Famicom Disk System Bootlegs and Forgeries

Started by P, June 21, 2022, 01:59:29 pm

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June 21, 2022, 01:59:29 pm Last Edit: June 29, 2022, 12:52:24 pm by P
A continuation of the discussion in this thread.
Edit: Seems the original thread was deleted. Doesn't really matter, it was a thread about forgery of FDS obi, cases and rewriting services that bought up this subject.

One problem with Famicom Disk System disks is that they are fully writable, and ever since people discovered how to write over them there are no longer a way to guarantee that a disk is factory written unless it's sealed (and perhaps not even in that case).

Being able to rewrite them isn't really a bad thing in itself, they are magnetic and will eventually fall to data rot as they loose their magnetic orientation. Rewriting the disk with its original data is the only way to restore such a disk, given that the original data had been backed up before it went corrupt, not all versions of every FDS disk has been dumped however (that large Nintendo leak some time ago only contained the latest version of every game, as that was what Nintendo had archived).

If we ignore all the problems with seemingly perfect forgeries, there is still a reoccurring problem that disks written on one disk drive doesn't seem to be readable on other drives that otherwise can read factory written disks, so why is that?

One reason Nintendo chose the quickdisk technology for their Disk System was probably the very affordable price compared to conventional floppy disk drives at the time which were very pricey. But this cheaper price tag came with another price. Supposedly the quickdisk technology is much more error prone than more conventional forms of FDD technology because of the single-spiral track that the QD format uses, a screw pulls the head while the disk is spun by the motor (normal FDDs uses a stepper motor which are very reliable at making uniformly distanced steps).
This is a cheap and simple system, but is also more demanding as it requires that the drive that writes the disk is correctly aligned in the centre. Most people seems to just adjust it until games starts to work and then leave it like that. Even if it's a bit off centre it may read properly written disks, but if you write disks with a drive like that they may be too much off centre for another drive that is aligned too much off centre in the other direction.

And this is a common problem since virtually all stock drive belts have melted at this point, every working disk drive has had its belt replaced and is potentially incorrectly aligned. Then people write new disks with these drives which results in a disk that will work on about 50% of drives depending on in which direction they are off centre in.

Nintendo probably had a good way to make the factory calibration correctly but I'm not sure if that method is known. It probably involves those markings on the spindle and the plastic cogs which a lot of people ignore.


That was a great post. I knew about the problem of having drive A write a disk and drive B and C being unable to read it, but now I know why.

Knowing about disk rewriting and how easy it is, I've written off on ever knowing if the data is factory. To be fair, with the diskwriter kiosks from back in the day, a lot of factory data is long gone anyway.

I would say half my disks error code in the 20s. Part of me wants to write working data on there, the other half says this is part of FDS life, leave it as a relic of an era and to just use my FDSstick.  The calibration issue mapped out in P's post makes me want to stay towards the latter.

At least the ones I have that do work have save data that leans toward original. I was playing Murasame Castle over the weekend (why the hell did they put next to no healing in this game) and there were 3 Japanese names in the save slots which was neat to see. Then I deleted one and put my friend ClawX's name in the slot to start my own save. RIP video game history


Half of what I wrote in my post is just what others more technical people have told me and half of it is my own conclusions of the situation based on this knowledge.
I feel like this is a subject that is very hard to find good and accurate information about and should be discussed more often.

It's easy to tell if a disk has been in the Disk Writer, (if the current understanding is correct) the Disk Writer recorded the rewrite count in the header of the disk itself, and any disk that were sold as a pre-written disk would have the rewrite count as 0.

Disks rewritten in a basement will of course not have these fields updated correctly (and can technically have any numbers written here), but at least it makes it easy to tell if the game on a disk is a Disk Writer or pre-written version.

It's hard to tell if your disk drive is poorly aligned, the disks themselves are ones that have been rewritten on a poorly aligned drive or if there is some other problem with the disk. Error 20 is the most common error and basically seems to just mean that reading the disk didn't work as it should for some reason.

Heh I don't know if I would care as much about a previous owner's data as I do about the game itself. I usually just delete it to make it factory fresh again (though that's not always possible with Famicom Disk System disks). But I suppose we might not be saying that in another 50 years or so. When someone in the future discovers data from the '80s or so on a floppy or memory card it may be regarded a precious part of history, like a tiny window back to how the world was like when the game was new and the first owner had just beaten the game before eventually selling it to Bookoff or whatever.

Anyway, I think the main problem we have to solve is to learn how a disk drive is properly factory calibrated and teach it to people. EricJ's website has the best guide as far as I can tell, but I'm not sure how adequate it is.