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Alternate Reality official version with partial copy protection


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#1 ijor OFFLINE  

ijor

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Posted Tue Nov 21, 2017 7:31 PM

As it is well known, Alternate Reality The City is one of the heaviest copy protected titles for the Atari 8-bits. At the hardware side of the protection, it was one of the first titles that had weak bits. It has several sectors of weak bits on the same track. It is rather unique in that it combines both duplicate sectors and sectors with weak bits (it has dups of weak sectors). It is very strict when it checks the extent of the weak bits in the sector. And it has other, more common, protections as well. Philip Price at his best :)

 

Recently we found that there is a version that doesn't have any weak bits at all. The track with the weak bits is identical except that the sectors instead of weak bits they are "stable" with a "normal" CRC error. As if that track would have been copied with something like a Happy that can't reproduce weak bits. The rest of the protection was not altered. My initial reaction was that it was either a duplication defect or a hacked version. But now we found multiple copies of this version, they all match and are identical. That would mean it is very unlikely it is a hack. And the code was altered to ignore the result of the protection checking for the weak bits. Or at least it seems so. That would discard a mastering or duplication defect. The check for the "common" protection remains. It is still copy protected.

 

I don't know why they removed the weak bits. A possible idea is that at some point they used cheaper duplication that couldn't master the weak bits.

 

Regardless it would be important if we can confirm that this version works correctly. Unfortunately it is very difficult for this type of games. If somebody very familiar with this game would like to test it, please let me know and I'll send you images of this version.

 

For the time being, until confirming the exact behavior of this version I would prefer to avoid a public post. But we are not hiding it either. If somebody wants the images right now, just ask.



#2 _The Doctor__ OFFLINE  

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Posted Tue Nov 21, 2017 8:10 PM

Sometimes when my originals got corrupted for one reason or another I would do things similar to this and put the programs back on the labeled purchase disks


Edited by _The Doctor__, Tue Nov 21, 2017 8:10 PM.


#3 Farb ONLINE  

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Posted Thu Nov 23, 2017 12:25 AM

Sometimes when my originals got corrupted for one reason or another I would do things similar to this and put the programs back on the labeled purchase disks

 

 

In this case, the two copies of AR came from different shrink-wrapped boxes so the chance of this, while still possible, is highly unlikely.



#4 kheller2 OFFLINE  

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Posted Sun Nov 26, 2017 9:42 PM

I could be misremembering this, but I thought there were two releases of ARTC. Or was that the dungeon 2.0 vs 2.1? It’s been so long since compuserve forum days.

#5 x=usr(1536) OFFLINE  

x=usr(1536)

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Posted Sun Nov 26, 2017 10:44 PM

Somewhat off-topic, but related: does anyone have recommendations for overviews of the types of copy protection used on Atari disks (or tapes or cartridges, for that matter)?

I've been following some of the stuff that 4am has been doing with Apple ][ copy protection, and it's been fairly fascinating. Is there anything out there for the A8 in a similar vein?

#6 Rybags OFFLINE  

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Posted Sun Nov 26, 2017 11:43 PM

I don't think so.  Some games get notoriety for being the first to carry a certain type of protection that the existing addons like Happy couldn't handle at the time.

Atari games probably more than most were cracked before being widely distributed since by default and unlike the C64, A2 and many others, almost all protection schemes couldn't be dupilcated on a standard drive.

 

I remember getting Great American Cross Country Road Race to work using a standard drive with no crack.  The game attempts to read a high sector and only cares that an error is returned, no other sectors on that track are accessed, and no sector after it on the disk.  So I copied it by just partly formatting a disk (eject at the right time) then copying the used portion to the blank.

 

There's some books and docs around but pretty sure they describe protection in a generic sense and usually refer to software houses when grouping types rather than getting down to individual games.

 

AR - Dungeon I don't think at the time could be copied with Happy - fairly sure it used something like duplicate sectors, missing sectors as well as a CRC error.



#7 ijor OFFLINE  

ijor

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Posted Mon Nov 27, 2017 7:58 PM

Somewhat off-topic, but related: does anyone have recommendations for overviews of the types of copy protection used on Atari disks (or tapes or cartridges, for that matter)?

 

You have this: http://www.atarimani...-Techniques.pdfand this: http://www.atarimani..._Techniques.pdf ...

 

There are also a couple of modern notes. But due to the way the Atari drives operate, the protections are very few and much simpler than the ones on most other platforms.
 



#8 x=usr(1536) OFFLINE  

x=usr(1536)

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Posted Mon Nov 27, 2017 9:40 PM

You have this: http://www.atarimani...-Techniques.pdfand this: http://www.atarimani..._Techniques.pdf ...
 
There are also a couple of modern notes. But due to the way the Atari drives operate, the protections are very few and much simpler than the ones on most other platforms.


Sweet, thank you! Those should give me some good starting points.

#9 DjayBee OFFLINE  

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Posted Tue Feb 13, 2018 2:06 AM

Somewhat off-topic, but related: does anyone have recommendations for overviews of the types of copy protection used on Atari disks (or tapes or cartridges, for that matter)?

I've been following some of the stuff that 4am has been doing with Apple ][ copy protection, and it's been fairly fascinating. Is there anything out there for the A8 in a similar vein?

 

If you want to know which title uses which type of protection then you can have a look at the CSV and explanation attached to this post:

http://atariage.com/...-9#entry3959654






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