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PostPosted: 10 Jan 2017 10:17 
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First let me start by saying I'm old (& feeling it more every day ;) )

The ZX Spectrum 48k was the first platform I ever played games on after my older brother gave his one to me. Many hours of my life were spent watching lines scroll down the screen while the cassette loaded the game before I could play a game like paperboy, formula one, chuckie egg etc.

I was wondering why there isn't an official dat for those games, 1000's of games available on sites like world of spectrum, is it because sites like share them or because no one has collected the full collection to build the dat?


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PostPosted: 11 Jan 2017 17:20 
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No-Intro is about preservation.

How do you acurately preserve magnetic media?
It's taken years for 'groups' to decide the most accurate method of backing up optical media, and I doubt this is 100% correct. This includes how to deal with copy protection/encryption, etc.


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PostPosted: 11 Jan 2017 19:20 
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Connie wrote:
No-Intro is about preservation.

How do you acurately preserve magnetic media?
It's taken years for 'groups' to decide the most accurate method of backing up optical media, and I doubt this is 100% correct. This includes how to deal with copy protection/encryption, etc.

Thanks for the reply Connie


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PostPosted: 12 Jan 2017 09:45 
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Joined: 11 Jun 2016 12:29
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Hi,

Do you know any place where I could read a bit more about tape preservation?

My point is I believe most of the difficulties to preserve magnetic disks comes from the fact that data can be structured in different ways and some disk features (weak sectors, bits not written at all so they return a different value each time they are read...) can't be properly read/written using normal drives.

Is the above applied also to tapes? the data is stored linearly and the writer/readers doesn't have any extra feature (as far as I know). Just guessing... so I would like to read a bit about it to build a proper opinion.

(...I've been waiting ages for a proper tape preservation project...)

Regards


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PostPosted: 15 Jan 2017 04:09 
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The current most accurate format for tape preservation is the .tzx format. An alternaltive format, with the best preservation, is a .wav recording of the tape.


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PostPosted: 15 Jan 2017 15:51 
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The problem with wavs is that two different recordings cannot be compared in terms of hash so they are not "dateable".


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PostPosted: 15 Jan 2017 16:28 
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Kyroflux (used by SPS) is currently the most accurate way to preserve magnetic disk media. The problem is that it measures and saves the levels of magnetic flux as raw data, which means that over time, this raw data is constantly changing.
While the data (code) may be preserved and could be written back to disk, you couldn't use it to make a 1:1 preserved copy.

It's similar to how reading a UVROM (with it's erase window uncovered) over time would produce different dumps as data is slowly erased/lost. Only a dump at day 0 could be considered 'original' and therefore preserved.


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