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                                                                   Exhibit 10.5A


                      [APPLIED INNOVATION INC. LETTERHEAD]


                                 March 24, 1997

                                                         PERSONAL & CONFIDENTIAL

Mr. William H. Largent
1249 Crooked Tree Court
Westerville, OH 43081


Dear Bill:

With this letter, we are pleased to offer you the position of Senior Vice
President, Operations and Chief Financial Officer with Applied Innovation Inc.
(Company). We are very excited about you joining the Company, and I look forward
to working with you to grow Applied to a substantial sized business for the
benefit of all of our employees and stockholders. I think you have the ability
to make a major and lasting contribution to Applied's future performance as a
senior officer.

As you know, Applied has grown substantially over the past 10 years, and we see
no reason why growth is not sustainable with the right team in place. We want
you to be a part of that team. We believe that your broad business experience in
industry, particularly at Liebert, will be very beneficial in helping Applied
build an even larger and more innovative business.

Let me now review the terms of our employment proposal.

1.       EMPLOYMENT
         ----------

         You will be employed by the Company commencing not later than May 15,
         1997, although we hope that you can start earlier.

         As Senior Vice President, Operations and Chief Financial Officer, you
         will report directly to me as Chairman and President. You will be
         responsible for directing the business administration, financial,
         accounting, information systems, human resources, and manufacturing
         activities of the Company.
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Mr. William H. Largent
March 24, 1997
Page -2-


         We also see you as the senior business person working on teams with
         other key officers and employees on many projects involving sales and
         marketing initiatives, merger and acquisition opportunities, technology
         transfers, and a variety of business initiatives.

2.       COMPENSATION
         ------------

         Your compensation will be at an annual base rate of $145,000, payable
         in accordance with the normal payroll practices of the Company.

         You will also be eligible for a cash bonus consistent with my plan for
         1997, which is based on the Company attaining pre-tax, pre-bonus income
         as follows:

         PRE-TAX, PRE-BONUS INCOME                    % OF BASE SALARY
         -------------------------                    ----------------

         $2,750,000 to $3,437,499.99                         40%
         $3,437,500 to $4,124,999.99                         50%
         $4,125,000 or more                                  60%

         Under our bonus program, the bonus is paid in cash by March 31, 1998,
         provided you remain employed by the Company throughout 1997. Since you
         would be employed in 1997 only about 8 months, your bonus will be
         calculated as a percentage of your base salary actually earned in 1997,
         so your bonus would effectively be pro rated for 1997 (e.g., if you
         started April 1, 1997, your base for calendar 1997 would be 66.7% of
         $145,000 or $96,666 and your bonus would be computed on that amount.)
         The above "Pre-tax, Pre-bonus Income" schedule will be adjusted to
         reflect variance from plan for the period of January 1 to April 30,
         1997 (e.g., if plan for January to April was to earn $500,000 and
         actual was $100,000 then the ranges would be as follows: $2,350,000 to
         $3,037,499.99 - 40%; $3,037,500 to $3,724,999.99 - 50%; and $3,725,000
         - 60%).

3.       STOCK OPTIONS
         -------------

         On the date of your employment, the Company will grant to you an
         incentive stock option to purchase 50,000 shares of common stock at an
         exercise price equal to the closing price as quoted by NASDAQ on the
         day before you commence employment. The option will be granted under
         the Company's 1996 Stock Option Plan (copy enclosed), and the option
         agreement will provide that the option will vest and become exercisable
         as to 20% of the option shares on each anniversary of the date of your
         employment with the Company, and that the option will terminate on the
         sixth anniversary of the date of grant.
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Mr. William H. Largent
March 24, 1997
Page -3-


4.       OTHER BENEFITS
         --------------

         You will also be entitled to participate in any employee benefit plans,
         including vacation provisions, that the Company maintains during your
         employment and which are made generally available to all other
         management employees, in accordance with their terms as from time to
         time amended. This includes a 401(k) and profit sharing plan, and paid
         medical insurance. The Company has historically matched 25% of employee
         contributions up to 6%. The Company has also made contributions to the
         profit sharing plan in the past several years. The contribution for
         1996 was $200,000, which is allocated among all employees based on base
         salary. Employees are eligible for both plans upon employment. It is
         agreed that during your first year of employment you will be entitled
         to two weeks of vacation at any time during your first year. It is
         agreed that the Company will pay any necessary COBRA payments on your
         behalf due to any break in medical coverage for any reason, including
         pre-existing conditions.


5.       EXECUTIVE SEARCH FEE
         --------------------

         You represent that no personnel or executive search firm has been
         involved in or facilitated your employment by the Company and that no
         such fees are payable to any such firm for assisting you.


6.       TERM
         ----

         As with all of our employees and officers, your employment would be an
         at-will employment and may be terminated by either the Company or
         yourself at any time.

         However, if the Company elects to terminate you without cause you will
         be paid as severance pay your regular monthly base salary for up to six
         (6) months after termination in accordance with the Company's normal
         salary payment schedule, except that the severance pay will terminate
         when you find another job and you will be paid an extra month severance
         pay if you find another job within four months of your termination.

         If the Company terminates you for cause, it may do so immediately and
         without further obligation to you. For these purposes, "cause" will
         mean an intentional failure to abide by directions or policies of the
         Board of Directors or the President of the Company, an intentional
         failure to perform your duties, any action that involves a
         misappropriation of
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Mr. William H. Largent
March 24, 1997
Page -4-


         Company assets, or any breach of this letter agreement or the
         Assignment, Confidentiality and Non-Competition Agreement. You will
         have the right to submit the Company's determination of "cause" to
         arbitration in Columbus, Ohio before a single arbitrator under the
         rules of the American Arbitration Association.

         If you terminate your employment, you will continue working for the
         Company during a 14-day notice period, but only if the Company so
         desires to continue your employment and to compensate you during such
         period.


7.       FULL TIME EMPLOYMENT
         --------------------

         Your employment will be full time with the Company. You will not
         participate in any other business activities, including consulting
         activities, or serve as a director or officer of other business
         enterprises, without the prior written consent of the President of the
         Company. The Company acknowledges that you presently serve as a
         director of Amerilink Corp., Maximation Incorporated, Metatec
         Corporation, and BellePointe, Inc., and you may continue in these
         outside director positions if you choose, so long as such time
         commitments do not interfere with your responsibilities at the Company.
         You will, of course, be permitted to hold totally passive business
         investments and take part in community, civic, or charitable activities
         that neither interfere with nor are inconsistent with your
         responsibilities to the Company.


8.       ASSIGNMENT, CONFIDENTIALITY AND NON-COMPETITION AGREEMENT
         ---------------------------------------------------------

         In consideration of your employment, you will enter into an Assignment,
         Confidentiality and Non-Competition Agreement with the Company on the
         date of your employment (form enclosed), except that if the Company
         terminates you without cause, you will be excused from the
         non-competition restrictions of the agreement.


9.       NO RESTRICTIONS ON EMPLOYMENT
         -----------------------------

         You represent and warrant that you are not a party to any agreement,
         oral or written, or subject to any other legal restriction whatsoever
         which would prevent you from performing your duties to the Company as
         contemplated in this letter or which would expose the Company to a risk
         of suit by reason of your employment by the Company.
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Mr. William H. Largent
March 24, 1997
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I hope that this letter sets forth acceptable terms for you to join the Company.
To confirm acceptance of this offer, please sign the enclosed extra copy of this
letter and return it to me.

Those of us who have met you and talked with you believe that you will be a
significant asset to the Company. We also believe that Applied Innovation will
offer you the challenge and satisfaction of being an architect of our business
as it continues to grow.

                                         Sincerely,

                                         /s/ Gerard B. Moersdorf, Jr.

                                         Gerard B. Moersdorf, Jr.
                                         President


Enclosures:
         1996 Stock Option Plan
         Assignment , Confidentiality and Non-Competition Agreement


AGREED:


   /s/ William H. Largent
-----------------------------
       WILLIAM H. LARGENT

       April 24, 1997
-----------------------------
             DATE