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Comment by AgentME | Hacker News Reader

Drat, I was hoping it was like a cassette tape adapter and would work in unmodified disk drives. Do floppy disks advertise their own size, or do systems assume that they can only hold 1.44mb? You might need special driver support I guess, which takes some fun away.

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They advertise their size. Back in the day, there were programs that let you reformat disks with tweaked parameters -- sectors per track, interleaving, etc -- so you could get a greater capacity. Windows 95 was shipped on a disk formatted for 1680k, for example [1]. Off the shelf disks were hit or miss as far as how big you could reformat them to, with some able to handle close to two megs, and others not able to handle much more than 1.44mb.

[1] https://en.wikipedia.org/wiki/Distribution_Media_Format

Exactly, it reminds me of the time when I formatted a HD 3.5" floppy to 2M with the aforementioned excellent 2M3.0 tool by Ciriaco García de Celis (Facultad de Ciencias de Valladolid: Grupo Universitario de Informatica). It provided 500 Kb of more available data beyond the 1.44M (more then fdformat). From a 2M dos bootdisk I launched a stripped version of win3.1, extracted the WIN3.UC2 archive to a ramdrive of 6M or so and launched it. In this way I could edit my assignments with wysywig WRITE.EXE instead of the dos based WP51 on the library computers. People were wondering how I could have windows running as it wasn't installed. So nowaydays we have 100000M instead of 2M in a smaller package.

> HD 3.5" floppy

It's slightly amusing to me that floppy disks were once called "HD", even though the abbreviation stood for high density rather than high definition.

Before those, you had double density "DD" disks -- and extended density "ED" disks after that. With the sleeve encased floppies you could even throw in single-sided and double-sided variants. Growing up, we had a lot of 1200KB 5-1/4 disks. IIRC, they were enough cheaper than 1440KB 3-1/2 disks for close to the same storage.

This was a somewhat popular program at the time:

https://en.wikipedia.org/wiki/2M_(DOS)

It worked by combining two completely separate techniques; the first, using more tracks, is pretty self-explanatory --- a lot of floppy drives, despite officially supporting 80 tracks, could actually move the head to 81st and 82nd tracks (rarely, even higher), and since the media was in the form of a uniform magnetisable disk, that let an extra 2 tracks worth of data be accessed.

The second technique was to reduce the number of sectors per track and the gaps between them, by making each sector bigger. To ensure interoperability with different drives rotating at different speeds, there's actually quite a lot of "padding" between each sector, as well as ID/CRC data for each one. If I remember correctly, in the highest capacity mode, 2M wrote only one huge sector per track instead of over a dozen in the usual format. This is similar to how hard disks have transitioned to using 4KB sectors internally, instead of the traditional 512B.

> They advertise their size.

Everything is under the control of the drive, not the media.

They advertise their size as in: tell the drive what to expect. But the drive is in full control of where to write on the disk, and how densely.

Sort of yes, sort of no. Later drives were just black boxes with their own on-board logic that read metadata off the disk, sure. Early drives, though (of the 5.25" variety) relied on the first track of the disk to contain what was basically the disk controller firmware†.

As such, you could actually teach an old drive new tricks by coming up with a firmware that used a better encoding scheme, and then encoding the rest of your disk with that scheme.

† (though it ran on the CPU, rather than some microcontroller in the drive. "DOS" stands for Disk Operating System for a reason: a large part of it is a set of routines programs can call to make the CPU micromanage the read-head and stepping motor of the dumb disk-drive controller, with concepts like "files" being a mostly-optional thin wrapper above that, rather than some impenetrable abstraction layer.)

"and others not able to handle much more than 1.44mb"

My first experience installing Linux was using a bunch of disks which were unable to handle even 1.44MB (even though they were sold as 2HD). I couldn't tell, of course, and I had no idea why my install kept on failing or generating errors part way through the installation process :(

> Drat, I was hoping it was like a cassette tape adapter and would work in unmodified disk drives.

Oh, that exists! From 1998: https://en.wikipedia.org/wiki/FlashPath

A floppy disk drive-compatible SD card adapter. Needs special software, though.

We used to drill holes in a 720K floppy so it would advertise itself as a 1.44MB drive.

But in the end it's all about the density of the disk so I'm not sure if you could use a driver to store more data.

Also you will need very accurate positioning of the head. So the drive is also a limiting factor.

I think the largest floppies where 32MB.

I expected something like the 3.5mm-to-cassette adapters that exist for older cars with tape decks.

http://www.amazon.com/Car-Cassette-Adapter-iPod-Sirius/dp/B0...

Or SmartMedia flash cards that actually did work in a standard 3.5" floppy drive https://en.wikipedia.org/wiki/SmartMedia

edit: Didn't realize they even made MemoryStick and SD Card floppy adapters. So this already existed, sort of! https://en.wikipedia.org/wiki/FlashPath

You can also get drives that can connect to a motherboard floppy port, and take SD cards.

http://www.floppyemulator.com/

Note that i think you need to use special files that are read by the drive.

I think they are meant as a life extension for older CNC machines and industrial looms.

Man total flashback. I didn't even remember those existed, though I think I might have had one now that I think about it...

> Do floppy disks advertise their own size, or do systems assume that they can only hold 1.44mb?

The second. With a better read/write head you could store more data on them (for example 2.88mb was available).

But the physical media of the disk may or may not have the necessary resolution.

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