Questions tagged [floppy-disk]

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

Filter by
Sorted by
Tagged with
5
votes
1answer
129 views

Could a double-sided Commodore disk be written to be used as a “flippy” on a 1541, without requiring flipping on a 1571?

Although the 1571 is capable of reading and writing both sides of a disk, accesses to the second side using the second head will be performed with the drive spinning in opposite direction from how it ...
10
votes
1answer
505 views

Is it possible to boot C64/C128 from floppy

When powered on 1541 reads the disk for a brief moment. Is it used to boot system from floppy? Is it possible to create a bootable commodore 64 floppy?
0
votes
3answers
134 views

I need to find a controller card for an apple II 5.25 inch floppy drive, the 20 pin connector wont work on the 34 pin controller card i have

I cant find any adapters or secondary connectors, can anybody get me a link to a working floppy controller card that works or possibly a connector that goes from 20 pin male to 34 pin female? i have ...
6
votes
1answer
140 views

What floppy disk format and layout and what disk image format are used for the Coleco Adam?

I just found out that emulators for the Coleco Adam use a disk image file format with the DSK file extension. This is a very very overused extension on many different disk formats. Though a few DSK ...
6
votes
1answer
225 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....
3
votes
0answers
70 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 ...
4
votes
2answers
183 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
votes
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 ...
2
votes
0answers
69 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
vote
1answer
71 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
votes
1answer
79 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
votes
1answer
119 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
votes
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
votes
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
votes
2answers
271 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
votes
3answers
1k 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
votes
1answer
86 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
votes
1answer
110 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
votes
1answer
88 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
votes
1answer
55 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
94 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
79 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
596 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
138 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
139 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
votes
2answers
153 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 ...
1
vote
0answers
50 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
votes
2answers
163 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
votes
2answers
127 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
votes
4answers
976 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
votes
0answers
129 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
votes
2answers
104 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 ...
4
votes
2answers
147 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
votes
2answers
537 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
votes
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
votes
2answers
197 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
votes
2answers
174 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
votes
2answers
905 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
404 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
votes
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
vote
0answers
200 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
votes
2answers
686 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
votes
2answers
782 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
votes
1answer
254 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. ...
26
votes
9answers
6k 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″ disks. I assume it managed it by destroying some redundancy like a backup ...
8
votes
3answers
662 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
votes
2answers
407 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 ...
16
votes
0answers
631 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 ...
12
votes
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 ...