Low End Mac's Online Tech Journal

Apple's AAUI Ethernet Connector

Low End Mac Reader Specials

Memory To Go Special: MacPro 8 Core Memory 4GB kit $192 / 2GB kit $109. MacBook Pro / MacMini / iMac Intel Core2 DUO 2GB $44 1GB $23--Free shipping available.

Download Typestyler, still the Ultimate Styling Tool for Internet, Print and Video Graphics. Works great in Classic with a Native OS X Version on the way. Free Tryout: www.typestyler.com

LA Computer Company: LA Computer Company: Specials on AppleCare, Apple Displays, MacBooks, iMac's, MacBook Pros, Laptop and iPod accessories and more. Apple A/C Adapters for laptops starting at $25.00 Call 1-800-941-7654 or Click Here.

Other World Computing: Power up your PowerMac G4! Make you trusty PowerMac G4 like new again with up to 2.0GHz Processor Power. G4/1.2GHz for $199, Dual 1.8GHz $498, & More Plug & Play for like new A-OK for OS 9 & OS X, etc.

Mac users can finally play Party Poker for Mac. Not only that, they can also learn how to play PokerStars for Mac.

Laptop Hardware Provided by TechRestore - Overnight Mac & iPod Repairs.

MacPro Memory 667Mhz With Apple Spec Heat Sink 2GB Kit $ 90 / 4GB Kit $140 / 8GB Kit $278 Click to Maximize your Macs...

Dan Knight - 2007.09.04

When we think of ethernet today, we think of wired networking with RJ-45 ports and plugs. These connectors look like an oversized phone jack.

Ethernet History

But that's not what ethernet is. It's a frame-based protocol for communication between networked devices, such as computers, printers, and network attached storage drives. The protocol itself is hardware agnostic; that is, it doesn't care whether you're running coaxial cable, twisted-pair wiring, fiber optics, or going wireless.

In the early days of networking, ethernet competed with token ring, FDDI, ARCNET, and other protocols rarely mentioned today. Until the rise of 802.11 WiFi, ethernet dominated to the point that it is the de facto protocol for wired networks - and twisted-pair ethernet has become by far the most common form of ethernet.

Robert Metcalfe is considered the father of ethernet. He and David Boggs began developing the protocol at Xerox PARC in 1973 and presented their first draft standard "some time before March 1974." Xerox patented ethernet in 1975 and began using it at PARC in 1976. The first version of ethernet ran at 3 Mbps over coaxial cable and was limited to 256 devices on the network.

After Metcalfe left Xerox in 1979, he founded 3Com and worked to convince DEC, Intel, and Xerox to jointly promote ethernet as an industry standard for networking. The new version of ethernet ran at 10 Mbps and used 48-bit addresses. Twisted-pair ethernet was developed a few years later, replacing costly, less flexible coaxial cable with the same type of inexpensive wiring used for telephone systems. Using RJ-45 connectors, this became as 10Base-T ethernet.

For many years following this ethernet cards often included both coaxial and 10Base-T ports.

Ethernet at Apple

The Quadra 700 and Quadra 900, both introduced in October 1991, where the first Macs with ethernet ports. Apple had three options:

  1. Choose coaxial or twisted-pair ethernet exclusively.
  2. Include both coaxial and twisted-pair ethernet, which would increase costs.
  3. Do an end run around the issue by using an Attachment Unit Interface (AUI)

There was already an established AUI standard. Unfortunately for Apple and for Mac users, it used the same 15-pin DA-15 connector that Apple had standardized on when it introduced the Mac II and external monitors in 1987. Using the same physical connector would have created havoc.

AAUI port on Quadra 700To address this, Apple invented its own AUI, the Apple Attachment Unit Interface (AAUI), which it used for most Quadras, a few PowerBooks, several LaserWriters, and almost all pre-G3 Power Macs.

Apple's AAUI ethernet port was marked with <··>, as seen in the photo of an AAUI port on a Quadra 700. (The Q700 was designed as a minitower. It could also be put on its side, as in the photo. This is why the port marking appears sideways.)

The flexibility Apple gained by not choosing coaxial or twisted-pair wiring saved the company money - and meant that Mac users couldn't network with ethernet without investing in an AAUI adapter. 10Base-T ethernet so dominated that in 1995 Apple began including it alongside AAUI. With the Power Mac G3 of November 1997, Apple discontinued its proprietary network connector.

We have a full list of Macs and LaserWriters that included AAUI but not 10Base-T at the end of this article.

What AAUI Means for Mac Users

3 AAUI adaptersWhat this means for Mac users is that Macs and LaserWriters with built-in ethernet from the 1991-1995 era can't use 10Base-T ethernet without an adapter, which means an extra expense. And, these days, some time spent trying to locate an AAUI-to-10Base-T adapter.

There were several brands, such as the Asanté and Farallon ones shown here. Some have very short tails between the AAUI plug and the module itself, and some (such as the Asanté shown here) have lots of wire.

One of my favorites was also one of the most expensive. The Farallon EtherWave Transceiver not only connected a Mac with AAUI to 10Base-T ethernet, it also provided a second 10Base-T ethernet port, allowing you to daisy-chain a second ethernet device. This could be invaluable in an office setting if you want to avoid the expense of running yet another length of cable to your hub. (Farallon also made an EtherWave Transceiver that bridged LocalTalk to ethernet. Very cool!)

AAUI adapter clips sometimes come looseThe biggest problem I've run into with AAUI adapters is that the clips that hold them to the port on the Mac or LaserWriter come loose too easily. If you're moving your hardware and lose your network connection, it's the first thing to check.  LEM

Places to Look for AAUI Adapters

Macs with AAUI and no 10Base-T

  • Centris 610 (not entry-level model), 650 (not entry-level model), 660av
  • Quadra 610, 650, 660av, 700, 800, 840av, 900, 950
  • Power Mac 6100, 7100, 8100
  • PowerBook 500 Series

LaserWriters with AAUI and no 10Base-T

  • LaserWriter IIg
  • LaserWriter Pro 630
  • LaserWriter 12/640PS
  • LaserWriter 16/600PS

Further Reading

Recent Online Tech Journal Columns

Recent Content on Low End Mac

About LEM | Support | Usage | Privacy | Contacts

Entire Low End Mac website copyright ©1997-2008 by Cobweb Publishing, Inc., unless otherwise noted. All rights reserved. Advice presented in good faith, but what works for one may not work for all. Please report errors to .
  LINKS: We allow and encourage links to any public page as long as the linked page does not appear within a frame that prevents bookmarking it.
  Access our RSS news feed at http://lowendmac.com/feed.xml.
  Email may be published at our discretion; email addresses will not be published without permission, and we will encrypt them in hopes of avoiding spammers. If you prefer your message not be published, mark it "not for publication." Letters may be edited for length, context, and to match house style.
  PRIVACY: We don't collect personal information unless you explicitly provide it. For more details, see our Terms of Use.
  Low End Mac is an independent publication and has not been authorized, sponsored, or otherwise approved by Apple Inc. Apple, the Apple logo, Macintosh, iBook, iMac, eMac, iPod, PowerBook, MacBook, Mac Pro, Apple TV, and AirPort are registered trademarks of Apple Inc. Additional company and product names may be trademarks or registered trademarks and are hereby acknowledged.


Have a question?
Ask an expert!

Low End Living

Amazon.com

Navigation

Used Mac Dealers
Apple History
Best Used Macs
Video Cards
Email Lists
InfoMac's Low
End Mac Forum

Favorite Sites

MacSurfer
MacMinute
MacInTouch
MyAppleMenu
InfoMac
Macs Only!
The Mac Observer
Accelerate Your Mac
RetroMacCast
PB Central
MacWindows
The Vintage Mac
   Museum
DealMac
DealsOnTheWeb
Mac2Sell
ramseeker
Mac Driver Museum
JAG's House
System 6 Heaven
System 7 Today
the pickle's Low-End
   Mac FAQ
Abandonware
   Petition
Mac vs. PC Info

Affiliates

The Apple Store
Mac Connection
MacMall
TechRestore
MacResQ
ExperCom
Crucial Memory
batteries.com

Advertise

All of our advertising is handled by BackBeat Media. For price quotes and advertising information, please contact at BackBeat Media (646-546-5194). This number is for advertising only.

Open Link

Problems viewing this page with Internet Explorer 5.5 or 6? It works fine in other browsers, including IE 7. We recommend Firefox for those using Windows, as it is standards based and more secure than IE 6 (and earlier). More LEM visitors use Firefox than any other browser.