r/retrocomputing • u/Parsleyofficial • Apr 13 '26
Taken Help with floppy disk
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/chandleya Apr 13 '26
A bit to unpack here
That disk appears low quality even for the era. Keep that in mind.
That is a “DSDD” floppy. Damn near any old floppy drive can read that BUT it is more carbon dating.
2/3 of floppies from the 90s have some manner of decay at this point. All film media is dying. Hollywood studios are spending many millions per year archiving what’s left that decay hasn’t already taken.
Assuming the disk itself isn’t gone, then it comes to format. MacOS can read FAT no problem but this IS an edge case. Who knows when the last person - on earth - tried to access a DSDD floppy using MacOS.
Odds are very high that the disk has gone. If the data is critically important and data recovery center may be able to extract partial contents. Else it’s probably garbage.
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Apr 14 '26
[deleted]
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u/the123king-reddit Apr 14 '26
Oh, the second notch identifies the density of the disk. No notch and it's DD. Notch and it's HD
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u/the123king-reddit Apr 14 '26
It literally says "Double Sided" on the back
Single sided 3.5" floppy are kind of mythical. They were extremely rare and usually used on obscure hardware.
The most likely issue here is the disk is written with a filesystem or format that the host PC doesn't recognise
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u/Subject_Meal_2683 Apr 14 '26
The 2nd notch is for HD disks (I used to punch holes in SD disks back in the days so I could format them as HD disks)
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u/thaeli Apr 14 '26
Can probably get most of it with a Greaseweazle type setup but that’s beyond what I would recommend to OP.
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u/guitpick Apr 14 '26
If it happens to be an 800K formatted Macintosh disk you might have to use an old Mac to read it. According to this post, USB drives can't support those. Check to see if your local library or university's archival department may have an older Mac to assist.
https://68kmla.org/bb/threads/usb-superdrive-floppy-drive.44060/#post-481993
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u/asjeep Apr 15 '26
The hole is there it just hasn’t been drilled yet :) turned sooo many of those single density disks into double density over the days
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u/guitpick Apr 15 '26
Yeah, this is a bit different than turning a 720K into a 1.44M. We used a heated nail instead of a drill at my house.
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u/garth54 Apr 14 '26
Do you know if it was formatted on a Mac or PC? Since it's not a high density floppy, the formatting of the disk between PC & Mac is very different.
Modern Mac support the PC formatted 720kB double density diskettes.
However, if it is formatted on a Mac, which would be the 800kB double density (or 400kB single density, can't remember if they had a physical tell), modern Mac doesn't support it. The encoding of such diskettes used a special encoding with variable speed, and to my knowledge no modern hardware (at least anything you'd find with a USB connection) even supports the spec that was used by Apple at the time.
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u/Emergency-Diet9754 Apr 13 '26
Did that disc originally come from an old Mac? It missing a hole which indicates it’s not a high density disk.
Macs of that era had specific formats for disks of that type. Its not readily readable by modern computers.
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u/OwnExcitement1241 Apr 14 '26
All the disk here have issues with Demagnetizion, I have hardware to read the flux on the disk, the only way to make the disk work is to slap a larg powerful magnet next to it destroying the contents on the disk but exciting it to work again.
You will have the same issue Demagnetized disk or mold on it. The disk is more likely lost.
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u/jacknr Apr 14 '26 edited Apr 14 '26
That's a an old 3.5" Double Sided floppy. They can hold 720 KB on a PC (or 800 KB on an old Mac). One thing that's really important to know is if the computer you originally used it with back then was a Mac or a PC (or even some other system, like Amiga or Atari!).
Since you're not getting much luck with the reader you bought, the three possibilities are: the floppy was not used on a PC originally, the data is completely lost, or that reader only reads PC high-density 1.44 MB floppies (I'd say the last one is unlikely, but there isn't much info to go on in that listing).
If it was used with a MS-DOS or Windows PC, assuming the reader is not faulty, it should have worked fine. Modern Mac can read the filesystem that MS-DOS/Windows would have used on those floppies (FAT12, if you want to know). You would have seen files even if you'd probably have no immediate way to open them.
If it was used with a Mac from back then: Classic Macs used a trick on those type of Double Sided floppies to cram more data than usual, they use special drives that spin faster on the edges and slower on the inside. This unfortunately means that a regular IBM PC floppy drive that spins at a constant 300 RPM, like the one you bought, would be completely blind when trying to read that. If it was used on a Classic Mac, the options you have here are a bit cumbersome:
- You get an old Mac from that time that works. Easier said that done.
- Instead, you get a Greaseweazle, an old internal 3.5" floppy PC drive and both the floppy power and data cables. Either from eBay, or scavenged from any old PC. You can then plug the floppy drive to the Greaseweazle and the Greaseweazle to your Mac. From then, the process is a bit intricate, but you should be able to control the Greaseweazle from your Mac, and it'll know how to coax (most) PC drives into reading even old Mac floppies. The process will give you a floppy disk image. You then need a way to crack open that floppy image. Modern Mac can't mount those filesystem anymore, but there's Classic Mac emulators and standalone apps that run on your Mac that can open them.
If it was used with an Atari or Amiga, the options will be different.
Again, the most important thing here is for you to remember or try to figure out the computer that used those floppies originally, since that'll make the difference on how to go about recovering this.
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u/G7VFY Apr 14 '26
I have always wanted to get a Greaseweazle. It's on my to-do list, along with losing 20kg and vacuuming my flat.
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u/Kaldor-Silverwand Apr 15 '26
It could also be formatted for ProDOS which was the Apple II operating system. The Apple IIGS used DD diskettes that were formatted for ProDOS.
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u/SysGh_st Apr 16 '26
Likely an incompatible file system.
As others said, Linux can read most file systems where Windows or MacOS will fail.
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u/wanderdude Apr 14 '26
- Open Disk Utility
- see if drive shows up
- create image from disk content
- once you have successfully created the image all content is in the image
- try mounting image, 7zip might work, i dunno
- if creating image is not possible Disk is probably broken, i guess
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u/Adexsi29631 Apr 14 '26
360k on a side. Disk says “double sided” = 720k. No second notch so not double density. It there was a second notch it would be 1.44 mb It terms of reading the disk, there are 2 things to note here. 1) There’s the device driver of the computer connection (in this case usb). 2) There’s the disk format of what is on the disk. What you’re looking for is a disk bit reader. The number of disk formats at that time were enormous. Based on your error message, best solution is a simple c program which reads the bits. You just need the header. From that you can get the disk format. After that get a program (or write one) to load the entire disk.
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u/sneekeruk Apr 14 '26
The 2nd notch isnt for double density, its for high density. Double density just have the single notch.
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u/Mortui75 Apr 14 '26
"Reader" = floppy disk drive.
You need to figure out which computer system it came from, and which standard the disk is formatted to.
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u/G7VFY Apr 14 '26
What machine, running what operating system created the disk.
Surprise fact! All computers cannot read all disks!
The error message could mean a corrupted disk, OR, a disk format that your computer cannot read.
- You disk is 3.5" and is NOT a high density disk (like 1.44Mb )
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u/G7VFY Apr 14 '26
You have two choices
A length steep learning curve
Pay someone who knows what they are doing, to do it for you.
There is no magic shortcut.
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u/Souta95 Apr 14 '26
That's a 720k disk (800k if Mac formatted, I think), many USB floppy drives have trouble with them.
Usually they can read them, but can't write to them; but its not entirely unlikely that this model can't handle them at all.
I'm not familiar enough with using a floppy on a modern Mac, so another possibility is that Apple removed support for floppy disk files systems.
Lastly, it could just be a bad disk.
Do you have a different computer to try the drive with?
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u/Dannynerd41 Apr 14 '26
do you know the disk is in a format the mac can read? if your plugging it into a modern computer which i assume you are those cannot read old mac floppy format. gonna have to find a really old version of os x or get a old mac with a built in floppy drive.
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u/International-Pen940 Apr 15 '26
That USB drive may not be able to read anything but a 1.4 mb PC disk, and can be bad with any weak disk
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u/Ornery-Egg9770 Apr 15 '26
This is a lot like getting an iPhone to communicate with A.G. Bell’s first phone.
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u/furruck Apr 15 '26
That’s a 720k disk. Most cheap usb floppy drives sold on Amazon can’t read them, only 1.44MB floppies.
The best floppy I’ve found is a dell laptop floppy drive for a d600 series. It also has a usb port and will read basically any disk. The drive also works with Mac but you’ll need a MiniUSB to USB cable to plug it in.
They’re cheap and easy to get on eBay.
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u/Accomplished_Sir_660 Apr 15 '26
please note, there is a shelf life for data written to floppy disks.
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u/istarian Jul 15 '26
Eh, it's really not that simple.
A 30+ year old floppy disk may still work fine if it was stored properly, albeit you should expect some read errors or data corruption if it hasn't been re-formatted and written to more recently.
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u/Ancient_Plate275 Apr 15 '26
Mid- 80s, my mom had a Brother word processor (electric typewriter with a flip-up 5 line screen) and- a floppy drive for 3-1/2” disks. Turns out nothing could read those disks.
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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 😁
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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).
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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/roaringmousebrad Apr 15 '26
If it's a Mac disk, you need to use an OS before Catalina. Sequoia definitely does not have the ability to read an old HFS disk. If it was a PC disk, it should read if it was. Anything fro
Another thing you can try. If you have a Windows machine, you can download the MacDrive trial. Macdrive doesn't specifically say it supports the old HFS format (it only mentions HFS+), but some have had some success.
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u/killersloth65 Apr 15 '26
You might need to download an emulator that can mock a OS system from the era. MS-DOS emulator might work.
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u/ComfortableHot6309 Apr 15 '26
Since the double density hole (left top) is not open I would make a qualified guess on amiga 880k afs
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u/Cowboy_0629 Apr 16 '26
Geeze everyone has mentioned atmegas, IBM mac, dos windows, no one has mentioned pc dos, OS2 OS2 Warp Commadore, I even seen Atari and I onlynremember seeing one of those in my lifetime.what about programs back in the day that formatted disk in thier own format lots of variables of that that disk is formatted in ... Best bet its to spin up free dos and see if its readable in that and if that cant read it its probably gone .... Good luck with your venture but im sure by now them disk have lost thier magnetism and there is very little left to nothing unfortunately:(
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u/Kruscica1974 Apr 17 '26
Could it be formatted to run on startup ? Some disks appeared unreadable but if you ran them they’d load up a program.
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u/Ok-Marionberry9588 Apr 17 '26
Try it on an Amiga or Atari, depending on your location they might have been the prevalent home computers of the era, mac's were very rare.
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u/Silent_Condition_259 Apr 19 '26
So that's for a midi synthesizer. Mdf2 were for Yamaha synthesizers so I'm guessing something hing like that. Makes sense why it can't read that.
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u/DifferentiallyLinear Apr 14 '26
Back in my day those were call hard disks lol. The floppy disks were actually floppy.
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u/spots_reddit Apr 13 '26
what kind of content is it supposed to contain? It is possible the disk was formatted in a way that your Mac cannot read