Questions tagged [floppy-disk]
For questions related to the use, restoration and imaging of floppy disks.
156
questions
10
votes
2answers
402 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
201 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 ...
3
votes
2answers
198 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 ...
26
votes
5answers
10k 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
119 views
How can I format a higher capacity 3 inch disc on a regular CPC6128?
A standard Amstrad 3 inch disc can be formatted to CP/M Data format on the machine:
single sided, single track, 40 tracks, 9 sectors/track, 512-byte sectors, no reserved tracks, 1k blocks, 2 directory ...
2
votes
3answers
133 views
First time using an Amstrad CPC 6128 Disc Drive [duplicate]
I recently got my first Amstrad CPC and started refurbishing it. Now I wonder, I saw a video, on someone using the RPM test tool for the Amstrad. I found the download online, but this question might ...
0
votes
1answer
70 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?
10
votes
3answers
531 views
How can I boot or extract files from an IBM PS/1 with a DoubleSpace-compressed hard drive?
I’m trying to boot an old IBM PS/1, mostly with the intention to read out its hard disk. I realized quickly that the original floppy disk drive was broken, so I replaced it with a Gotek floppy ...
8
votes
3answers
474 views
How to transfer AT&T 6300 “.360” disk images onto physical floppies
I got these MS-DOS 3.3 disk images for the AT&T 6300 from archive.org:
ATDOS331.360
ATDOS332.360
ATDOS333.360
ATDOS334.360
Supposing that I have access to a physical 5.25″ floppy drive running ...
6
votes
1answer
176 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
613 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
187 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
159 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
243 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
73 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
210 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
75 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
86 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
107 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 ...
11
votes
1answer
248 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
29 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
297 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
108 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 ...
11
votes
1answer
120 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
116 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 ...
3
votes
1answer
85 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
105 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
115 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
680 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
146 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
149 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
3answers
286 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 ...
1
vote
0answers
63 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
190 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
158 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
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 ...
2
votes
0answers
150 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
210 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
180 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
2answers
591 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
228 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
256 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 ...
12
votes
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, ...
6
votes
2answers
425 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
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
vote
0answers
251 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 ...
