Many years ago I found the Atari 8-bit Ethernet Project (https://www.atari8ethernet.com/index.html) and wanted to make one of those cards. Unfortunately, the board use by it, IP Dragon II, is not sold anymore, so that was a dead end.
A few months ago I found the CS/A65 computer project by Andre Fachat, and its ethernet board (http://www.6502.org/users/andre/csa/etholi/index.html) that is somewhat similar (it uses an Olimex CS8900A-H board that it is 3.3V instead of 5V). So, I worked on a hybrid between them:
And it works! (Of course it is messy; it is just for development)
I'm only having a problem that, I think, it is related to the TCP stack (connecting to the webserver running on the Atari works fine if the client is wired, but the server gets on a weird state if the client is wireless). So I'm working on that now.
Just wanted to mention it... I'm very proud of myself.
Andres.

