Questions tagged [floppy-disk]

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

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14
votes
2answers
3k views

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 ...
9
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1answer
3k views

Approximately how many 3.5-inch floppy disks have been produced before manufacturing was stopped? [closed]

3.5-inch floppy disks are not produced anymore, with I think Sony being the last to stop manufacturing in March 2011. Meaning that all floppy disks that exist are currently in circulation and the ...
17
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5answers
2k 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 ...
5
votes
4answers
394 views

How did the Spectrum clones with TR-DOS and paged memory load and run code files from disk?

I've been playing with Spectrum emulators, their file formats and some reverse engineering tools recently. Thanks to this forum, I was able to parse the TR-DOS disk image format and find the bytes of ...
4
votes
1answer
197 views

What information could be recovered from visualized magnetic information?

I was wondering how the data on a floppy disk physically looks like. With data stored on a magnetic disk obviously that isn't visible. The Wikipedia article on floppy disks however shows a beautiful ...
4
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1answer
205 views

How to repair IIgs 3.5 floppy drive?

The Apple 3.5" Drive on my IIgs still reads disks, but eject no longer works. The failure to eject is silent, no errors, noise, or motion. With a paperclip I can get the disks ejected but this is ...
32
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12answers
12k 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 ...
11
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1answer
2k views

What is the (standardized) weight of a 3.5 inch floppy disk?

What is the weight of a 3.5 inch floppy disk and was the weight ever standardized?
2
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2answers
194 views

How to determine the required RPM for a 3.5-inch floppy disk?

In addition to my other related question Is it possible to read floppy disks at non-standard rotation speeds (RPM)?. How to determine the required RPM for a 3.5-inch floppy disk as disks can ...
1
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2answers
206 views

Is it possible to read floppy disks at non-standard rotation speeds (RPM)?

According to this article 3.5-inch floppies rotate 300-600 times per minute (RPM). It is possible to overclock the RPM and will that result in higher transfer speeds? Or is it possible to read a disk ...
9
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1answer
184 views

What is the effect of direct exposure of the magnetic disk of a floppy to ultraviolet (UV) light?

I was thinking of the mold issue of floppies and UV light (UV-C) came to mind. As ultraviolet (UV) is a form of electromagnetic radiation and floppies use a magnetic disk for storage and I vaguely ...
6
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1answer
236 views

Commodore 1581 crashes during format

I have a Commodore 1581 (800k 3.5" DD) floppy drive which reads and writes data just fine (with DD disks only of course), but it crashes (drive keeps spinning forever, stops moving the head and ...
5
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1answer
470 views

Copy content between floppy disks on Apple II

I own an Apple IIe with the Apple DuoDisk device. I've been trying to find out if it is possible to copy content from a floppy disk inserted into the disk 1 slot into a floppy inserted on the disk 2 ...
26
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3answers
4k views

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 ...
14
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6answers
1k 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 ...
8
votes
2answers
590 views

What's the timeline of Commodore diskette drives?

Commodore produced a number of different floppy diskette drive units, both 8" and 5.25", over the course of its history. Can someone provide a chronological list of the drives, their release dates, ...
23
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8answers
5k 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 ...
55
votes
9answers
20k views

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 ...
50
votes
20answers
14k 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 ...
37
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8answers
8k views

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 ...
4
votes
1answer
168 views

At which RAM address is the Microbee disk boot sector loaded and executed?

The Microbee was an early '80s Z80 microcomputer from Australia that was successful mostly in education. Looking at some disk image files I've downloaded I can see the disk layout seems to be very ...
3
votes
1answer
331 views

Algorithm to properly format 360k 5.25″ diskette in a 1.2M drive?

This is a low-level tech question, as I am developing a driver for an FDC at its command-set level. Having reviewed a number of sources, I cannot find the algorithm to format a 360K diskette using a ...
4
votes
0answers
140 views

What does a "DK" signature mean at the start of track 0 sector 3 of a Dragon 32/64 floppy disk?

I'm looking at disk image files for the Dragon 32 / Dragon 64 computers. The Dragon computers are very similar to the Tandy TRS-80 Color Computer "CoCo" but are not clones and are not the ...
31
votes
6answers
13k views

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 ...
12
votes
6answers
4k views

Is there a device that connects to a USB port and acts like a normal PC floppy drive?

I'm aware there are floppy emulators that are installed to 3.5″ bays where disk images are stored on a flash drive. But what I need now is the opposite: essentially a USB dongle that emulates the ...
6
votes
3answers
1k 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 ...
6
votes
3answers
3k views

What are D64, T64, D71 and D81 files?

The docs for the Ultimate-II+ expansion cartridge for the Commodore 64 state: It is able to read D64 files, as well as D71 and D81 files (no partitions), T64 files. So what are D64, T64, D71 and D81 ...
19
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9answers
14k 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'...
1
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1answer
439 views

How to write Apple IIgs .po disk images to Floppy Disks with an older Mac

I recently acquired an Apple IIgs with two 3.5" floppy drives and no hard disk. I'm very seasoned with older Macs, but I have no experience within the Apple II world. I search for a way to create ...
10
votes
9answers
4k views

Were any external disk drives stacked vertically?

There was a time when floppy disk drives were big, expensive devices that in many cases, instead of being components of a computer, would be separate machines connected by a cable, in some cases with ...
24
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4answers
3k views

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 ...
5
votes
1answer
244 views

How did games written for tape-based BBC micro, get officially and unofficially ported to disk, bearing in mind extra workspace needed by DFS ROM?

If I recall, PAGE = &E00 for a BBC Model B system with cassette tape based storage. On installation of Acorn DFS ROM (with 8271 Floppy disc controller), the ROM allocated more memory, increasing ...
1
vote
1answer
149 views

How to flash CDTV extended ROM using development board

I have a CDTV ROM development board, and I know it is possible to flash it using floppies. How to make such floppy with a custom rom?
19
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2answers
1k views

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. ...
30
votes
4answers
2k views

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 / ...
2
votes
1answer
206 views

"Restoring" a 1986 Compaq Portable II (Cabling question)

I am in possession of a working 1986 Compaq Portable II. However, I couldn't find a 5.25" floppy with the proper version of DOS on it to actually make the computer, ya know, work. I've since ...
7
votes
2answers
514 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?
18
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3answers
5k views

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 ...
7
votes
1answer
1k views

I can't read DS 1MB floppy disks

Using an USB external floppy drive, I've been able to use my Mac to back up files from a big box of 3.5 inch floppies (800K, HD 1.4MB). But I cannot even read my DS 1MB floppies using either the ...
27
votes
9answers
7k views

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 ...
10
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2answers
1k 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:\>...
10
votes
1answer
460 views

Understanding the DMK disk image file format used by TRS-80 emulators

DMK is a low-level disk image file format used by TRS-80 Model I & Model III, Tandy Color Computer, Dragon 32 & 64, and MSX emulators. It's capable of representing copy-protected disks and all ...
25
votes
5answers
11k views

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 ...
3
votes
2answers
257 views

Did any 5.25" floppy drives not based on the Apple Disk II offer quarter-track control

Unlike many drives, the Apple Disk II has inputs that control the individual head stepper coils. These are commonly described as advancing by half-tracks, since advancing a full track requires ...
11
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2answers
1k views

What physical size and density floppies are the intermediate-capacity options for the /F switch of the DOS/Windows/OS/2 FORMAT command meant for?

In MS-DOS 5.0 and newer, PC-DOS 5.0 and newer, Windows 9x, Windows NT 3.1-2000, and OS/2 4.x, the FORMAT command (present in some form or another in literally every single version of Q/86-/MS-/PC-DOS, ...
17
votes
3answers
2k views

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 ...
12
votes
2answers
689 views

How did 512 Bytes come to be the most common sector size?

It was long assumed by FS drivers that all diskette and harddisk units operate in blocks of size 512 Bytes. How did this happen to be the case, historically? Why not the "neater" 1 KiB, say?
1
vote
2answers
220 views

AST Laptop With No OS

I work in network design/IT for a church, and a someone came in with a AST Advantage Explorer 486SX/33. It looks like it has no OS. After failing to boot, it requests to go to the BIOS to look for an ...
41
votes
3answers
7k views

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 ...
0
votes
3answers
426 views

Can I use a 2880 KiB ED floppy disk in a drive that uses the standard 1440 KiB HD disk?

I am using Windows XP with an old accounting app, that will only back up to a ‘3.5 inch’ floppy disk. The backup requires a second disk to complete the job – a pain. Would an Extended Density 2880 KiB ...