When SALT goes bad While trying out my new CoCo SDC with my Color Computer 3, I found some strange issues.  Symptoms included garbage on the screen while turning on, garbage after hitting reset, computer not initializing with any text.  Any cartridge inserted would cause the system to not display any video. I also noticed something odd, the usual double click of the cassette relay when power was applied was missing.  All I heard was a single click, and pressing the reset button did not generate any clicking of the relay. I tried reseating the GIME, swapping out the memory card for a working 512k board, replacing the electrolytic capacitors over the entire board, and finally looking around for any anomalies that might explain why my Color Computer 3 was not working correctly. The basics troubleshooting I had done to this point had gotten me nowhere, I needed to get out the service manual and a digital meter to see what was actually going on.  My first stop was to make sure that

Photos: Cracking open the TRS-80 | CNET

I found this site interesting. They have cracked open a TRS-80 Color Computer 2 and have the pictures. This is a very recent posting, Feb 2008. Photos: Cracking open the TRS-80 | CNET

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: