Bigger capacity disc idea

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Twilighte
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Bigger capacity disc idea

Post by Twilighte »

Working on the fact that a disc is composed of concentric rings, where the distance on the outer ring is much greater than the distance on the inner, I wonder if it is possible to format each Track with an increasing number of sectors per track (as the head moves towards the edge of the disc)?

Sectors can be 256,512,768 or 1024 bytes long. If this idea worked, it could potentially triple the normal capacity of a 3.5" disc.
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Dbug
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Post by Dbug »

Except that I think that since the rotation (relatively to the head position) is faster the farther you got from the center, I fear that the pulses to read and write are getting longer and longer. (longer "bits") ?
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Post by Euphoric »

Absolutely...
We have a CAV (Constant Angular Velocity) disk system, which means that we store the same number of bits, whatever the track is...
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Post by carlsson »

Maybe you can interface a Commodore disk drive to Oric? The 1541 et.al use different amount of sectors depending on track. I've recently read that there were some Z80 systems which interfaced with a 1541, and the Oric probably shares more chips in common with a CBM than most home built Z80 systems.
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Post by nodoid »

carlsson wrote:Maybe you can interface a Commodore disk drive to Oric? The 1541 et.al use different amount of sectors depending on track. I've recently read that there were some Z80 systems which interfaced with a 1541, and the Oric probably shares more chips in common with a CBM than most home built Z80 systems.
If you want this insanity type drive, fish out an old Apple Mac which had this system on the floppy drive. Really screwed up!
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carlsson
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Post by carlsson »

I thought the Macintosh changed its rotation speed depending on which track you were reading? That is quite bizarre.
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Post by mmu_man »

Not bizarre, just unusual, but not so much, some CD readers do that at high speeds.
Since the outer tracks are bigger in length, with the same rotation speed it passes faster under the head. So lowering the rotation makes it pass the same linear speed under the head, but for a longer time, and so with more storable bytes.
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Post by JamesD »

I you are going to go to a larger capacity device you might as well go with an compact flash interface. The circuit is actually smaller than the floppy interface plans I saw for the ORIC and you can probably borrow most of the firmware from the Apple II IDE controllers.
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