Document:

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                                                                   EXHIBIT 10.6b

                                PRINTRONIX, INC.

             SECOND AMENDMENT TO RESTRICTED STOCK PURCHASE AGREEMENT

        This Agreement is made at Irvine, California as of April 2, 2001 by and
between PRINTRONIX, INC., a Delaware corporation (the "Company") and Robert A.
Kleist (the "Stockholder").

                                   RECITALS

        A. The Stockholder has acquired shares of the Company (the "Shares")
pursuant to a sale of restricted stock (as that term is used in the Company's
1994 Stock Incentive Plan) under a restricted stock purchase agreement (the
"Agreement").

        B. Payment for the Shares was made by promissory note (the "Note")
accompanied by a pledge of the Shares.

        C. The Note was replaced by a new note (the "1999 Note") which, among
other things, limited the Stockholder's ability to sell stock.

        D. The parties now desire to further amend the Agreement and substitute
another promissory note.

        NOW, THEREFORE, the parties hereto amend the Agreement as follows:

                                    AGREEMENT

        1. The parties substitute the promissory note attached hereto as Exhibit
A (the "2001 Note") in the place of the 1999 Note. The Stockholder acknowledges
that the Shares will not be released from the pledge until the 2001 Note has
been paid. The Stockholder may prepay the 2001 Note at any time.

        2. Except as so amended, the Agreement, as previously amended, remains
in full force and effect.

IN WITNESS WHEREOF, this agreement is entered into as of the date first-above
written.

THE COMPANY                                   THE STOCKHOLDER
PRINTRONIX, INC.

By: GEORGE L. HARWOOD                         ROBERT A. KLEIST
    ---------------------------               -------------------------
    George L. Harwood                         Robert A. Kleist
    Sr. Vice President & CFO

<PAGE>   2

                                 PROMISSORY NOTE

$483,572.58                                                   Irvine, California
-----------------                                             April 2, 2001

        For value received, the undersigned, Robert A. Kleist, hereby promises
to pay to PRINTRONIX, INC., a Delaware corporation, at 14600 Myford Road,
Irvine, California 92606, or order, on April 2, 2003, the sum of Four Hundred
Eighty-Three Thousand Five Hundred Seventy-Two Dollars and 58 Cents
($483,572.58) representing principal of Four Hundred Thousand Dollars ($400,000)
and interest of Eighty-Three Thousand Five Hundred Seventy-Two Dollars and 58
Cents ($83,572.58) accrued through April 2, 2001 on the Promissory dated April
1, 1999. This Note shall bear no interest.

        This Note may be prepaid, either in whole or in part, at any time.

        Payment shall first be credited on interest and then on principal. The
principal and interest are payable in lawful money of the United States of
America.

        This Note is made in connection with that certain Printronix, Inc. 1994
Stock Incentive Plan Restricted Stock Purchase Agreement dated as of October 8,
1997, as amended as of April 1, 1999 and amended again as of April 2, 2001,
between the undersigned and Printronix, Inc. The undersigned has pledged shares
of Printronix, Inc. stock as security for the repayment of this Note and
Printronix, Inc.'s sole recourse in the event of breach of the undersigned's
obligations under this Note is to such security.

                                                  ROBERT A. KLEIST
                                                  ---------------------------
                                                  Robert A. Kleist

                                    Exhibit A<PAGE>   1

                                                                   EXHIBIT 10.8b

                                PRINTRONIX, INC.

             SECOND AMENDMENT TO RESTRICTED STOCK PURCHASE AGREEMENT

        This Agreement is made at Irvine, California as of April 2, 2001 by and
between PRINTRONIX, INC., a Delaware corporation (the "Company") and George L.
Harwood (the "Stockholder").

                                    RECITALS

        A. The Stockholder has acquired shares of the Company (the "Shares")
pursuant to a sale of restricted stock (as that term is used in the Company's
1994 Stock Incentive Plan) under a restricted stock purchase agreement (the
"Agreement").

        B. Payment for the Shares was made by promissory note (the "Note")
accompanied by a pledge of the Shares.

        C. The Note was replaced by a new note (the "1999 Note") which, among
other things, limited the Stockholder's ability to sell stock.

        D. The parties now desire to further amend the Agreement and substitute
another promissory note.

        NOW, THEREFORE, the parties hereto amend the Agreement as follows:

                                    AGREEMENT

        1. The parties substitute the promissory note attached hereto as Exhibit
A (the "2001 Note") in the place of the 1999 Note. The Stockholder acknowledges
that the Shares will not be released from the pledge until the 2001 Note has
been paid. The Stockholder may prepay the 2001 Note at any time.

        2. Except as so amended, the Agreement, as previously amended, remains
in full force and effect.

IN WITNESS WHEREOF, this agreement is entered into as of the date first-above
written.

THE COMPANY                                     THE STOCKHOLDER
PRINTRONIX, INC.

By: ROBERT A. KLEIST                            GEORGE L. HARWOOD
    ----------------------------                -----------------------------
    President & CEO                             George L. Harwood

<PAGE>   2

                                 PROMISSORY NOTE

$362,679.44                                                   Irvine, California
-----------                                                   April 2, 2001

        For value received, the undersigned, George L. Harwood, hereby promises
to pay to PRINTRONIX, INC., a Delaware corporation, at 14600 Myford Road,
Irvine, California 92606, or order, on April 2, 2003, the sum of Three Hundred
Sixty-Two Thousand Six Hundred Seventy-Nine Dollars and 44 Cents ($362,679.44)
representing principal of Three Hundred Thousand Dollars ($300,000) and interest
of Sixty-Two Thousand Six Hundred Seventy-Nine Dollars and 44 Cents ($62,679.44)
accrued through April 2, 2001 on the Promissory dated April 1, 1999. This Note
shall bear no interest.

        This Note may be prepaid, either in whole or in part, at any time.

        Payment shall first be credited on interest and then on principal. The
principal and interest are payable in lawful money of the United States of
America.

        This Note is made in connection with that certain Printronix, Inc. 1994
Stock Incentive Plan Restricted Stock Purchase Agreement dated as of October 8,
1997, as amended as of April 1, 1999 and amended again as of April 2, 2001,
between the undersigned and Printronix, Inc. The undersigned has pledged shares
of Printronix, Inc. stock as security for the repayment of this Note and
Printronix, Inc.'s sole recourse in the event of breach of the undersigned's
obligations under this Note is to such security.

                                                  GEORGE L. HARWOOD
                                                  ------------------------------
                                                  George L. Harwood

                                    Exhibit A<PAGE>   1
                                                                   EXHIBIT 10.9b

                                PRINTRONIX, INC.

             SECOND AMENDMENT TO RESTRICTED STOCK PURCHASE AGREEMENT

        This Agreement is made at Irvine, California as of April 2, 2001 by and
between PRINTRONIX, INC., a Delaware corporation (the "Company") and C. Victor
Fitzsimmons (the "Stockholder").

                                    RECITALS

        A. The Stockholder has acquired shares of the Company (the "Shares")
pursuant to a sale of restricted stock (as that term is used in the Company's
1994 Stock Incentive Plan) under a restricted stock purchase agreement (the
"Agreement").

        B. Payment for the Shares was made by promissory note (the "Note")
accompanied by a pledge of the Shares.

        C. The Note was replaced by a new note (the "1999 Note") which, among
other things, limited the Stockholder's ability to sell stock.

        D. The parties now desire to further amend the Agreement and substitute
another promissory note.

        NOW, THEREFORE, the parties hereto amend the Agreement as follows:

                                    AGREEMENT

        1. The parties substitute the promissory note attached hereto as Exhibit
A (the "2001 Note") in the place of the 1999 Note. The Stockholder acknowledges
that the Shares will not be released from the pledge until the 2001 Note has
been paid. The Stockholder may prepay the 2001 Note at any time.

        2. Except as so amended, the Agreement, as previously amended, remains
in full force and effect.

IN WITNESS WHEREOF, this agreement is entered into as of the date first-above
written.

THE COMPANY                                    THE STOCKHOLDER
PRINTRONIX, INC.

By: GEORGE L. HARWOOD                          C. VICTOR FITZSIMMONS
    -----------------------------              -------------------------------
    George L. Harwood                          C. Victor Fitzsimmons
    Sr. Vice President & CFO

<PAGE>   2

                                 PROMISSORY NOTE

$362,679.44                                                   Irvine, California
-----------                                                   April 2, 2001

        For value received, the undersigned, C. Victor Fitzsimmons, hereby
promises to pay to PRINTRONIX, INC., a Delaware corporation, at 14600 Myford
Road, Irvine, California 92606, or order, on April 2, 2003, the sum of Three
Hundred Sixty-Two Thousand Six Hundred Seventy-Nine Dollars and 44 Cents
($362,679.44) representing principal of Three Hundred Thousand Dollars
($300,000) and interest of Sixty-Two Thousand Six Hundred Seventy-Nine Dollars
and 44 Cents ($62,679.44) accrued through April 2, 2001 on the Promissory dated
April 1, 1999. This Note shall bear no interest.

        This Note may be prepaid, either in whole or in part, at any time.

        Payment shall first be credited on interest and then on principal. The
principal and interest are payable in lawful money of the United States of
America.

        This Note is made in connection with that certain Printronix, Inc. 1994
Stock Incentive Plan Restricted Stock Purchase Agreement dated as of October 8,
1997, as amended as of April 1, 1999 and amended again as of April 2, 2001,
between the undersigned and Printronix, Inc. The undersigned has pledged shares
of Printronix, Inc. stock as security for the repayment of this Note and
Printronix, Inc.'s sole recourse in the event of breach of the undersigned's
obligations under this Note is to such security.

                                                  C. VICTOR FITZSIMMONS
                                                  ------------------------------
                                                  C. Victor Fitzsimmons

                                    Exhibit A

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