Mapper 30 is similar to Mapper 2 by design. It can help someone play ROM hacks that were never tested (and wouldn't work) on real boards which is a win for the person buying the product, but a purposeful choice against accuracy. And it's a valid reason! Commercial flashcarts (Powerpak/Everdrive) run on real hardware, but still value permissiveness to the extent that it's possible. For FCEUX in particular, bus conflicts may be one reason for the failure of header edited NES Maker ROMs working. Permissiveness is the opposite of accuracy. I would not discount things that do not run them as inaccurate by that test, only less permissive than things that do. The size/bus conflict parts mean that any emulator/hardware that rejects any NES Maker game with a swapped header totally has a valid reason for doing so. Any NES Maker game (including mapper 2 Troll Burner, I was surprised to find) is 512KB. Most important: The largest size for mapper 2 (as far as actual produced, licensed carts) is 256KB to my knowledge.
#HOW TO SET UP RETROLINK NES CONTROLLER ON FCEUX CODE#
NES Maker ROMs do not do this (although it's not hard to do so and there is commented out code to make that change). You have to write to a place with the same value in ROM as the bank you want to switch to guarantee that's what you'll get. (Since I believe it to be the self flashable board.) What this means is the bank you write is not necessarily the bank you get on UNROM/UOROM. UNROM/UOROM is subject to bus conflicts, NES Maker's mapper 30 is not. "implementation defined." On both, the lowest bits are which PRG bank, but Mapper 30 gets one more bit for it that's not "implementation defined". In Mapper 30, the highest bit is a mirroring select, the next two bits control which CHR bank. The byte written's format is slightly different. In mapper 30, write a byte to $8000-$FFFF to bank swap. In mapper 2/UNROM/UOROM, write a byte to $8000-$FFFF to bank swap.
There's a really short version at the bottom of the post. I haven't tested NES Classic Edition hakchi or Retropie versions.Ĭonsole/Emulator - Mapper30_test - Mapper02_test Real hardware tests were conducted using a Powerpak with Power Mappers and not rewired UNROM carts or available UNROM-512 carts. Here is a quick list of emulators/hardware that passed on doing a header swap only with no other bank adjustments. To change header info I simply used the iNES Header Checker and swapped mapper 30 for mapper 2, all other info was left the same. Using a powerpak cart and real hardware, it works with only a header change so any emulator that doesn't load and boot the rom with only a changed header I consider inaccurate and only use for quick debugging. A simple change of headers will work as I've been experimenting with which emulators fail with changed headers and which succeed. Truthfully you don't need to do any bank alterations for emulators. I've charted out the banks here and so long as 4.1.0 doesn't make major changes, the info should be accurate. I don't think anyone has really documented the process, but I've done a lot of personal research and experimenting during the days of the beta mapping out the banks and converting NESmaker games from mapper 30 to mapper 02 for porting over to other NES based platforms like the Playchoice 10 and Vs. FCEUX however will bawk at the change and throw up a gray screen but it's not an emulator known for it's hardware accuracy it's used more for it's easy to use debug tools which most I enjoy more then Mesen which is better for it's more robust debugger and memory watcher. The PowerPak will do this without issues which is what I use and Mesen. Many emulators and even real hardware will function just fine by simply swapping the iNES header from Mapper 30 to Mapper 2. One could take a standard UNROM game say for instance Castlevania and convert it to a NESmaker game with little effort aside from rudimentary electronics skills.
UNROM-512 assigned as iNES mapper30 is remarkably close to UNROM/Mapper 2, it only needs a couple more chips for the extra banks to function. Many have been well documented though, least enough to where emulators can mimic them in software. UxROM, that is UNROM and UOROM use discrete logic from common off the shelf parts while other memory managing chips were custom/proprietary chips and though some of them have been reverse engineered and duplicated for cart reproduction, many have not.
It's not nearly as easy as simply flipping a switch. When one says 'mapper' they're basically talking about the memory management hardware in the NES carts used to help map the program RAM and ROM and work around the NES' limitations.
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