Ref: 15990013
Title: Problem Using the EtherLink Plus at I/O Base Address 2F0
Date: 2/27/90

Copyright 3Com Corporation, 1991.  All rights reserved.

In many AT-compatible computers, it is not possible to use the EtherLink
Plus adapter (3C505) at an I/O base address of 2F0.

The EtherLink Plus uses all sixteen addresses for its base address instead
of the eight addresses that many other boards use.  If you choose the base
address of 2F0 (hex), you are using 2F0-2FF, not just 2F0-2F7.

If 2F0 is chosen, it will conflict with the standard DOS COM2 port, which
uses a base address of 2F8.  This is true even if the second COM port is
not installed, because DOS accesses it during initialization to determine
if the port is active.  The EtherLink Plus adapter is properly initialized
by the ETH505.SYS or PSH.SYS drivers, but when DOS loads, it writes
to I/O addresses in the 2F8-2FF range, thus resetting the adapter and
rendering it inoperable.

This can also happen on other adapter boards besides the EtherLink
Plus.  The only solution is to not use base address 2F0.

