Not my expertize, but was it not for connecting digital tape recorders? It gave something like 56 channels at 48kHz. Of course, both ends of the cable has to follow MADI. Well, to think about it, the cable as well.

Why are you asking? And what about doing a search on google for "madi protocol"?

Gunnar

Multichannel Digital Audio Interface

to connect digital equipment together.

Single RG58 wire or fibreoptics are possible. It depends on the length.

You can transmitt 64 channels with 44.1/48 kHz in one direction or 32 in both directions.
There are different implementations from different manufacturers.

RME has designed and built a PC-Card with ASIO drivers and Totalmix. Very interesting.
And Euphonix, Stagetech and Studer are still using the protocol in their digital solutions.

Some links:

http://www.aes.org/standards/b_pub/aes-10id-1995.pdf
http://www.aes.org/standards/b_pub/aes10-2003.pdf