[Coco] [Color Computer] coco ethernet project

[afra at aurigae.demon.co.uk]

Quoting James Dessart <skwirl42 at gmail.com>:

> On 4/23/09, Kevin Zee <psycho at hughes.net> wrote:
>> If you can get Ethernet to work with a PIC then the memory should not be
>>  an issue. Getting it to work with a PIC is trivial.
>
> I don't know if a parallel ethernet chip has been done with a PIC, but
> I know it has with AVR chips. uIP has definitely been ported to them.

Yep, Microchip ENC28J60, I am using just a setup in my in-development  
network port tester for work. AVR Mega 644, ENC28J60 running avr-uip,  
plus some of my own non-ip packet detection code for detecting things  
like Cisco/Extreme descovery frames.

>> There is also a standalone ethernet controller from microchip that  
>> uses SPI, if I
>>  remember right. I have a development board for it, as a matter of fact.
>
> Sounds cool.

ENC28J60, available in DIP, so prety easy to prototype with, it's a  
3.3V chip but, the SPI and reset inputs are 5V tollerent, so should be  
reasonably easy to interface to a CoCo.

>>  I think the 8900 would be a better choice, though (which I have never
>>  messed with).
>
> An SPI ethernet controller might be a good choice, since there wont be
> much IO space taken up. You'd just have to set up some registers to
> hold the SPI data.

Well I know someone that has bit banged SPI to an MMC/SD card with a  
6522VIA on an Acorn Atom (6502 based machine @ 1MHz, also uses the  
6847 btw :). So that would probably be possible using a 6821PIA.

Also I know of another project that implemented a SPI interface in a  
Xilinx 9572 44 pin CPLD, this was designed to interface to a 6502,  
which as we know uses a similar bus architecture to the 68xx chips, so  
should be easy to adapt.

Cheers.

Phill.

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