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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14 votes
6 answers
2k views

Was drilling 3"5 720 KiB floppies to 'upgrade' them to 1440 KiB at all reliable?

I remember back then, there were few people that used to drill an extra hole on them to double their capacity. Surprisingly, it worked! While the other way around is plausible I am quite unsure of the ...
1 vote
0 answers
83 views

Can a floppy disk be formatted in another size for (read-only) backwards compatibility? [duplicate]

Is it possible to format a 3.5″ floppy disk in another size? For example an original 1440 KiB floppy as a 720 KiB or 360 KiB disk thats (at least read-only) compatible with 720 KiB or 360 KiB drives? ...
26 votes
4 answers
4k 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 ...
4 votes
1 answer
236 views

Are the ACTUAL DISKETTES different for 360KB Single, or Double sided? 1.2M? [duplicate]

I have lots of old IBM 5.25" diskettes. I have 360 kB "Single sided", 360KB "Double Sided" and 1.2 MB diskette drives. Are the diskettes THEMSELVES different for use in these ...
11 votes
2 answers
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?
17 votes
1 answer
1k views

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?
3 votes
0 answers
343 views

What was the last 5.25-inch floppy disk drive manufactured?

Assuming that no manufacturer of removable-media disk-drives is still manufacturing disk-drives for 5¼-inch floppy disks - what was the last drive model manufactured / sold and who was the ...
8 votes
3 answers
434 views

Reading data of floppies from a ZX Spectrum Swift Disc

Back in the day when we had a Sixword Ltd. Swift Disc floppy-drive we were ahead of the game on our speccy, allowing us to use 3.5inch floppy disks. See: https://www.worthpoint.com/worthopedia/swift-...
9 votes
0 answers
117 views

On the TRS-80 models I and III when is the directory track number written in the third byte of sector zero, and when in the second byte?

Earlier I had found that many but not all TRS-80 Model I and Model III disks begin with the three bytes 00h FEh 11h. This is the beginning of the boot sector where the CPU interprets it as a NOP ...
20 votes
4 answers
2k views

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 ...
26 votes
2 answers
5k views

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 ...
11 votes
2 answers
672 views

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

If one inserts an ED disk (Extra-high Density disk) into a floppy drive, which supports sizes only up to HD (High Density), how does it cope with ED?
4 votes
1 answer
279 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 ...
5 votes
3 answers
363 views

Confused about FM encoding

I'm finding what appear to be two different descriptions of how FM encoding on early floppies worked. In this description (see page 2 if it didn't go there directly) it appears that FM is nothing more ...
5 votes
1 answer
311 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 ...
9 votes
2 answers
744 views

I get I/O errors when writing a disk image to a new old-stock floppy in a USB drive. How can I resolve this?

I wish to create a bootable DOS 3.3 installation floppy disk (3.5″, 1.44MB, 2HD, Sony branded) for my AST Premium Exec 386SX/20 laptop. I have bought a new USB floppy disk drive and connected it to an ...
13 votes
4 answers
3k views

Writting DSK images onto a 3″ floppy for Amstrad/Sinclair computers

For a project I'm working on, I need to write some disks to test on my Amstrad CPC 6128. I've got some 3″ blank disks, and all my Amstrad computers (CPC and PCW) have 3″ disks, as well as my Spectrum +...
26 votes
5 answers
7k 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 ...
7 votes
1 answer
384 views

Did OSes write the floppy's logical sector number resulting from sector interleave/skew in the IDAM sector ID, or was it up to the OS?

I've been looking at MicroBee floppy disk image files. They use the DSK/EDSK image file format originally created for Amstrad CPC emulators, probably because both systems use derivatives of the CP/M 2....
6 votes
3 answers
557 views

Were commercial Amiga floppy disks shipped with write protection?

In this Amiga "quick kickstart guide" magazine thing that I have from when I bought an Amiga 1200 long ago (it seems to be printed in late 1995), they really go out of their way to point out ...
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 ...
4 votes
1 answer
343 views

What did "double track" mean in relation to floppy disks?

I mostly used 3½″ floppies back in the day but I also used 5¼″ floppies to some extent on Apple II's and TRS-80's. I was never exposed to 3″ floppy disks as used mainly on Amstrad microcomputers and ...
17 votes
6 answers
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 ...
14 votes
4 answers
1k views

How to build a workstation to handle bulk quantities of floppy disks?

I need to handle bulk quantities of floppy disks, where I archive their contents, then recycle them by formatting them for use on old Amiga/Atari/MS-DOS computers. I have a 3.5" floppy disk drive ...
0 votes
2 answers
196 views

Could visual inspection of the magnetic disk be used to detect the quality (or damages) of a floppy disk?

The magnetic floppy disk is sometimes used as an (infrared) light filter as shown on some pictures below. That led me to think about the actual magnetic disk and if inconsistencies or damaged could be ...
4 votes
3 answers
358 views

How do I know where the file directory is stored on a Spectrum +3 disk layout?

I'm trying to parse Spectrum +3 disk images. I only ever had a tape-based Speccy back in the day. The +3 had a built-in floppy drive but was late to the party and not that successful. It had the same ...
1 vote
4 answers
438 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 ...
3 votes
2 answers
241 views

What do abnormal sounds or vibrations of a spinning floppy disk inside a floppy drive mean?

I saw this floppy drive sound emulator and this floppy disk sound video and wondered if the sound of a floppy drive or more specifically a the sound of a floppy disk spinning in the drive, could tell ...
15 votes
2 answers
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 votes
1 answer
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 ...
5 votes
4 answers
514 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
1 answer
244 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 ...
32 votes
12 answers
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 ...
2 votes
2 answers
247 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 ...
9 votes
1 answer
223 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 votes
1 answer
259 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 votes
1 answer
646 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 votes
3 answers
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 ...
8 votes
2 answers
607 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 votes
8 answers
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
9 answers
21k 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
20 answers
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 votes
8 answers
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 ...
3 votes
1 answer
378 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
0 answers
151 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
6 answers
14k 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
6 answers
5k 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
3 answers
2k 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
3 answers
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 votes
9 answers
15k 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'...