hacking an AUI network port

Question

Does anyone know what's entailed in connecting a computer that has only an 'AUI' network interface into a modern LAN? By AUI port, I'm referring to one of those 15-pin D connector arrangements that used to be popular in the early 1990's. I know that establishing a network protocol will undoubtedly be a challenge in its own right, but that's beyond the scope of this question. At the moment, I just want to "get a link light" from it on one of my ethernet switches.

I would almost swear I once saw a jury-rigged connector that had just four wires with pins crimped on them jammed into selected points on the 15-pin D, though I don't recall what these wires ran to, but I thought it was an RJ-45. Could easily be mistaken on that. Just b/c someone had something wired with an RJ-45 doesn't necessarily mean it was 10BaseT.

Anyway, there are references to the AUI signal set being part of the IEEE 802.11 standard. Could it really be as simple as mapping a certain 4 of the 15 to the 1,2,3, and 6 of 10BaseT? Or could it be done with just a couple of line driver/receiver IC's?

I know there are $30 commercial solutions to the problem, but I am loathe to invest even that much on the system in question, as it would already be on its way into the electronics recycling bin but for academic curiosity about the old interface.

Answer 1

I believe the AUI interface provides access to the Ethernet MAC directly. You might be able to make it talk to an older 10BASE-T switch, but it definitely won't work with a 100BASE-T or Gigabit Ethernet switch.

In modern devices, the MAC connects to what's called a PHY chip-- the chip that generates the MLT-3 waveforms required for higher data rates. Without a PHY chip (which is probably what those $30 adapters contain), it won't work.

But with an older switch, you might have a chance. The data might come out Manchester-encoded, which might be comprehensible to a 10BASE-T port. I'd start with the AUI description in Spurgeon's Ethernet book: http://books.google.com/books?id=VbTvnxBKzUgC&pg=PA118

Answer 2

How about putting $9.10 into it? There are AUI to 10-Base-T transceivers on eBay for that price with free shipping. I didn't even look that hard, there are probably cheaper ones yet.

As for connecting to modern commodity network gear, I've never had any problem putting a 10Mb device on a 10/100 Mb switch. Pretty much all switches are store and forward these days, so when there's a speed difference between two ports, the frames are buffered by the switch and sent on at the proper link speed of the destination device.

Answer 3

A transceiver or MAU. Their availability is starting to be a bigger question now, I still have a few from my real computer days.