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 News.com
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
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 :)
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