[game_preservation] Preservation of analogue game media

[Devin Monnens]

Hi Kieron,

Haven't posted any responses as I was on the conference track the past week
- makes it difficult to read things! Anyway, great detail here and it's all
quite fascinating! At first I thought this was for scanning documents ( >.<
) but as I see, it's new information!

Authenticity is a problem that hackers are dealing with, too, which is why a
lot of the sites that rip disc-based games are now including MD5 and CRC
check files. (Unfortunately, I think they are encoding all their audio into
FLAC, which has some advantages, but is not a preservation standard. FLAC
does contain the CRC information of the original WAV though).

Another thing to consider is whether (and sometimes how) to preserve the
copy protection data. I am assuming your backups include these as well?

On another note, I have found very little high-quality Super Mario Bros.
development art on the web despite the fact that it's in tons of magazines
and promo materials. You would think a site like The Mushroom Kingdom would
have it...

Devin


On Wed, Feb 25, 2009 at 3:16 AM, Andrew Armstrong <andrew at aarmstrong.org>wrote:


>  I'm interested in hearing more and how people can help. Responses on this

> mailing list widely vary, and there isn't as many institutions as I'd like

> to see involved here, we'll need to invite more people on :)

>

> Andrew

>

> Kieron Wilkinson wrote:

>

>  I'm not sure how much interest there is in this, but I'll carry on

> regardless. :)

>

>  In my previous post, I summarised what I thought were the technical

> challenges faces in preserving games stored on floppy disk media. I them

> split those points into two categories, which I will now detail further.

>

>  a) Reading the disks in the first place

>

> Getting hold of appropriate disk drives seems to be easy enough for the

> majority of disk types, the problem is getting the raw data off the disk.

> Floppy disks are an analogue storage medium, and data is not directly stored

> as 0's and 1's like on Compact Discs and flash drives, but as magnetic

> polarity changes ('flux transitions'). The problem is that you cannot

> generally read these flux transitions through a computer, as there is

> hardware in the way way to make accessing the data "easier" (and did it's

> job well, but now is a problem for preservation). This "raw" form is the

> ideal thing for preservation. Once you have this, you don't care about disk

> formats or copy protection - you are just doing a raw read of a disk - and

> it all comes along for the ride.

>

>  You might think that if the computer can read the data, there shouldn't a

> problem. Unfortunately that is not the case, the only way to get a computer

> to read particular things is to write it in a special way on special

> hardware, a concept that underlies many copy protection techniques.

>

>

> b) Knowing that what you have read is correct

>

> Secondly, there is knowing whether the disk image you have made is correct.

> There is little point of trying to preserve games if you cannot be sure

> whether those disk images are okay or not. With most types of storage media

> we use today, this is not a problem - the data is checked as it is copied.

> But games on floppy disks are a special case, you often do not know where

> the checksum/integrity information is stored on the disk, and even for known

> disk formats, games developers applied copy protection that deliberately

> wasn't covered by the integrity data. The disks are old already, the data

> may already be broken, and you won't know if you need to find another copy

> without being confident in your disk images.

>

> You cannot play the game to check it, the corruption may not be apparent

> until, say, level 14. Also, how do you know the copy protection passed? It

> is not always obvious. Borrowed Time on the Commodore Amiga has very nice

> protection, if it fails, you can't find some items to allow you to proceed

> in the game, they simply don't appear - and that is not the only example.

>

>  It gets worse, what if somebody modifies a game disk (virus, accident,

> malicious intent, save games)? There will be no corruption, but it certainly

> is no longer an authentic copy suitable for preservation.

>

> I firmly believe that any disk images produced also require some sort of

> checking to be confident in their preservation status. I'll drop a small

> note here that The Software Preservation Society check for all of above for

> every single game preserved (nearly 3000 so far).

>

>

>  I think all that covers the points raised in my last email.

>

>

> With these sorts of difficulties, it is no wonder that game preservation

> (for computers at least) has historically been in such a poor state.

> In my next post, I will detail some new developments that I believe makes

> the future brighter for everybody.

>

> If anyone has any comments on any of this, please feel free to chime in

> with your thoughts.

> Kieron

>

>

>  On 13 Feb 2009, at 23:05, Kieron Wilkinson wrote:

>

>

>  Since I have been away for a while, I was trying to get a feel for how

> things have changed, and I thought this was a good place to start. I guess

> there doesn't seem to be many people here involved with that side of things,

> perhaps it is still very much an ad-hoc process.

>

> As I said before, there does seem to be a number of common technical

> problems in preserving game media. Here are the ones I can think of:

>

>  1) Devices required to read the disks

>  2) The different and custom disk formats in use (I don't mean the

> physical disk format here, but how the software data is structured on the

> disk)

> 3) The presence of any disk-based copy protection (the whole purpose of

> which is to hide itself)

> 4) Degradation of original disks, leading to corrupted reads

> 5) Authenticity (ensuring disks are original and unmodified)

>

> I'd like to cover these points as two distinct problems...

>

> a) Reading the disks in the first place (points 1, 2 and 3).

> b) Knowing that what you have read is preservable (points 4 and 5, but also

> involves 2 and 3).

>

> I don't want to go into too much detail in one post, so I will leave it at

> this for now, and follow up this two issues separately later.

>

> If anyone has any comments on any of this, please feel free to chime in

> with your thoughts.

> Kieron

>

>    ------------------------------

>

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>



-- 
The sleep of Reason produces monsters.

"Until next time..."
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