ZyXEL Communications Corp.

                                                     edited by Manfred Recla

                                                            February 3, 1997





   Release Note on ZyXEL's "G3" Modem series (= U-288R/RE, U-336E/S)

   Version 1.02

   =================================================================





 1. Fix modem bugs :

 -------------------

    * Remote digital loop back may  fail for U-336S model:

      If we initiate RDL or RDLST from the LCD panel, it will fail .

    * leased line mode:

      When the line is broken under abnormal condition after a long period

      of time the modem may fail to restart handshaking.

    * command ATI0 response:

      The modem responses "2864" in old version.In new version, it will

      response according to different modem type:

         U-288RE will response "33601"

         U-336R  will response "33602"

         U-336S  will response "33603"

         U-336E  will response "33604"

    * In testing mode, the modem will not set pin 25 of RS232 active.

    * MNP4,MNP5 mode:

      Sometimes it can't send or receive data in MNP4,MNP5 mode.

    * V.32bis and ZyX-19k2 mode:

      If the initial setting contains "Q2&K3" and it connects by ZyX-19k2

      or V.32bis mode, the modem will hang after transmit a few characters.



 2. Change the modem factory default settings:

 ---------------------------------------------

    S6 is changed to 10 for Russia.

    S7 is changed to 45 for Taiwan (rack).



 3. Improve performance:

 -----------------------

    * Improve V.34 performance.



 4. Known Bug:

 -------------

    * Software flow control problem:

      The modem will lose data in software flow control mode at high

      connect speed.

    * AT&Wab, Remote write profile functuion error. Remote can't reset from

      profile b.







---------------------------------------------------------------------------







                                                            January 16, 1997



   Release Note on ZyXEL's "G3" Modem series (= U-288R/RE, U-336E/S)

   Version 1.01

   =================================================================





 1. Add new features:

 --------------------

    * V.34bis 33600 bps, 31200 bps.



 2. Fix modem bugs :

 -------------------

    * V.32bis mode connection:

      Sometimes it can't sense the abnormal carrier drops.

    * Special dialing feature:

      Modem does not finish dialing of numbers specified after P modifier

      and hangs for a time specified in S7 register. For example when

      "ATDT9WP8W10-886-3-578-7045" is entered, modem will report "NO CARRIER"

    * Ring false alarm:

      When pulse dial  by the telephone set connected to modem, the modem

      will report ring.

    * Synchronous mode: (&M3)

      The modem will not give the answer tone when auto answer.

    * Compatibility:

      .Multi-Auto connection:

       The modem can't connect with Motorola Power 288 V.32bis mode .

      .Fail to connect at error control mode:

       Sometimes the modem will connect at none error control mode with

       Rockwell chip set based modem.



 3. Improve performance:

 -----------------------

    * Improve V.34 performance.

    * Improve answer tone detection sensitivity.

    * Improve the modem realibity.



 4. Known Bugs:

 -------------

    * Software flow control problem:

      The modem will lose data in software flow control mode at high connect

      speed.

    * AT&Wab, Remote write profile functuion error. Remote can't reset from

      profile b.