Homebrew NMM memory card emulation technical details?

Joined
May 1, 2015
Messages
12
Trophies
0
Age
33
XP
81
Country
I recently dusted off my old Wii, and remembered how many compatibility issues there are with No More Memory.

I was wondering, did the people who developed this leave behind any documents on how it was made or why certain games couldn't work with it? This out of technical curiosity than anything else, I don't expect it to help me to get things more compatible.
 

Cyan

GBATemp's lurking knight
Former Staff
Joined
Oct 27, 2002
Messages
23,719
Trophies
4
Age
44
Location
Engine room, learning
XP
15,430
Country
France
not technical info, but this is a quick explanation how it's working :

a game can store in the memory card different files or data binary, which are then pack together to form a single savegame package. this "package" can be selected in the memory card management as single data to copy/move/delete which are usually extracted and shared as .gci file using homebrew and emulators.

usually, emulators are emulating the full memory card binary with all the games, not the individual game binary (gci), nor the individual files stored in the gci "package".

NMM is not emulating the memory card but redirecting the individual files accessed by the game inside the savegame "package" (sorry, not the best word I found) to SD or USB.
the files have a filename, and data (like on a computer, you save your data in a file, and give a filename to that file).

The issue is that some games are not using FAT32 compatible characters for the filename, resulting in a different/converted filename. the game send the command to save using a specific filename, but NMM use a different filename due to FAT32 limitation. the file is saved and the game gives you "game saved successfully". When the game try to load, the expected filename can't be found and loading fails.


Another issue is with Mario Kart double dash, it seems that this game is saving the ghost data without providing a filename, and FAT32 require a filename so the beginning of the binary data is used as filename.
as a result, the data inside the file is incomplete. and also some characters used in the filename are incompatible with FAT32 because it's raw binary values and not compatible ASCII.



This is only some explanation. If you really want the technical details you should check DM/DML sources.
 

You may also like...

General chit-chat
Help Users
  • DinohScene @ DinohScene:
    do not listen to Veho, this man is clearly on drugs and wants you to eat pixels
    +1
  • M4x1mumReZ @ M4x1mumReZ:
    @DinohScene, Judging by the looks of things, yes.
  • Veho @ Veho:
    I don't deny that I'm on drugs.
    +1
  • M4x1mumReZ @ M4x1mumReZ:
    You honest about that? :creep:
  • M4x1mumReZ @ M4x1mumReZ:
    Someone on drugs would be holding a knife.
  • DinohScene @ DinohScene:
    no, I'm just holding a lighter
    +1
  • DinohScene @ DinohScene:
    trust me, I'm green
    +1
  • M4x1mumReZ @ M4x1mumReZ:
    I can see that you are.
  • Veho @ Veho:
    It's not easy being green.
    +1
  • Veho @ Veho:
    I came across yet another one of those "gaming on a $2 laptop" videos and I'm irked, again.
    +1
  • Veho @ Veho:
    This time it's a "budget phone" that costs $99... on a Cyber Monday sale... if you sign a two year contract with the provider... only in America. It's $600 everywhere else.
    +1
  • M4x1mumReZ @ M4x1mumReZ:
    Well, can't you just select 'Don't recommend channel' so that YT wouldn't keep recommending them?
  • Veho @ Veho:
    Because it's not just one channel doing it.
    +1
  • M4x1mumReZ @ M4x1mumReZ:
    It could be just YT in general.
  • Veho @ Veho:
    It's like wack-a-mole, you ignore
    one video and two more pop up.
    +1
  • M4x1mumReZ @ M4x1mumReZ:
    That happens to me A LOT
  • M4x1mumReZ @ M4x1mumReZ:
    Don't know why that is, but it's really annoying
  • M4x1mumReZ @ M4x1mumReZ:
    Had to unsubscribe to some channels, but they keep coming back
  • M4x1mumReZ @ M4x1mumReZ:
    So I do feel your pain :(
  • M4x1mumReZ @ M4x1mumReZ:
    The site went down it seems.
  • M4x1mumReZ @ M4x1mumReZ:
    Been getting unexpected database errors and then BOOM! Cloudfare went down.
  • Sonic Angel Knight @ Sonic Angel Knight:
    Who gave pac-man arms and legs? :blink:
  • M4x1mumReZ @ M4x1mumReZ:
    @Sonic Angel Knight, I don't get what you mean?
    Veho @ Veho: https://i.imgur.com/CSv9gmZ.mp4