Ref: 02550003
Title: IEC/M (EC/2) Board Types and Jumpering
Date: 10/2/89

Copyright 3Com Corporation, 1991.  All rights reserved.

All current ESD products which attach to Ethernet and are based
upon the Series/1 chassis have an IEC/M (also known as EC/2) board.
Products based upon the Series/1 chassis which are more than
four years old may have an "EC/1 Combo" consisting of an ETI
(Ethernet Transceiver Interface) board and an ESB (Ethernet
Shared Buffer) board.  The IEC/M board replaced the EC/1 Combo.

Sytems which are, or have been, based upon the Series/1 chassis
include, but are not limited to, the following:

CS/1, LS/1, GS/1, GS/3, IB/1, IB/2, and IB/3.

There have been several IEC/M (EC/2) boards; they are as follows:

06-0021-00  =  256K for slot B.
06-0021-01  =  256K for slot H (may be jumpered for slot B).
06-0021-02  =  256K for NCS/1 (not easily useable in Series/1).
06-0021-03  =  512K for slot B (aka IEC/M-SNA).
06-0021-04  =  1M, was sold to an OEM.  Not used by any ESD
                   products.
06-0021-05  =  512K for NCS/2 (not easily useable in Series/1).
06-0021-06  =  512K with M1EC2B EPROMs which were once used on IB/3s
   and are no longer used.  If PROMs are changed to M1IECM
   EPROMs, the board is the same as an 06-0021-03.
06-0021-07  =  512K for any slot (Slots B and H are the only slots
   normally occupied by an IEC/M).

3Com does not support IB/2s with a mix of EC/2 sizes; either both
are 512K or both 256K.


Jumpering of 06-0021-01 and 06-0021-07 is identical for base
address and interrupt level, and is slot dependent.

Slot B - A single jumper at E89, pins 7-8; no jumpers at E101.
Slot H - A single jumper at E89 pins 11-12; a single jumper at
         E101, pins 7-8.

Pin numbering for E89 and E101 follow (the silkscreened numbers
at E89 and E101 on the IEC/M Board are not pin numbers):

   E89 (interrupt)              E101 (base address)

   1  2  3                      1  3  5  7  9  11 13 15
   4  5  6                      2  4  6  8  10 12 14 16
   7  8  9
   10 11 12

