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Double Dragon II: The Revenge for DOS from 1989 was distributed on two floppy disks, one of which contained the entire source code in a deleted archive file, in

Double Dragon II: The Revenge for DOS from 1989 was distributed on two floppy disks, one of which contained the entire source code in a deleted archive file, invisible from the DIR command but easily recoverable: https://tcrf.net/Double_Dragon_II:_The_Revenge_(DOS) https://tcrf.net/Double_Dragon_II:_The_Revenge_(DOS)

jpsouth 2y ago
This might be a silly question, but how does this even happen? I would have thought they’d finalise the game, get a ‘master’ of sorts and then send it to a mass production facility - how would the deleted archive end up on the master? Did they accidentally copy it over, then remove it before shipping? Edit: definitely should have read the comments here before adding my own!
- MenhirMike 2y ago
  Yeah, Duplication Houses usually duplicate the disk sector-by-sector, instead of on a file system level. (This makes a lot of sense, because it allowed the disk to contain any file system). But that also means that data that was still on the physical sectors of the disk got copied as well, regardless of whether the file system on the disk was still referencing that data.
  - Rinzler89 2y ago
    >Yeah, Duplication Houses usually duplicate the disk sector-by-sector I think they went even deeper. From the vintage computing nerds I saw on YouTuber, I think the duplication houses were replicating the raw magnetic flux off the disks as-is, since game studios were implementing some crafty low level anti-piracy measures on the golden disks to ensure that if you did sector level copies at home you wouldn't be able to run the game.
    - MenhirMike 2y ago
      That makes sense, I do remember some Commodore 64 games that even a Nibbler couldn't properly duplicate, and how some people modified their 1541 drives to have a different timing to work with some of that stuff.
    - EvanAnderson 2y ago
      I wonder if anybody ever made an analog flux reversal-level disk copier out of consumer floppy drives. I'm not an electronics person but it sounds like it would something like a "dubbing" tape deck. Provided the reading and writing drives' spindle motors and heads were synchronized (which, presumably, could be done with an encoder on the reading drive) I would think it would be a fairly simple device. All the analog circuitry for reading and writing would be in an off-the-shelf floppy drive.
      - Rinzler89 2y ago
        The hardware you're talking about you can buy today. It's used by retro computing geeks working in SW preservation. Pretty sure it also existed back in the day. The point wasn't to make copying impossible, it was to make it impossible for home users.
        TacticalCoder 2y ago
        Hence the cracking scene: home users would get pirated version of the games, with the copy protection removed from the code. P.S: if I'm not mistaken in some cases original, legit, disks were physically damaged on purpose (for example with a hole being physically punched at a precise location) and then the copy-protection would try to write something at that spot and re-read it. If the write/re-read succeeded, they knew the floppy was good and hence they knew it couldn't be an original disk.
        deaddodo 2y ago
        That doesn't make sense, no? Most of these disks had their read-write tab blocked and so the floppy drive would just operate in read-only mode anyways.
        TacticalCoder 2y ago
        > That doesn't make sense, no? Most of these disks had their read-write tab blocked and so the floppy drive would just operate in read-only mode anyways. You are right that that doesn't make sense so I may be remembering incorrectly. I'm nearly sure the disk physically had holes, on purpose, though. So maybe the copy-protection was simply trying a regular read, expecting it to fail... And if it didn't throw an error, then it'd know it was a copy.
    - deaddodo 2y ago
      In some cases this would be a sort of DRM, sure. But it certainly wasn't universal. Most smaller-midsize distribution houses just used something like this: https://www.awp1.com/st.html https://www.awp1.com/st.html Or, if they were very small, they would just use multiple smaller scale devices that could do 2-4 copies at a time, like this: https://pbs.twimg.com/media/Dgr_J-NUEAAHZ0I?format=jpg&name=large https://pbs.twimg.com/media/Dgr_J-NUEAAHZ0I?format=jpg&name=... Some of the expensive ones of these could do magnetic signal copying, but most just did sector-by-sector. At least, that's my understanding. Bit before my time.
    - chriscjcj 2y ago
      The TRS-80 Color Computer's "Sands of Egypt" employed this very strategy. They planted a glitch on a certain sector of the disk. If memory serves, you could copy the disk, but doing so would "fix the glitch." The game checked for the presence of the glitch on the disk and wouldn't run without it. https://www.cocopedia.com/wiki/index.php/Sands_of_Egypt https://www.cocopedia.com/wiki/index.php/Sands_of_Egypt
      - ghusbands 2y ago
        That was such a common technique that it's odd to talk about just one game in particular doing it.
  - jpsouth 2y ago
    Thanks for the explanation, that makes it much clearer.
  - esafak 2y ago
    This reminds me of the low-level disk cloning utilities crackers used to circumvent copy protection, and how they competed to build faster ones.
benjaminpv 2y ago
I always liked the cases where people have broken open ROMs only to find that the compilation process stuffed a bunch of directory and filenames in the silicon. It's funny to think that in a time when literally every byte cost money there's a fair number of carts that have people's FAT entries burned into them. https://forums.nesdev.org/viewtopic.php?t=17324 https://forums.nesdev.org/viewtopic.php?t=17324
- toast0 2y ago
  Well... every byte costs money, but it's really quantized. If your game doesn't fit in a power of 2, you have to pay more to get the bigger one (and maybe even a lot more if you also need to include a mapper, plus using a mapper means you've got to adjust your code and what not). But if you're using 75% of your quantized space, you don't need to be that picky.
  - bryanlarsen 2y ago
    The last time I built a ROM (in the 90's) it had 7 free bytes of space. That was not a coincidence. It was larger than that and then optimized until it hit a nice power of two and then I stopped optimizing.
  - repiret 2y ago
    It is quantized, but not necessarily to a power of two. RAM and flash sizes of 3x2^n are common even in contemporary microcontrollers, and it’s clearly possible to use fewer R chips then your bus decoder supports in the less integrated computers of yore. And once you have a project with a fixed amount of ROM, either because the hardware is at a point in its life cycle where you can’t change it, or it’s third-party hardware and you have to use what you get, or because you’re already at your BoM budget, then your software will behave like an ideal gas - it will expand to fill the available ROM. This happens because until you run out of ROM, you will write your software in whatever way is easiest to get your job done. But then once you run out of ROM, you will go back and look for something that you can make smaller. Then you can add a few more features or whatever, until you run out of space again. This process will repeat until you’re done, but your ROM will always be nearly full.
hypertexthero 2y ago
This was the second multiplayer game I ever played, when visiting a friend’s house, on his dad’s computer. The first, on the same computer, was a DOS version of Spacewar! If I remember right, we’d reach a boss and the game would freeze, so we never managed to beat Double Dragon II. Good memories.

jpsouth 2y ago

This might be a silly question, but how does this even happen? I would have thought they’d finalise the game, get a ‘master’ of sorts and then send it to a mass production facility - how would the deleted archive end up on the master? Did they accidentally copy it over, then remove it before shipping? Edit: definitely should have read the comments here before adding my own!

MenhirMike 2y ago
Yeah, Duplication Houses usually duplicate the disk sector-by-sector, instead of on a file system level. (This makes a lot of sense, because it allowed the disk to contain any file system). But that also means that data that was still on the physical sectors of the disk got copied as well, regardless of whether the file system on the disk was still referencing that data.
- Rinzler89 2y ago
  >Yeah, Duplication Houses usually duplicate the disk sector-by-sector I think they went even deeper. From the vintage computing nerds I saw on YouTuber, I think the duplication houses were replicating the raw magnetic flux off the disks as-is, since game studios were implementing some crafty low level anti-piracy measures on the golden disks to ensure that if you did sector level copies at home you wouldn't be able to run the game.
  - MenhirMike 2y ago
    That makes sense, I do remember some Commodore 64 games that even a Nibbler couldn't properly duplicate, and how some people modified their 1541 drives to have a different timing to work with some of that stuff.
  - EvanAnderson 2y ago
    I wonder if anybody ever made an analog flux reversal-level disk copier out of consumer floppy drives. I'm not an electronics person but it sounds like it would something like a "dubbing" tape deck. Provided the reading and writing drives' spindle motors and heads were synchronized (which, presumably, could be done with an encoder on the reading drive) I would think it would be a fairly simple device. All the analog circuitry for reading and writing would be in an off-the-shelf floppy drive.
    - Rinzler89 2y ago
      The hardware you're talking about you can buy today. It's used by retro computing geeks working in SW preservation. Pretty sure it also existed back in the day. The point wasn't to make copying impossible, it was to make it impossible for home users.
      - TacticalCoder 2y ago
        Hence the cracking scene: home users would get pirated version of the games, with the copy protection removed from the code. P.S: if I'm not mistaken in some cases original, legit, disks were physically damaged on purpose (for example with a hole being physically punched at a precise location) and then the copy-protection would try to write something at that spot and re-read it. If the write/re-read succeeded, they knew the floppy was good and hence they knew it couldn't be an original disk.
        deaddodo 2y ago
        That doesn't make sense, no? Most of these disks had their read-write tab blocked and so the floppy drive would just operate in read-only mode anyways.
        TacticalCoder 2y ago
        > That doesn't make sense, no? Most of these disks had their read-write tab blocked and so the floppy drive would just operate in read-only mode anyways. You are right that that doesn't make sense so I may be remembering incorrectly. I'm nearly sure the disk physically had holes, on purpose, though. So maybe the copy-protection was simply trying a regular read, expecting it to fail... And if it didn't throw an error, then it'd know it was a copy.
  - deaddodo 2y ago
    In some cases this would be a sort of DRM, sure. But it certainly wasn't universal. Most smaller-midsize distribution houses just used something like this: https://www.awp1.com/st.html https://www.awp1.com/st.html Or, if they were very small, they would just use multiple smaller scale devices that could do 2-4 copies at a time, like this: https://pbs.twimg.com/media/Dgr_J-NUEAAHZ0I?format=jpg&name=large https://pbs.twimg.com/media/Dgr_J-NUEAAHZ0I?format=jpg&name=... Some of the expensive ones of these could do magnetic signal copying, but most just did sector-by-sector. At least, that's my understanding. Bit before my time.
  - chriscjcj 2y ago
    The TRS-80 Color Computer's "Sands of Egypt" employed this very strategy. They planted a glitch on a certain sector of the disk. If memory serves, you could copy the disk, but doing so would "fix the glitch." The game checked for the presence of the glitch on the disk and wouldn't run without it. https://www.cocopedia.com/wiki/index.php/Sands_of_Egypt https://www.cocopedia.com/wiki/index.php/Sands_of_Egypt
    - ghusbands 2y ago
      That was such a common technique that it's odd to talk about just one game in particular doing it.
- jpsouth 2y ago
  Thanks for the explanation, that makes it much clearer.
- esafak 2y ago
  This reminds me of the low-level disk cloning utilities crackers used to circumvent copy protection, and how they competed to build faster ones.

benjaminpv 2y ago

I always liked the cases where people have broken open ROMs only to find that the compilation process stuffed a bunch of directory and filenames in the silicon. It's funny to think that in a time when literally every byte cost money there's a fair number of carts that have people's FAT entries burned into them. https://forums.nesdev.org/viewtopic.php?t=17324 https://forums.nesdev.org/viewtopic.php?t=17324

toast0 2y ago
Well... every byte costs money, but it's really quantized. If your game doesn't fit in a power of 2, you have to pay more to get the bigger one (and maybe even a lot more if you also need to include a mapper, plus using a mapper means you've got to adjust your code and what not). But if you're using 75% of your quantized space, you don't need to be that picky.
- bryanlarsen 2y ago
  The last time I built a ROM (in the 90's) it had 7 free bytes of space. That was not a coincidence. It was larger than that and then optimized until it hit a nice power of two and then I stopped optimizing.
- repiret 2y ago
  It is quantized, but not necessarily to a power of two. RAM and flash sizes of 3x2^n are common even in contemporary microcontrollers, and it’s clearly possible to use fewer R chips then your bus decoder supports in the less integrated computers of yore. And once you have a project with a fixed amount of ROM, either because the hardware is at a point in its life cycle where you can’t change it, or it’s third-party hardware and you have to use what you get, or because you’re already at your BoM budget, then your software will behave like an ideal gas - it will expand to fill the available ROM. This happens because until you run out of ROM, you will write your software in whatever way is easiest to get your job done. But then once you run out of ROM, you will go back and look for something that you can make smaller. Then you can add a few more features or whatever, until you run out of space again. This process will repeat until you’re done, but your ROM will always be nearly full.

hypertexthero 2y ago

This was the second multiplayer game I ever played, when visiting a friend’s house, on his dad’s computer. The first, on the same computer, was a DOS version of Spacewar! If I remember right, we’d reach a boss and the game would freeze, so we never managed to beat Double Dragon II. Good memories.