Borrower from time to time
until the Expiration Date, in an amount in the aggregate at any time outstanding
not to exceed  $12,000,000 (the "Line of Credit").  The "Expiration  Date" means
December  31,  2001,  or such  later  date as may be  designated  by the Bank by
written  notice to the Borrower.  Advances under the Line of Credit will be used
for working  capital,  acquisitions  or other general  business  purposes of the
Borrower.

         The Borrower may request that the Bank, in lieu of cash advances, issue
standby letters of credit  (individually,  a "Letter of Credit" and collectively
the "Letters of Credit") under the Line of Credit having expiration dates not to
exceed the earlier of one (1) year from the date of issuance and the  Expiration
Date; provided,  however, that the total amount of outstanding Letters of Credit
issued  hereunder (in the Bank's sole  discretion  and subject to  documentation
satisfactory to the Bank) shall not exceed  $2,000,000.00.  The  availability of
advances  under the Line of Credit  shall be reduced by the face  amount of each
Letter of Credit issued and outstanding  (whether or not drawn). Each payment by
the Bank under a Letter of Credit shall in the Bank's  discretion  constitute an
advance of principal under the Line of Credit and shall be

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STV Group, Incorporated
February 3, 2000
Page 2

evidenced  by the Note (as  defined  below).  The  Letters  of  Credit  shall be
governed by one or more reimbursement  agreements  executed by the Borrower (the
"Reimbursement Agreement").  Each request for the issuance of a Letter of Credit
must be accompanied by the Borrower's  execution of an application on the Bank's
standard  forms,  together  with all  supporting  documentation.  Each Letter of
Credit will be issued in the Bank's sole  discretion and in a form acceptable to
the Bank.  The Borrower shall pay the Bank a per annum issuance fee in an amount
equal to 1.5% of the face amount of each Letter of Credit,  payable quarterly in
arrears on a basis of a year of 360 days,  together  with such  other  customary
fees,  commissions and expenses  therefor as shall be required by the Bank. This
letter is not a  pre-advice  for the  issuance  of a letter of credit and is not
irrevocable.

2. Note.  The  obligation  of the Borrower to repay  advances  under the Line of
Credit shall be evidenced by a promissory  note (the "Note") in form and content
satisfactory to the Bank.

         This  letter  (the  "Letter  Agreement"),  the Note and the other  loan
documents  delivered  pursuant  hereto  will  constitute  the "Loan  Documents."
Capitalized  terms not defined herein shall have the meaning ascribed to them in
the Loan Documents.

3. Interest Rate.  Interest on the unpaid balance of the Line of Credit advances
will be charged at the rates,  and be payable on the dates and times,  set forth
in the Note evidencing the Loan.

4. Repayment.  Subject to the terms and conditions of this letter,  the Borrower
may borrow,  repay and reborrow  under the Line of Credit  until the  Expiration
Date, on which date the outstanding principal balance and any accrued but unpaid
interest shall be due and payable.

5. Security.  The Borrower must cause or has previously  caused the following to
be executed and  delivered to the Bank in form and content  satisfactory  to the
Bank as security for the Loan:

         (a) a security  agreement  granting the Bank a first priority perfected
lien on the Borrower's existing and future personal property,  including but not
limited to accounts, inventory,  equipment, general intangibles,  chattel paper,
documents and instruments.

         If all or any portion of the tangible collateral is located on property
which is not owned by the Borrower or which is subject to a mortgage in favor of
another lender,  the Borrower will deliver to the Bank Landlord's or Mortgagee's
Waivers,  as  applicable,  acceptable in form and substance to the Bank for each
such location.

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STV Group, Incorporated
February 3, 2000
Page 3

         Hazard insurance must be maintained on all inventory, equipment or real
property  securing  the Loan in such  amounts  and with  such  coverages  as are
acceptable to the Bank,  containing a standard  lender loss payable or mortgagee
clause in favor of the Bank.

         The Loan  will be  cross-collateralized  and  cross-defaulted  with all
other present and future Obligations of the Borrower to the Bank.

6.  Covenants.  Unless  compliance  is  waived in  writing  by the Bank or until
payment in full of the Loan and  termination  of the  commitment for the Line of
Credit:

         (a) The  Borrower  will  promptly  submit to the Bank such  information
relating  to the  Borrower's  affairs  (including  but  not  limited  to  annual
financial  statements for the Borrower) or any security for the Loan as the Bank
may reasonably request.

         (b) The Borrower  will notify the Bank in writing of the  occurrence of
an Event of Default or an act or condition which,  with the passage of time, the
giving of notice or both might become an Event of Default.

         (c) The Borrower  will comply with the  financial  and other  covenants
included in Exhibit "A" hereto.

7.  Representations  and  Warranties.  To induce the Bank to extend the Loan and
upon the making of any  advance to the  Borrower  under the Line of Credit,  the
Borrower represents and warrants as follows:

         (a) The Borrower's latest consolidated financial statements provided to
the Bank are true,  complete and  accurate in all  material  respects and fairly
present  the  financial  condition,  assets and  liabilities,  whether  accrued,
absolute,  contingent or otherwise, and the results of the Borrower's operations
for  the  period  specified  therein.  The  Borrower's   consolidated  financial
statements  have been prepared in accordance  with GAAP (as defined in Exhibit A
hereto)  consistently  applied  from  period  to period  subject  in the case of
interim statements to normal year-end adjustments.  Since the date of the latest
financial  statements  provided to the Bank,  the  Borrower has not suffered any
damage,  destruction  or  loss  which  has  materially  adversely  affected  its
business, assets, operations, financial condition or results of operations.

         (b)  There  are  no  actions,   suits,   proceedings  or   governmental
investigations pending or, to the knowledge of the Borrower,  threatened against
the  Borrower,  including  without  limitation  those  described on the attached
Exhibit B, which  could  result in a material  adverse  change in its  business,
assets, operations, financial condition or results of operations and there is

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STV Group, Incorporated
February 3, 2000
Page 4

no basis known to the Borrower or its officers,  directors or  shareholders  for
any such action, suit, proceedings or investigation.

         (c) The Borrower has filed all returns and reports that are required to
be filed by it in  connection  with any  federal,  state or local  tax,  duty or
charge levied, assessed or imposed upon the Borrower or its property,  including
unemployment,  social security and similar taxes and all of such taxes have been
either paid or adequate reserve or other provision has been made therefor.

         (d)  The  Borrower  is duly  organized,  validly  existing  and in good
standing under the laws of the state of its  incorporation  or organization  and
has the power and  authority  to own and  operate  its assets and to conduct its
business as now or proposed  to be carried on, and is duly  qualified,  licensed
and in good standing to do business in all jurisdictions  where its ownership of
property or the nature of its business requires such qualification or licensing.

         (e) The  Borrower  has full  power  and  authority  to  enter  into the
transactions  provided for in this Letter Agreement and has been duly authorized
to do so by all necessary and appropriate action and when executed and delivered
by the  Borrower,  this  Letter  Agreement  and the other  Loan  Documents  will
constitute the legal, valid and binding obligations of the Borrower, enforceable
in accordance with their terms.

         (f) There does not exist any default or violation by the Borrower of or
under any of the terms,  conditions or  obligations  of: (i) its  organizational
documents;  (ii) any  indenture,  mortgage,  deed of trust,  franchise,  permit,
contract,  agreement,  or other instrument to which it is a party or by which it
is bound;  or (iii) any law,  regulation,  ruling,  order,  injunction,  decree,
condition or other requirement applicable to or imposed upon the Borrower by any
law or by any governmental authority, court or agency.

         (g) The  Borrower  has  reviewed  the areas  within  its  business  and
operations  which  could be  adversely  affected  by,  and has  developed  or is
developing a program to address on a timely basis the risk that certain computer
applications  used by the  Borrower  may be  unable  to  recognize  and  perform
properly  date-sensitive  functions  involving dates prior to and after December
31, 1999 (the "Year 2000 Problem").  The Year 2000 Problem will not result,  and
is not  reasonably  expected to result,  in any material  adverse  effect on the
business,  properties,  assets,  financial  condition,  results of operations or
prospects of the Borrower, or the ability of the Borrower to duly and punctually
pay or perform its obligations hereunder and under the other Loan Documents.

8. Fees.  Beginning  on the first day of the quarter  after the date of the Note
and continuing on the first day of each quarter  thereafter until the Expiration
Date, the Borrower shall pay a

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STV Group, Incorporated
February 3, 2000
Page 5

commitment fee to the Bank, in arrears,  at the rate of .375 percent (.375%) per
annum on the average  daily  balance of the Line of Credit which is  undisbursed
and uncancelled during the preceding quarter. For the purpose of calculating the
commitment  fee,  the face amount of any  outstanding  Letters of Credit  issued
under the Line of Credit shall be deemed to be  disbursed.  The  commitment  fee
shall be  computed  on the  basis  of a year of 360 days and paid on the  actual
number of days elapsed.

9.  Expenses.  The Borrower will  reimburse  the Bank for the Bank's  reasonable
out-of-pocket  expenses  incurred or to be incurred in conducting UCC, title and
other  public  record  searches,  and in filing and  recording  documents in the
public records to perfect the Bank's liens and security interests.  The Borrower
shall also reimburse the Bank for the Bank's expenses  (including the reasonable
fees and expenses of the Bank's outside and in-house counsel) in documenting and
closing this  transaction,  in connection with any amendments,  modifications or
renewals  of the  Loan,  and in  connection  with the  collection  of all of the
Borrower's  obligations  to the Bank,  including but not limited to  enforcement
actions relating to the Loan.

10.  Depository.  The  Borrower  will  establish  and  maintain  at the Bank the
Borrower's primary depository accounts.

11. Additional Provisions. Before the first advance under the Loan, the Borrower
shall execute and deliver to the Bank the Note and other required Loan Documents
and such other  instruments  and documents as the Bank may  reasonably  request,
such as certified  resolutions,  incumbency  certificates  or other  evidence of
authority.  The Bank will not be obligated to make any advance under the Line of
Credit  if any  Event of  Default  or event  which  with  the  passage  of time,
provision  of notice or both would  constitute  an Event of  Default  shall have
occurred and be continuing.

12.  Other  Conditions  to  Advances.  The Bank will not be obligated to make an
advance under the Line of Credit until the Borrower has provided the  following,
all in form and content  satisfactory  to the Bank:  evidence of cancellation of
all  commitments  from and evidence of repayment in full of all  indebtedness to
First Union  National  Bank except for  obligations  relating to four letters of
credit outstanding on the date hereof, which are listed on the attached Schedule
B, which shall be replaced no later than June 30, 2000;  evidence of termination
of all  existing  liens in  favor of First  Union  National  Bank;  transfer  of
Borrower's primary operating accounts to the Bank.

         Prior to execution of the final Loan Documents,  the Bank may terminate
this Letter  Agreement if a material  adverse  change occurs with respect to the
Borrower,  any  guarantor,  any  collateral  for the Loan or any other person or
entity connected in any way with the Loan, or if the

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STV Group, Incorporated
February 3, 2000
Page 6

Borrower  fails to comply  with any of the terms and  conditions  of this Letter
Agreement,  or if the Bank  reasonably  determines  that  any of the  conditions
cannot be met.

         This Letter  Agreement is governed by the laws of the  Commonwealth  of
Pennsylvania.  No modification,  amendment or waiver of any of the terms of this
Letter  Agreement,  nor any consent to any departure by the Borrower  therefrom,
will be  effective  unless made in a writing  signed by the party to be charged,
and then such waiver or consent shall be effective only in the specific instance
and for the purpose for which given.  When accepted,  this Letter  Agreement and
the other Loan Documents will constitute the entire  agreement  between the Bank
and  the   Borrower   concerning   the  Loan,   and  shall   replace  all  prior
understandings,  statements,  negotiations and written materials relating to the
Loan.

         THE BORROWER AND THE BANK IRREVOCABLY WAIVE ANY AND ALL RIGHTS THEY MAY
HAVE TO A TRIAL BY JURY IN ANY ACTION, PROCEEDING OR CLAIM OF ANY NATURE ARISING
OUT OF THIS  LETTER  AGREEMENT  AND THE  TRANSACTIONS  CONTEMPLATED  HEREBY  AND
ACKNOWLEDGE THAT THE FOREGOING WAIVER IS KNOWING AND VOLUNTARY.

         If and when a loan closing occurs,  this Letter  Agreement (as the same
may be amended  from time to time)  shall  survive the closing and will serve as
our loan agreement throughout the term of the Loan.

         To accept  these terms,  please sign the  enclosed  copy of this Letter
Agreement as set forth below and the Loan  Documents and return them to the Bank
within  ten (10) days from the date of this  Letter  Agreement,  or this  Letter
Agreement may be terminated  at the Bank's option  without  liability or further
obligation of the Bank.

         Thank  you for  giving  PNC Bank  this  opportunity  to work  with your
business.  We look  forward  to other ways in which we may be of service to your
business or to you personally.

Very truly yours,

PNC BANK, NATIONAL ASSOCIATION

By:      /s/ Amy T. Petersen

Title:   Vice President

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STV Group, Incorporated
February 3, 2000
Page 7

                                   ACCEPTANCE

With the intent to be legally bound hereby,  the above terms and  conditions are
hereby agreed to and accepted as of this 3rd day of February, 2000.

                                    BORROWER:

                                    STV GROUP, INCORPORATED

                                    By:  /s/ Peter W. Knipe   (SEAL)
                                    Print Name:  Peter W. Knipe
                                    Title: CFO

                                    STV INCORPORATED

                                    By:  /s/ Peter W. Knipe   (SEAL)
                                    Print Name:  Peter W. Knipe
                                    Title: CFO

                                    STV CONSTRUCTION SERVICES, INC.

                                    By:  /s/ Peter W. Knipe   (SEAL)
                                    Print Name:  Peter W. Knipe
                                    Title: CFO

                                    STV INTERNATIONAL, INC.

                                    By:  /s/ Peter W. Knipe   (SEAL)
                                    Print Name:  Peter W. Knipe
                                    Title: CFO

                [SIGNATURES ARE CONTINUED ON THE FOLLOWING PAGE]

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STV Group, Incorporated
February 3, 2000
Page 8

                                    STV/ENVIRONMENTAL, INC.

                                    By:  /s/ Peter W. Knipe   (SEAL)
                                    Print Name:  Peter W. Knipe
                                    Title: CFO

                                    STV SURVEYING, INC.

                                    By:  /s/ Peter W. Knipe   (SEAL)
                                    Print Name:  Peter W. Knipe
                                    Title: CFO

                                    STV CONSTRUCTION, INC.

                                    By:  /s/ Peter W. Knipe   (SEAL)
                                    Print Name:  Peter W. Knipe
                                    Title: CFO

                                    STV ARCHITECTS, INC.

                                    By:  /s/ Peter W. Knipe   (SEAL)
                                    Print Name:  Peter W. Knipe
                                    Title:  Secretary

                                    STV SILVER & ZISKIND ARCHITECTS, P.C.

                                    By:  /s/ Peter W. Knipe   (SEAL)
                                    Print Name:  Peter W. Knipe
                                    Title:  Secretary

                [SIGNATURES ARE CONTINUED ON THE FOLLOWING PAGE]

<PAGE>
STV Group, Incorporated
February 3, 2000
Page 9

                                    STV ARCHITECTS, P.C.

                                    By:  /s/ Michael D. Garz  (SEAL)
                                    Print Name:  Michael D. Garz
                                    Title:  President

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STV Group, Incorporated
February 3, 2000
Page 10

                                   SCHEDULE A

         STV Construction Services, Inc.

         STV International, Inc.

         STV/Environmental, Inc.

         STV Surveying, Inc.

         STV Construction, Inc.

         STV Architects, Inc.

         STV Silver & Ziskind Architects, P.C.

         STV Architects, P.C.

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STV Group, Incorporated
February 3, 2000
Page 11

                                   SCHEDULE B

         LC#                        Amount                    Expiration Date

         519935                     $45,415                   10/30/2000
         598895                     $77,000                   11/22/2000
         SM407974                   $180,000                  03/02/2000
         SM409608                   $650,000                  07/29/2000

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STV Group, Incorporated
February 3, 2000
Page 12

                                    EXHIBIT A

         A.  FINANCIAL REPORTING COVENANTS:

         (1) The Borrower will deliver to the Bank:

                  (a) Financial  Statements  for its fiscal year,  within ninety
(90) days after fiscal year end, audited and certified without  qualification by
a certified public accountant acceptable to the Bank.

                  (b) Internally  prepared Financial  Statements for each fiscal
quarter,  within  forty-five  (45) days after the  quarter  end,  together  with
year-to-date and comparative figures for the corresponding  periods of the prior
year, certified as true and correct by its chief financial officer.

                  (c) With each delivery of Financial Statements, the Borrower's
chief  financial  officer shall also deliver a certificate  as to the Borrower's
compliance with the financial  covenants,  if any, for the period then ended and
whether  any Event of Default  exists,  and,  if so, the nature  thereof and the
corrective  measures the Borrower  proposes to take. This certificate  shall set
forth all detailed calculations necessary to demonstrate such compliance.

         "Financial Statements" means the consolidated and consolidating balance
sheet and  statements  of income  and cash flows  prepared  in  accordance  with
generally  accepted  accounting  principles in effect from time to time ("GAAP")
applied on a  consistent  basis  (subject in the case of interim  statements  to
normal year-end adjustments).

         B.  FINANCIAL COVENANTS:

         (1) The  Borrower  will  maintain at all times a minimum  Tangible Net
Worth of $12,500,000.

         (2) The Borrower will maintain at all times a ratio of current  assets
to current liabilities of at least 1.2 to 1.0.

         (3)  The  Borrower  will  maintain  at all  times  a  ratio  of  total
liabilities to Tangible Net Worth of less than 3.0 to 1.0.

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STV Group, Incorporated
February 3, 2000
Page 13

         "Tangible  Net Worth" means  stockholder's  equity in the Borrower less
any  advances  to third  parties,  and less all  items  properly  classified  as
intangibles, in accordance with GAAP.

         C.  NEGATIVE COVENANTS:

         (1) The Borrower will not create,  assume, incur or suffer to exist any
mortgage,  pledge,  encumbrance,  security interest,  lien or charge of any kind
upon any of its property,  now owned or hereafter acquired,  or acquire or agree
to acquire any kind of property under conditional sales or other title retention
agreements; provided, however, that the foregoing restrictions shall not prevent
the Borrower from:

                  (a) incurring  liens for taxes,  assessments  or  governmental
charges  or  levies  which  shall  not at the  time  be due and  payable  or can
thereafter  be paid  without  penalty  or are being  contested  in good faith by
appropriate  proceedings  diligently  conducted and with respect to which it has
created adequate reserves;

                  (b) making pledges or deposits  under  workers'  compensation,
unemployment insurance and other social security legislation;

                  (c) maintaining  purchase money security interests in personal
property which are in effect on the date hereof ("Existing Interests"),  or from
granting  purchase  money  security  interests  after the date  hereof  ("Future
Interests") in personal  property of the Borrower  existing or created when such
property is acquired,  provided  that the principal  amount of the  indebtedness
secured by each such security interest does not exceed the purchase price of the
related  property,  and provided  further that the aggregate  amount of all such
Future Interests shall not exceed $2,000,000;

                  (d) granting liens or security interests in favor of the Bank;

                  (e) carriers',  warehousemen's and mechanics' liens in respect
of property of any Borrower  imposed by law which were  incurred in the ordinary
course of business;

                  (f)  pledges or deposits  to secure the  performance  of bids,
trade  contracts  (other than for  borrowed  money),  leases,  surety and appeal
bonds,  performance bonds and other obligations of a like nature incurred in the
ordinary course of business;

                  (g) easements, rights-of-way, restrictions or minor defects or
irregularities  in title  incurred  in the  ordinary  course  of  business,  and
encumbrances   consisting   of   zoning   restrictions,   easements,   licenses,
restrictions on the use of real property or minor imperfections in title thereto

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STV Group, Incorporated
February 3, 2000
Page 14

which,  in the  aggregate,  are not material in amount,  and which do not in any
case materially  detract from the value of the real property  subject thereto or
interfere with the ordinary conduct of the business of any Borrower;

                  (h) liens consisting of judgment or judicial  attachment liens
(including  prejudgment  attachment)  the  enforcement  of which is  effectively
stayed to the reasonable satisfaction of the Bank or payment of which is covered
in full (subject to a  commercially  reasonable  deductible)  by insurance as to
which the relevant insurance company has acknowledged coverage, and which do not
otherwise result in an Event of Default under any of the Loan Documents; or

                  (i) any obligations or duties affecting any of the property of
any  Borrower  to any  municipality  or public  authority  with  respect  to any
franchise,  grant,  license or permit which do not materially  impair the use of
such property for the purposes for which it is held.

         (2) The Borrower will not create,  incur,  guarantee,  endorse  (except
endorsements  in the  course  of  collection),  assume  or  suffer  to exist any
indebtedness, except:

                  (a)  indebtedness to the Bank;

                  (b) open account trade debt incurred in the ordinary course of
business and not past due, or

                  (c) indebtedness in respect of which liens are permitted under
subparagraph  (1)(c)  above,  and any  refinancings  thereof;  provided that the
amount of the refinancing  indebtedness is not more than the outstanding  amount
of the refinanced  indebtedness,  and the terms of the refinancing  indebtedness
are  no  more  favorable  to  the  lender  than  the  terms  of  the  refinanced
indebtedness.

         (3)  The  Borrower  will  not  liquidate,  or  dissolve,  or  merge  or
consolidate with any person, firm, corporation or other entity, except that upon
prior written  notice to the Bank (i) STV Group,  Inc., may merge or consolidate
with one of its subsidiary Borrowers or with a corporation acquired as permitted
under subparagraph (5) below, provided it is the surviving corporation, and (ii)
any of the subsidiary Borrowers may merge or consolidate with each other.

         (4) The Borrower shall not sell,  lease,  transfer or otherwise dispose
of all or any substantial  part of its property or assets,  whether now owned or
hereafter acquired, except upon prior written notice to the Bank, the subsidiary
Borrowers may transfer assets to each other or to STV Group, Inc.

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STV Group, Incorporated
February 3, 2000
Page 15

         (5) The Borrower will not make acquisitions of all or substantially all
of the  property or assets of any person,  firm,  corporation  or other  entity,
except such acquisitions which do not in the aggregate exceed $1,500,000.

         (6) The Borrower  will not declare or pay any  dividends on or make any
distribution  with respect to any class of its equity  (other than (i) dividends
which in the  aggregate in any fiscal year, do not exceed an amount equal to 25%
of the  Borrower's  net income for the prior  fiscal year or (ii)  dividends  to
another Borrower),  and will not purchase,  redeem,  retire or otherwise acquire
any of its equity.

         (7) The  Borrower  will  not  make or have  outstanding  any  loans  or
advances to or otherwise extend credit to any person, firm, corporation or other
entity, except in the ordinary course of business and in an amount which, in the
aggregate, does not exceed $500,000.

         (8) The  Borrower  will  not make or permit any change in the nature of
its business as carried on as of the date hereof.

M:\LEGAL\Simon\STV Group\Letter Agreement4COMMITTED LINE OF CREDIT NOTE
                               (Index LIBOR Note)

$12,000,000.00                                                  February 3, 2000

FOR  VALUE  RECEIVED,  STV  GROUP,  INCORPORATED  and STV  INCORPORATED  and its
SUBSIDIARIES  listed on the attached  Schedule A (individually and collectively,
the  "Borrower"),  with an  address  at 205  West  Welsh  Drive,  Douglassville,
Pennsylvania  19518,  promises  to pay  to  the  order  of  PNC  BANK,  NATIONAL
ASSOCIATION  (the  "Bank"),  in lawful money of the United  States of America in
immediately  available  funds at its  offices  located  at 1600  Market  Street,
Philadelphia,  Pennsylvania,  19103,  or at such other  location as the Bank may
designate  from  time to time,  the  principal  sum of  TWELVE  MILLION  DOLLARS
($12,000,000.00) (the "Facility") or such lesser amount as may be advanced to or
for the benefit of the Borrower  hereunder,  together with interest  accruing on
the outstanding principal balance from the date hereof, as provided below:

1. Rate of Interest.  The principal amount outstanding under this Note will bear
interest  at a rate per annum  (computed  on the basis of  actual  days  elapsed
within a year consisting of 360 days) equal to the sum of (A) LIBOR plus (B) two
hundred (200) basis points (2.0%) (the "Applicable LIBOR"). The Applicable LIBOR
shall remain in effect until  adjusted by the Bank as of the first  calendar day
of each month, without notice to the Borrower.

For the purpose hereof, the following terms shall have the following meanings:

                           "Business Day" shall mean any day on which commercial
         banks settle payments in U.S. dollars in New York City and London other
         than a Saturday or Sunday or a legal holiday on which  commercial banks
         are  authorized or required to be closed for business in  Philadelphia,
         Pennsylvania.

                           "LIBOR" shall mean,  for all advances  outstanding at
         any time during any month,  the interest  rate per annum  determined by
         the Bank by  dividing  (the  resulting  quotient  rounded  upwards,  if
         necessary,  to the nearest  1/100th of 1%) (i) the  Published  Rate for
         such  month by (ii) a number  equal to 1.00  minus  the  LIBOR  Reserve
         Percentage.  As used  herein,  "Published  Rate" shall mean the rate of
         interest  published on the first Business Day of each month in The Wall
         Street  Journal  "Money  Rates"  listing  under  the  caption   "London
         Interbank Offered Rates" for a one month period (or, if no such rate is
         published  therein for any reason,  then such rate published therein on
         the most  recent  Business  Day prior to the  first day of such  month;
         provided,  that if no such rate of  interest is  published  therein for
         longer than 30 consecutive  days,  then the Published Rate shall be the
         eurodollar  rate  for a one  month  period,  as  published  in  another
         publication determined by the Bank).

                           "LIBOR  Reserve  Percentage"  shall mean the  maximum
         effective  percentage  in effect on such day as prescribed by the Board
         of  Governors  of the Federal  Reserve  System (or any  successor)  for
         determining the reserve requirements (including, without limitation,

<PAGE>

         supplemental, marginal and emergency reserve requirements) with respect
         to  eurocurrency   funding  (currently  referred  to  as  "Eurocurrency
         liabilities").

LIBOR shall be adjusted on the effective date of any change in the LIBOR Reserve
Percentage as of such  effective  date. The Bank shall give prompt notice to the
Borrower  of LIBOR as  determined  or  adjusted in  accordance  herewith,  which
determination shall be conclusive absent manifest error.

If the Bank determines (which determination shall be final and conclusive) that,
by reason of circumstances  affecting the eurodollar market generally,  deposits
in dollars (in the  applicable  amounts)  are not being  offered to banks in the
eurodollar  market for the  selected  term,  or adequate  means do not exist for
ascertaining  LIBOR,  then the Bank shall give notice  thereof to the  Borrower.
Thereafter,  until the Bank notifies the Borrower that the circumstances  giving
rise to such suspension no longer exist,  (a) the availability of the Applicable
LIBOR  shall be  suspended,  and (b) the  interest  rate for all  advances  then
bearing  interest under the Applicable LIBOR shall be converted on the first day
of the next calendar  month to a rate of interest per annum  (calculated  on the
basis of actual days elapsed within a year  consisting of 360 days) equal to the
Prime Rate (the  "Applicable Base Rate").  For purposes hereof,  the term "Prime
Rate" shall mean the rate  publicly  announced  by the Bank from time to time as
its prime rate. The Prime Rate is determined  from time to time by the Bank as a
means of pricing some loans to its borrowers.  The Prime Rate is not tied to any
external rate of interest or index, and does not necessarily  reflect the lowest
rate of  interest  actually  charged  by the  Bank to any  particular  class  or
category of customers.  If and when the Prime Rate changes, the rate of interest
with respect to any amounts  hereunder to which the Applicable Base Rate applies
will change automatically without notice to the Borrower,  effective on the date
of any such change.

In addition,  if, after the date of this Note, the Bank shall  determine  (which
determination shall be final and conclusive) that any enactment, promulgation or
adoption of or any change in any  applicable  law,  rule or  regulation,  or any
change  in  the  interpretation  or  administration  thereof  by a  governmental
authority,  central bank or comparable agency charged with the interpretation or
administration thereof, or compliance by the Bank with any guideline, request or
directive  (whether  or not  having  the  force of law) of any  such  authority,
central bank or comparable  agency shall make it unlawful or impossible  for the
Bank to make or maintain or fund loans bearing  interest based on the Applicable
LIBOR,  the Bank shall notify the Borrower.  Upon receipt of such notice,  until
the Bank  notifies  the  Borrower  that the  circumstances  giving  rise to such
determination  no longer apply,  (a) the  availability  of the Applicable  LIBOR
shall be  suspended,  and (b) the  interest  rate on all  advances  then bearing
interest  under the Applicable  LIBOR shall be converted to the Applicable  Base
Rate  either (i) on the first day of the next  calendar  month,  if the Bank may
lawfully  continue to maintain  advances at the Applicable LIBOR to such day, or
(ii)  immediately  if the Bank may not  lawfully  continue to maintain  advances
under the Applicable LIBOR.

In no event will the rate of interest  hereunder exceed the maximum rate allowed
by law.

2. Advances.  The Borrower may borrow,  repay and reborrow  hereunder  until the
Expiration  Date,  subject to the terms and conditions of this Note and the Loan
Documents (as defined  herein).  The "Expiration  Date" shall mean December ___,
2001, or such later date as may be designated by the Bank by written notice from
the Bank to the Borrower.  The Borrower acknowledges and agrees that in no event
will the Bank be under any  obligation  to extend or renew the  Facility or this
Note  beyond  the  Expiration  Date.  In no event  shall  the  aggregate  unpaid
principal  amount of  advances  under this Note  exceed the face  amount of this
Note.

                                      -2-
<PAGE>

3. Advance Procedures.  A request for advance made by telephone must be promptly
confirmed  in  writing  by such  method as the Bank may  require.  The  Borrower
authorizes  the Bank to accept  telephonic  requests for advances,  and the Bank
shall be  entitled  to rely upon the  authority  of any  person  providing  such
instructions.  The Borrower hereby  indemnifies and holds the Bank harmless from
and  against  any and all  damages,  losses,  liabilities,  costs  and  expenses
(including  reasonable  attorneys'  fees and  expenses)  which  may  arise or be
created by the  acceptance of such  telephone  requests or making such advances.
The Bank will  enter on its books and  records,  which  entry  when made will be
presumed correct,  the date and amount of each advance,  as well as the date and
amount of each payment made by the Borrower.

4. Payment Terms. Accrued interest will be due and payable monthly in arrears on
the first day of each month,  beginning  with the  payment due on  _____________
___, 2000. The outstanding principal balance and any accrued but unpaid interest
shall be due and payable on the Expiration Date.

If any payment under this Note shall become due on a Saturday,  Sunday or public
holiday under the laws of the State where the Bank's office  indicated  above is
located, such payment shall be made on the next succeeding business day and such
extension of time shall be included in  computing  interest in  connection  with
such payment.  The Borrower hereby  authorizes the Bank to charge the Borrower's
deposit  account  at the  Bank for any  payment  when  due  hereunder.  Payments
received  will be applied to charges,  fees and expenses  (including  attorneys'
fees),  accrued interest and principal in any order the Bank may choose,  in its
sole discretion.

5. Late  Payments;  Default Rate.  If the Borrower  fails to make any payment of
principal,  interest or other amount  coming due pursuant to the  provisions  of
this Note within 15 calendar days of the date due and payable, the Borrower also
shall pay to the Bank a late charge  equal to the lesser of five percent (5%) of
the amount of such  payment or $100.00 (the "Late  Charge").  Such 15 day period
shall not be  construed  in any way to extend the due date of any such  payment.
Upon maturity,  whether by acceleration,  demand or otherwise, and at the Bank's
option upon the occurrence of any Event of Default (as hereinafter  defined) and
during the  continuance  thereof,  this Note shall bear  interest  at a rate per
annum (based on a year of 360 days and actual days  elapsed)  which shall be two
percentage  points  (2%) in excess of the  interest  rate in effect from time to
time  under  this Note but not more than the  maximum  rate  allowed by law (the
"Default  Rate").  The  Default  Rate  shall  continue  to apply  whether or not
judgment  shall be entered on this Note.  Both the Late  Charge and the  Default
Rate are imposed as  liquidated  damages for the purpose of defraying the Bank's
expenses  incident to the handling of delinquent  payments,  but are in addition
to,  and  not in lieu  of,  the  Bank's  exercise  of any  rights  and  remedies
hereunder,  under the other Loan Documents or under applicable law, and any fees
and expenses of any agents or attorneys which the Bank may employ.  In addition,
the Default Rate  reflects the  increased  credit risk to the Bank of carrying a
loan that is in default.  The  Borrower  agrees that the Late Charge and Default
Rate are reasonable  forecasts of just  compensation  for anticipated and actual
harm incurred by the Bank,  and that the actual harm incurred by the Bank cannot
be estimated with certainty and without difficulty.

6. Prepayment.  The indebtedness  evidenced by this Note may be prepaid in whole
or in part at any time without penalty.

7. Yield  Protection.  The  Borrower  shall pay to the Bank,  on written  demand
therefor,  together with the written evidence of the justification therefor, all
direct costs incurred, losses suffered or payments made

                                      -3-
<PAGE>

by Bank by  reason  of any  change in law or  regulation  or its  interpretation
imposing any reserve,  deposit,  allocation of capital,  or similar  requirement
(including  without  limitation,  Regulation  D of the Board of Governors of the
Federal  Reserve  System)  on the  Bank,  its  holding  company  or any of their
respective  assets.  The Bank's  determination  of an amount  payable under this
paragraph  shall,  in the absence of manifest  error, be conclusive and shall be
payable on demand.

8.  Other  Loan  Documents.  This  Note is issued  in  connection  with a Letter
Agreement  between the Borrower and the Bank dated on or before the date hereof,
and the other  agreements  and  documents  executed in  connection  therewith or
referred to therein, the terms of which are incorporated herein by reference (as
amended,  modified  or  renewed  from  time  to  time,  collectively  the  "Loan
Documents"),  and is secured by the property described in the Loan Documents (if
any) and by such  other  collateral  as  previously  may have been or may in the
future be granted to the Bank to secure this Note.  All  capitalized  terms used
herein and not otherwise defined herein have the meanings given them in the Loan
Documents.

9. Events of Default.  The  occurrence  of any of the  following  events will be
deemed to be an "Event of Default"  under this Note:  (i) the  nonpayment of any
principal,  interest or other  indebtedness  under this Note within two (2) days
after the date when due; (ii) the  occurrence of any event of default or default
and the lapse of any notice or cure period under any Loan  Document or any other
debt, liability or obligation to the Bank of any Obligor; (iii) the filing by or
against any Obligor of any proceeding in bankruptcy,  receivership,  insolvency,
reorganization,  liquidation, conservatorship or similar proceeding (and, in the
case of any such proceeding  instituted against any Obligor,  such proceeding is
not dismissed or stayed  within 60 days of the  commencement  thereof,  provided
that the Bank shall not be  obligated  to advance  additional  funds during such
period); (iv) any assignment by any Obligor for the benefit of creditors, or any
levy,  garnishment,  attachment or similar  proceeding is instituted against any
property of any Obligor held by or deposited  with the Bank;  (v) a default with
respect  to any other  indebtedness  of any  Obligor in excess of  $250,000  for
borrowed  money,  if the  effect  of such  default  is to  cause or  permit  the
acceleration  of  such  debt;  (vi)  the  commencement  of  any  foreclosure  or
forfeiture  proceeding,  execution or attachment against any collateral securing
the obligations of any Obligor to the Bank; (vii) any material adverse change in
the business, assets,  operations,  financial condition or results of operations
of the Obligors, taken as a whole; (viii) the Obligors cease doing business as a
going concern; (ix) any change shall occur in the equity ownership of STV Group,
Incorporated which results in its current employee stock option plan owning less
than sixty percent (60%) of the voting control of STV Group,  Incorporated;  (x)
any  representation  or  warranty  made by any  Obligor  to the Bank in any Loan
Document, or any other documents now or in the future evidencing or securing the
obligations of any Obligor to the Bank, is false, erroneous or misleading in any
material adverse respect;  (xi) any Obligor's  failure to observe or perform any
of the Financial Reporting Covenants contained in Section A of Exhibit A to that
certain  Letter  Agreement  dated  February ___,  2000 (as amended,  modified or
renewed  from time to time,  the  "Letter  Agreement"),  or any of the  Negative
Covenants contained in Section C of Exhibit A to the Letter Agreement, provided,
however,  that if such failure is capable of being cured and  Borrower  promptly
undertakes to effect such cure,  such failure  shall not  constitute an Event of
Default  hereunder  unless it remains  uncured for a period of ten (10) days; or
(xii) any  Obligor's  failure  to  observe  or  perform  any  covenant  or other
agreement with the Bank  contained in any Loan Document  (other than as provided
in clause (xi) above) or any other documents now or in the future  evidencing or
securing the obligations of any Obligor to the Bank provided,  however,  that if
such  failure is capable of being  cured and  Borrower  promptly  undertakes  to
effect  such  cure,  such  failure  shall  not  constitute  an Event of  Default
hereunder  unless it remains  uncured for a period of thirty (30) days.  As used
herein, the term "Obligor" means any Borrower.

                                      -4-
<PAGE>

Upon  the  occurrence  of an Event of  Default:  (a) the Bank  shall be under no
further  obligation  to make  advances  hereunder;  (b) if an Event  of  Default
specified in clause (iii) or (iv) above shall occur,  the outstanding  principal
balance and accrued  interest  hereunder  together with any  additional  amounts
payable  hereunder shall be immediately due and payable without demand or notice
of any kind;  (c) if any other Event of Default  shall  occur,  the  outstanding
principal  balance and accrued interest  hereunder  together with any additional
amounts payable hereunder,  at the Bank's option and without demand or notice of
any kind, may be accelerated and become immediately due and payable;  (d) at the
Bank's option, this Note will bear interest at the Default Rate from the date of
the occurrence of the Event of Default;  and (e) the Bank may exercise from time
to time any of the rights and  remedies  available  under the Loan  Documents or
under applicable law.

10. Right of Setoff.  In addition to all liens upon and rights of setoff against
the Borrower's money, securities or other property given to the Bank by law, the
Bank shall have,  with respect to the  Borrower's  obligations to the Bank under
this Note and to the extent permitted by law, a contractual  possessory security
interest in and a contractual  right of setoff against,  and the Borrower hereby
assigns,  conveys,  delivers,  pledges  and  transfers  to the  Bank  all of the
Borrower's right, title and interest in and to, all of the Borrower's  deposits,
moneys,  securities  and other property now or hereafter in the possession of or
on deposit  with,  or in transit  to, the Bank or any other  direct or  indirect
subsidiary  of PNC Bank Corp.,  whether held in a general or special  account or
deposit, whether held jointly with someone else, or whether held for safekeeping
or otherwise, excluding, however, all IRA, Keogh, and trust accounts. Every such
security  interest and right of setoff may be exercised  without  demand upon or
notice to the Borrower.  Every such right of setoff shall be deemed to have been
exercised  immediately  upon the  occurrence  of an Event of  Default  hereunder
without any action of the Bank,  although  the Bank may enter such setoff on its
books and records at a later time.

11. Miscellaneous. All notices, demands, requests, consents, approvals and other
communications required or permitted hereunder must be in writing (except as may
be agreed  otherwise  above with  respect  to  borrowing  requests)  and will be
effective  upon  receipt.   Such  notices  and  other   communications   may  be
hand-delivered, sent by facsimile transmission with confirmation of delivery and
a copy sent by  first-class  mail,  or sent by nationally  recognized  overnight
courier service,  to the addresses for the Bank and the Borrower set forth above
or to such other  address  as either  may give to the other in writing  for such
purpose.  No delay or omission on the Bank's part to exercise any right or power
arising  hereunder will impair any such right or power or be considered a waiver
of any such right or power,  nor will the Bank's  action or inaction  impair any
such right or power.  No  modification,  amendment or waiver of any provision of
this  Note nor  consent  to any  departure  by the  Borrower  therefrom  will be
effective  unless made in a writing signed by the Bank.  The Borrower  agrees to
pay on demand, to the extent permitted by law, all reasonable costs and expenses
incurred  by the Bank in the  enforcement  of its rights in this Note and in any
security therefor,  including without limitation reasonable fees and expenses of
the Bank's  counsel.  If any  provision of this Note is found to be invalid by a
court,  all the other  provisions  of this Note  will  remain in full  force and
effect.  The  Borrower  and all other  makers and  indorsers of this Note hereby
forever  waive   presentment,   protest,   notice  of  dishonor  and  notice  of
non-payment.  The  Borrower  also waives all  defenses  based on  suretyship  or
impairment  of  collateral.  If this Note is executed by more than one Borrower,
the obligations of such persons or entities hereunder will be joint and several.
This Note  shall bind the  Borrower  and its  successors  and  assigns,  and the
benefits  hereof shall inure to the benefit of the Bank and its  successors  and
assigns; provided,  however, that the Borrower may not assign this Note in whole
or in part  without  the  Bank's  written  consent  and the Bank at any time may
assign this Note in whole or in part.

                                      -5-
<PAGE>

This Note has been  delivered  to and accepted by the Bank and will be deemed to
be made in the Commonwealth of  Pennsylvania.  THIS NOTE WILL BE INTERPRETED AND
THE RIGHTS AND LIABILITIES OF THE BANK AND THE BORROWER DETERMINED IN ACCORDANCE
WITH THE LAWS OF THE  COMMONWEALTH  OF  PENNSYLVANIA,  EXCLUDING ITS CONFLICT OF
LAWS  RULES.  The  Borrower  hereby   irrevocably   consents  to  the  exclusive
jurisdiction  of any state or federal  court in the county or judicial  district
where the Bank's  office  indicated  above is  located;  provided  that  nothing
contained in this Note will prevent the Bank from bringing any action, enforcing
any  award  or  judgment  or   exercising   any  rights   against  the  Borrower
individually,  against  any  security or against  any  property of the  Borrower
within any other county,  state or other foreign or domestic  jurisdiction.  The
Borrower  acknowledges  and  agrees  that the venue  provided  above is the most
convenient  forum for both the Bank and the  Borrower.  The Borrower  waives any
objection to venue and any  objection  based on a more  convenient  forum in any
action instituted under this Note.

12. WAIVER OF JURY TRIAL. THE BORROWER IRREVOCABLY WAIVES ANY AND ALL RIGHTS THE
BORROWER MAY HAVE TO A TRIAL BY JURY IN ANY ACTION,  PROCEEDING  OR CLAIM OF ANY
NATURE  RELATING TO THIS NOTE,  ANY DOCUMENTS  EXECUTED IN CONNECTION  WITH THIS
NOTE OR ANY  TRANSACTION  CONTEMPLATED  IN ANY OF SUCH  DOCUMENTS.  THE BORROWER
ACKNOWLEDGES THAT THE FOREGOING WAIVER IS KNOWING AND VOLUNTARY.

The Borrower  acknowledges that it has read and understood all the provisions of
this Note,  including the waiver of jury trial,  and has been advised by counsel
as necessary or appropriate.

WITNESS the due execution  hereof as a document under seal, as of the date first
written above, with the intent to be legally bound hereby.

WITNESS/ATTEST:                                STV GROUP, INCORPORATED

/s/ Lori Jo Berk                               By:  /s/ Peter W. Knipe    (SEAL)
Print Name:  Lori Jo Berk                      Print Name:  Peter W. Knipe
Title:  Admin. Asst.                           Title:  CFO

WITNESS/ATTEST:                                STV INCORPORATED
/s/ Lori Jo Berk                               By:  /s/ Peter W. Knipe    (SEAL)
Print Name:  Lori Jo Berk                      Print Name:  Peter W. Knipe
Title:  Admin. Asst.                           Title:  CFO

                [SIGNATURES ARE CONTINUED ON THE FOLLOWING PAGE]

                                      -6-
<PAGE>

WITNESS/ATTEST:                                STV CONSTRUCTION SERVICES, INC.

/s/ Lori Jo Berk                               By:  /s/ Peter W. Knipe    (SEAL)
Print Name:  Lori Jo Berk                      Print Name:  Peter W. Knipe
Title:  Admin. Asst.                           Title:  CFO

WITNESS/ATTEST:                                STV INTERNATIONAL, INC.

/s/ Lori Jo Berk                               By:  /s/ Peter W. Knipe    (SEAL)
Print Name:  Lori Jo Berk                      Print Name:  Peter W. Knipe
Title:  Admin. Asst.                           Title:  CFO

WITNESS/ATTEST:                                STV/ENVIRONMENTAL, INC.

/s/ Lori Jo Berk                               By:  /s/ Peter W. Knipe    (SEAL)
Print Name:  Lori Jo Berk                      Print Name:  Peter W. Knipe
Title:  Admin. Asst.                           Title:  CFO

WITNESS/ATTEST:                                STV SURVEYING, INC.

/s/ Lori Jo Berk                               By:  /s/ Peter W. Knipe    (SEAL)
Print Name:  Lori Jo Berk                      Print Name:  Peter W. Knipe
Title:  Admin. Asst.                           Title:  CFO

WITNESS/ATTEST:                                STV CONSTRUCTION, INC.

/s/ Lori Jo Berk                               By:  /s/ Peter W. Knipe    (SEAL)
Print Name:  Lori Jo Berk                      Print Name:  Peter W. Knipe
Title:  Admin. Asst.                           Title:  CFO

WITNESS/ATTEST:                                STV ARCHITECTS, INC.

/s/ Lori Jo Berk                               By:  /s/ Peter W. Knipe    (SEAL)
Print Name:  Lori Jo Berk                      Print Name:  Peter W. Knipe
Title:  Admin. Asst.                           Title:  Secretary

                [SIGNATURES ARE CONTINUED ON THE FOLLOWING PAGE]

                                      -7-
<PAGE>

WITNESS/ATTEST:                                STV SILVER & ZISKIND ARCHITECTS,
                                               P.C.

/s/ Lori Jo Berk                               By:  /s/ Peter W. Knipe    (SEAL)
Print Name:  Lori Jo Berk                      Print Name:  Peter W. Knipe
Title:  Admin. Asst.                           Title:  Secretary

WITNESS/ATTEST:                                STV ARCHITECTS, P.C.

/s/ Lori Jo Berk                               By:  /s/ Michael D. Garz   (SEAL)
Print Name:  Lori Jo Berk                      Print Name:  Michael D. Garz
Title:  Admin. Asst.                           Title:  President

                                      -8-
<PAGE>
                                   SCHEDULE A

         STV Construction Services, Inc.

         STV International, Inc.

         STV/Environmental, Inc.

         STV Surveying, Inc.

         STV Construction, Inc.

         STV Architects, Inc.

         STV Silver & Ziskind Architects, P.C.

         STV Architects, P.C.

                                      -9-

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