Questions tagged [floppy-disk]

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

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4
votes
2answers
144 views

Why does Amiga 500 reset when reading a faulty disk

I have a copy of Syndicate disks for Amiga (I have original as well) and apparently the disk is damaged / faulty. It loads up to language selection menu, then tries to read disk and resets the ...
13
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4answers
1k views

Can special tools recover data from floppy disks when Windows Explorer fails to do so?

I have many 1.44MB floppies 20 years old or older. My FDD, which I just bought online and received recently, cannot read them. The FDD can often display the contents of a floppy, but not successfully ...
1
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0answers
40 views

What does a “DK” signature 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 ...
1
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1answer
64 views

How many different standard boot sectors are there for Apple II DOS 3.3?

When formatting a blank 5¼ disk on an 8-bit Apple II using the INIT command, was there only ever one variation of the boot sector code that was written, or was it updated from time to time over the ...
4
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1answer
58 views

Determining which sectors in an Apple II floppy disk/image are used when the boot sector declares more than 1 sectors

The Apple II disk bootstrap process looks at the first byte of track zero sector zero to see how many sectors long the bootstrap code will be. It then loads these sectors at location 0x0800 and jumps ...
7
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1answer
100 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 ...
3
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0answers
28 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 interpets it as a NOP ...
7
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2answers
1k views

Could Tandy TRS-80 Color Computers boot from disk at all?

I'm trying to find out if any of the Tandy CoCos could boot from disk. I'm thinking the answer is no but I'm having trouble confirming it. I believe that non-disk machines booted from the standard ...
4
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2answers
260 views

Can I still save data on a floppy that lost its magnetic charge over time

I have original Microsoft floppies, unfortunately they appear unreadable. Were stored in protector, in a box, in a dark and dry place for the last 20 years. No dust, moisture or exposure to magnetic ...
4
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3answers
895 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 ...
3
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1answer
73 views

Converting Apple II ProDOS blocks to DOS tracks and sectors

The 8-bit Apple II had two disk operating systems with different disk access semantics. DOS used tracks and sectors. A sector is 256 bytes. ProDOS used blocks. A block is 512 bytes. But mapping ...
10
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1answer
108 views

In TRS-80 parlance when talking about disks, what are “granules” and “lumps”?

In my reading to try to learn about the disk layout, directory, and boot process of TRS-80 Model I and Model III, I see some unusual words come up again and again. Along with the common terms "track" ...
3
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1answer
80 views

What is the process for TRS-80 Model I & III to boot from disk?

I can find enough mentions of bootable disks for TRS-80 Model I and Model III to be confident that they could boot from disk, but so far I'm failing to find much info on how that worked. In ...
2
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1answer
45 views

What is the layout of the directory track on a TRS-80 Model I/Model III disk?

I've decided to add support for some more classic Z80 computers I used to use to my Ghidra modules, and the first Z80 systems I used were the TRS-80 model I and model III. I've found documentation ...
3
votes
2answers
91 views

Is there a “most correct” name for the disk format / filesystem used by Amstrads and Spectrum +3's?

The native floppy disk format/layout or "filesystem" used by Amstrad microcomputers such as the CPC and PCW range and by the Sinclair Spectrum +3 are versions of one that came from CP/M. In Amstrad ...
3
votes
1answer
78 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
votes
1answer
564 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
vote
1answer
134 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
votes
1answer
131 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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2answers
129 views

Can I use a 2.88MB ed floppy disk (3.5in) in a drive that uses the standard 1.44 HD DS disk?

I am using a Windows XP with an old accounting app, that will only back up to a 3.5 in floppy disk. But the backup requires a second disk to complete the job -- a pain. Would a ed 2.88 mb floppy (if ...
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0answers
43 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
156 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 ...
0
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2answers
117 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 ...
4
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4answers
937 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 ...
2
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0answers
117 views

Algorithm to properly format 360k 5.25" diskette on 1.2M drive?

This is a low level tech question, as I develop the driver for the FDC at its command set level. Having reviewed a number of sources I can not find the algorithm of how to format the 360k diskette ...
0
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2answers
66 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 ...
3
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2answers
133 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
520 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
1k 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
192 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
149 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 ...
10
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2answers
880 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, ...
6
votes
2answers
392 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, ...
19
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1answer
2k 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
180 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 ...
6
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2answers
636 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 ...
9
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2answers
658 views

How can I read a 5-1/4 drive on 1996-2007 equipment?

In my organization's archive I just found some 5-1/4" 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 ...
2
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1answer
217 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. ...
25
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8answers
5k 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 5 1/4" disks. I assume it managed it by destroying some redundancy like a ...
8
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3answers
586 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 ...
59
votes
2answers
18k 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 ...
8
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2answers
339 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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0answers
444 views

Oxford C compiler for Commodore 64

I kept one floppy from my Commodore 128 (which I used mostly in C64 mode), which is written Oxford C compiler. It is a 5.25" floppy. Don't ask me why I kept just this one; probably because I thought I ...
11
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4answers
3k 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
4k 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
493 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
554 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 ...
8
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8answers
3k 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
962 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 ...
23
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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 ...