Comment by kmm
21 days ago
And a megabyte is depending on the context precisely 1000x1000=1,000,000 or 1024x1024=1,048,576 bytes*, except when you're talking about the classic 3.5 inch floppy disks, where "1.44 MB" stands for 1440x1024 bytes, or about 1.47 true MB or 1.41 MiB.
* Yeah, I read the article. Regardless of the IEC's noble attempt, in all my years of working with people and computers I've never heard anyone actually pronounce MiB (or write it out in full) as "mebibyte".
Well the 1.44 MB, was called that because it was 1440 KB, twice the capacity of the 720k floppy, and 4x the 360k floppy. It made perfect sense to me at that time.
It may "make sense" but that's actually a false equivalence. The raw disk space for a 3.5" high-density floppy disk for IBM PCs is 512 bytes per sector * 18 sectors per track * 80 tracks per side * 2 sides = 1,474,560 bytes. It is 1.47 MB or 1.40 MiB neither of which is 1440 KB or KiB. The 1440 number comes from Microsoft's FAT12 filesystem. That was the space that's left for files outside the allocation table.
Sectors per track or tracks per side is subject to change. Moreover a different filesystem may have non-linear growth of the MFT/superblock that'll have a different overhead.
https://en.wikipedia.org/wiki/List_of_floppy_disk_formats
Not my downvote, good chart actually.
It is worse of a downer when there is a complete failure to make further sense like that, but I'll try to do something.
Of course one chart does not an expert make, I don't understand half of it but at least I worked with 3.5 floppies since they first came out.
3.5 floppies are "soft sectored" media and usually the drives were capable of handling non-standard arrangements too. What made non-standard numbers of sectors uncommon was it would require software most people were not using. DOS and Windows simply prepared virgin magnetic media with 2880 sectors, or reformatted them that way and that was about it.
PC's were already popular when 3.5 size came out, and most of the time they were not virgin magnetic media, they were purchased pre-formatted with 2880 sectors (of 512 bytes per sector) already on the entire floppy, of which fewer sectors were available for user data because a number of sectors are used up by the FAT filesystem overhead.
On the chart you see the 1440kb designation since each sector is considered 1/2 "kilobyte".
512 bytes is pretty close to half a kilobyte ain't it?
(The oddball 1680kb and 1720kb were slightly higher-density sectors, with more of them squeezed into the same size media, most people couldn't easily copy them without using an alternative to DOS or Windows. Sometimes used for games or installation media.)
With Windows when partitioning your drive if you want a 64 GB volume you would likely choose 64000 MB in either the GUI or Diskpart. Each of these GB is exactly 2880000 sectors for some reason ;)
But that's the size of the whole physical partition whether it contains only zeros or a file system. Then when you format it the NTFS filesystem has its own overhead.
> I've never heard
It doesn't matter. "kilo" means 1000. People are free to use it wrong if they wish.
All words are made up. They weren’t handed down from a deity, they were made up by humans to communicate ideas to other humans.
“Kilo” can mean what we want in different contexts and it’s really no more or less correct as long as both parties understand and are consistent in their usage to each other.
I find it concerning that kilo can mean both 10^3 and 2^10 depending on context. And that the context is not if you're speaking about computery stuff, but which program you use has almost certainly lead to avoidable bugs.
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That's a terribly nihilistic outlook on language.
We agree to meaning to communicate and progress without endless debate and confusion.
SI is pretty clear for a reason.
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> “Kilo” can mean what we want in different contexts
Fair enough.
1000 watts is a kilowatt
1000 hertz is a kilohertz
1000 metres is a kilometre
1000 litres is a kilolitre
1000 joules is a kilojoule
1000 volts is a kilovolt
1000 newtons is a kilonewton
1000 pascals is a kilopascal
1024 bytes is a kilobyte, because that's what we're used to and we don't want to change to a new prefix
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>> It doesn't matter. "kilo" means 1000. People are free to use it wrong if they wish.
> All words are made up.
Yes, and the made up words of kilo and kibi were given specific definitions by the people who made them up:
* https://en.wikipedia.org/wiki/Metric_prefix
* https://en.wikipedia.org/wiki/Binary_prefix
> […] as long as both parties understand and are consistent in their usage to each other.
And if they don't? What happens then?
Perhaps it would be easier to use the words definitions as they are set up in standards and regulations so context is less of an issue.
* https://xkcd.com/1860/
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Yes!
(And by that I mean "what the fuck, no...")
All you've done is created a homonym for no good reason at all.
If Bob says "kilobyte" to Alice, and Bob means 5432 bytes, and Alice perceives him to mean 5432 bytes, then in that context, "kilobyte" means 5432 bytes.
What are the odds of Charlie meeting Bob and Alice?
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No, in that context, kilobyte means 1024 bytes, like in every other context. :)
Man let a drug dealer give me a binary 'kilo' of some drug. That's almost a free ounce included!
In North America blackmarket drugs are often sold in pounds and ounces but measured in grams so you do see some rounding.
Such a myopic view when reality and marketing is messier than dramatic self-righteousness. This unnecessary bikeshedding nonsense has already been solved by using mebi, kibi, etc. to disambiguate sloppy abuse of SI units.
Fortunately SI doesn’t get to own terms or prefixes and trying to enforce different usage by fiat fails in the real world, exactly as it should.
Exactly.
If you're talking loosely, then you can get away with it.
I worked with networked attached storage systems at pib scale several years ago and we referred to things in gib/tib because it was significant when referring to the size of systems and we needed to be precise.
That being said, I think the difference between mib and mb is niche for most people
Speaking of significant Pib vs PiB is 8x. I assume you meant the latter.
Interestingly, HD floppies actually are 2 "MB" unformatted without the various overhead. This is how 1.68 "MB" DMF is possible. Extra-high Density (ED) 2.88 "MB" is similarly 4 "MB" unformatted.
> classic 3.5 inch floppy disks
90 mm floppy disks. https://jdebp.uk/FGA/floppy-discs-are-90mm-not-3-and-a-half-...
Which I have taken to calling 1440 KiB – accurate and pretty recognizable at the same time.
> 90 mm floppy disks. https://jdebp.uk/FGA/floppy-discs-are-90mm-not-3-and-a-half-...
That page is part right and part wrong.
It is right in claiming that "3.5-inch" floppies are actually 90 mm.
It is wrong in claiming that the earlier "5.25-inch" floppies weren't metric
"5.25-inch" floppies are actually 130 mm as standardised in ECMA-78 [0]
"8-inch" floppies are actually 200 mm as standardised in ECMA-69 [1]
Actually there's a few different ECMA standards for 130 and 200 mm floppies – the physical dimensions are the same, but using different recording mechanisms (FM vs MFM–those of a certain age may remember MFM as "double density", and those even older may remember FM as "single density"), and single-sided versus double-sided.
[0] ECMA-78: Data interchange on 130 mm flexible disk cartridges using MFM recording at 7 958 ftprad on 80 tracks on each side), June 1986: https://ecma-international.org/publications-and-standards/st...
[1] ECMA-69: Data interchange on 200 mm flexible disk cartridges using MFM recording at 13 262 ftprad on both sides, January 1981: https://ecma-international.org/publications-and-standards/st...
They should be more precise if they are talking about KiB in a context where the difference matters... luckily those contexts are usually written down.