Showing posts from 2005

More Ethernet Project Details

The current plan is to use a 3Com 3c509B ISA Ethernet card with the hardware that I plan to build and finally give the Color Computer Ethernet capabilities. One advantage of the 509B card is that is has off-loading capabilities in hardware for checksums. The 6809 in the CoCo can use all the help it can get! The other thing about this card is you can purchase them cheap from eBay. At least a year ago you still could... One site that I have found has some example drivers click here . For a detailed copy of the 3Com 3c509B hardware (zipped PDF) click here . Finally, this site has an IP Stack for use with microcontrollers.

Still no further Ethernet project progress

I have at least been adding internet links of interest :) check some of them out if you are looking for something new!

Internet Access Broke - Again

I know this has nothing to do with my project here, but I need to vent. Looks like my previous internet provider is long gone. They are no longer on the internet and I cannot dial in to my account. So rather than work on my project this Thursday and Friday I had to search for internet access (128K ISDN). Luckly I found and was able to get setup again with 128k ISDN service today, so it's back to business as usual.

Busy, Busy, Busy

Too much going on here lately. No progress to report, but I would rather report no progress rather then have no posts at all :)

Proposed Ethernet Board Layout

Here is sample of how the board will be layed out:

Design notes

Use a frequency of 4Mhz for the SPI bus. This will allow the Mega8 Atmel AVR chip to communicate over the same SPI bus as the MMC/SD cards will. Have a way to disconnect the SPI pins from the programmable logic chip so that in system programming of the Mega8 part can occur. Use a two byte 'window' for the ISA bus port. This will allow for 6809 assembly instructions such as LDD and STD to work where two bytes can be read/written faster. Have two bytes to determine the ISA address we are going to address. This will allow access to locations on the ISA bus from $0-$FFFF. Could add extra pins for greater address space if necessary.

WinCupl download and install

Installed and configured latest version of WinCupl from Atmel web site (version 5.30.4). For this project I am going to use the same CPLD part (Atmel ATF1508AS 84 pin PLCC 20ns part). According to the WinCupl fitter tool there are 50 percent of the I/O pins still available and only 20 percent of the internal logic is being used. This should allow for the ISA bus logic to be included in the same part. Here is my latest CPLD code for this project. The link is here . This code does not yet have any ISA bus logic added at this point :)


Worked further on CPLD pinout for ISA bus to COCO bus.

Start of Ethernet Project

Started an online record of my work to bring ethernet to the Color Computer 3 using OS-9 and my custom hardware.