Ref: 11640125
Title: ITC/M Rev. 00 May Cause Transmission Errors at Low Speeds
Date: 4/18/90

Copyright 3Com Corporation, 1991.  All rights reserved.

ITC/M boards of Rev. 00 that have an MMI (Monolithic Memories Inc.) PAL
at location U77 may exhibit an increased rate of framing and CRC errors
if jumpered for low-speed transmission (<= 500Kbps).  The errors are
generated on transmission and are detected upon reception of the
packets.  The percentage of packets transmitted with errors will
increase as line utilization increases.

Note:  If you use the ITC/M only for high-speed transmission (>=500Kbps),
Rev. 00 works fine.

In ITC/M Rev. 00, the equation used to generate the Slow Clock Signal
(programmed on the PAL) caused a race condition.  Although 3Com has not
been able to produce the error with PALs made by companies other than
MMI, it is possible that the problem could occur with any PALs
programmed with the original equation.

It is believed that the problem will be most prevalent on ITC/M boards
manufactured from 10/89 to 3/90.

All ITC/M boards returned for repair or upgrade will be upgraded to Rev.
01.  In ITC/M Rev. 01 the PAL at U77 (SCLK PAL, P/N 39-0019-00 Rev. 00)
is replaced by a GAL (SCLK GAL, P/N 39-0030-13 Rev. 00).

