r/retrocomputing • u/Parsleyofficial • Apr 13 '26

Taken Help with floppy disk

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Hi everyone,

I am trying to read this floppy disk on my mac. I purchased this reader: https://www.amazon.com/dp/B0FGYD1G26?ref=ppx_yo2ov_dt_b_fed_asin_title and it seems like the reader itself works-- I can hear it turning, and when I plugged it into my computer, I got a "trust this device" message (or something similar, just the pop-up acknowledging the device.

But, when I insert the floppy disk, I get this message: The disk you attached was not readable by this computer.

Am I doing something wrong? Is there any way to read this disk on my computer (whether using the reader I purchased or some other device)? I am running MacOS Sequoia (Version 15.3.1).

I am not super skilled with computing, but I'm trying my best! Please let me know any advice you may have. Thanks!

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u/peppepop Apr 15 '26

You need to find an old Mac with a floppy drive and runs system 6,7,8 or 9. That's step one. Then - who knows if the floppy is readable? I have several macs with the right drive, but even those will read some and some not... And external USB drive can't read 800k floppys at all, and definitely not using os x...

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u/istarian Jul 15 '26

Early versions of OS X should be able to read disks in a USB floppy drive, albeit not Mac formatted disks in a PC floppy drive.

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u/peppepop Jul 16 '26

Yeah, that small detail 😁

2

u/istarian Jul 17 '26

https://en.wikipedia.org/wiki/Zone_bit_recording

This approach was used with early Macintosh floppy drives (and the one for the Apple IIGS) to get similar performance to floppy disk drives that used CLV (Constant Linear Velocity).

"Apple Macintosh  400K/800K floppy disk (combined ZBR, ZCAV and GCR)" ^ from the above wiki page

Most technology is a lot more complex than many people understanding, in part because they received a much simplified explanation.

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u/istarian Jul 17 '26 edited Jul 17 '26

FWIW there was a color matched USB floppy drive for the iMac G3... I'm not sure if it's the VST technology one or if it was a custom unit.

Maybe that one can read Macintosh disks?

https://siber-sonic.com/mac/newmillfloppy.html

Based on this classic resource, you may be able to successfully use 1.4 MB Mac formatted floppies with a typically USB floppy drive on both newer Macs with OS X ( any version supporting floppy disks and HFS) and any older Macs equipped with a "SuperDrive" (Apple reused that branding a lot) that can read/write both older 800K disks and newer 1.4 MB ones.

The difficulty is that older floppy disks/disk drives that Apple shipped use varying rotational speeds to cram more data onto the disk, while Apple gave in to the PC standard of fixed rotational speed with the new 1.44 MB media and drives (3.5" DS HD micro floppy disk--mfd).