Se30

SEthernet and SEthernet/30

Modern, low-cost 10/100 Ethernet for the Macintosh SE and SE/30.

Introduction

It's an unfortunate reality of retrocomputing that, as time goes on, original hardware only ever becomes more scarce, and usually more expensive.

While PDS ethernet cards are certainly not scarce yet, the collector appeal of Compact Macs means that cards are in high demand, with consequent high prices. As of this writing (October 2023), the going eBay rate for them seems to be of the order of $US 150-200, which is a bit steep for those of us who remember finding them in electronics-recycler dollar bins.

While other projects have aimed to clone these original cards, such an approach comes with a downside - the ethernet controller chips used in them have been out of production for many years, and the controllers and (even more so) their supporting components, are difficult to find.

While cloned cards trade off parts sourcing difficutly (and cost) for the significant advantage of being able to use existing drivers, this project takes the opposite approach: design an all-new card using a modern, readily-available ethernet controller, and write a new driver for it. How hard can it be? ¹

Hardware Overview

Both the SEthernet and SEthernet/30 use the Microchip ENC624J600 all-in-one embedded ethernet controller. It's cheap, readily available, has a straightforward software interface without too many glaring misfeatures (I'm looking at you, RTL8019AS), and amongst its multitude of configurable host-bus modes, it has one that matches the 68k processor bus nicely.

Since the Macintosh SE lacks any real infrastructure for expansion beyond "here's a connector with the CPU bus on it," the SEthernet board is a very dumb device. It simply maps the ENC624J600 into a vacant chunk of memory at 0x80 0000-0x80 ffff and connects it to an interrupt line. Hardware detection, interrupt vector interception, and device configuration are all left to the driver to implement.

The Macintosh SE/30 is a more civilised machine, and the SEthernet/30 provides a declaration ROM and multiple addressing options (configurable by jumper) to take full advantage of the Slot Manager and coexist with multiple PDS cards. Potentially, the driver could even be built into the declaration ROM, allowing for a truly plug-and-play solution. To facilitate driver updates, the declaration ROM is a flash chip, with logic to allow for in-system programming.

Current project status

Hardware

Hardware Revision 1 is largely 'done', and corrects the numerous issues of my initial "Revision 0" boards. A few mechanical tweaks remain to get mounting holes in exactly the right spot, and relocate connectors for easier access.

Software

The core driver is functional and stable enough for everyday use. Real-world performance is marginally better than a comparable vintage card, but there is likely room to improve - especially in the rather convoluted receive routine.

Support for promiscuous mode, and the ERead call are not yet implemented.

The installer has some rough edges (no hardware detection or driver version detection on the SE), but functions as a way to get drivers onto a system.

The SE/30 board's Declaration ROM must be programmed before the card can be recognized. This can be done in-system using the programROM application provided on the installer disk, but right now this is a very ugly and user-unfriendly console application, and really should be turned into a proper GUI app.

Testing has been done on my unmodified SE and SE/30 under Systems 6.0.8, 7.1, and 7.5.5.

A driver for A/UX 2 and 3 can be found at https://github.com/rhalkyard/SEthernet-AUX.

Project files

Schematics: SEthernet - SEthernet/30 - Breakout Board

Glue Logic: SEthernet - SEthernet/30

SEthernet30 Declaration ROM

Driver

Required tools

Schematics, board layout and BOM

KiCad 7

Programmable Logic

WinCUPL and ATMISP (see pld/README.md for notes on WinCUPL)

Declaration ROM, driver and software

• Retro68 built with Apple Universal Interfaces (at the time of writing, the default free-software Multiversal Interfaces do not include some necessary headers)

• CMake

• Python 3

Installer

• hfsutils

• Python 3

• Mini vMac

License

The hardware components of this project (board designs and programmable logic) are licensed under the Strongly-Reciprocal CERN Open Hardware License, version 2.

The software components of this project are licensed under the GNU General Public License v3.0.

While my choice to make this project open-source is very much a deliberate one, I have a few further requests, on the basis of "I can't and won't enforce these, but I'd appreciate if you respected them." It's unfortunate that I have to mention this, but given how a few recent projects in the retro-hardware community have splintered, I feel that it's necessary to say:

• Please don't sell cards commercially/for profit without checking with me first. I have plans for a sales and manufacturing partnership that will sell boards affordably, with full support. I don't mind if you order a batch of boards for yourself and sell the extras on a break-even basis, but please make it clear that these are not 'official' SEthernet products.

• Please contribute back, rather than simply forking the project. I strongly encourage people to modify the design, adapt it to other systems, integrate it into other devices. But unless what you're working on is a radical departure from the basic SEthernet design, I'd much rather see a unified, collaborative effort that is supported by a single software stack, rather than having it be fragmented.

If you have any questions, feel free to reach out to me, I don't bite!

Useful reference material

• ENC624J600 datasheet

• Designing Cards and Drivers for the Macintosh Family (3rd Edition)

• Inside Macintosh (1994): Networking

• Inside Macintosh (1994): Devices

• Glenn Anderson's ethernet driver page - contains C source for a DP8390-based card.

• Mac Driver Museum: Network Drivers - good material for reverse-engineering. In particular, the Dayna ethernet drivers contain debug symbols, which are quite handy for our purposes.

• Rob Braun's declaration ROM page has useful information about declaration ROMs and how they work.

Footnotes

1. [Arrested Development narrator voice]: It was, in fact, quite hard ↩