Wanted Z80 In Circuit Emulator for Loan/Rent/Buy

Just a general maybe way off the wall comment. I have done this several times, and hand wired lots of z80s. In every case where its a almost run, it is power. Have you put a scope on vcc and see that its rock solid? You describe a random case it fails at different points, this has to be either power to cpu, or buffers and eproms not presenting the cpu with valid data. There is no other cause, and a emulator wont help you find it. This is hardware, look at, with 2 probes the buffered I/O on each bit (in, signal, out signal). Brute force replace any buffer drivers. Who else is on the same wire, remove any shared bussed devices, I hope they are sockets. The problem that it is chip failures is almost zero. It is power, a bad decouple cap somewhere, like when all address lines roll and the buffer chip pulls a slug, sagging the rest down. Look at all address and data lines on the scope, should be a clean cat eye with never a trace in the middle or floating. This is fun stuff, enjoy. Randy _________________________________________________________________ Windows Live?: Discover 10 secrets about the new Windows Live. http://windowslive.com/connect/post/jamiethomson.spaces.live.com-Blog-cns!5…