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Thread: Any apple II 5.25" drives do 40 tracks?

  1. #1
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    Default Any apple II 5.25" drives do 40 tracks?

    So, I needed to stuff a tiny bit more data on a Prodos disk, and I recalled from some old experiments that the Laser 128 drives could do 40 tracks. I was well aware that the early Disk II full height systems used on II/II+/IIe computers only supported 35 tracks (well, technically they could get 36).

    Wasn't sure about Apple IIc drives, but figured they had to be a bit more advanced, right? Nope.

    Dug up an old hack that enabled 40 tracks on Prodos, applied that, and it formatted and verified a disk fine on a Laser 128 external drive attached to the IIc. Tried it on the IIc internal drive, and BZZZZZ. It didn't like that.

    Not too surprised, but now that I am thinking about it, I'm wondering if that would have worked on any of the later unidisk models sold with later IIe or IIgs machines.

    It still baffles my mind that even the last 5.25" drive apple cranked off of their assembly line with the IIgs machines were still only single sided, and never adapted to more than 35 tracks.

    Heck, I recall once a long time ago having a generic Apple II clone drive that actually had two heads, but the second was unused. Apparently it was cheaper for some manufacture to just lobotomize an existing double sided drive. (Or a perhaps a creative way to reuse defective drives)

    I have read about some other clone drives that did double sided or even quad density, and I think most half height clones did 40 tracks fine. But not Apple?

  2. #2
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    All but the earliest Disk IIs should be able to format/R/W 40 tracks just fine, even the IIc drives (I would have the drive check if it doesn't).

  3. #3

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    I don't know of the official reason for Apple not officially supporting 40 tracks and/or double-sided disk. But I have a good educated guess - and you have to place yourself in the late 1970s / early 1980s to understand the train of thought behind this - that 35 tracks and one-sided was the most stable specifications, given that users WILL attempt to go out and use inferior diskettes. Not all diskettes of the time can do 40 tracks, and not all single-sided disks were certified for two-sided/double-sided use. Even if you tell the customer hey, you're using single-sided disks, the customer won't really understand. Woz and Jobs targeted Joe Blow customers with the Apple II. We're talking about customers who have never experienced anything that even closely resembles a personal computer. I'm pretty certain that every floppy ever made during that period could support 35 tracks and single-sided, and therefore that would be a logical specifications if you're looking to avoid incompatibility issues.

  4. #4

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    You don’t want to start changing the drive and have a lot of incompatible disks. You could’ve ended up with each model having it’s own incompatible drive.
    If you wanted more the there were aftermarket drives like the Rana Elite 3 with 160 tracks. You could also get 8” drives. Before ProDOS DOS had to be patched for those.

  5. #5
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    The early drives (Shugart included) limited the number of tracks to 35 because of "bit crowding" issues, which were more severe on 5.25" than on 8" drives.

    At least that's my understanding.

  6. #6

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    Quote Originally Posted by dorkbert View Post
    All but the earliest Disk IIs should be able to format/R/W 40 tracks just fine, even the IIc drives (I would have the drive check if it doesn't).
    There used to be patches for DOS3.3 not sure about ProDOS to read 37 Tracks to the floppy... in theory you could increase the track maximum until the heads hit the stop... and they were all different... 37 was common, after that it became more drive dependent.

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