Questions tagged [floppy-disk]

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

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3
votes
1answer
178 views

Where can this "boot.B" file be coming from on this Spectrum TR-DOS disk image?

After working on some tools that parse the TR-DOS disk image format .TRD files for a while I just noticed that one of the game disk images I had downloaded "La Abadia Del Crimen", only has three files ...
3
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1answer
925 views

Problem reading 720KB floppy disks containing dat [closed]

I am using a USB connected "Sabrent FD-05PUB" 3.5" floppy drive to read data using Windows 10 computer. It shows in Device Manager as "TEAC USB UF000x USB Device" The 1.44MB disks read just fine. All ...
1
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1answer
171 views

How does the Spectrum +3 know how many files are in the disk's directory?

The Spectrum+3 uses a version of the Amstrad and CP/M disk layout. The Speccy version has a directory at the start of the disk after any reserved tracks and it can hold up to 64 files. Each ...
0
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1answer
185 views

What did "double track" meaning 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 ...
0
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3answers
428 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 ...
2
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0answers
94 views

Transfer a TeleDisk image of a 5.25 disk to a 3.5 disk

I am trying to power on an old Siemens PG675. It need a 5.25 disk but unfortunately it is missing. I found a TeleDisk image (.TD0) of this disk, and I would like to transfer it to a 3.5 floppy disk (I ...
3
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2answers
277 views

Why did the Apple Disk II version 3.3 change the boot protocol?

From what I understand, early versions of the Disk Controller II required that there never be two or more consecutive bit times without a phase transition (which would read as "0") but an upgrade to ...
1
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2answers
216 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 ...
5
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4answers
1k views

How does the Spectrum +3 know whether a disk is bootable or not?

I've been looking through documentation on The Sinclair/Amstrad Spectrum +3 which was the only Spectrum that came with a built-in floppy disk drive. The disk format was based on The Amstrad CPC and ...
3
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1answer
332 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 ...
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2answers
461 views

Reading 360k floppy disk in 1.2M drive

I formatted several 5.25" diskettes with 360k and 1.2M on the Windows XP PC using 1.2M (HD) drive. I am using the same drive to read data from 360k diskette back using custom driver. The controller ...
5
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4answers
398 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 ...
3
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2answers
694 views

What file formats were used for binary executable files on later Sinclair ZX Spectrums?

The last official version of the Sinclair ZX Spectrum was the +3, released after the company was owned by Amstrad. It included a 3-inch floppy disk drive as used on other Amstrad computers. But even ...
13
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5answers
2k views

How are blocks stacked on a floppy or older HD

I tried to understand how to read a floppy image format (.sdk). The format is based on CP/M 2.2 filesystem. I've lost track, and I think it's my third attempt. Now I am looking more into what these ...
6
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2answers
304 views

Why does _Beneath Apple DOS_ show FM encoding rather than GCR?

From the beginning in 1978 the Apple II floppy disk system used GCR encoding to convert data bytes to sequences of binary values to be written to the diskette: first 4-and-4 encoding (never released), ...
5
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2answers
543 views

Mismatched floppy disk/drive reading and writing, what should one keep in mind?

Mismatched disk/drive refers to, for example, reading/writing a 720K disk with a 1.44M drive. Don't forget LS-120 and LS-240 SuperDisk drives, they can use standard floppies too. What can and can't ...
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, ...
8
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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, ...
20
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1answer
3k views

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 ...
1
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0answers
396 views

How can I read/write/format 5.25" 40-track MFM floppies on modern systems?

I've got a Fujitsu FM-7 with an external 5.25" floppy drive unit; it has a pair of 40-track, double-sided, double-density¹ drives. These use a fairly common low-level track format: the standard "IBM ...
7
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2answers
1k views

How to backup/dump Atari 520st floppy disks on modern hardware

I know the real answer is to download cracked games but in the era before Internet was afordable I have a lot of community games which never reached the Internet which I would like to rescue as some ...
11
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2answers
843 views

How can I read a 5¼″ drive on 1996–2007 equipment?

In my organization's archive I just found some 5¼″ floppies, presumably IBM PC 320/360k. They contain information that we have on paper, but I'd really like to have on electronic media, not least so ...
2
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1answer
452 views

What are the differences between the various HxC Floppy Emulator hardware options when used with an Apple II?

I have an Apple IIc for which I would like an FDD emulator and I am considering buying an HxC Floppy Emulator to use with it. The Slim model does work with the Apple II, as demonstrated in this video. ...
27
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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 ...
8
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3answers
1k views

Are there any open-source C64 DOS wedges and fast loaders?

The ever-so-popular EPYX Fast Load cartridge for the Commodore 64 included a DOS wedge (adding commands such as $ to list the files on a disk, /filename to load a file and @ to show the disk error ...
61
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2answers
20k views

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 ...
10
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2answers
1k views

What are the most common Apple II disk image formats and what hardware disk drive emulators can use them?

Archive.org has plenty of Apple II disk images, such as this DOS 3.3 image which is a .dsk file. I also see .nib and .d13 files, e.g. in this ASIMOV LISP collection. There seem to be further formats ...
13
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4answers
4k views

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 ...
23
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4answers
5k views

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?
6
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1answer
788 views

How-to destroy sensitive data on floppies?

What was considered the best practice, or "military-grade" procedure, for protecting secrets stored on floppy disks when disposing of the old disks?
6
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2answers
792 views

Is there a program I can run on the C64 to speed up booting of a game?

Though I had several friends back in the day with a Commodore 64, I only recently acquired one after a friend gave me his old one before he moved house. As such, I'm diving in to learning about the ...
10
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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 ...
9
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5answers
2k views

Drilling 720Kb floppies to 'upgrade' them to 1440Kb?

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 ...
24
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6answers
6k views

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 ...
27
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2answers
5k views

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 ...
4
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3answers
4k views

Gotek drives for MS-DOS (plus few more constraints)

I have installed two gotek device instead of two old unworking floppy disk drives (in particular on an Olivetti PCS 86). And the result is something like this: (The one on the right should the the A:...
19
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1answer
3k views

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 ...
21
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6answers
9k views

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 ...
5
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3answers
649 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 MS-DOS-compatible 720k Double Sided Double Density disk. Stuff like GAP/SYNC patterns, ID and CRC Field structure, standard ...
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 ...
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 ...
2
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1answer
2k 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, ...
16
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4answers
5k views

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 ...
6
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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 ...
5
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2answers
578 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 ...
9
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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?
14
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1answer
856 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. ...
7
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1answer
2k 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 ...
6
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2answers
3k 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, ...
4
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2answers
128 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 ...