[Coco] Serial to Ethernet

[Allen Huffman]

> On Feb 10, 2015, at 1:13 PM, William Mikrut <wmikrut72 at gmail.com> wrote:
> 
> I would think it could be done as a plug in cartridge.   Wired properly,
> the Coco can communicate with a wired cable.

Yes, yes. Initially my CoCo Ethernet box is external, and is basically a customized iModem type device (RS232 to Ethernet) you plug in to an RS232 port. With different software, it could plug to the bitbanger and be a DriveWire ethernet interface.

Ultimately, I want to get it mapped in to the I/O space as a cartridge to get the speed up. This would require completely different DriveWire drivers though, but I see two others in the repository so this is something that has already been done.

> You would then need a light port of TCP/IP in the system... likely 16k
> would be sufficient to run the stack.

In the case of the previous RS232/Ethernet adapter, the WIZNET chips do the stack and have a small buffer. The 5100 can handle four socket connections at a time, and does TCP and UDP. The heavy lifting of the transport protocol is done in the chip, so only the high level protocol on top (http, ftp, imap, etc.) would have to be done on the CoCo. I haven't looked, but I expect much of the work done for the DriveWire "telnet", "httpd", etc. commands could be leveraged.

> You could likely use a chip and integrate it into the cart IO.
> 
> It would be cool... not sure why nobody has done this yet.

This was going to be the iChip stuff added to the Cloud-9 Superboard about ten years back. At the time, I was incredibly excited about this, but as technology marched on, much of what we could have done then (web) is no longer practical (html5, javascript, flash, java, etc.). BUT, there was an external iModem the iChip company sold which was RS232 on one end, and Ethernet on the other. It was about $250, if I recall and was meant to be an easy way to evaluate their iChip. I was in touch with them for awhile on pricing and such to try to bring out a box back then, but today, with Arduino and such, it can all be done with custom software at a fraction of the iModem price back then.

So I think it was mostly price, back then.

		-- A