Great!KaterKarli wrote:I did replace the 273 latch and the main processor is doing something , I got bus activity.
Does the main CPU also get reset? Is the watchdog triggering and/or operating at all?KaterKarli wrote:but after 1 second it resets the sound cpu.
The main CPU might not be able to complete initialization, therefore it is not yet lifing the RESET signal to the sub CPU. In this case it is probably normal that it doesn't want yet to poke into the sub CPU bus.KaterKarli wrote:The Sub cpu is ALWAYS Reset LOW Never high ... Seems very strange to me.
On Main CPU Schematic:
The 244 and 245 driver are all replaced -> no change
the pal has on the Dir Pin of the 245 activity but on the OE of 245 dead silence ....
what does this mean ?
I had a bootleg with initialization problems a while ago. The main CPU was running very awkwardly and getting reset by the watchdog after a second, before it had time to crash completely. My issue was IC27 (74LS32). Maybe that is the case with you as well, or maybe the data coming out of your program EPROMs is not good. Have you dumped the EPROMs already? Tried replacing the RAM?