Apple external 3.5 inch floppy disk drive compatible machines

Mr. Fahrenheit

Tinkerer
Founder
Sep 2, 2021
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There are a few models of Apple 3.5 inch external floppy disk drives. From what I can find, there are:

Apple 3.5” 800kb Drive
Apple 3.5” UniDisk Drive
Apple 3.5” SuperDrive

Is this all of them? The unidisk and 800kb drives both read and write 800kb disks. Are both of these drives compatible with the Apple II and are they also Mac compatible?

I ended up buying a few of these drives and I don’t want to short something out putting the wrong drive on the wrong computer. I’ve read mixed info online so asking about personal experience.
 

Daniel Hansen

Tinkerer
Oct 29, 2021
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Apple made three different 800k externals - the Apple 3.5", the Macintosh 800k, and the UniDisk. Then there's the 1.44M FDHD / SuperDrive. And of course there's also the 400k drive. There's also the PB100 and 2400c externals, but I don't suppose these are a concern in this question. But I think that's all of them.

I don't own a UniDisk or FDHD, so I can't comment on those from personal experience. But I've had no issues using the Apple 3.5" and Mac 800k on the IIci, SE, or Plus. Also, my 512k has the upgraded ROMs, so it can use the 800k drives as well.

My understanding is that there is no risk of damage with any 3.5" drive - just incompatibilities. i.e. they just don't work. The UniDisk is apparently incompatible with any Mac (as it was designed for use with Apple II's and has its own IWM). Also, 128k's can only make use of the 400k drive, and the 512k needs the HD20 INIT loaded (or updated ROMs) to make use of the 800k drives. There are varying reports of compatibility with the 400k drive on Macs with SWIMs.

I've only heard of damage warnings when trying to use a 5.25" drive with a Mac.

I'm curious to hear others' experiences.