Network Wiring
Bridging LocalTalk and Ethernet
There are two kinds of wiring typically used on the Macintosh:
LocalTalk and ethernet (see LocalTalk and
Ethernet for more details).
LocalTalk is usually run on phone wire using Farallon PhoneNet
adapters or a generic equivalent. Speed is about 1/4Mbps. LocalTalk
has been built into every Mac since the 1986 Mac Plus - until the
iMac.
Beginning in the Quadra era, Apple began installing ethernet
ports as standard features. Today, every Macintosh made has
ethernet. Regular ethernet can reach 10Mbps (40 times the speed of
LocalTalk), and the newer 100Base-T ethernet is ten times
faster.
The Macintosh can communicate over both types of cable using
AppleTalk, the network protocol Apple invented in the Mac's
infancy. Macs with ethernet can also use the TCP/IP protocol, which
is the protocol of the internet.
The Problem
It's not uncommon to see Mac networks at home, at school, and in
the office. LocalTalk made it both easy and inexpensive, especially
after Farallon created PhoneNet. And today, 10Base-T ethernet isn't
particularly expensive, making it the norm for networking.
But there's a problem when you need to put both a new iMac or
Blue and White Power Mac G3 and an old LaserWriter or Mac Plus on the same
network. The newest Macs are ethernet only. The older Macs,
LocalTalk only.
Several Solutions
How you solve the problem depends on how much equipment of the
one type you need to connect to a network of the other type. In
larger installations, you may end up with both a LocalTalk network
and an ethernet network with a bridge between them.
Hardware
If all your hardware uses ethernet, but you need to run an old
LocalTalk printer (older LaserWriters, StyleWriter 4000 series, HP
DeskWriters, etc.) or connect to some old Macs, the easy solution
is a simple Ethernet-to-LocalTalk adapter.
Thanks to the ethernet-only iMac, such adapters have recently
become popular again. The Farallon
iPrint, Asante AsanteTalk,
and Asante
Micro AsantePrint adapters bridge up to 8 LocalTalk devices to
an ethernet network at a very affordable price.
If you need more LocalTalk devices, you could use more than one
bridge or try to locate an old Farallon StarRouter. This very
expensive device had a dozen switched LocalTalk ports, each of
which could easily support four devices. The StarRouter has another
advantage as well: it can act as a MacIP gateway, giving LocalTalk
only Macs access to the internet.
Another hardware solution is the SCSI-to-ethernet adapter, a
device that connects to the SCSI port on the Macintosh and puts it
on an ethernet network. For a single older Mac, this can be less
expensive than the Farallon and Asante bridges mentioned above.
Farallon has a unique solution that provides a faster connection
than the LocalTalk-to-ethernet bridge: EtherMac
and EtherWave
adapters. By clocking the LocalTalk port at a higher than usual
speed (something even the first Macintosh allowed), these adapter
let your Mac communicate over ethernet at about 3x the speed of
LocalTalk. An added advantage of the EtherWave adapter is a
pass-through port for daisy chaining ethernet devices. Drawbacks
include price (compared to a bridge) and no support for
OpenTransport.
The final hardware solution: an ethernet card. It is possible to
find used NuBus ethernet cards for under $30, which will connect
any Mac with a free NuBus slot to ethernet at full speed. If you
search, you can even find ethernet cards for the LC processor
direct slot, the ancient Macintosh SE, the 030 PDS in the SE/30 and
IIsi, and the processor direct slot in the Centris 610.
But for most PowerBooks, the Mac Plus, and a lot of single-slot
Macs that have accelerators, an ethernet card is not an option.
Since originally writing this, the following
hardware has been recommended by readers:
Software
Apple has two software solutions, the LaserWriter Bridge and
LocalTalk
Bridge. Each must be run on a Macintosh.
LaserWriter Bridge is specifically for connecting a single
printer to an ethernet network via a Macintosh hose. A recent
search of Apple's site didn't turn up a copy of LaserWriter Bridge,
which Apple made freely available some time ago. However,
everything LW Bridge could do, LocalTalk Bridge can also do.
LocalTalk Bridge is a control panel (no longer supported by
Apple, but apparently available for free download) that connects a
LocalTalk network to an ethernet network. The host computer should
be active as a bridge before any LocalTalk printers are turned on
or any time any devices need to communicate between the LocalTalk
and ethernet networks.
Unsolved Problem
Except for the Farallon StarRouter, none of the bridge solutions
allow use of TCP/IP, which means the oldest Macs can't access the
internet.
Of the other products, the Farallon EtherMac and EtherWave
adapters will allow TCP/IP connection, although only using Classic
Networking. (They do no support OpenTransport.) The
SCSI-to-ethernet adapters and network cards also support TCP/IP,
which can make them attractive.
A future article will look at ways to connect LocalTalk devices
to the internet via your network.
Next: Sharing an internet connection
Go to Low End Mac
Networking.
