Trying to save with MMC1 and FCEUX

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frantik
Posts: 332
Joined: Tue Mar 03, 2009 3:56 pm

Trying to save with MMC1 and FCEUX

Post by frantik » Wed Sep 02, 2020 9:14 pm

I have an MCC1 ROM with (I think) the battery backed RAM bit in the iNES header set (1A = 11010), same as Zelda 2 which is saving correctly

I write to $6000-$7000. I can see the values in memory when I inspect it

When setting the PRG bank number, I write to $E000 the 4th (high) bit is not set as specified in the wiki

But FCEUX does not save a .sav file and the memory contents are lost when I close the rom or even just cycle the power

I feel like I'm missing something simple

edit also not working in other emulators so doesnt seem to be FCEUX specific

lidnariq
Posts: 9655
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: Trying to save with MMC1 and FCEUX

Post by lidnariq » Wed Sep 02, 2020 10:18 pm

Maybe try Mesen's or Nintendulator's header editor?

Also, SNROM has two separate PRG RAM enables, although FCEUX doesn't pay attention to the one at $A000.

It looks like FCEUX will not correctly handle four-screen MMC1 games - you'll have to set the mapper to 171 instead.

frantik
Posts: 332
Joined: Tue Mar 03, 2009 3:56 pm

Re: Trying to save with MMC1 and FCEUX

Post by frantik » Thu Sep 03, 2020 1:42 am

lidnariq wrote:
Wed Sep 02, 2020 10:18 pm
Maybe try Mesen's or Nintendulator's header editor?
thanks I used Nintendolators editor and realized I was looking at the wrong byte in the header :roll: :roll: :roll: I knew it was something simple

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rainwarrior
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Re: Trying to save with MMC1 and FCEUX

Post by rainwarrior » Thu Sep 03, 2020 2:39 pm

If FCEUX is your main emulator, might be worth pointing out that it also has an iNES header editor at this point. It's in the debug menu. (It's not in the 2.2.3 official release, but the interim build here has it.)

frantik
Posts: 332
Joined: Tue Mar 03, 2009 3:56 pm

Re: Trying to save with MMC1 and FCEUX

Post by frantik » Sun Sep 06, 2020 2:45 pm

rainwarrior wrote:
Thu Sep 03, 2020 2:39 pm
If FCEUX is your main emulator, might be worth pointing out that it also has an iNES header editor at this point. It's in the debug menu. (It's not in the 2.2.3 official release, but the interim build here has it.)
thanks I'll check it out.. also just subbed to your you tube channel last night, I recognized that avatar :mrgreen:

frantik
Posts: 332
Joined: Tue Mar 03, 2009 3:56 pm

Re: Trying to save with MMC1 and FCEUX

Post by frantik » Wed Sep 09, 2020 6:31 am

got dem save games going.. aww yissss even added a nice lil menu interface ala super mario world.. some of the most complex 6502 code I've written so far, starting to pretty comfortable with it as a language

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