nesdev.org

Ok, now I have cut off A0 as well and made some measurements.
The results were only slightly different than before, A1 still showed very different values compared to A0.

@lidnariq: we have thought about that but unfortunately the logic screws up at the time when it drops, but after that the logic behaves correctly. I guess that makes it a lot more difficult. @l_oliveira: by 'completely disconnected', do you mean like I did with A1 (i.e. cut off)? In that case I have...

Tried pull-up, still same result. When you ran without a cartridge connected, did you add some resistors to drive the data bus? no. Then my friend decided to just cut A1 off (in a way that is easy to reconnect ;)) to see if it still behaved the same way, and it did, which means the cpu is damaged (a...

We have only tested with Boulder Dash and no cartridge. Both give the same result on A1.
And no, I do unfortunately not have any programmable cartridges.

Regarding bus conflict, are there any other parts than the cpu that can put addresses on the bus?

So finally we have made some tests with oscilloscope! I'll report our findings so far: CLK is indeed 26.6 MHz M2 is 1.667 MHz (close enough i guess) The rest was a bit more difficult to get consistent behaviour on, probably due to bad connection sometimes. But most of the time all of the address pin...

I fired it up once more and this time it was blinking. Which must mean that the CIC is ok i guess. I made it stop blinking and then did some tests with a voltmeter. Vcc showed a solid 5.00V so that's fine. /RST was 4.99-5.00 /NMI and /IRQ showed 4.94V. (could this be interpreted as they are triggere...

Ok, a little update. I realized I could just borrow a connector from one of my other NESs (I know, pretty obvious, should have thought of that from the start). So I did just that and started it up to see if what he told me was correct. And it was, kind of. But it wasn't white but rather gray. I comp...

Thank you! I'll check it out as soon as I can and let you know what I find out.
Too bad I don't have the cartridge connector. Guess I have to attach some cables with tape or something...

I have access to multimeter and oscilloscope but unfortunately no logic analyzer. Though I'm considering making my own cheap one with a PIC if that's not too hard.

A friend of mine has a NES that he managed to damage through some experiments. Now I would like to find out what part of it is damaged and fix it if it's easy to replace or otherwise at least save the working parts. So I wonder if anyone knows of any good ways to approach this problem, or maybe some...

some docs call them SKB and SKW (SKip Byte/Word).

ah! thanks^^

What's an effective read?

hmm...
As I've understood it, the read occurs at the end of the fourth cc of lda $2002, that must be on the 12th ppu cc (i guess). then it must be as I said in the previous post. Is that correct?
(sorry if my questions are silly, I just need to get things clear)

Hmm this is complicated.
So the only case when this happens is when lda $2002 starts on ppucycle 329 of line 240? or do I get it all wrong?