                                                  ZyXEL Communications Corp.
                                                     edited by Manfred Recla
                                                              April 12, 1999


        Release Note on ZyXEL's "G1" Modem series (=> U-1496xx)
        Version 6.20                             April 12, 1999
        =======================================================


1.) filenames:
--------------------------------------------------------------------------
R620.TXT ............ These release notes for U-1496 series firmware v6.20

RM620BP.U24 ......... U-1496B+          -> firmware v6.20 for EPROM U.24
RM620BP.U25 ......... U-1496B+          -> firmware v6.20 for EPROM U.25

RM620B.U24 .......... U-1496B           -> firmware v6.20 for EPROM U.24
RM620B.U25 .......... U-1496B           -> firmware v6.20 for EPROM U.25

RM620E.U24 .......... U-1496E           -> firmware v6.20 for EPROM U.24
RM620E.U25 .......... U-1496E           -> firmware v6.20 for EPROM U.25

RM620EP.U24 ......... U.1496E+          -> firmware v6.20 for EPROM U.24
RM620EP.U25 ......... U-1496E+          -> firmware v6.20 for EPROM U.25

RM620RN.U24 ......... U-1496R and RN    -> firmware v6.20 for EPROM U.24
RM620RN.U25 ......... U-1496R and RN    -> firmware v6.20 for EPROM U.25

RM620RNP.U24 ........ U-1496R+ and RN+  -> firmware v6.20 for EPROM U.24
RM620RNP.U25 ........ U-1496R+ and RN+  -> firmware v6.20 for EPROM U.25

RM620S.U24 .......... U-1496S           -> firmware v6.20 for EPROM U.24
RM620S.U25 .......... U-1496S           -> firmware v6.20 for EPROM U.25

RM620SN.U24 ......... U-1496SN          -> firmware v6.20 for EPROM U.24
RM620SN.U25 ......... U-1496SN          -> firmware v6.20 for EPROM U.25

RM620SP1.U24 ........ U-1496S+          -> firmware v6.20 for EPROM U.24
RM620SP1.U25 ........ U-1496S+          -> firmware v6.20 for EPROM U.25
-------------------------------------------------------------------------


2.) fixed following modem bugs:
-------------------------------
 . Celluar mode:
   ATO1 after connection may cause modem hang up.
 . The retrain counter reported by ati2 is incorrect.
 . The second retrain will force modem to drop the connection speed.
 . V.27/V.29 can't connect again after hang up in LL mode.
 . set ats55.7=1 will let DSR follow the CD if &S1.
 . V.22bis mode:
   .The compatibity problem with Tainet modem in LL mode. (But bit 2 of s38
    must be set (ats38.2=1) when ZyXEL U-1496 is at originate mode.)
   .The modem will generate some garbages after connection in none error
    control mode.
 . Can't modify data format when the setting is leased line and sync (sd)
   mode.
 . Let ats35.1=1 be factory default for countries cc=222 (China) or 223
   (ChinaT)
 . Pseudo Carrier Dedect (ats12.7=1):
   set ats12.6=1 will disable Rx timer check when enabled Pseudo CD.
 . In 4-wire Leased-Line, the modem can't sense carrier drop while only
   two line is broken.

3.) fixed following fax bugs:
-----------------------------
   .Improve the compatibility with Fax machine.
   .The modem can't be quickly aborted after issue "ATD" command.
   .Fax Class 1:
    If "AT+FRH=3" time out, the modem can't accept any AT command.
   .The modem should respond "OK" instead of "No Carrier", after issue "ATH"
    command.

