Talk:Floppy disk

Divide history and structure sections

I'm thinking of refactoring & merging the "History" and "structure" sections, so "history" is subdivided into "8 inch", "5 1/4 inch", "3.5 inch". What does everyone else think? -- Tarquin 11:31 Sep 10, 2002 (UTC)

I don't know where 8 inch disks originated, but for 5 1/4 inch I have heard it was originally pushed by Apple for the Apple ][ computers, and that the manufacturer of the disk drive was a company named Shugart (named after its founder?) which later became Seagate. Somewhat later, Apple again pioneered the 3.5 inch drive for the MacIntosh (at least in the US market?) I think creating sections based on these different standards is a good idea.

Seagate was another co founded by same guy (Alan Shugart). I think it has now bought Shugart Assoc. It's a complex corporate and patent history. IBM sued Shugart over the floppy since it was their design. ww 17:17, 9 Aug 2004 (UTC)

More data on 20 cm (8 inch) disks

Some of the 8-inch floppies held more data than 160K. Xerox released a CP/M machine, the 820, which had double-sided variations, as well as "double-density" and "super-density". --Robert Merkel 10:01 30 Jun 2003 (UTC)

Southwest Technical Products produced an 8" drive system (ca 78 or 79 and continuing into the mid 80s) which stored 1.2 MBs per disk (2 sides, double density). Several other personal computer vendors did the same. ww 17:18, 9 Aug 2004 (UTC)

Swapped pictures

the pictures are swapped...when you click on the 5 1/4" disk, the 3.1/2" pic pops up...and vice versa

-Chris Cino, GE Ion Track, Sept 29, 2003

I did that to connect the two related images -- Tarquin

Standarize fractional

I guess we should rather standardise on a single notation for 'fractional' floppy disk sizes, i.e., either    3.5" & 5.25"    or    3½" & 5¼".    It would certainly make the article seem more encyclopedic :-)One should of course include the alternative notation as well, to signify its existence.
-- Wernher 23:58, 29 Oct 2003 (UTC)

I have reverted the raw fraction characters to HTML entities because meta:MediaWiki User's Guide: Creating special characters#Unsafe characters. --Yath 21:13, 30 May 2004 (UTC)

I have changed all references to 3.5 and 5.25 to 3½ and 5¼ respectively (in the main article, not this Talk: page :-). I have also added an explanation to that start of the relevant chapters regarding this. Frodet 17:15, 15 August 2005 (UTC)

Downscaling the 9cm (3.5 inc photo)

How about downscaling the photo of the 3½" disk drive relative to the photo of the 5¼" drive, so that it doesn't incorrectly look like the former is of equal or bigger size than the latter? A good example to follow is the diskette photos earlier in the article.  -- Wernher 22:22, 3 Nov 2003 (UTC)

Good idea. Also of course the article is begging for photos of an 8" disk and disk drive. Perhaps a collector could take a single snapshot of all 3 disks together and all 3 drives together to indicate scale correctly. Tempshill 05:31, 5 Nov 2003 (UTC)

oxide coatings

Another advance in the oxide coatings allowed for a new "extended-density" ("ED") format at 2.88MB introduced on the second generation NeXT Computers in 1991, but by the time it was available it was already too small to be a useful advance over 1.44, and never became widely used.

Is this really the story? IT departments worldwide throughout all of the 1990s probably would have appreciated 2.88MB floppies. Tempshill 05:55, 5 Nov 2003 (UTC)

Yes, that sounds correct. I remember that 2.88M floppies did exist, but no one really used them. Hard disk technology was more coming into its own then, I think? Dysprosia 05:58, 5 Nov 2003 (UTC)

I remember the machines at my college could take 2.88. Though I thought at the time it was called XD for "extended-density". (stupid name anyway!) I don't think I ever saw any disks though! -- Tarquin 09:36, 6 Nov 2003 (UTC)

Yep, I bought 2.88s at OfficeMax and used them in the NeXT slab where I worked. That's the only machine I can remember that would read them.

Does anyone remember enough about the 10-inch floppy disk to include something about them in the article? (They did exist, here's a picture. They were current in the early '80s, I used them on some sort of TI mini.) - Hephaestos 23:00, 1 Jan 2004 (UTC)

The 2.88 3.5" floppies were the consequence of Fujitsu (or Toshiba, I can't remember which) discovering a way to do vertical recording on floppy membrane media. They used barium oxide as the magnetic media and required special r/w heads and electronics. IBM adopted them for some of their PC machines (probably in the ill fated patented bus they introduced for the some of the PS/2 machines) and a few others used them as well. The disks were expensive (more than 2x the cost of HD disks) and the drives were too. They were never adopted by enough folks to gain much economy of scale and so the price never dropped enough... And then there were the hard drives which were much higher capacity, very much faster, and not too much more expensive. ww 17:24, 9 Aug 2004 (UTC)

When 2.88 disks came out, there were already a number of different floppy-type drives and media that could store about 20 megabytes on a 3.5" disk. None of these ideas had the critical mass to become a de facto standard until 1995, when Iomega figured out how to attach an external drive to a computer via the parallel port, and introduced their Zip disk. Samboy 22:43, 7 Jan 2005 (UTC)

25 cm (10 inch) floppies?

The comment above by Hephaestos about "10-inch" floppy discs is probably actually about "8-inch" floppies. The photo he links to is actually a composite of three discs, but is incorrectly labelled. It looks much more like a '8" / 5.25" / 3.5"' photo. Were it relabelled (ie the caption removed), it would answer the comment by Tempshill about a composite photo (pity they are superimposed, though. - Tim

I also have a couple of 3" double sided floppies from an Oric Atmos (but no drive), but have no camera (or login) - Tim

Wiki metrification

Metrified the article. Imperial equivalents are given in brackets. I hope this helps US readers to familiarize with the metric system. It is good practise to keep old imperial sizes for future reference.

Because 5.25"=13.34 cm= 133.4 mm I've decided to round to the nearest centimetre. I feel some readers would be discouraged if they found 133 mm references everywere. even if it is not 100% acurate, it's easier to read 13 cm, than 133.4 mm.

TheWikipedian

I hope this helps US readers to familiarize with the metric system. - this sounds very much like a political manoeuvre of an utterly POV kind - why on earth should US readers need or want your 'help' in becoming 'familiarized' with the metric system, and moreover, why on earth should wikipedia be complicit in this? As far as I was aaware, wipedia policy on this matter was units used should be in context and, rather like the policy on British/Amaerican spelling, should not be changed simply to make articles "American" or "European". '13 cm floppies' is an absurd name, and no one but the most avowed and fanatical metricist would know what you were going on about. By all means specify the size in millimetres in the text of the article if you wish - it provides additional information - but changing the names is nothing but an attempt to politicise wikipedia, and is POV in the extreme. 80.255 12:23, 6 Apr 2004 (UTC)

Metrification is fine, when it's appropriate, but I strongly suggest that it not be done when it obscures things - the use of the name "3 1/2" and "5 1/4" are synonymous with these sizes of disk. If you ask someone for a 9 cm disk, I would reckon they wouldn't have a clue what you're talking about... Dysprosia 11:55, 6 Apr 2004 (UTC)

Then, would it be ok if I wrote the other way around, that is, first imperial, then metric in brackets? For instance :3 1/2 (90mm), 8 inch (13 cm) TheWikipedian 13:58 GMT+2

I think that would be perfectly all right, once, at its first mention. Dysprosia 12:00, 6 Apr 2004 (UTC)

Quite right. It's quite silly to start trying to call things by new names that no-one uses. A five and a quarter inch floppy disc is called a five and a quarter inch floppy disc. That's its name. Sure, mention that it's 13cm across once, but call it by name. Tannin 12:01, 6 Apr 2004 (UTC)

What are they called in fully metric places? Surely not 3.5 inch disks! In any case, it is well to remember that Congress made the US officially metric sometime in the late 1800s. The news just takes a while to get around. ww 17:26, 9 Aug 2004 (UTC)

In Germany the terms 3,5zoll and 5,25zoll where commonly used (cm where never used when refering to media). --Anonymous

As in Norway (also a "fully metric place"). Actually, I myself, being a computer geek since the early eighties, never heard of "metric designations" on floppies until reading about them in this very article. :-) --Wernher 21:21, 28 Jan 2005 (UTC)

It might be worth noting the external link regarding the sizes (3.5 inch discs are NOT 3.5 inches.. they were actually specified in mm) but the names of the discs should be in imperial obviously.

on a related note it would be good to note the overall physical dimensions of the discs (WxDxH)... here would be a valid time to use both imperial and metric.. and I am not aware of a wikipedia standard on the use of cm but (in the uk at least) mm should be used instead..

Kibs/Mibs vs KBs/MBs

There appears to be an inconsistant use of these units in the article. There should only be one type in the article. I know the differnece between them, but most people are only familar with KB and MB. Krik 15:00, 30 Apr 2004 (UTC)

I agree. That said, I sure wonder how KiBs and MiBs (in principle a Good Thing) are going to fare, given the 'measurement unit conservatism' residing in people like myself. :) Totally ambivalent, I regulary find myself being slightly annoyed at people insisting on inches, feet and pounds, instead of once and for all embracing metric units. Oh well... --Wernher 23:06, 30 Apr 2004 (UTC)

I'm 99% sure IBM used 2.8 meg floppies, too

The article refers to them as having been used in the NeXT machine, but I'm almost certain that one of IBM's machines, the high-end model of the original PS/2's IIRC used them as well. No time to check right now, though. Dpbsmith 22:38, 4 May 2004 (UTC)

I remember seeing workstations at my university that were marked as supporting them, in the mid-90s. I think they were IBMs. -- Tarquin 19:37, 5 May 2004 (UTC)

100% sure - the IBM PS/2 Model 50 came with a 2.88 meg drive and, if you weren't very careful when formatting a diskette, would happily produce diskettes that other machines with 3.5 inch drives could not read. Scott Mueller's "Upgrading and Repairing PCs, 2nd Ed." says that Toshiba started producing the 2.88 Meg diskette in 1989 and that MS DOS 5 and up supported them. --Wtshymanski 20:22, 1 May 2005 (UTC)

Not ready for a metric disk??

I don't agree that the reason the 3½ inch floppy was advertised and marketed as such, instead of calling it a 90 mm disk (which reflects its actual design), was due to the fact that the public was "not ready", as the article states.

After all, the public was "ready" for 35 mm film and 2 liter bottles of cola. The disk could just as easily have been advertised as a 90 mm disk. It was probably more of a marketing decision based on the fact that Apple Computers was an American company, and the fact that they were trying to emphasize how this new disk, which was standard in their new Macintosh computer, was smaller than the existing 5¼ inch disk.

Steggall 19:23, 21 May 2004 (UTC)

That partly supports my point; almost nobody would have noticed (implied by the name), that a 9 cm or 90 mm disk would be smaller than the previous 5¼". And until today, there are e.g. still 17", 21".. monitors and nobody seems to care about metric in that field at all, at least as far as names are concerned. (Not that it bothers me, I do know what a 17" looks like :) --Palapala 05:47, 2004 May 22 (UTC)

Like spelling in English, the whole thing makes little sense. And consider that even in Europe (a fully metric region) spark plugs are still sized in imperial units. Homer Simpson would be proud. ww 17:28, 9 Aug 2004 (UTC)

Shape of floppy disc

The following para was deleted without reasons.

The shape of a floppy disc is usually approximately a square but not exactly so, for example the 3½" disk is around 90 cm x 93 cm. The main reason for this is to make it impossible for the floppy to be put in the wrong direction into the drive. Though this might seem an obvious fact, this was an innovation in design that was not there from the beginning.

Whoever did this , couldn't you give reasons or discuss before deleting someone else's contribution? Regarding its veracity, I am 100 percent sure. Maybe it requires rewording KRS 12:50, 28 May 2004 (UTC)

Well, as you could easily see from the page's history, I did. But not without reason: (1) early floppy disks were square, not "approximately" so; (2) the 3½" disk is "not around 90 cm x 93 cm" but of the dimension stated earlier in the article (90.0×94.0 mm); (3) and as far as the "innovation" goes, the retention spring had to go somewhere (okay, the disk wouldn't fit in sideways, not being square anymore, agreed). If I happened to have hurt your feelings, I herewith apologize. --Palapala 16:51, 2004 May 28 (UTC)

Maybe there are technical reasons, but the primary one is ergonomic and it was not thought about at all for a long time. KRS 01:38, 29 May 2004 (UTC)

Actually the fact that a floppy can only be inserted in one direction is worth mentioning, since it was expounded upon with great admiration in the HCI expert Donald Norman's book The Design of Everyday Things. Perhaps even a fair-use quote is in order.

Derrick Coetzee 00:30, 29 May 2004 (UTC)

Thanks!!! I thought I will wait until I find the source. KRS 01:38, 29 May 2004 (UTC)

IBM team vs Nakamats(u) as inventors

I notice that Nakamats(u)'s claim to have invented the floppy disk is disputed at many internet sites. Because of this, and in order to preserve the prose flow of the article, I moved the passage about Nakamats(u) below the IBM/Shugart paras. --Wernher 18:53, 15 Jan 2005 (UTC)

Great article ... but where are the references?

I agree with the banner at the top of talk that this is an excellent example of an article except for one point ... a lack of references. Could the people who added information consider adding salient references for their material? I think that would go a ways in increasing my confidence in the large amount of factual data included here. Thanks. Courtland {2005-01-23}

Follow-up ... less than 24 hours after I posted this, a kind soul added a number of references to the article. Thanks! Courtland {2005-01-23}

Dangerous trivium deleted

Someone entered an item in the trivia section saying that viewing a solar eclipse through a floppy disk (removed from its protective casing) was totally safe for avoiding eye damage. This is incorrect and might even lead people unwittingly to destroy their eyes! I therefore deleted the item. See, for instance, the following extract from (three quarters down) the page Using Safe Solar Observing Methods at the web site of Continental Capers Travel Center, Inc.:

"Filters made from sunglasses, Polaroid filters, smoked or dark glass, typical photographic neutral density filters, CDs, floppy disk media, cellophane and mylar food packaging, undeveloped film, color films, slides or negatives, X-ray films with images, and chromogenic photographic emulsions are not safe! These filters may transmit dangerous amounts of ultraviolet or infrared radiation even if the filter appears opaque. They may also have small pinholes or non-uniform coatings that can allow unsafe amounts of light through."

--Wernher 17:57, 8 Mar 2005 (UTC)

Good catch — in fact, this is such a dangerous popular myth that I decided to add it back in debunked form, with links explaining why it's a bad idea. Deco 02:23, 11 Mar 2005 (UTC)

"1 MB = 1,000 KB for floppy storage"

Calling 1440 KB 1.44 MB is a simple error, nothing more. Stating "1 MB = 1,000 KB for floppy storage" is unnecessary. Do we say "pi = 3 for biblical history"? Or "2 + 2 = 5 for confused kindergarteners"? No, we just say that someone made an error. The table at the top of the article is broken at this time. --Yath 01:28, 10 Apr 2005 (UTC)

it's not nice i agree but calling it a mistake when every single manufacturer that sells the things uses it doesn't seem right either.

the fact is mega=kilo*kilo and kilo has two different meanings in computing. If you think of megabyte as kilo-kilo byte and understand that one of the kilos comes from the arbitary measures of the particular disk size and the other from twice the fundamental sector size it makes perfect sense Plugwash 02:32, 10 Apr 2005 (UTC)

It makes sense only when considered an error. I'm going to remove it from the article. --Yath 05:59, 17 Apr 2005 (UTC)

Like it or not it is the normal way of reffering to those disk sizes i've changed the body of the table to use kilobytes only and put a somewhat reworded note at the bottom what do you think of it now? Plugwash 12:53, 17 Apr 2005 (UTC)

A 3/4 inch pipe has no dimension that is 3/4 of an inch. A 2 x 5 at the lumber yard is no-where near 2" by 4" in section. "Trade" sizes may not match physical dimensions of products but are a useful short-cut for product identification. --Wtshymanski 20:05, 4 Jun 2005 (UTC)

Did 3" DD (720K) disks ever exist?

Can someone provide a source/example or at least an announcement that such a format has existed or has at least been planned? I never heard of it, and Amstrads/Spectrums were limited to 360KB or less. Maybe some connection with MSX systems, which used 720 3½ floppies right from the start? EpiVictor 13:38, 12 Apr 2005 (UTC)

it shuold be noted that at least from 5¼ inch onwards all the drives spun at the same speed and used the same hardware interface. So it wouldn't need a 720K 3 inch standard as such just a controller that could do 720K and a drive of high enough quality to support the data rate. Plugwash 16:26, 12 Apr 2005 (UTC)

Yes but have there even been 3" drives with a hardware controller similar to the 3½ one or at least capable of coping with denser tracks/higher data rate? At least the Amstrad drives were cleary 5¼ -based (down to the point of using an identical format for both 3" and 5¼ disks), but what about 3½ ??? Have there EVER been DD disks (with better magnetic medium) and capable drives? Have they even been used in some system? EpiVictor 12:44, 13 Apr 2005 (UTC)

At least the Amstrad PCW8512 and PCW9512 used 720 KB floppies. I have updated the Amstrad PCW entry to reflect that. Frodet 16:31, 15 August 2005 (UTC)

and there was also double density stuff for the beeb and i'm sure 3 inch floppy drives were sold as suitable for use with that. Plugwash 03:30, 17 August 2005 (UTC)

800kB 3.5" Macintosh disks?

This site lists some early Macintosh computers (Mac Plus, Mac SE) as using "800kB" 3.5" floppy disks. They don't seem to be mentioned in the article (the only 800 kB 3.5" disks mentioned are for the Commodore 128). If anyone knows how they fit in, please add them to the article. —Steven G. Johnson 15:10, Apr 17, 2005 (UTC)

probablly a format for DD disks The pc formats were quite conservative compared to other formats around at the time. The archimedies version of ADFS also did 800K on dd disks. User:Plugwash

The Mac is mentioned in the "Using the disk space efficiently" section. "400 KB per side". The first version was single sided. Mirror Vax 17:23, 17 Apr 2005 (UTC)

Applie II, Commodore, Victor Sirius 9000, and classic Macs did not use MFM for recording on diskette but rather one or another type of GCR - a different way of writing data to the diskette. A GCR format allowed a bit more data on a diskette but was incompatible with MFM-only data separators. Later Mac's had both types of data separator installed so that they could read both their own and PC-compatible disk formats. --Wtshymanski 20:29, 1 May 2005 (UTC)

Although it's a common belief, it's not true that GCR provided more storage - just the opposite. GCR formats that allow two 1s (transitions) in a row run at half the clock speed of MFM, which doesn't allow two 1s in a row. Thus MFM is the more efficient format. Mirror Vax 20:51, 1 May 2005 (UTC)

Would it be more nearly correct to say that GCR gave more data on a disk than FM (what we used to call single-density)? And 800 K is more than 720 K, is it not? In the CP/M days many machines put 390K on what a PC formatted as a 360K diskette, so the difference is not huge anyway. I understood GCR was picked for the Apple II because it didn't need a very complex data separator...I wonder why GCR didn't become more popular. It was a great drawback for some people who only had GCR data separators on their machines because they could never exchange disks with people locked into FM or MFM. (The standard IBM PC disk controller couldn't do FM (single density) disks, either.) --Wtshymanski 23:57, 2 May 2005 (UTC)

Yes, GCR is superior to FM, but inferior to MFM. The Mac got 800K because of the variable motor speed. On the inner tracks, the Mac only had 8 sectors - less than the standard 9 for the PC. The Mac controller is just a single-chip version of the Apple II controller. This article explains FM/MFM: [1] - Mirror Vax 01:25, 3 May 2005 (UTC)

btw the acorn archimedies also did 800K on dd floppies (and 1600K on HD floppies in its last incarnations) and i'm pretty damn sure that didn't use a special drive of any kind. Plugwash 15:06, 12 May 2005 (UTC)

Origin of 5.25 inch Form Factor

Is there an inconsistency in the history section on 'the 5¼-inch minifloppy'? The first paragraph on Burroughs says of 1975 'to reflect the knowledge that IBM's audio recording products division was demonstrating a dictation machine using 5.25" disks.' The next paragraph has the story of the napkin as the origin of the size happening in 1976. :Hcharles 07:04, 19 Apr 2005 (UTC)

I find the former story more credible. The latter is probably an urban legend. I have no evidence though. Deco 00:43, 5 Jun 2005 (UTC)

3-inch floppies in Smith-Corona word processors

For a short time, Smith-Corona used a 3-inch floppy disk format which was not quite the same as the one used by Amstrad. I don't have much information handy on this, but I do recall the disk being hard plastic, square, and with one corner "cut" diagonally like its 3½ inch cousin, but without a sliding dust cover door. -- Todd Vierling 16:49, 16 Jun 2005 (UTC)

Grave ambiguities

Measuremente units are still ambiguous in the article. Measurements are given in both traditional and metrical systems, without stating which one is the precise one and which the approximation. Worse, capacity is given in round numbers followed by both decimal and binary units without stating which one is the correct one.

There is a historical aspect on this. At the time of introduction and martketing of these devices the only designation in use was KB (often just K), or MB later on. So for historical reasons it makes sense to use the KB/MB notation. I even believe that the HiFD format was marked as 150/200 MB formats. However, I do agree that the accurate figures should go somewhere. What I propose to do is to introduce a table for each physical format (a single table for all formats would get too big) giving a (hopefully) clear view of the different logical formats available, but use the terms KB and MB consistently throught the prose. Any objections? Frodet 21:40, 17 August 2005 (UTC)

I had plannned to include tables like this in the main article. How do the rest of you feel about that? It might be a bit too big....perhaps a separate article?

8-inch diskettes:

Category	Drive designation	23FD	33FD			43FD		53FD
	Media designation	N/A (read only)	Type 1			Type 2		Type 2D
	App. size	80 KB	242 KB	284 KB	303 KB	492 KB	568 KB	985 KB	1,136 KB	1,212 KB
Drive	Heads (data surfaces)	1	1	1	1	2	2	2	2	2
	Spindle motor speed (RPM)	90	360	360	360	360	360	360	360	360
Controller	Transfer rate (Kbits/s)	33.333	250	250	250	500	500	500	500	500
	Encoding	FM	FM	FM	FM	FM	FM	MFM	MFM	MFM
Media	Track density (TPI)	32	48	48	48	48	48	48	48	48
	Bit Density (BPI)	1,594	3,268	3,268	3,268	3,408	3,408	6,816	6,816	6,816
	Density designation	SS SD	SS SD	SS SD	SS SD	DS SD	DS SD	DS DD	DS DD	DS DD
Geometry of the index cylinder (0)	Sectors	N/A	N/A	26	26	26	26	26	26	26
	Sector size (bytes)	N/A	N/A	128	128	128	128	(side 0:128 1:256)	(side 0:128 1:256)	(side 0:128 1:256)
	Size (bytes)	N/A	N/A	3,328	3,328	6,656	6,656	9,984	9,984	9,984
Geometry of remaining cylinders	Usable cylinders	32	73 (74)	75	75	75	75	75	75	75
	Sectors per track	8	26	15	8	26	15	26	15	8
	Number of sectors	640	1,898	1,110	592	3,848	2,220	3,848	2,220	1,184
	Sector size (bytes)	319	128	256	512	128	256	256	512	1024
Capacity	Formatted (bytes)	81,664	242,944	284,160	303,104	492,544	568,320	985,088	1,136,640	1,212,416
	Formatted (KiB)	79.75	237.25	277.5	296	481	555	962	1,110	1,184
SD = Single Density; DD = Double Density; SS = Single Sided; DS = Double Sided; N/A = Not Applicable; TPI = Tracks per Inch; BPI = Bits per Inch

Several other formats were also introduced:

Category	Drive designation	DEC RX01	DEC RX01	DEC RX02	DEC RX02
	App. size	250 KB	500 KB	500 KB	1.0 MB
Drive	Heads (data surfaces)	1	2	1	2
	Spindle motor speed (RPM)	360	360	360	360
Controller	Transfer rate (Kbits/s)	250	250	500	500
	Encoding	FM	FM	MFM	MFM
Media	Track density (TPI)	48	48	48	48
	Bit density (BPI)	3,200	3,200	6,400	6,400
	Density designation	SS SD	DS SD	SS DD	DS DD
Geometry	Cylinders	77	77	77	77
	Sectors per track	26	26	26	26
	Total sectors per disk	2,002	4,004	2,002	4,004
	Sector size (bytes)	128	128	256	256
Capacity	Formatted (bytes)	256,256	512,512	512,512	1,025,024
	Formatted (KiB)	250.25	500.5	500.5	1,001
SD = Single Density; DD = Double Density; SS = Single Sided; DS = Double Sided; TPI = Tracks per Inch; BPI = Bits per Inch

5.25 inch floppy disk capacities/formats on the IBM PC family

There were a variety of formats for 5.25 inch disks on the IBM PC, some of which are not reflected in this article. Sizes/formats were:

 8 sector, 40 track, 1 side =  160 kb
 9 sector, 40 track, 1 side =  180 kb
 8 sector, 40 track, 2 side =  320 kb
 9 sector, 40 track, 2 side =  360 kb
17 sector, 80 track, 2 side = 1200 kb

The first four were commonly called "double density"; the last was "quad density".

The format command included switches to force any of these formats (see the help screens of DOS 6.22). However a 360 kb or less diskette formatted in a 1200 kb drive often could not be read by a 360 kb drive. The explanation I recall was that the 1200 kb drive's tracks were physically narrower than those of a 360 kb drive, too narrow to be read accurately by the wider gap in the 360 kb drive head. --Jm546

yes an 80 track drive double stepped to 40 (whether by software or by a hardware 40/80 switch) can cause problems with real 40 track drives sometimes due to the narrower head. Plugwash 22:11, 25 August 2005 (UTC)

Kilobaud?

I came to the article looking for the standard floppy drive read speed, which the article states as being "500 kilobaud." Kilobaud? This is an article about floppy disks, not RS-232, right? How about using the more modern KB/sec (or even Kb/sec) metric?

That is a figure I found in the famous fdformat floppy disk formatting utility. Along with other parameters, one could choose between two data rates, specified in Baud, 500 KBaud or 250 KBaud for DD drives. The fact that the data is expressed in Baud merely reflects the fact that there is other (non-data) information written on a floppy disk (e.g. sector headers/stops, CRC etc.) that are read and written along with the "real" data. So, the only safe thing to say is that floppy disks read 500 KBaud (or "symbols") out of a floppy disk, whose "conversion" to real data can be tricky and very variable with one's system or floppy's format. EpiVictor 23:33, 6 September 2005 (UTC)

My formatted 3.5 MSDOS disks have different sizes...

and that is, 1,457,664 bytes! Nothing with 1.47-something MB! I reckon that the KiB/MiB nonsense is the greatest bullsh*t in IT history (Die IEC!), hence I will calculate in traditional units. Let 1 MB be 1 KB x 1 KB, that is 1,048,576 bytes. 1,457,664 divided by this size gives about 1.39 MB, augmented by roughly 1/10000. Hence in good ol' MB (1 KB squared), the size is about 1.39, not 1.47.

You are confusing two things; Firstly, the reason you get 1,457,664 bytes is because the FAT file system has an overhead of 16,896 bytes. This totals to 1,474,560 - hence ~1.47 MB. Secondly: 1,474,560 bytes / 1,024 bytes = 1,440 KiB (or 1.40625 MiB).

IMO the biggest problem with the IEC reccomendation is they introduced the unambiguos KiB/MiB/GiB but they decided that KB/MB/GB were fine for the decimal prefixes. This means that we still have no unambiguous way to reffer to the decimal prefix without using extra words or adding riders to our documents. Plugwash 22:10, 6 September 2005 (UTC)