USB floppy disk unit ?

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RobeInie
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USB floppy disk unit ?

Postby RobeInie » Tue Oct 23, 2018 7:38 am

A question I have in mind: would be possible to use original (or copied) disks via USB floppy disk unit ? for example, in Amiga or Atari core (or in other cores).

¡¡ Thanks !!

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DrOG
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Re: USB floppy disk unit ?

Postby DrOG » Tue Oct 23, 2018 8:14 am

It's very unlikely, as USB FDDs are designed for PCs and use different format (720kB) than Amiga (880kB).

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Re: USB floppy disk unit ?

Postby MasterOfGizmo » Tue Oct 23, 2018 11:58 am

DrOG wrote:It's very unlikely, as USB FDDs are designed for PCs and use different format (720kB) than Amiga (880kB).


This would in theory work for the Atari ST core since the Atari ST disks are basically DOS formatted. But these USB drives are unable to read e..g amiga disks. For that you'd need a kryoflux or the like. But that's imho overkill ....

BTW: I once bought a floppy for that purpose. I had a hard time obtaining one that could actually read 720k DD disks and not the common 1.44MB HD disks PCs later used. But i also failed in controlling this floppy via USB. They differ significantly in their behaviour from e.g. USB sticks which i was partly able to support.
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Re: USB floppy disk unit ?

Postby ijor » Tue Oct 23, 2018 12:21 pm

Actually even for the ST core, it won't be able to read all the disks. USB floppy drives can only read disks with standard 9 sectors per track geometry. And as you know, many ST disks have 10 or even 11 sectors per track.
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DrOG
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Re: USB floppy disk unit ?

Postby DrOG » Tue Oct 23, 2018 12:54 pm

Hi!

I'm absolutely no familiar with Atari ST hardware, but the floppy drive implementation should be similar to the solution used in the case of Enterprise 128. This computer was a commercial failure everywhere, but very popular in Hungary, as it gave a relative powerful hardware for a low price. The EP's floppy controller contained a WD1772 IC with enhanced data separator, and was able to write not only 9, but 10 or even 11 sectors to one track. And besides it was possible to add extra tracks to the disk, the 'Hungarian Standard' was 840kB (84 tracks/10 sectors - 11 sectors were sometimes unreliable), but in theory the maximum was 990kB on a standard DS/DD disk (90 tracks, 11 sectors). And the same for 5,25" drives!!!

I found a nice description about it, sorry, it's in Hungarian, but Google translate may help..:

http://ep128.hu/Ep_Hardware/PC_FDD.htm

Gábor

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Re: USB floppy disk unit ?

Postby MasterOfGizmo » Tue Oct 23, 2018 1:36 pm

We know how the ST floppy works. But USB floppy drives come with a lot of internal intelligence and they do all the low level stuff themselves. Thus they can only read what they were designed to read. And that's usually DOS/FAT formatted 3.5" 1.44MB HD floppy disks. Some of them can read 720k DOS DOS formatted DD disks. Even fewer can write or format them.

To summarize: I am absolutely sure that it's not worth the effort. At most you would perhaps be able to read a few standard formatted ST disks but as Igor pointed out no 10 or 11 sector disks, no single sided disks and no disks with more than 80 tracks and of course no disks with copy protections. What's left is so boring that it's not worth to spend the time required to implement it.
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