Recent content by nauman

Love that you put a lot of work and heart into the community. Just hope they also pay you equally if it is officially done for them.

gotcha :) B1 wouldn’t have different pinout so you are pretty safe to try running a wire to another A20 spot and see what happens.

Have you seen this project? :) https://github.com/Board-Folk/NeoGeoAES-3.5/blob/main/NeoGeoAES3_5-Schematics.pdf I believe the pin is 115 and should map to A20 in that case.

The watchdog / reset circuit is a core part of the B1 ic. If the reset doesn't happen, it can point to a broken B1, and maybe reset is not the only part that is actually broken inside it. The screen you are seeing comes from the LSPC still producing a picture, but with random data from the RAM...

I am not 100% familiar with the MV1C board although the C3 would act as a "filter" for the battery power line which would indicate that most values would work without harm. Even without it, it would probably work fine. If i recall correctly, when the BIOS tries to set/read the time, it is...

C1/C2 are capacitors to stabilize the crystal and depending on which crystal you have it can be different values. 18pF or 22pF are valid starting points although removing the remaining C2 from the circuit and measure it would be the preferred way.

If I am not mistaken, some of the NEO-BUF chip on a MV1A are handling controller input, which previously was done by the NEO-C1 chip on other revisions. Since you ruled out external factors like controllers / jamma cables, it is highly likely that any of the NEO-BUF got broken since they are...

At a normal start up, the reset signal would be low for a short period of time and then keep it low until watchdog releases it. https://wiki.neogeodev.org/index.php?title=Reset If there are no click-of-death afterwards (the reset line i changing often), then the system assumes the code is...

I would agree with this one. If you are running the system with US region, the coin system is not shared between players and hence giving the effect you are describing. Since you are running Unibios, just change it to match your desire, which most likely is Europe.

Great job! Did you order it with "edge-connector" applied? Was always curious about what is actually ment more than a rounded edge. Maybe more flat pin surface as well? :)

If nothing else pops up as the obvious fix, I would personally try to remove as many via:s as possible and try running address and data line close (but not to close) to each other like the attached example. This would improve two aspects, one is that the ground plane would be more solid and...

Ooohhhh, NVM! Got fooled by the missing dot on the traces! My bad :)

So the CE can be traced to ground no problem, but the OE must only be traced to the U7 74LVC244 in your case. To me it looks like it is also traced to ground which makes it shorted and therefor always low/active. You can try bending the pin up (be careful though, those are small pins :p) and...

Great and interesting work! I believe there is a error in OE-pin since all memories cannot be active all the time. Attached a reference from a KOF 97 prog board. Edit: uploaded the whole prog-board pdf instead of a bad picture :)

There is a small delay in the BIOS between the X / Y select and the actual reading of the input pin. It takes into account that the SIT-board needs some time to adjust the trackball output, but it also assumes the signal to be continues. You can either just continue writing the output of the...