One of the things I really love about how the Quantel DPB-7001 "Paintbox" treats disks is how it could be a case study in how to responsibly not care about data integrity.
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There are no sector checksums. There are no sectors *to* checksum. There are no track checksums, because tracks are an illusion, it's just a set of cylinders containing unstructured, sequential lines of image data.
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In fact, other than the directory listing on the first cylinder, the whole concept of a disk in general is illusory. It's treated more like linear video tape. And does linear video tape have integrity checking? Of course not.
![[ColeJ]](https://pbs.twimg.com/profile_images/1043000626056065024/vDRPnUpt_normal.jpg)
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Will bad data cause a crash? No, because the CPU doesn't even involve itself in the loading of images or brushes. The disk controller just hoovers up bytes and deposits them linearly in the frame stores or brush store.
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As long as the PLL can maintain sync with the MFM stream, you're hot to trot. Any bad bytes will simply cause small speckles or spans of missing pixels, and the end result will still end up looking better than a still frame off a VTR.
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Uusi keskustelu -
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Digital VTRs do have some error correction and then concealment when that fails. Final gen DigiBeta used the ‘read the tape more than once’ technique rather than tracking accurately ISTR.
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What resolution to digital VTRs usually supply, though?
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Uusi keskustelu -
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Well, some later VTR formats did include error recovery facilities. But back when D1 tape ruled the roost the data just arrived and old disks were a darn site less reliant on error correction than currently.
Kiitos. Käytämme tätä aikajanasi parantamiseen. KumoaKumoa
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D1’s Manchester coding was pretty rudimentary; that format relied on reliable RF recovery. By the time Digital Betacam came along the Viterbi decoder did much of the error recovery and that format had quite clever error concealment.
Kiitos. Käytämme tätä aikajanasi parantamiseen. KumoaKumoa
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