Windows vs Macintosh - floppy drives and diskettes

How can I read old Mac diskettes on my modern Windows (Linux) PC? or on an old Mac? Or can I 'connect' Apple floppy drives to my Windows computer to read Mac diskettes?"

This is a question about Apple Macs which I also cover in my List of frequent Macintosh questions. Go there to read specific answers to specific questions with brief commentary. Also, I cover floppy disk drive technology on my Tech information on floppy disks drives and media.. I sell and describe Apple Macintosh floppy drives on the linked Web page. I have a specific Web page about non-standard floppy controllers for old or recent Windows/Linux PC's, to read non-MS-DOS diskettes. This document provides more background. This document was last updated April 14 2022. (c) Herb Johnson 2022.

Standards not the same

Question: Can I hook a Mac drive to my Windows computer to read Mac disks? What is the interface for the Mac "high density" 1.4M 3.5" floppy drives? Are they a standard interface which could be used in a modern Windows PC?

The short answer is no. Further, the word "standard" is terribly misleading, especially when comparing Apple Macintosh products to PC Windows/MS-DOS products. "Apple" and "Windows" have very different hardware and software "standards". And there were floppy drives before either the Apple Mac or "Windows" existed.

What computer can read what?

Many (but not all) older Macs with floppy drives, can read and write PC/Windows diskettes. Generally speaking, NO Windows PC can read and write Mac format diskettes, - not without additional, specialized hardware or hardware "tricks". To understand these issues, one has to know about the binary level of drive interface hardware, the binary level of disk formats, and have some background in digital electronics. But knowing "it won't work" doesn't require one to know these details.

very different diskette formats, controllers, drives

Question: how are old Macintosh floppy disks "written" and why can't an old PC floppy drive read them?

"Format" for floppy disks, means how the individual bits are written and read. Disks must be "formated" before use. Formats establish patters of where data goes on a diskette, and the details of the patterns of data. Formats are not all the same. Formats are produced by a drive controller and software, not by the physical drive itself - the drive just reads and writes the data given, and moves the heads around. Please, please keep in mind: there's physical floppy drives, and then controllers, and then diskettes. "Format" is what the controller sends to the drives to format diskettes; or what the drives "read" as run by the controller. "files" reside as data, "in the format" established by the drive as controlled under software and hardware.

Mac floppy drives are connected via a 20-pin cable. Also, their floppy drives rotate at different rates depending on where the data is located on the diskette. Apple also has a scheme for their "file system" - how files are described and the file data is distributed on the diskette, They call that HFS (and a very early version was MFS). Use these keywords to find details elsewhere.

The old Apple Macintosh floppy drive formats, were supported by Apple's very specific floppy controller software and hardware. Apple developed what's called a "GCR" data scheme for their 400K and 800K floppy drive format. That's a description of how the bits are arranged on the diskette. Then files are written or read, expecting that format on the diskettes. Details can be found elsewhere.

The old Windows/MS-DOS 3.5" drives are supported at the BIOS ROM level in software. In hardware, a floppy controller "chip" technology was developed in the late 1970's for early personal computer use. These floppy drives use a 34 pin cable. This scheme was also used on 5.25" inch drives. The bits on these drives are written and read in a binary data format scheme called "MFM" (even older, "FM"), and these drives rotate at a constant rate. The scheme for file descriptions and where data is on the floppy diskette, is called "FAT". This scheme was established in the 1980's on MS-DOS based computers. Use these keywords to find details elsewhere.

When Apple's 1.4M floppy drive was developed, Apple developed their own MAC format for use, similar to the 800K format. But they also developed means to read and write "MFM" data to support "DOS format" 1.4M and 720K diskettes. Mac files under "DOS format" don't have all the features of "Mac format" files.

In either case, Mac or Windows, these formats for binary data and file data are produced by floppy controller hardware and software. They are not "inside the floppy drive". That is a common misconception. "Magically" hooking up a physical Mac floppy drive to a PC/Windows computer, or vice versa, won't help you out. The problem is in the Windows PC's controller hardware and software. The Mac drives won't "fit", the controller can't "control" it. This will not work.

Meanwhile: All but the earliest Apple Macs with 1.4M Apple drives can, with proper hardware and software, produce and read both Apple 1.4MB and 800K diskette formats, and PC 1.44MB and 720K diskette FAT formats. (The oldest Mac 400K format is a little less available, check your Mac model for specifics.) That's due to the MAC COMPUTER'S software and hardware controller, and Apple support software. However, the hardware and software on a PC/MS-DOS/Windows computer cannot create or read the Apple Macintosh 400K and 800k formatted diskettes. PC hardware is not able to read the "GCR" bits, or change the speed of the drives used on PC's.

more details

Question: what old Mac can I get, to read old Macintosh diskettes, and to transfer files to MS-DOS format diskettes?

If you want to read old Mac diskettes to recover files onto your "modern" computer, you might get an old Mac to read them and rewrite the contents into MS-DOS FAT format 1.4M diskettes,. Then read them on your "modern" computer - if it has a floppy drive (USB or internal). The old Mac will have to have 1.4M floppy drives, and run an OS that supports Apple File Exchange, which was introduced into later versions of Apple's System 7. Most desktop Macs which run System 7.5 or OS 8, and have a "68K" processor or Power PC processor, "ought" to be able to do this. This is not a guarantee or warranty - check your specific Mac and OS. Also look at my Mac FAQ which discusses File Exchange a bit more.

Question: what old PC or MS-DOS computer or Windows computer can I get, to read old Macintosh diskettes, and to transfer files to MS-DOS format diskettes?

Your old PC can only read FAT format diskettes. Some Mac disks are in Mac format, you cannot read those. The problem is in the PC floppy controller, and the PC floppy drives. "Normal" old PC or MS-DOS computers don't have the "Apple" controller. In the 20th century, there were a few specialized PC cards that could read Apple-format diskettes. I have a specific Web page about these non-standard floppy controllers, for old or recent Windows/Linux PC's, to read non-MS-DOS diskettes.

Question: so what is available today for my modern Windows PC, or OS X computer, to read floppy diskettes?

By the 2010's, what used to be a "standard" on Windows/MS-DOS PC's - a floppy disk drive controller chip or equivalent function in a larger chip - is now out of modern PC production. The same applies to Apple's computers, they also stopped offering floppy drives about or before that time.

Modern Mac and Windows computers can operate a USB to floppy "adapter" - an external 3.5" floppy drive with an internal microcontroller and a USB cable. That little controller in the "drive" is a small computer that ONLY supports 1.44Mb and 720K PC formated (MS-DOS, MFM) diskettes. So, to the desktop computer, this USB device is simply some device with files on it, like a USB thumb drive, a USB attached digital music player, etc. I'm not aware of any simple, commerical "USB floppy drives" other than those produced to format, read and write Windows FAT format 800K and 1.4M floppy diskettes. You'll need a "driver" to operate these. Later Windows systems "searched the Web" to find the correct drivers. I don't know how OS X supports these drives.

In the 21st century, there MAY be specialized USB-based floppy controllers (often sold without drives) that support Apple's 800K or 1.4M disk formats - read their support information very carefully, to see if they do so and how they do it. They may only support MS-DOS FAT formats, or other computer formats. This will not be "plug and play" technology!!! Typically these are non-commercial "hobby" devices that may only be available for a few years at a time: you may have build them from components; they may have software for Linux and not Windows. And they may not operate like hard-drives and thumb-drives, you may have to run specific programs to "transfer files". Find all the information you can on some particular "kind" before you buy.

Otherwise these noncommercial items come and go from year to year. I can't reliably point to any persistant producers in the 21st century; I haven't "endorsed" any brand or model. I have other Web pages which discuss some of these. Your best bet for these devices is to do a Web search, find what has persisted and see how people are using it.

- Herb Johnson

Herb Johnson
New Jersey, USA
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