Apple "Twiggy" disks

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r09
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Joined: Sun Nov 14, 2010 1:34 pm

Apple "Twiggy" disks

Post by r09 » Sun Aug 14, 2011 7:30 pm

Hi, I didn't really know where to put this thread, as it isn't really a feature request, but most discussions about "strange" formats are in this forum, so...

Well, let's get to the point. Just out of curiosity, has anyone done any experiments with Apple "Twiggy"/FileWare disks? They were used only in the first revision of the Apple Lisa (the Lisa 2 used standard 3.5" disks, like the Mac) and apparently they are a weird custom 5.25" format with two heads on opposite sides of the drive (and, consequently, two "slots" on the disk) and several notches all over the sleeve.

Image

As far as I know, no one has ever dumped one of these things (all the Lisa dumps out there are from Lisa 2 disks, and I think they were dumped with a Mac drive), so I'm wondering if they would be readable on a regular 5.25" drive connected to a KryoFlux, since they at least look mechanically compatible...

RJMcInty
Posts: 81
Joined: Fri Nov 26, 2010 12:26 am

Re: Apple "Twiggy" disks

Post by RJMcInty » Mon Aug 15, 2011 12:48 am

I have no idea whether KryoFlux can read this, but that thing's amazing!!!!! I've never seen a floppy like that. After reading about them on Wikipedia, though, I'm not sure that I'd ever want one of those in my computer! :D

Thanks for sharing!
Robert

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IFW
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Re: Apple "Twiggy" disks

Post by IFW » Mon Aug 15, 2011 11:44 am

If you can attach a stepper that can actually step to the correct track positions...
http://www.brouhaha.com/~eric/retrocomp ... wiggy.html

According to this article the TPI is non-standard, so it won't be readable by other drive types, unless the stepper gets replaced...
Apart from that it should be readable though whether it's the same encoding as other Apple formats already supported or not - I'd rather not guess :lol:

balrog
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Joined: Sat Feb 12, 2011 2:57 pm

Re: Apple "Twiggy" disks

Post by balrog » Tue Sep 13, 2011 6:09 pm

What about using an IBM 2.4MB 5.25" floppy drive? It is 192 TPI, which means about three steps per track (Twiggy is 62.5 TPI) — still not exact, but the data probably could be extrapolated.

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IFW
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Re: Apple "Twiggy" disks

Post by IFW » Wed Sep 14, 2011 11:07 am

I doubt that... at least not reliably.
A custom stepper is the solution.

RJMcInty
Posts: 81
Joined: Fri Nov 26, 2010 12:26 am

Re: Apple "Twiggy" disks

Post by RJMcInty » Tue Oct 04, 2011 4:22 am

balrog wrote:What about using an IBM 2.4MB 5.25" floppy drive? It is 192 TPI, which means about three steps per track (Twiggy is 62.5 TPI) — still not exact, but the data probably could be extrapolated.
Balrog, I don't suppose you have any info on one of these drives? I've picked one up for a different project, but can't seem to make it step @ 192 tpi mode... :(

Thanks!
Robert

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IFW
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Re: Apple "Twiggy" disks

Post by IFW » Tue Oct 04, 2011 10:12 am

Anybody with a service manual?

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