103 votes

What is between the sectors of floppy disks?

This calls for a lengthy Floppies 101. For one, never assume a floppy as something with an inherently byte orientated structure. There is none. Just magnetic reversing areas. It's more like a magnetic ...
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  • 173k
71 votes
Accepted

What is the "two-drive trick" that can read Amiga disks on a PC?

This only works with 2 drives on the same controller and cable. The floppy controller doesn't know when the disk (hardware) has been switched on the port (software), so a transfer command can be ...
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70 votes

Dealing with oversized files decades ago? Data transfer in the age of floppy disks

Forty years ago, a 7MB file would be unheard of, at least in contexts where floppies would be the only available means of transferring it. (Tapes were commonly used for large transfers on minis and ...
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  • 96.6k
68 votes

Did personal computers ever support 8" floppies?

The Radio Shack Model II had a built-in singled-sided Shugart 500k 8" floppy drive. https://en.wikipedia.org/wiki/TRS-80_Model_II
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  • 1,186
64 votes
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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 As so often it depends on your definition of 'personal computer' If it's ...
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  • 173k
63 votes

Why were floppy drives not any faster?

That answer is somewhat trivial: Hard disks and optical drives are contact-less technologies - Nothing touches (or is even allowed to touch) the media while it spins. On a hard disk or CD-ROM, the ...
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  • 28.4k
60 votes

How long can a floppy disk spin for before wearing out?

Anecdotal evidence (*1) We had a bank as customer with branch offices all over the state. These were the 70s, the final years of batch only, although, already using remote batch with local data ...
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  • 173k
50 votes
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What makes a floppy disk bootable?

The notion of a bootable-vs-non-bootable floppy is a little odd. It's worth noting that almost all floppies you're likely to have are actually bootable: it's just that they boot a program that isn't ...
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  • 12.4k
47 votes

Why were floppy disks invented after hard disks?

Floppy disks are harder to get right than hard disks. Early hard disks were enormous; the IBM 350 used fifty 24-inch platters. They were also rather fragile and cumbersome (heavy and power-hungry). To ...
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  • 96.6k
43 votes
Accepted

Why were floppy drives not any faster?

As you mentioned, speed was considered sufficient for the typical applications at the time they were introduced. Also, any significant rotational speed increase would have meant: More complex data ...
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40 votes
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What is the (standardized) weight of a 3.5 inch floppy disk?

The short answer / TLDR: One 3.5-inch floppy disk weighs between 15 - 25 grams. The average (mean) weight of one 3.5-inch floppy disk is 18 grams, the median is 17 gram. Of that weight 75% is ...
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  • 1,321
39 votes
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Magnetic exposure to floppy disk damages file system and requires complete reformat?

A formatted disk contains markers which identify the start of each track and the start of each sector within the track. These markers are fixed magnetic sequences that are picked up by the drive ...
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  • 7,609
39 votes

Why were floppy drives not any faster?

I used to work for a company called ‘Rimage’ who manufactured robotic duplicators for floppy disks, the company still exists and today manufactures robotic equipment to publish/duplicate cd, dvd and ...
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39 votes
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When did 5.25″ floppies exceed the capacity of 8″?

In practice, 5.25" drives equalled or exceeded the capacity of 8" drives when 5.25" floppy drives started using HD media. The Evolution of 5.25" Drive Systems There are only two ...
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  • 21.9k
38 votes
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What modification is required from a PC floppy for use in Amiga?

The differences between PC floppy drives and Amiga floppy drives are as follows: PC floppy drives normally answer to drive select 1 (DS1), internal Amiga drives answer to DS0 pin 34 on the connector ...
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  • 96.6k
37 votes
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Why were floppy disks invented after hard disks?

While Stephen Kitt's answer already hits the core, I believe it needs a bit more history, as direct access magnetic storage did start quite a while before the IBM 350. Drums and Disks First there were ...
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  • 173k
37 votes

Why was the shrinking from 8″ made only to 5.25″ and not smaller (4″ or less)?

A 2005 interview with Don Massaro, vice-president of engineering and manufacturing, and George Sollman, product manager, both of Shugart Associates, lists the design constraints that resulted in the ...
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37 votes

Twist in floppy disk cable - hack or intended design?

This was a good piece of production engineering. IBM expected to sell lots of twin-floppy PCs, even after the launch of the XT (personal experience in a UK reseller in late 1984). To assemble a twin-...
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  • 1,062
36 votes

How long can a floppy disk spin for before wearing out?

I did some assembly development on a dual-floppy (5 1/4" double-sided) IBM PC 5150 in 1982/83 (PC DOS 1.1 and onward). Boy, did that exercise the floppy drives! We wore out floppies all the ...
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  • 579
34 votes

How long will floppy disks maintain data integrity?

Can you take these disks off the shelf 30 years later and still expect to read their data? Yes. Although we all experienced floppies fragility, the magnetic media in fact is one of the longest-...
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  • 469
34 votes
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Why are the magnetic floppy disk drives (FDD) heads not frictionless?

TL;DR: "Frictionless" Floppies are called Hard Disks (*1), consisting of a hard media platter and a head in distance of the media (flying or otherwise) Floppies are 2D tapes. While slower ...
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  • 173k
33 votes
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Is there a better way to the 6 disks install of Windows 3.1

If my memory serves well, Windows can be installed from a directory on hard disk. You need a means of reading all disks and storing its files on the same directory on the hard disk of your target ...
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33 votes
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Why were 5.25″ floppy drives cheaper than 8″?

A few miscellaneous thoughts: Less Materials: On a certain level, a smaller device is cheaper, simply because it uses less raw materials. You need less of the magnetic coating if you're applying it ...
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  • 7,664
32 votes
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Why did connecting the IBM PC 3.5" FDD backwards cause the problems it did?

One side of the cable is normally all ground. The other is all signals. This was done so a ribbon cable would have a ground wire between each signal wire, which helps prevent crosstalk. Flipping the ...
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  • 701
32 votes

Did personal computers ever support 8" floppies?

Back in the day I used to use an Intel MDS-80 which had an 8 inch floppy beside the screen. We often had a pair of expansion drives (also 8") in an expansion unit below the main system box. One ...
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  • 489
32 votes

Why not constant linear velocity floppies?

But as the linked article indicates, while this is used on optical disks, it has generally not been used on floppy disks. It has. Apple's famous Twiggy drive was one attempt to do so. It featured 6 ...
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  • 173k
32 votes

How long can a floppy disk spin for before wearing out?

My 1980 edition of the Apple II DOS manual mentions that, for a 5.25" disk: With reasonable care a diskette will give you an average life of 40 hours——which is a lot, when you consider the few ...
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  • 421
31 votes
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How does "bit-slip" copy protection work?

The Apple II reads disk tracks as a continuous stream of bits. To make sense of the data, it's necessary to figure out where individual bytes start. This is done with self-sync bytes. Standard self-...
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  • 7,591
31 votes

Dealing with oversized files decades ago? Data transfer in the age of floppy disks

40 years ago - 1978 - there was no home/hobbyist/small office computing to speak of. Maybe a few hundred people altogether. So you must be talking about commercial/industrial computing. For large ...
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  • 4,134
30 votes
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What were the differences in floppy disk formats between Amiga and IBM/PC compatible computers?

The Amiga disk format stores 512 bytes per sector, 11 sectors per track (a track is one side of a cylinder), double sided (i. e. 2 tracks per cylinder) with 80 cylinders per disk, which makes 80 * 2 * ...
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