Copy Protection on AGI DOS Disk Games

[Great Hierophant]

Apparently, when Sierra made their AGI games installable and runable with DOS, they still expected you to use the floppy disks.  The first disk was a key disk, and while you could backup the other disks all you wanted, the original first disk had to be in the drive in order for the game to work.  If it wasn't, the game would ask for it and refuse to start until it was. 

Sierra put a bad track on the disk, which the encrypted .com executable checked to make sure the disk in the drive had a bad track.  Unfortunately, DOS will not copy bad tracks, so to duplicate the bad track, you would need a program like CopyIIPC.  I have found an archive of many, many disk dumps and all the dumps of the Sierra AGI games will not work properly for this reason.  However, if you replace the interpreter with one from a compilation CD, then the game will work just fine. 

[Marten]

Another solution would be to play the games under ScummVM, which integrated support for AGI games from the (now defunct) Sarien project.

[NewRisingSUn]

Sierra didn't program that copy protection scheme themselves, they used the product Softguard SuperLok, version 2.3. However, instead of using that program's loader with its strong (relatively) secure anti-debugging code, they reprogrammed the loader (and only that) themselves, becoming rather easy to "crack". Other games which use the SuperLok scheme, albeit with the proper loader, are Taito games like Arkanoid or Bubble Bobble.

CopyIIPC still won't copy those disks; it will prompt you to use "NoGuard", which was Central Point Software's "cracking" software. I once managed however to format a disk so that it would be accepted. It doesn't actually replicate the rather complicated structure of the copy-protected track faithfully, just enough to fool the checking routine. It also required a high-density disk for such a copy, when the original of course was a low-density disk.

Another solution would be to play the games under ScummVM

Which has a weird inaccurate sound emulation and the fugliest 8x8 font I've ever seen.

[MusicallyInspired]

I asked them about their AGI sound support and if there was ever any plans to incorporate true Tandy 3-voice sounds in its AGI emulation and they didn't even know it was wrong to begin with.

[Marten]

You can criticize them, or you can get involved... which will have a more desirable result?

[NewRisingSUn]

Given how fixing any of ScummVM's sound problems would likely require a complete rewrite of the incredibly messy (from what I've seen) sound code, which is next to impossible for project outsiders, neither of the two.

I once tried fixing the one remaining Tandy sound problem in Zak McKracken, which is the result of a peculiarity of the Tandy sound chip, which would have been trivial with any regular Tandy sound emulation code, but I couldn't make any sense whatsoever of that coded weirdness. Likewise, with the current sound system, it's not possible to disable the MT-32's reverb on selected channels, like the DOS version does.

Don't get me wrong, I love ScummVM, mostly for its ability to use MT-32 music and Adlib sound effects in Monkey2, but the sound code is unfixably (for outsiders) messy nonetheless.

[Great Hierophant]

Other games which use the SuperLok scheme, albeit with the proper loader, are Taito games like Arkanoid or Bubble Bobble.

Fortunately, they have also been cracked, so the good news is that it is not impossible.

Likewise, with the current sound system, it's not possible to disable the MT-32's reverb on selected channels, like the DOS version does.

Does that refer to their emulation of the MT-32 or using a real MT-32?

Don't get me wrong, I love ScummVM, mostly for its ability to use MT-32 music and Adlib sound effects in Monkey2, but the sound code is unfixably (for outsiders) messy nonetheless.

I didn't know about that.  One of the few things I like about Scummvm is that you can use a mouse with the NES version of Maniac Mansion.  One of the things I hate is that Scummvm refuses to work with the prototype version of that game, which is mostly uncensored and thus superior to the released cartridges.  Also, for Indy and Monkey 2 FM Towns, scummvm will only output Adlib sound, not FM Towns FM sound.   

In short, Scummvm is an emulator for those who can't be bothered, for whatever reason, with using system emulators for the games it supports. 

[NewRisingSUn]

Does that refer to their emulation of the MT-32 or using a real MT-32?

Both. You can hear in Monkey2 that the "glob" sound when selecting the difficulty level has reverb on ScummVM, when it shouldn't. Same with ReggaeBass and Elec Org 2 during the title music.

One of the things I hate is that Scummvm refuses to work with the prototype version of that game, which is mostly uncensored and thus superior to the released cartridges.

Is there any reason to use the NES version (prototype or regular) when you can play the C-64 or the enhanced IBM/Tandy version?

Also, for Indy and Monkey 2 FM Towns, scummvm will only output Adlib sound, not FM Towns FM sound.

That's because the FM-Town's sound data files are the same as the PC's, plus a few additional PCM sounds. The FM-Towns interpreter executable is probably translating OPL2 instruments to whatever FM chip the FM towns uses on-the-fly. And in that case, you might as well play the OPL2 data directly.

[Great Hierophant]

Is there any reason to use the NES version (prototype or regular) when you can play the C-64 or the enhanced IBM/Tandy version?

It is nice to play the game on the NES, the music is cool and the graphics are pretty decent.  The C64's lack of a mouse and slow loading times (not to mention the fact that I don't have a physical C64) is an issue.  The IBM/Tandy version is pretty good, but you can't play it on a TV with good color. 

That's because the FM-Town's sound data files are the same as the PC's, plus a few additional PCM sounds. The FM-Towns interpreter executable is probably translating OPL2 instruments to whatever FM chip the FM towns uses on-the-fly. And in that case, you might as well play the OPL2 data directly.

I thought that that was the case.  Still, it would be nice to have the option to play the games as the FM Towns would have played it, translated OPL and all, in addition to an idealized version.