Installing N516550AN's on a DIGIBOARD PC/4

[CAT-TALK Maint. Account]

System: SCO Xenix 2.3.2, 386 20MHz machine
        Digiboard PC/4
        4 USR Courier HST modems. DCE-DTE speed locked at 9600 baud.

Problem: Garbage characters get inserted into the data stream, serial
         port or modem wont reset after a call (SD,RD lites on the modem
         stay on constantly and the TR light goes out.)

I was told that the I/O chips on the PC/4 are "dumb" and have problems
handling high speed calls. In this case every call is high speed as the
DTE-DCE rate is locked at 9600 baud. Someone suggested replacing the chips
on the PC/4 with N516550AN's. Is this chip plug-compatible with whats on
that board?? Thanks in advance for your help.

jpp at ddmi.com