GARTHWILSON wrote:
The WDC processor has bus-enable (BE) on pin 36 which needs to be high. Does your board pull it down? Pin 36 was NC on previous 65c02's. The WDC processor has a very weak internal pull-up on 36, so weak that contamination on the board could be pulling it down.
Hello,
thank you so much, you solved my problem. I tried to repair a vintage chess computer (from 1984) running at 3.7MHz, and its processor was definitely dead; when I replaced it with another old 65C02 the computer worked. Since I needed this replacement processor for another computer I bought some new WDC65C02.
Pin 36 of the 65C02 was not connected on the board. I soldered a pull-up resistor between VDD and BE, and now it works.
Thanks again to all who replied to my post.
Thomas.