Desperado
Veteran Member
- Joined
- Nov 25, 2017
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Pin 1 of E7 and E8
Pin 1 of E7 and E8
Pin 19 of E9 and E10.
i am desperate!!! i can't see any waveform signal in these pins!!!!!It is now probably worth looking at the data bus signals on pins 26 to 33 (inclusive) o the 6502 CPU. we are looking for 'clean' signals - and nothing like UD2 pin 9!
UD2 pin 3 to 17 ??They don’t look that strange. I am guessing the ‘strange line’ is when the data bus is not being driven and it is floating.
I am just seeing a ‘snapshot’ of what you are seeing.
OK, can you remove the NOP generator and complete the latter steps identified back in post #1,403.
Dave
Correct.
As the NOP generator cycles through all of the memory addresses - an opcode read (memory read) is performed and the result discarded in favour of replacing it with NOP/$EA.
This means we can observe the actual state of the data bus itself and check for any bus contention occurring as a result of incorrect address decoding etc.
Dave
Good morning, today it is a very hot day in MilanIs this using your logic probe or scope? Please use your scope.
We are looking for narrow low-going pulses.
Pin 4 with NO SIGNAL is also wrong.
Pin 17 would be good - this is selecting the ROM at $Fxxx.
I would also expect to see ‘blips’ of pulses on pins 1 and 9 also. All of the other pins should be HIGH.
Dave