06 Jun 2018 @ 7:46 PM 

Flash Memory, like anything, is no stranger to illegitimate products. You can find 2TB Flash drives on eBay that are 40 bucks, for example. These claim to be 2TB, show up as 2TB- but, attempting to write data beyond a much smaller size, and the Flash data is corrupted because it actually writes to an earlier location on the drive. My first experience with this was actually with my younger brother’s Gamecube system; when he got it, he also got two "16MB" Memory cards (16 megabit, so 2 Megabytes) However, they would rather frequently corrupt data. I suspect, looking back, it was much the same mechanism- the Memory card was "reporting" as larger than it was and writing beyond the end was corrupting the information on it.

This brings me to today. You can still find cheap Memory cards for those systems which claim sizes such as 128MB. even at the "real" 128 Megabits size that it is, that’s still 16MB which is quite substantial. I’ve recently done some experiments with 4 cheap "128MB" Gamecube Memory Cards that I picked up. Some of the results are quite interesting.

First, I should note that my "main" memory cards for the system are similar cheap cards I picked up online 12 years ago or thereabouts. one is a black card that simply says "Wii/NGC 128 MEGA" on it, the other is a KMD Brand 128MB. The cheap ones I picked up recently have the same case as the KMD and, internally, look much the same, though they feel cheaper; They are branded "HDE". Now, for the ones I have, I’m fairly sure they are legitimate, but not 100%- the Flash chips inside are 128 Megabit and one is even 256Megabit. (Of course this means "128 Mega" and "128 MB" actually means 16MB and 128 Megabits, but whatever).

Since the 4 cards were blank, I decided to do a bit of experimenting with a little program called GCMM, or Gamecube Memory Manager. This is a piece of homebrew that allows you to pretty much do whatever you want with the data on memory cards, including making backups to an SD Card, restoring from an SD Card, copying any file between memory cards, etc. The first simple test is easy- just do a backup and a restore. it shouldn’t matter too much that the card is blank. I backed up the new card no problem. However, when I tried to restore it- it gives a write error at block 1024. This is right at the halfway point. No matter what I couldn’t get passed that point for any of the "new" cards. This indicates to me that the card(s) are actually 8MB cards, with approximately 1024 blocks of storage. What a weird "counterfeit" approach. 8MB is already a rather substantial amount of space, why "ruin" the device by having it report the wrong size and allow data corruption? I found that I could cause raw restores to succeed if I was able to take the card out during the restore process right before it got to 1024.

This discovery is consistent with what I understand of counterfeit flash- the controller will basically write to earlier areas of the memory when instructed to read beyond the "real" size, and will usually overwrite, say, file system structures, needing it to be formatted. Interestingly, If I rip it out before it get’s there, everything backed up up to that point is intact. Something else interesting I found was by looking inside the raw dump I originally created on one of the "new" cards. I found some very interesting data in the raw image. the File system itself was clean but that data remains in the memory, and was still there for viewing. I could see that Wrestlemania 2002 was probably used for testing the card at some point, as there was "w_mania2002" in the raw data, as well as a number of other tidbits that referenced wrestler’s that appeared in that game. What I found much more interesting, however, were a number of other strings: "V402021 2010-06-08" suggests a date that the card might have been manufactured. "Linux-"… Now this is interesting! Linux was involved in some way? This wouldn’t be surprising if it was constructed with some sort of embedded system, however it doesn’t make a lot of sense that this would appear on the memory card data itself. Similarly, I found various configuration files:


Due to a lot of network information, WLAN IDs, etc. my suspicion is that these flash chips are not actually new, but were taken from some sort of networking device, such as a router or switch. This is supported because googling a few of the configuration settings seems to always lead me to some sort of Chinese ADSL Provider, so I suspect perhaps these Flash chips were re-used from old networking equipment. That, in itself, does add another concern to these Memory Cards- if they were used before they found themselves in these Memory Cards- how much were they used? And how? Were they used to contain the firmware, for example? or were they used to hold a small file system for the networking device?

Overall, for something so seemingly mundane, I found this ti be a very interesting distraction and perhaps this information could prove useful or at least interesting to others.

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Posted By: BC_Programming
Last Edit: 06 Jun 2018 @ 07:46 PM

Categories: Programming


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