#Snes9x bad checksum error fix code
#Snes9x bad checksum error fix plus

So the next step would perhaps be to logic-analyze the SA-1 pins to get an idea of what happens after the SNES system is powered on, which, given the existence of different SA-1 variants, would also have its own merits with regards to emulation accuracy / preservation.

#Snes9x bad checksum error fix code

Obviously, the patches do something that official ROMs don't, but comparing the code introduced by the patches with the code of official SA-1 ROMs may be like looking for a needle in a haystack, the cause may be timing-related et cetera. Indications are that officially released ROMs that make use of the SA-1 work with all SA-1 chips.

But what's more important is that the patches can be improved to work with all of them, so that one wouldn't have to worry about this anymore. It's inconvenient if one intends to build a conversion and fishes out a non-working exemplar. While sample size was small, a change in the package coinciding with a change in circuit design, in turn leading to some nuanced changes in behavior, would have been plausible.

#Snes9x bad checksum error fix plus

On the plus side all this soldering practice has really helped improve my soldering skills, which was one of my main aims of this project, so that's a win! But this has definitely got me very confused. The last thing I can try is swapping the RAM off the working Japanese version and seeing if that changes things, as maybe it's a faulty RAM chip. So the ROM chips are both working fine on the Japanese build, the SA-1 is working fine but both dot and chamfer behave the same, and the game runs fine with the original ROM chip of PGA European tour on it. Removed the RAM and inspected the pads, but everything looks fine. Put the ROM chip off the PAL version onto the Japanese version and this runs fine. Swapped the ROM for the working Japanese version of Gradius, and this had the exact same booting issue, stuck on the white boxes Passed this test as the game booted and ran fine Swapped the ROM for the original PGA ROM to confirm SA-1 was working OK. Same boot crash issue where it only shows the white boxes I replaced the SA-1 chip with a chamfered edge one. I have done quite a few bits to try and get the PAL version to work, but to no avail.