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Questions tagged [floppy-disk]

For questions related to the use, restoration and imaging of floppy disks.

2
votes
3answers
179 views

What was the DOS FAT12 720k floppy raw disk format structure?

I am looking for detailed info on the low-level floppy disk structure of an MSDOS-compatible 720k Double Sided Double Density disk. Stuff like GAP/SYNC patterns, ID and CRC Field structure, standard ...
6
votes
4answers
534 views

Amiga floppy disks and GCR vs MFM

According to https://en.wikipedia.org/wiki/Group_coded_recording the Commodore 1541 disk drive used a particularly efficient GCR encoding scheme to cram 170K onto the same 5.25" disks that in an Apple ...
18
votes
7answers
3k views

Why not constant linear velocity floppies?

The outer tracks of a disk are longer than the inner tracks, and could therefore potentially hold more data. Constant angular velocity puts the same number of bits on every track, which wastes much of ...
2
votes
1answer
126 views

How to read old 3.5" Macintosh formatted floppies on a MacBookPro

I have connected a USB external floppy drive to my Macbook Pro (OSX El Capitan). I am unable to "view" the external drive, and hence unable to access the floppy content. I have inserted a floppy, ...
15
votes
4answers
3k views

Why did 3.5" floppies win? [duplicate]

It's an open question whether desktops would've kept using 5.25" until the end of the floppy era, but laptops meant something smaller was going to be introduced; that much was essentially ...
4
votes
2answers
261 views

Can a Harlequin ZX Spectrum clone be modifed to run CP/M?

The ZX Spectrum (and therefore the Harlequin) has its ROM from $0000 to $3FFF, while RAM further up to $5AFF is used for the screen (see Memory-Map). As CP/M expects RAM from $0000 upwards the two are ...
4
votes
2answers
123 views

Tools for creating disk images on Mac Plus

I got BMOW's floppy emulator and have been pulling a bunch of files from 30 year old floppies (which have a miraculously low rate of failure) onto my SD card. One of the things I wanted to copy was a ...
8
votes
4answers
2k views

Purpose of two disk drives on the Osborne 1

I recently discovered the Osborne 1 computer, and I noticed it had two floppy disc drives. What was the purpose of including two drives?
12
votes
1answer
348 views

What did Microsoft customize on Windows 95 installation floppy disks?

I have a Windows 95 Upgrade 3.5" DMF installation disk set where several disks were infected by the boot sector virus known as "Chance.A". I'm interested in restoring these to their original contents. ...
5
votes
1answer
335 views

How to install System 7.5.5 on a Macintosh SE/30 using floppies?

I have a Macintosh SE/30 with a formatted Disk. I'd like to install the latest System 7 on it that will run. According to Wikipedia that should be 7.5.5. According to several sources Apple has made it ...
3
votes
2answers
291 views

How can I use ImageDisk (.IMD) images with VirtualBox, WinImage, etc.?

I've got ImageDisk installed on my old 486, and I've been ripping some disks for archival purposes (some 3.5", some 5.25"). It spits out .IMD files, which contain some amount of header and metadata, ...
3
votes
2answers
80 views

FDD data dropouts after changing disks

I'm building a FDD controller out of a $10 microcontroller. It's mostly working pretty well, and I can read both 720kB and 1440kB PC MFM disks (the only ones I have to test with). However... if I ...
8
votes
1answer
319 views

Weak bits on floppy for copy protection

How did the vendors using copy protection create weak bits on the floppies? This always fascinated me as a kid. I ended up finding a weak bit emulator that would intercept the floppy disk interrupt ...
11
votes
3answers
686 views

Finding byte boundaries in floppy disk MFM bitstreams

I'm building myself a floppy disk interface based on a microcontroller. I'm successfully reading the bitstream off the disk and (probably) decoding the MFM bitstream into actual bits, based on the ...
47
votes
20answers
12k views

Did personal computers ever support 8" floppies?

When I look at the following picture, it seems a bit awkward to me that personal computers ever supported 8" floppies (unless the size of your computer case was as big as a fridge !): Am I right or ...
5
votes
1answer
500 views

Copying disk images to Commodore 64 floppy disks

For some time now I have been on a mission to get back into playing games on a Commodore 64. I have bought an original Commodore 64C. I got hold of a original 1541 disk drive. I also got hold of a ...
32
votes
8answers
9k views

Why were floppy disks invented after hard disks?

For those of us who grew up with personal computers in the 1970's or 1980's, the experience was a very gradual migration from floppy disks to hard disks as the primary persistent storage. So, based on ...
4
votes
1answer
172 views

Which DOS for a TRS-80 Model 4P?

Looking at the TRS-80 Disk Software Page, there's a rather extensive selection of DOS options that seem to work with the 4P and also claim high compatibility with the Tandy "TRSDOS" option. ...
1
vote
2answers
514 views

Commodore Amiga 600 Software Failure. “Error: 8000 0004 Task: 000026D0”

Software Failure on Commodore Amiga 600 when I insert a floppy in drive. Software Failure. Press left mouse button to continue. Error: 8000 0004 Task: 000026D0 Independent from the floppy I ...
3
votes
1answer
208 views

Using floppy disk interface on Future Domain TMC-1680 SCSI ISA card

I have this old card, a Future Domain TMC-1680 ISA SCSI card that has a 34-pin floppy disk connector on it. I am trying to research that to see if I can make it work (before anyone asks - just for the ...
11
votes
8answers
2k views

Why did common floppies never advance past 1.4 MB in size?

The chronology of some early floppy standards was: 80 kB, 160 kB, 360 kB, 720 kB, 1.2 MB, finally 1.44 MB. (There were less common sizes such as 250 kB, 800 kB, ...
8
votes
4answers
956 views

Were external floppy drives for Atari ST and Amiga inter-compatible?

Were external floppy drives for Atari ST and Amiga inter-compatible? For example, Commodore 1541* had its own serial bus protocol. But what about the external 3.5" DD floppy disk drive on 23pins D-...
8
votes
3answers
955 views

How to spin up 1541 drive without C64

I have a 1541 drive and I want to make it spin but I don’t have a Commodore computer. I don’t need to read data, I would just like the drive to spin. Can I manually tell it to spin using a raspberry ...
12
votes
4answers
4k views

Installing Windows 95 by floppy?

Ok so I have an old laptop with only a floppy drive. It came with windows 95 on it but suffered from some terrible BSODs that I could not resolve. I figured I would just download some windows 95 ...
9
votes
4answers
581 views

Is my opened floppy disk useless now?

I was wondering if floppy disks are ruined if, say, a terror of a 3 year old rips them apart... I had important pictures on a floppy disk. I was doing some spring cleaning and came across it and ...
9
votes
2answers
255 views

Disk drive long storage, with or without disk inside?

I am asking myself what is the best when storing a 3.5 disk drive for a long time but still planning to use it in the future, what is the best: Store it with a disk inserted, or leave it empts ?
0
votes
1answer
113 views

My floppy drive in my IBM model 8525-001 doesn't seem to be working

I tried to put a floppy disk into my IBM model number "8525-001" and it doesn't seem to be processing it. The light below the floppy drive blinks yellow every once in a while (such as when I turn the ...
7
votes
1answer
693 views

Availability of 5.25" floppy emulators?

Emulators from Gotek or HxC support 3.5" floppies. However none seem to support 5.25" PC drives. Are there any alternatives out there?
4
votes
3answers
1k views

Recovering old Commodore 5.25" floppy disks

I picked up a Commodore 64 with about 1,500 floppy disks. Many of them are de-magnetised and there is currently only one disk I can run (been through about 100, I can see the files of 2 or 3 disks, ...
3
votes
2answers
262 views

Commodore VIC-20/64/128/16/Plus 4 floppy disk drive replacement

We all know that floppy disks are getting hard to find, and floppy drives are fragile to begin with (especially Commodore's 1541 drive). I know that several companies and parties have released floppy ...
7
votes
6answers
3k views

Formatting a 720K floppy disk over USB fails with Windows 10

I've read many times that USB floppy drives will not format (or read/write) 720K disks. But then I read several posts online where people say they have done it. Even with Windows 10 (which is what I'...
12
votes
5answers
2k views

Adding the third floppy drive?

I've seen a few computers with more than two floppy drives, most with two 3.5" and one 5.25". My question is how was this achieved? I've heard that it could be done with a second controller card, but ...
8
votes
5answers
2k views

USB floppy drive emulator, is there such a thing? and if so, where can I get one

I'm aware of the floppy emulators that are installed to 3.5" bays where "disks" are stored on a flash drive. But what I need now is the opposite - essentially a USB dongle that emulates the floppy ...
-1
votes
4answers
504 views

Can a HiFi speaker erase a floppy disk?

I played 20 minutes of music with a floppy disk directly in front of the speaker's subwoofer. No damaged sectors at all. Can a speaker actually erase a floppy disk? How close does it need to be?
2
votes
1answer
184 views

How does a HD floppy drive react to an ED disk?

If one inserts an ED disk into a floppy drive, which supports sizes only up to HD, how does it cope with ED?
28
votes
11answers
10k views

Dealing with oversized files decades ago? Data transfer in the age of floppy disks

I can imagine the following situation 20 to 40 years ago inside a working office between two colleagues: "Can I have a copy?" "Sure, wait a moment....done! [eject] I'll pass that floppy disk onto ...
-4
votes
2answers
558 views

How long can a HD floppy disk hold 2.88MB before erasing itself?

From Wikipedia - Floppy_disk: to format or write to this high-coercivity media, the high-density drive switched its heads into a mode using a stronger magnetic field. When these stronger fields ...
41
votes
9answers
15k views

Why were floppy drives not any faster?

180rpm to 360 rpm, unlike 12000rpm on optical discs, was how fast floppy disks got. I am not sure, whether all drives had the same speed, but 360rpm is not close to the physical stress limitations of ...
11
votes
6answers
1k views

How to at least partially read damaged sectors of floppy disk?

It is necessary, that the floppy drive, just like CD-ROM, attempts achieving 100% data integrity using the help of error correction. If a sector is not readable, it just does not get sent to the ...
4
votes
1answer
507 views

DD vs HD vs ED floppy disks: lifespan/writecycle difference? Other differences?

DD, HD and ED floppy disks have individual materials to match their densities. But is density their only difference? Are there any differences regarding: Maximum allowable rotation speed? Rewrite ...
2
votes
2answers
186 views

Do DD floppy disks need regular full reformats?

http://retrocomputing.stackexchange.com/a/5449?noredirect=1 Floppy Disks have tracks that can be destroyed by a magnet, which would cause it to need full reformats, as stated in the answer link above....
25
votes
3answers
4k views

Magnetic exposure to floppy disk damages file system and requires complete reformat?

What I noticed is, that formatting a floppy disk takes three times as much time for the same data amount as writing a file to the disk normally. The accoustically perceivable jumps of the head between ...
7
votes
3answers
1k views

Was there a special drive, that saved much more than 1.44MB on an HD floppy disk?

I think that I have once seen an Internet article, which stated, that special drives are capable of making many megabytes of data out of one ordinary MF-2HD floppy disk. But I am unable to find it ...
3
votes
3answers
780 views

Is there anything useful for a retro in these cheap Chinese floppy drives?

Looking on eBay for floppy drives, I came across these incredibly cheap Chinese 3.5" USB drives (there are lots of them on offer). https://www.ebay.com/itm/USB-1-1-2-0-Portable-External-3-5-1-44MB-...
6
votes
2answers
315 views

Why might I get “drive not ready” when formatting a floppy?

I have a 3.5" floppy drive in an IBM XT 286 (5162). I can boot DOS from the floppy just fine but when I try to run FORMAT, it always says that the disk drive is not ready. Specifically: A:\>...
8
votes
2answers
948 views

Why is the RDY signal on floppy disk drives disabled?

While look at some 3.5" floppy disk drives I have, I noticed they have a little resistor missing next to RDY and, looking it up online, I find some instructions for adding a resistor there to enable ...
4
votes
4answers
581 views

Does low-level formatting improve floppy disk longevity?

I have a dozen or so 3.5" floppy disks from the 90's and most of them show bad blocks when I scan them with badblocks. If I do a low-level format, where the sectors are laid down again, will that make ...
19
votes
5answers
5k views

What makes a floppy disk bootable?

A lot of web sites describe how to create a bootable floppy disk using an existing image (via dd). But what about the image makes it bootable? I'm interested in making my own bootable floppy images ...
1
vote
0answers
404 views

What computer (possibly a PC compatible) rendered a spinning floppy disk on the screen on a boot error?

I recall seeing an IBM PC compatible or similar system many years ago in a business environment that had a distinctive boot error screen. The system showed a spinning floppy disk on the screen, ...
10
votes
4answers
658 views

Looking for an easy to use Commodore 64 disk/sector editor

First, let me say I understand that 'recommendation style' questions can be very subjective, but I believe there is enough value in a few good beginner resource pointers that others could benefit from ...