nesdev.org

This forum is pretty quiet recently, so I though I would share something with you.

My flash cartridge had a very interesting bug, the CPLD chip was too fast! It would cause graphics corruption in certain games like Donkey Kong Country, and if I turned on the 'turbo bits' to speed up the chip it wouldn't work at all.

My theory is the different logic level (its a 3.3v part thats 5v tolerant) and faster speed made it turn off the bus buffer and address decoder before the graphics chip was actually finished reading, like a hold time violation.

I fixed the problem 100% by soldering a 100pf cap from the cart's CEn to GND. I have heard of a similar problem with the PowerPak, so I wonder if this could help with that.

Known problem on nes. Was fixed on nes by using resistors on the data/adress lines.

I wonder if the cap would work for the powerpak

That sounds way better then cutting 8 traces and soldering resistors over them

Ya plus a delayed ce line should do the exact same thing....
Maybe someone should try?

With the EPROM emulator I use (it's an old one from 1993), there are times where there would be one or two glitched sprites when using sprite-DMA. Adding series resistors to the data bus fixed that also.