Questions tagged [floppy-disk]

Use, restoration and imaging of floppy disks; low-level formats of floppy media. Consider [file-system] for high-level formatting.

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What is the "two-drive trick" that can read Amiga disks on a PC?

Standard belief is that the floppy disk controllers used on PCs are incapable of reading Amiga floppy disks, due to the PC disk controller expecting a very specific low-level format of disks, whilst ...
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55 votes
9 answers
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How long will floppy disks maintain data integrity?

This was on CNN today: The U.S. is still using floppy disks to run its nuclear program Which led me to read through this article: Think the floppy disk is dead? Think again! Here’s why it still ...
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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 ...
aybe's user avatar
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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 ...
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What is between the sectors of floppy disks?

I've found this page which has an informative description of how sectors were encoded on floppy disks: http://nerdlypleasures.blogspot.com.au/2015/11/ibm-pc-floppy-disks-deeper-look-at-disk.html Do ...
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How long can a floppy disk spin for before wearing out?

I'm mainly interested in 3.5" floppies here, as they're what I have lying around, but other sizes could also be interesting to hear about if anyone has the data. As I understand it, the head rubs ...
spacer GIF's user avatar
36 votes
8 answers
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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 ...
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What modification is required from a PC floppy for use in Amiga?

Around the end of the time of Amiga popularity, obtaining a replacement Amiga floppy drive was a nuisance, while PC drives were ubiquitous and cheap. One could install a PC drive in Amiga after ...
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Why did connecting the IBM PC 3.5" FDD backwards cause the problems it did?

When the 3.5" FDD was introduced for the IBM PC and compatibles (or possibly earlier), someone made a decision to make the data cable between the controller and drive unkeyed. This, of course, meant ...
user's user avatar
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What are the three or four holes on the back of a 3.5inch floppy disk indicating and used for?

Why do 3.5 inch floppy disks have sometimes three and others four holes on the backside? What's the difference, what do this holes indicate and what are these used for?
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Dumping and archiving C64 disks

Doing spring cleaning with family, I found some old C64 disks. These are really old and no one knows what to do with them. Archiving or dumping them seems to be options but we are unsure how to do so ...
Anthony Pham's user avatar
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32 votes
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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 ...
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How does "bit-slip" copy protection work?

Some Apple II 5.25" floppies used a special pattern of bytes that could not be automatically detected by disk copying software. How could the pattern be invisible to disk copiers but detectable by ...
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What were the differences in floppy disk formats between Amiga and IBM/PC compatible computers?

The capacity in Amiga Old File System format (OFS, OS version 1.x) was 840KB, with the Fast File System ("FFS" (!)) introduced for OS 2.x onwards able to store 880KB. The PC format stored 720KB on the ...
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Can I image Amiga floppy disks on a modern computer?

Is there any way of reading Amiga floppy disks to a PC hard drive? Can I use a standard floppy drive with a firmware program that will translate it? Do I need an external drive or a working Amiga ...
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Absolute maximum number of nibbles on an Apple II floppy disk track?

The Apple 2's disk drive controller and 5¼" floppy disks have the following metrics: The disks is spun at (roughly) 300 RPM (Revolutions per Minute), which means it takes = 1000 ms/sec / (300 RPM / ...
Michaelangel007's user avatar
29 votes
3 answers
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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 ...
neverMind9's user avatar
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27 votes
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What other tricks were there to get more data onto floppy disks?

I remember using a utility back in MS-DOS 3.3 days, called MAXI Disk, that somehow magically managed to get 420K on a 360K 5¼″ disk. I assume it managed it by destroying some redundancy like a backup ...
user230910's user avatar
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Why were 5.25″ floppy drives cheaper than 8″?

The first floppy disks were eight inches. This size was set by IBM; I haven't been able to find any indication of why they chose it, but maybe it was just because it seemed quite small to them ...
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Twist in floppy disk cable - hack or intended design?

There are many documents (e.g. this) describing the twist on two-drive floppy disk cable on IBM PC compatibles. While this is not the most proud example of clean hardware design, how much of this was ...
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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 ...
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When did 5.25″ floppies exceed the capacity of 8″?

When 5.25″ floppies were introduced, in the mid-to-late seventies, they would have had less capacity than the older 8″ because, well, less area on which to store data. On the other hand, being cheaper ...
rwallace's user avatar
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Which software was the first to use copy protection?

While researching early magnetic storage around 1980, I've come to ponder if we know of the first piece of software on removable media that employed copy protection? The Wikipedia article mentions ...
Micropolis's user avatar
26 votes
4 answers
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Cleaning 5¼" floppy drives

Going to the store is treacherous for me. So I prefer doing stuff at home, including cleaning up 5¼" floppy disks with only home supplies. Unfortunately, I do not know how or which materials/chemicals ...
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Did something like floppy disk jukeboxes for home computers exist in the 70s or 80s? Would that have been a feasible concept?

Many home computers in the 1970s and 1980s had two floppy disk drives, or owners bought a second drive, to reduce having to play disk jockey. A second drive was especially popular with Commodore Amiga ...
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24 votes
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Why was the shrinking from 8″ made only to 5.25″ and not smaller (4″ or less)?

Answers and comments to Why were 5.25" floppy drives cheaper than 8"? suggest some reasons why floppy disks moved from 8" to 5.25"; basically it seems the smaller size reduced engineering ...
rwallace's user avatar
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23 votes
8 answers
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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 ...
rwallace's user avatar
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Can my floppy disk still work without a shutter spring?

One of my floppy disks' shutter spring got lost. Now the shutter can't slide normally. Can I still use the floppy disk?
Ryan Almirañez's user avatar
21 votes
9 answers
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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'...
cbmeeks's user avatar
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21 votes
2 answers
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Is there a better way to the 6 disks install of Windows 3.1

I want to install Windows 3.1 on my MS-DOS 6.22 Machine. I have the 6 disk images. But I only have 1 or 2 spare Floppy disk that I can write the disk images onto. One way I can think of is to write ...
Tom Shen's user avatar
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21 votes
6 answers
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Wanted: 5.25" floppy to USB adapter

I have found inexpensive (~$15) 3.5in floppy to USB adapter cables but have been unable to find a similar adapter for 5.25 floppy drives. Does anybody make such a thing? Are the pinouts of a 3.5 the ...
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Can powering on/off a 1541 damage a disk left inside?

The User's Guide for the Commodore 1541 disk drive includes a vague warning, on page 7, to "remember to always remove the diskette before the drive is turned off or on". Some third-party ...
Psychonaut's user avatar
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When low-level formatting a floppy, how does one ensure any existing sector markers are overwritten?

If a formatted floppy diskette is reformatted with a low-level¹ format, how does the formatting routine make sure that any previous sector markers are fully overwritten? In particular, how does it ...
cjs's user avatar
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How did the Apple IIGS automatically slow 5.25 inch disk I/O code for backwards compatability?

Apple II software often used hard-coded timing for 5.25 inch floppy disk I/O, for example to control the duration of each track step or the rate at which bytes are written and read from the disk. ...
bmow's user avatar
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1 answer
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Did 5.25" floppies undergo a change in magnetic coating?

3.5" floppy disks, in the transition from 720K to 1.44M, changed the actual coating to a different compound that was magnetically 'stiffer'. This was necessary to support the higher density, but meant ...
rwallace's user avatar
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Can you use 5.25 HD floppy disks in a DD drive?

Is is possible to format and use 5.25 high density disks in a double density drive?
Matthew's user avatar
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Is it possible to adapt a standard PC floppy drive to work in an IBM PS/2?

I have three different IBM PS/2 machines and all of them are in perfect working order—except for the floppy drives. None of the floppy drives will read disks, which means all I can do is key in BASIC ...
Cody Gray - on strike's user avatar
17 votes
6 answers
3k views

How does a floppy drive identify the first and last sectors and tracks?

I've recently found a more modern application "Floppy Disk Master-7"(Picture 2) (FDM) that visualized the bad sectors, tracks and clusters(Picture 1) on a floppy disk in a similar (but ...
Bob Ortiz's user avatar
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17 votes
3 answers
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What were practical uses of SCSI floppy drives?

I've always been fascinated by the rarity and elitism of such devices. However, from a practical standpoint, I don't understand why such low transfer rate device ended up in a bus commonly used for ...
aybe's user avatar
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Why did 3.5" floppies win (and not another size)?

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 ...
rwallace's user avatar
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16 votes
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Did the original Macintosh not have any MIDI or similar music capabilities?

The original version of Shadowgate for the Macintosh is an eerie experience after you have played the NES version, with its amazing soundtrack. The Mac version is entirely mute, save for some random ...
user27284's user avatar
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5 answers
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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 ...
redsPL's user avatar
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16 votes
4 answers
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Is there any way today to recover/dump 2M disks?

2M disks where formatted using 2MGUI to increase 3"1/2 & 5"1/4 DD/HD/ED disks' capacity. Is there any way today to recover/dump these disks to a file with modern hardware? Specially the 5"1/4 ...
NataliaPC's user avatar
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16 votes
3 answers
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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 ...
David Given's user avatar
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15 votes
8 answers
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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, ...
jwzumwalt's user avatar
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15 votes
2 answers
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Why are the magnetic floppy disk drives (FDD) heads not frictionless?

After reading this answer to the question How long can a floppy disk spin before wearing out? ... one could see thru the floppy... Not just badly worn, but the magnetic coating was outright polished ...
Bob Ortiz's user avatar
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15 votes
7 answers
2k views

Amiga floppy disks and GCR vs MFM

According to the Wikipedia article on GCR, 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 drive only ...
rwallace's user avatar
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15 votes
3 answers
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Windows 95 installation floppy images are larger than 1440 KiB. How can I fit their contents on standard floppies?

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 install ...
Mark's user avatar
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15 votes
4 answers
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Where can I find an external 8-inch floppy disk drive?

Where can I find an external 8-inch floppy disk drive? I have some data I would like to retrieve from a really old 8-inch (200 mm) floppy disk, but have no working computer than has a drive to read ...
Jeff's user avatar
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15 votes
2 answers
3k 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 ...
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