Armour-Geddon

There is a sealed copy of the original Armour-Geddon currently on ebay UK with 5 days to go... I am surprised that there has not been any IPF of this yet.

[mr.vince]

Well... I can't recall why it's not been dumped yet... maybe it has and was bad...

Unfortunately, new items tend to go for insane prices...

What would be a respectable price to pay for this?
Its currently on for only a couple of £s.
Also there is a copy of Zork III on for around £8... i see this has not been released by SPS yet...
Should I chill out and ignore these missing games from SPS or are you still looking to get hold of them??

[dlfrsilver]

I have imaged for the moment Armour-Geddon in extended ADF.

Not IPFied yet because it uses the special psygnosis protection (Obitus, Nitro, Killing Game Show, and yesss Armour Geddon).

[gimbal]

Originally Posted by dlfrsilver

Not IPFied yet because it uses the special psygnosis protection (Obitus, Nitro, Killing Game Show, and yesss Armour Geddon).

Probably is mentioned somewhere already, I might have even read it and forgotten about it, but I'm curious: what is so special about the protection?

[Galahad/FLT]

Originally Posted by gimbal

Probably is mentioned somewhere already, I might have even read it and forgotten about it, but I'm curious: what is so special about the protection?

The protection format is written with virtually no error checking/checksum verification which means as time passes, the disk format is likely to degrade through bit rot which means some sectors/tracks won't contain the correct information.

Some of the Psygnosis games have needed imaging from many different disks to get a 100% correct single image.

[mr.vince]

Looking at the FTP... we do have some dumps of it. But due to the missing verify information István has not processed them yet. I think the wording was to keep them for a long and rainy day. Then KryoFlux came along.

BTW might be a good idea we do a highly oversampled dump of it, just in case.

But again, buying sealed stuff has become insanely expensive, so we usually don't burn the few project bucks we have for single titles. At least not for these.

[dlfrsilver]

Not counting i did an extended ADF that works very well with the whdload install !

[mr.vince]

sure. but does the whdload installer in fact verify the files' contents? or does it just put the data into another container? the thing (in these cases) would be playing the game many times until you see the end, with all different flavours of gameplay etc.

[dlfrsilver]

the whdload installer read the content, then create a disk image. If it's bad it's stop loading indicating an error.

[Toni Wilen]

Originally Posted by dlfrsilver

the whdload installer read the content, then create a disk image. If it's bad it's stop loading indicating an error.

It knows what kind of data to expect, not that it is 100% confirmed correct data.. Only disk checksums or play testing can do that.

[Harry]

That format has integrity information (and the ingame loader and whd-install-imager of at least Nitro and Killing Game Show use it), it is just not accessible without decoding the entire sequence, so it was duplicated without verification.
See http://www.softpres.org/wip:2003-04-04 for details.

[dlfrsilver]

yes, if i understood well the thing, every information relative to the disk structure and how the information are stored are INSIDE the program that need to be accessed.

Otherwise it's impossible from outside to know what is where and so on, right ?

in other games, by having a look at the bootblock and the main loader you got the informations. here this trick doesn't work.

Tell me if i'm wrong

Thanks anyway for explain that !

[mr.vince]

It's as explained in the link Harry found (thanks for looking it up). It is impossible to verify the data unless you read all of it through the in-game loader mechanism. Normally, there's integrity information somewhere each track, like a duplicator checksum, or a checksum present because of the track format itself (e.g. ADos).

To verify a dump of one of these games, all data must be checked through the game's own mechanisms, which basically means you have to know in which order whatever is read. Basically, you'd reverse engineer the complete loader, and then, like an onion, peel off layer by layer.

The IPF format itself is very flexible an can store any kind of data, you just have to script it. Like IFW wrote:

This decoding requires a new Psygnosis transport layer in the analyser (see previous WIPs), and a new decoder module in the library. This is quite a lot of work, so we may not continue with it right now.

Lots of work... for four titles. We still can collect dumps, we just do not interpret them right now.

[dlfrsilver]

I find that excellent as a system. I would have been a coder, i would have implemented terrible schemes and for sure you'd still be scratching yer head

[IFW]

not really... as duplicators would not make disks for you

[dlfrsilver]

Psygnosis got the disks duplicated Obitus is a very common game

[mr.vince]

Yes, they did dupe them. But... Working with related media today... Returns tend to hurt you because dealers return the full product, they do not ask for replacement media.

I bet this was less worse because people actually had to get to the point where their disk turned out to be faulty. Anyway... Producing media without being able to verify is just stupid.

[dlfrsilver]

the purpose of special scheme and protections is to be not recognized and traced down ?

By the way, Psygnosis had an excellent policy of disk replacements, i remember having Agony with 2 disk 2 (missing disk 3 in fact), i sent the disk back from France to Liverpool, and they sent me back the missing disk !.

All their products had the same warranty against defects.

I have Obitus in 2 or 3 copies at home, and the disks are still neat and work well.

Psygnosis surely told their little secret to the duplicator while everyone outside didn't know how it behaves

[mr.vince]

Originally Posted by dlfrsilver

the purpose of special scheme and protections is to be not recognized and traced down ?

Well today you are protecting e.g. DVDs. Because optical media uses a stamper, you can assume that if some test discs made are good, the rest is good until the stamper is worn. You still check regularly, and of course, you can check the integrity, even if the media is protected. I know no one around who'd want to replicate without making a bit check (checking every bit from the master with the bits coming from a replicated disc).

For magnetic media, you produce the medium first, then you record the information. So you have to verify every single disk, otherwise you might end up shipping damaged products.

As for your disks still being good: You can be happy they are. Due to bit rot they are not getting better and due to the fact that the data is stored as digital information, the problems will come qickly. You won't notice any snow, or dropouts like on VHS tapes. If the loader behind this is good, it will retry and you won't notice for a long time. The moment you notice, it's too late.

If you want to believe that there's a secret about how to verify this data, please do.

I believe they just did not care. We know a Trace can't verify it. We don't know any other replication machine that could. As explained above, this is much work for four titles so far, so will have to wait.