Ref: 10820006
Title: History of the NETBuilder's Upgrade Path
Date: 03/18/91

Copyright 3Com Corporation, 1991.  All rights reserved.

The following is a brief history on the upgrade path for the NETBuilder:

First NETBuilder version:  A two-port Internetwork Bridge.  The two ports
were both AUI interfaces (Ethernet).  Two onboard thin Ethernet transceivers
were soon added.  The NETBuilder was still only a two-port IB, but it had the
option of using either thick or thin Ethernet.  This iteration of the board
had 1 MB of private RAM and 512 KB of shared RAM.

Second NETBuilder version:  A High Speed Serial (HSS) board was added.  The
HSS board had two V.35 and two RS-232 connectors, and could run two paths,
either one of which may be V.35 or RS-232.  Both paths may be run at up to
full T1 rates (2.048M in Europe) simultaneously.  One drawback was that
when one of the HSS ports is enabled, the second Ethernet (!2) port must
be disabled.  To run the new code, the motherboard's firmware and memory
required an upgrade.  The firmware upgrade was to recognize the HSS board
and the additional 1 MB of RAM (the memory upgrade).  This resulted
in 2 MB of private RAM and 512 KB of shared RAM.

Third NETBuilder version:  The HSS board was changed to become capable of
handling RS-449 data.  This has not required a firmware upgrade.

Fourth NETBuilder version (not released as of 2/20/91):  An additional 512 KB
of shared RAM, a 2 MB 3.5" floppy drive, and a rev. 00I (not 001) EPROM will
be added to recognize the additional RAM and to talk to the new floppy drive.
The 2 MB floppy drive is required because the code for BR 3.0 and IB 4.0 will
be larger than 1 MB.  The 2 MB drive can handle both 1 MB format and 2 MB
format media, so make sure that the correct media is used when copying the
new code.  There are two products for upgrading to the fourth NETBuilder
version:

   *  P/N 3C5855, for a NETBuilder that has 1 MB private RAM and 512 KB
      shared RAM

   *  P/N 3C5852, for a NETBuilder that has 2 MB private RAM and 512 KB
      shared RAM

Both upgrade products include the 2 MB floppy drive.

At the time of the BR 2.0 release and IB 3.2 release, all NETBuilders
that are shipped from the factory will contain 2 MB private RAM, 1 MB shared
RAM, and a 2 MB floppy drive.
