Can non hd floppys format to 1.44mb?
Posted by Lunao_@reddit | vintagecomputing | View on Reddit | 80 comments
I found these today and im under the impression that its a 720kb disc?
I thought discs without hd and the second hole on the lower half couldn't format to 1.44mb, yet this one formats and holds 1.44mbs, maybe I'm stupid but i dont care if they are only 720 but if they are 1.44 id like to know.
KAPT_Kipper@reddit
No, the media is that much different. Also DD, 720K floppies are harder to find and HD floppies don't work in old machines.
bhiga@reddit
Most of my "converted" 720K disks still held their data when I went through them with Kryoflux after about 20 years. The ones I had real trouble with were the ones formatted to 800K with MaxiDisk as i couldn't load the driver to read it without an actual DOS machine.
rasteri@reddit
Can kryoflux not do maxidisk?
bhiga@reddit
It read the disk and imaged it, but having trouble mounting the image as MaxiDisk is nonstandard layout.
jbennett1337@reddit
I drilled the 2nd hole in plenty of floppies and was able to format and use 1.44mb. Used a drill press, worked great.
Ghazzz@reddit
Oldschool tech involved both modifying the floppy drive to have an external switch, or just drilling the hole.
It does not work well for all 720kb disks, but later generations tended to use the same disk for both 720 and 1.44 diskettes, so it was fairly common.
LisiasT@reddit
Well, been there, done that. They will format in 1.44MB, and the better quality ones will even hold the data. For some time...
It was a good hack in the days for short term storage, like sending data to someone else - where you won't want to use a more expensive 1.44 disk on the task (you will never see that floppy again).
But to long term store, to save your valuable data? Nope, really nope.
Not to mention that nowadays things had inverted - 720 disks are scarcer than 1.44 nowadays. At least, around here where I live.
the123king-reddit@reddit
I have a stash of 720k disks for my RCA MS2000.
The drives are so early they don’t even open the floppy shutters automatically. Using it costs about 3 inches of sellotape a time
Far_Relationship_742@reddit
You sure the drive isn’t broken? Auto-opening shutters were part of Sony’s microfloppies from the get go. Did RCA make a semi-compatible clone?
the123king-reddit@reddit
https://www.macgeek.org/museum/sony400kdrive/
The OA-D30V was the very first sony microfloppy drive and did not support opening the shutters.
Far_Relationship_742@reddit
Wild.
fondow@reddit
Exactly. Now, 720k disks are rares, and very useful specifics on computers, such as Tandy 1000.
Now, it's the other way around. 1.44mb are not hard to fin and as such, I formatted a lot of them to 720kb by putting a tape on the corner.
LisiasT@reddit
YOu have the same problem though - but in the other way around.
The magnetic connectivity needed to safely store data on that HD substrate is somewhat higher than on a DD one.
The data will be stored, but somewhat weaken then ideally. Don't trust these disks in the same way you would trust them if done on the rigtht disk!
chandleya@reddit
I don’t trust floppies at all in 2026
TomOnABudget@reddit
Or ever. Even in the early 2000s, I had floppies that were unreadable between writing and bringing them to school or a friend.
That's why they vanished so quickly from common use once CD burners and later flash memory became common.
Far_Relationship_742@reddit
What did you do to them? I have never lost data on a floppy. Hell, I’ve recovered photos off a floppy that had mold growing on it. I don’t know what folks are doing to their disks, or if I just have spectacular luck, but I have lost more data to bad flash than bad magnetic media by at least a factor of 10:1.
One of the drives was fucked up if this is true.
TomOnABudget@reddit
Dunno. I had cheap ones that I carried in my backpack on a bicycle in humid weather in Germany.
Maybe it would have been different with expensive Sony or 3M floppies.
Same goes with CD-Rs and burned DVDs. The cheap noname crap would delaminate after a couple years while the good Verbatim and similar discs should still read after 25 years.
Far_Relationship_742@reddit
I’ve had that same experience with CDR’s.
TrannosaurusRegina@reddit
CDs were in no way a kind of replacement for floppies!
TomOnABudget@reddit
CD-RW.... Once 2000 rolled by, files too often were so large, you needed to split them over multiple diskettes using WinZip or WinRAR.
I also burned CD-Rs as hand ins for school assignments. They were cheap enough.
TrannosaurusRegina@reddit
CD-RWs were a wonderful idea, but never actually worked reliably at all in my experience!
I used floppies for all of my school assignments. I remember in 2006, everyone was given one to store our assignments on for the year! I used them for my assignments until 2012, when I discovered how slow they were to compile to directly, and frustrated by losing work.
Though they're still much more reliable than CD-RW or any flash memory in my experience (including SSDs)!
Floppies aren’t the most reliable either
TomOnABudget@reddit
You used floppies until 2012 😳?
Dell announced they'd drop floppy drives in 2002. Most Laptops stopped coming with floppy drives when the millennium hit. Apple's iMac G3 from 1998 dropped floppy drives.
Using floppies in 2012 is akin to using Fax in the 2020s.
LisiasT@reddit
Hey, we still have our old fax machine on my parent's house!!! :D
LisiasT@reddit
In the 80's, I totally trusted my floppies!
(I had not other option - tape was even worse on home computers!)
chandleya@reddit
I mean it was capacity that killed the floppy but I hear you. They definitely weren’t 99% reliable
fondow@reddit
I will keep that in mind. I was in the mistaken impression that formatting 1.44mb to 720kb was less problematic, since there is less data density.
As for trusting the disks, well, let's face it, there is not that much uses for floppy disks in 2026. I still use them as I don't like Gotek. I prefer the authenticity of disks, and I can use originals non pirated copies of programs/games. In most cases however, I mostly use network file transfer with programs such as Netmount, Netdrive and Etherdfs, or copy directly to the CF drive.
I also use floppies as boot disks, or for stubborn and not well written installer that requires to be on floppy disks. In other words, nothing that requires long term storage.
LisiasT@reddit
How much data you write is 100% on the FDC's shoulders (to be more precise, the data encoder).
If we manage to coerce the FDC to write at 250KBit/s instead of the 500KBit/s we usually do on HD floppies, the our problems would be solved.
We would be able to write 1MB bitstreams into a 2MB floppydisk using the right magnetic coercion.
Do you remember the times we had Chromo and Metal tape desks and cassetes? It's the same thing, you could record a "standard" tape signal into a Chrome or Metal tape, but you would be just wasting money - so we pushed the rigth button on recording, so the signal would match the substract and so we would have better signal/noise ration on the more expensive tape.
It's the same thing - we need to convince the drive to "push its internal HD button" while reading and writing to the floppy, even if the FDC says it's going to push bits only at 250KBit/sec.
Dunno if it would be simple as to short some pin on the drive, or if we need to hack something on it - as we do to use PC drives on Amiga computers.
the123king-reddit@reddit
I’m interested in your last sentence. I have an idea for a project that’s reliant on DD floppies but DD drives are stupid expensive
Far_Relationship_742@reddit
Do you need filesystem access or volume access? Greaseweazle will happily write DD images onto HD media in an HD drive.
LisiasT@reddit
You have my attention! :)
Far_Relationship_742@reddit
Better to refer to them as DD and HD, since the media is what matters and format is arbitrary. You could format an HD floppy as 100k volume if you wanted, that’s all software.
An HD drive can format either media. It can format an HD disk as a 720k volume if you want.
A DD drive can only reliably format DD media. You can format an HD disk, but it will fail about half the time, and the data may decay and become unreliable or unreadable quickly.
the123king-reddit@reddit
Strange you say that. I had an ICL disk that i suspect was HD media without a notch. It was not happy in my 1983 RCA MS2000. Read fine, but writing was not
pimpbot666@reddit
The trick is, you use a 1.4 MB disk, and put tape over the other hole, and it will format as a 720kb disk.
damieng@reddit
It's unfortunately nothing to do with quality but has everything to do with how much strength the magnetic medium needs to "flip bits".
1.44MB disks require a stronger magnetic field to hold their data as the medium itself has magnetic "resistance" known as coercivity. For 720KB disks this is around 600 Oe's and 1.44MB it's around 720. When you get up to the 2.88MB format then you're talking \~800.
So if you format 720KB disks as 1.44MB then the magnetic flux transitions are going to bleed into neighboruing transitions either on neighbouring bits on that track of on ones either side.
The problem is true in reverse as well. Format a 1.44MB disk in a computer that has a 720KB drive and you're going to get the opposite problem - where bits might never get written properly at all or might not retain their state resulting in "random" data when being read (also known as weak bits and a staple in 3.5" copy protection schemes).
LisiasT@reddit
My experience from that times says otherwise: good quality 720Kb disks performed "less worse" then cheap ones.
That happened because it would not make sense to have two manufacturing plants for deliver SD and DD floppy disks - so essentially everybody and the kitchen's sink just manufactured DD disks, and labeled SD the floppy disks that gone trough a more lenient quality assurance process.
SD were essentially FM encoding, while DD got the (at that time) fancy MFM one. But MFM flip bits more times than FM, and so manufactures that gone on the cheap increased the chances of corrupting the bistsream on that substract when using MFM.
We had similar process on RLL hard disks - MFM plates have a hard time withholding RLL data due how the bits flips on the plate, but sooner than later everybody were just manufacturing RLL plates. Soonr than later, all drivers were essentially RLL capable, and the difference between them were the price and the quality assurance process - plates being used on MFM drives didn't had to endure the same process the RLL ones had to.
Coercivity is not the only factor, coating also plays a role. You can mage the substract less dense to save some money on the long run and still be able to hold FM data on your disk, but you will have trouble on MFM.
damieng@reddit
I'm not saying that 720KB disks didn't have per-manuf quality issues affecting how they compare to other 720KB disks - just that a "high quality" 720KB disk doesn't count for much, if anything, if you're going to format it as 1.44MB.
My comment about SD and DD was specifically referring to the Hitachi/Amstrad CF disks. The majority of systems used MFM by default (Amstrad, Sinclair, Oric, Tating) on these systems even though the drive and oft-paired NEC 765 could do both.
I still work on fluxx imaging these disks these days for preservation. Got a bunch to get through hopefully they haven't rotted further. The CF2 disks aren't great especially given the abuse copy protection threw at them.
EsoTechTrix@reddit
More TL;DR Why it usually "worked" (but wasn't perfect): The magnetic coatings for 3.5" DD and HD disks are relatively close in properties: DD: ~665 Oersteds (Oe) coercivity. HD: ~720 Oe coercivity. That's only a small difference compared to older 5.25" formats (where the gap was much larger). An HD drive's stronger write head can usually magnetize DD media strongly enough to hold the tighter HD bit density (more flux transitions per inch). In practice: Many cheap/generic DD disks formatted fine as 1.44 MB and held data reliably for months or years. It was cheaper to buy DD blanks and "upgrade" them than to buy official HD ones. Some manufacturers even certified media that passed HD tests as HD and the rest as DD, which helped fuel the rumor we discussed earlier.
What did happen in manufacturing?
Quality control and certification: Every batch was tested (signal strength, error rates, durability, etc.). Disks that passed stricter tests could be sold as premium (or sometimes "certified" for higher densities). For some older formats like 5.25" Quad-Density (QD) vs. DD, the only real difference was sometimes the final verification/certification step — same media, different labeling after testing.
If it's for fun and playing with old drives with no concerns for data loss, it's doable and would tend to (sort of) work. The warnings being things like disks written on one drive may not work on another, etc.
HealthyArm9939@reddit
Holes punched on hundreds of floppy es. Most of the time it worked. Most of the time…
the123king-reddit@reddit
I believe they can be formatted to 1.44mb but read/write reliability is not guaranteed due to the physical magnetic medium being different.
Kurgan_IT@reddit
This. The medium is different, the drive itself will use a different intensity of magnetic flux to write to them. So while there is the hole as a way for the drive to know what kind of disc you are using, just making the hole will not make a 720 disc work as a 1.44 one.
Important-Bed-48@reddit
this is true. I had tons of low density blanks left over from my Amiga (880k low density format) when I upgraded which I would use if I giving someone a copy of something they were only gonna need to use once, because I learned the hard way if you formatted the low density disks in HD they would become corrupt randomly after multiple uses. I'm convinced AOL used low density disks which were free and ambiguous back in the 90s but could not stand much re-use if you tried to do something else with them.
Kurgan_IT@reddit
I believe this can happen because the drive uses a much stronger magnetic field when writing to HD discs, and this can "leak" to adjacent tracks on a disc that has a higher magnetic susceptibility. So you write to one track and damage the two adjacent ones. Maybe if you write once and sequentially from track 0 to the end, you can get a working copy. But once you rewrite multiple parts multiple times, it gets corrupted.
BetElectrical7454@reddit
Correct as a general rule. However later disks marked as DD used the same quality of medium because it was cheaper to use one formula on all disks rather than maintain two separate production lines. Similar to how CPU manufacturers use the same chip design but market higher and lower speeds based on the lowest speed they remain stable at. They may be capable of higher capacity but I wouldn’t trust them for important stuff.
garth54@reddit
Drive shouldn't allow it without the second hole on the disc, but maybe it's ignoring that (actually I'm not sure if this is drive or os level, so maybe the os doesn't think DD is a thing anymore).
As to actually doing it. There were hole punch devices made to make the system think it's a HD disc. Obviously, those were made because it could be possible for a DD disc to hold a HD formatting. However, the magnetic media coating between the two are different. So many DD would fail to work as HD, and if one did, there's a good chance it would be unstable and/or plagued with high error rate.
That said, an HD floppy would have no problem acting as a DD one. And such, there was a time where producing HD wasn't really more expensive then making a DD one, at least not once you account holding 2 parts. So some manufacturers, particularly toward the end of DD, produced DD discs but with a HD media. So if you have one of those, there's no problem getting it to act as HD (which was the primary target for those capacity hole punch devices).
Note that it's basically the same issue between HD and ED (2.88MB) discs. Different media coating, and it even used perpendicular recording technology. (From what I hear, Commodore had a specific drive that could convert an HD to ED, but the resulting disc would only work with drives of the same model).
Lumornys@reddit
In an HD drive. But an HD floppy formatted as DD may not work in a real DD drive, or so I heard..
garth54@reddit
For 3.5" floppies, it's usually "fine". There is a caveat for crappy 3.5" HD floppies used in some older DD drives having difficulties, particularly when the DD drive writes to the floppy. But this was mostly an edge case, you just had to do a test write/read the first time, and you'd know if that floppy was going to be ok to use with that DD drive.
Doing so, does limit how long the media will last. There's no hard data on this (at least none that I have ever seen), but what I remember being often quoted was: if the data is supposed to last 20years, it will only be good for 10 when doing this. (note my skepticism is on the numbers, not on the fact that it reduces the life).
People trying to use older computers, like say a Tandy 1000, are often stuck using HD floppies in their DD drives. And in the most part they don't have too many issues doing so.
Do note that this isn't true for 5.25" drives & floppies. The head on the HD drives are smaller than the head on the DD drive. The floppies had 40 tracks on DD and 80 on HD. So if you wrote on a DD formatted floppy in a HD drive, the top and bottom edge of the (DD) track would end up being different and cause all sorts of errors when read back in a DD drive. Every time you'd want to write on it in that case, you'd have to degauss the floppy and re-format it to keep things clean enough that the DD drive could read it. However, if you format the HD floppy in a DD drive and only write on it in a DD drive, then it would be fine, the problems comes whenever you try to write to it in a HD drive.
Lunao_@reddit (OP)
See id assumed there would have been stopping me from formatting it, both my ibm netvista and pc300pl do it without protest, both will also format to 720 so I'll just format them for 720 !
guiverc@reddit
Disks were 500KB, 1000KB & higher in unformatted capacity. The 1000KB when formatted using normal methods was usually about 720KB (DSDD), the 500KB was 360KB (DSDD) or 180KB (SSDD) or 100KB (SDSD), and I've only covered SD/DD (single-density/double-density) media here.
Media that was HD differed, and was capable of more densely packed sectors on the same tracks, where SD/DD was now HD & more sectors per track, thus had higher capacity (high-density).
Media and disk drive capacity should align; but you could format drives in non-standard formats as well; though inserting them into a different PC that wasn't configured to accept them may mean they won't be recognized; or that the media itself just gave you errors & you lost data.
720KB was a format used by 5.25" (96tpi, 80 track, DD) OR 3.5" (135tpi, 80 track DD) and relates to a formatted capacity. The person who formatted decided what 'format' (file-system & allocation table) they put on the disk.
You could try storing data on your DD media with a HD format, but other drives may have trouble with it, the media may not store the data that long (ie. problems reading it in a week/month etc) OR it may work flawlessly.
It wasn't that uncommon for higher quality media to be sold as lower quality discs, or the reverse, but there is always risk when you're using outside of what it was 'rated' (or tested) for use with.
Dannynerd41@reddit
no that’s a 800k drive. that’s like asking can i put two gallons of was in a 1 ounce bucket
AnnieBruce@reddit
Yes, though it may be less reliable than a floppy made to be 1.44 from the factory.
OldDiehl@reddit
Lots of the 720's could easily hold 1.44. Because I bought one of those 'fancy' hole punches to do just that. It looks like your drive might be ignoring the lack of a hole.
Far_Relationship_742@reddit
A punch for 3.5” floppies? That had to be a pretty beefy tool!
The_Jizzard_Of_Oz@reddit
I just used a drill 🤣
OldDiehl@reddit
It certainly was. Mine looked like this: https://share.google/TpcuVoCwEgPTDZ8wI
captain-braincell@reddit
Cut the corner off with a pair of scissors, then it'll format as 1.44mb.
Did this back in the amiga days, so I'd get a bit more storage when using my disks with the PCs at college. It works well enough, with some extra risk of bad blocks.
e-nightowl@reddit
Most can, yes. I have done it numerous times back in the day. However, I personally have had disks that worked just fine in DD, but data was corrupt after punching a hole in it to use it as HD. So, if you decide to use it as HD floppy, make sure to verify that the written data is readable afterwards.
leitz68@reddit
Yes they can you have to drill a hole in it. Used to do it a lot, i still have them, good luck
rezwrrd@reddit
I have a special square hole punch that was used for exactly this purpose. (On second thought, I can't remember if it worked on 3½” diskettes or just 5¼” disks.)
leitz68@reddit
I have one for 5¼” !
Zhakrin999@reddit
I had a specially made punch to add the hole back in the day.
Looked almost like a 2 hole punch but built for a 3.5" floppy
EsoTechTrix@reddit
Can it be done? Yes? What I had heard was that they quality tested the disks at 3M and the ones that did not meet a limit would be marked for low density.
Get a drill, put a hole in it, and do a low level format that tests every sector. You may not get the full disk capacity, but it will be more.
I would avoid storing anything important on it after that (or any floppy for that matter)
BCProgramming@reddit
Allegedly.
I didn't do it myself, but on a 386 I was given by my CS teacher in high school, he had modded the floppy drive and removed the sensor for the media hole to a rocker switch, so you could choose whether it saw diskettes as 720K or 1440K. He claimed that he saved money by buying cheaper 720K diskettes for years and formatted them as 1440K without any problem using this.
Though, would they have even been readable by other machines?
jacle2210@reddit
Oh the nostalgia; I still have a special hole punch for these 3.5 discs, lol.
pimpbot666@reddit
I have a friend who was a pretty hardcore cheapskate. She would basically punch a hole in the other corner to tell the floppy drive it was an HD disk. She said she never had an issue with it.
Then again, that was the early 90s.
Stoney3K@reddit
Within the spec, no. You're going to have read errors because the magnetic bias of the drive for a HD disk is going to be different from 720K media.
Think recording a plain ferro cassette on the chrome tape setting. It would sound bad playing it back.
Phydoux@reddit
For some reason, I remember having a disk notcher for both 5.25" and 3.5" disks. Notching the 3.5" disks pot a second hole at the top of the disk on the other side. That made the floppy drive access the other side of the disk... That's what I remember. It's been maybe 2 decades since I've even used a floppy drive in my PC.
As soon as CD and DVD writers came onto the scene in the late 90s I think, that was pretty much it for the floppies. And I most recently stopped using a DVD writer because even those are becoming obsolete now.
Far_Relationship_742@reddit
Other side of the disk is for 5.25 floppies, making a “flippy”. Punching the extra hole on a 3.5” disk makes the drive switch to HD recording current; except for some very early oddballs like the Tandy TPDD and the Mac 400k drive, all 3.5” floppies write on both sides.
thejpster@reddit
The drive mechanism has 80 tracks, two sides, and an infinitely repeating loop of magnetic media per track that repeats 300 times per minute (5 times per second). A floppy controller can read/write at either 250 kbit/sec or 500 kbit/sec off of / on to that loop.
The difference between a 1440 KiB floppy (it was never 1.44M for any rational value of M) and a 720 KiB floppy is whether the track is divided into 9 sectors of 512 bytes or 18 sectors of 512 bytes (plus headers, plus checksums). I guess you can just write 18 sectors at 500 kbit/sec on to an MF2-DD but the magnetic media wasn’t designed to hold that much data per inch and as others have said, it’ll be less reliable.
If you put the same drive in an Acorn RiscPC, it’ll happily store 10 sectors of 1024K per track (for 1600KiB total). The drive has no idea this has happened - it’s all in the floppy controller and the software that configures it.
thejpster@reddit
Also, if you don’t need MF2-DD disks, sell them to an Amiga or Atari owner. MF2-HD disks are unreliable in a DD drive, I think because they need a higher strength magnetic field.
michaelpaoli@reddit
DD isn't rated/certified/tested/manufactured for HD, so, if you do HD (e.g. 1440KiB) on 3.5" DD microfloppy diskette, all bets are off for data reliability. Also, without that extra hole to indicate HD, hardware will generally be wanting/expecting DD, not HD.
stromm@reddit
Some can.
By about 1990, ALL 3.5” disks used for 3.5” floppies were all manufactured on the same lines. There weren’t separate 720k and 1.44mb lines.
The only difference was quality control testing. Anything that failed 1.44mb testing was sent for 720k testing. If it passed, it was used in 720k labeled packaging.
Anything that failed 720k testing was scrapped.
Avery_Thorn@reddit
As someone who did this back in the day?
Yes, they can be, with a bit of tape and some arts and crafts. If you compare it to a 1.4 floppy, there's a difference in the notches. You have to tape over the notch that is there, and you may need to cut out the notch. Depends on the drive.
This will let you format the floppy, and it will even store 1.4MB of data after that. But be warned: you will start getting data errors pretty soon, and it's unlikely to hold the data for very long at all.
It works better if you do a magnetic bulking on the disk before you reformat to 1.4MB.
I, rather obviously, do not recommend this. How well it works depends on the quality of the disk and how late it was made. Some of the later 720 disks really were just 1.4 disks with the 720 formatting from the factory, and they would work fine, but there's no way of knowing for sure.
If you are using a vintage mac, and you cannot find vintage Mac disks... I have had fairly good luck derating 1.4mb disks to use in the mac drives. Just run a good magnet over it first - the larger the magnet and the more uniform the magnetic field, the better. (The absolute best is a bulk tape eraser, if you can find one.)
zorba-9@reddit
720 disk, no
damieng@reddit
Can you format it? Yes.
Will it be reliable? No.
Why? The two formats use different magnetic strengths and the disk medium is designed for that. Data is going to bleed in this scenario. You can't even reliably do the reverse for the same reasons. It was like this with 5.25" disks too.
gadget850@reddit
If you notch a 720 it will format to 1.44. The consensus back in the day was that the media was the same, just sold for different price points.
Accomplished-Camp193@reddit
DD is 720k max.
Unlucky_Age4121@reddit
I asked the same question many years ago on some bbs. If I remember correctly, the answer I got was that "The magmatic substance might have the ability to be formatted into holding HD data, but no guarantees."
Sad-Working-9937@reddit
There's a quality issue.
Floppies decay. there are various sizes of the magnetic particles on the disks. you might be able to get 1.4Mb on to it. It might read and test that day. Will it last? Are you just trying to use an old computer for fun for a day? Sure, try it.
But is that a 20 YO disk?? If so I wouldn't *trust* that with any amount of data.
Der_Unbequeme@reddit
yes, in a drive wich the HD index is deactivated.
flipadoodlely@reddit
No they are double density (DD) and not high density (HD) so 720KB. You would need to cut another hole on the right side (the left hole with the plastic slide is for write protect). But even then it would be unreliable.