High Density Floppy Disks on Commodore 1541? 

Back then, I remember asking for blank disks for my birthday/Christmas.

So glad I found this video...THANK YOU! I am a reseller & typically possess correct product knowledge, but I am not abundantly tech savvy and have somehow managed to obtain a good deal of NIB Gaming Box Sets & Software, as well as, new & used disks. I listed the NIB HD diskettes online & included all the package info for compatibility, assuming the consumer would be searching for specifics based on their need or interest, BUT I received a message this week inquiring about thw compatibility of these disks with thw Commodore 64. YIKES!... I hadn't the slightest clue, but I knew I needed to find out! And so, I DID! ... Thanks to you creating this video! Very helpful! And I will recommend ur youtube to them in my reply!😊

One thing I did many years ago when I encountered HD disks, was to use a strong magnet about 3 inches away from the disk on both sides. After doing that I think it would cancel out some of the peaks in the field placed there by an HD format on another machine. I could successfully write to the disks without any issue. I bet using a degauss coil would possibly work as well. Just wondering if anyone else has tried this.

I cringed when you pressed down on your 1541 with the notcher, but it was "for science" so thank you sir.

I did a bit similar in the MSX world, it is not that, the ring or the material, it is the original IBM formatted tracks, which are STEPED in different position are interfering with what you are trying to write, but IF you sweep with a good magnet all the original format, and the disk don't slide, IT must format and read OK, but, because always is a big "BUT", it won't LAST by years. IT is the difference in 80 tracks vs 40, So, if you are writing a wide track, the head can erase that part, but as originally is a pattern of 80 tracks, the TOO CLOSE to interfere next HD track will interfere.

Awesome video. It is funny how many people advocate using HD disks in place of DD. I have never been able to get them to work and wouldn't trust them if I did. Glad I found your channel, keep up the good work.

The HD disks seem a bit like the different types of audio-cassette tapes. Type I has a brown color while other types have darker colors and mixed-in cobalt and the writing is done differently for each type.

Thanks for the shout out! Glad you like the magazine :)

I didn‘t know about this. Would be intersting to scope the signal from the write head when readin DD and HD floppy disks. That might unveil a bit, maybe... gotta go to the basement and check...

IIRC, SD and DD disks were made from iron oxide (20kA/m coercive field strength), HD used cobalt-doped iron oxide (50kA/m coercive field strength). Thus, you would require twice the magnetic field strength to overwrite the disk, you might get away with a lower field when the magnetic layer has been demagnetized.

Interesting...this explains why I had issues with a couple of my disks back in the day. I think they were IBM branded. I managed to write to them ok but reading back was problematic. The fix was to open and close the drive door of the 1541 and then hold the door down with some pressure and most of time this would allow the game/data to load off the disk! Surprisingly this appeared not to damage the 1541 - the things we did when we were kids!

Binge watching your videos. Great stuff! On this one, I have to say LOL, you told that whole story about the guy that claimed HD disks. worked for him and you said you didn't THINK he was lying, etc, but then you went on to show a drive YOU own that it works on. So you knew the whole time :) haha. Yeah, when I was a kid, I heard the same thing from one of my friends. I hadn't tried a HD disk myself but I remember a kid saying it worked for his friend but you still only got 664 blocks. I was bummed because I hoped you could somehow get even more storage. Of course, we know that would be impossible. The 1541 is still going to utilize the media in the same manner with the same number of sectors and only 256 bytes/sector.

In high school, we had some of our computers in the same room with all the typewriters. I remember taking a 5.25" floppy and running through the typewriter and typing on the label... and it still worked! It looked like hell, and the sides were busting open from being cranked around that wheel, but it kept on reading and writing without a problem. Don't ask why I did it, because to this day I still don't know. :)

Back around the 2000s I wrote lots of Atari ST images to HD disks with the HD hole covered on a PC. Those disks worked fine on my ST back then, but none of those HD disks works now, 20 years later. But my DD disks still work like a charm even today.

I would like to tell you few things about the C1541 drive and the DD/HD disks problems. TL;DR: C1541 is weak and cannot overwrite the PC formatted disk. Long story: Hub ring - missing hub ring could, in some conditions, make the drive some problems when trying to spin the disk. But it is not the difference of the DD over the HD disk. Feromagnetic coating - this could be one of the sides of the main problem, but usually the HD disks are made of finer material than those DD ones. The coercivity could be just a part of the issue. The C1541 drive heads - this is what goes on in that case. The main problem is the output current for the writing head. On the PC the writing currents are higher, making the material magnetized deeper. And the C1541 drive is not powerful enough to revert the magnetization of the cells in the magnetic coating of the media. If there is no magnetization, it is strong enough to make it magnetized to some level. But the level used in PC drive is higher. You should know, that those HD disk usually came "preformatted" for the IBM PC standard! So if you would like to use those HD disks with your C1541 drives, be sure to have them "demagnetized" first. The best way is usually to use "the media cleaner", used in production companies/TV station productions, to clean their BETA tapes and so on. It has to use the "hi-frequency" electromagnetic field. Of course the C1571 drive is newer, advanced and uses stronger currents. The C128D uses this C1571 drive internally. So that's why the C128D was able to format the disk.

Thank you! I couldn't figure out what was wrong. Awesome. I checked and the disks I was having trouble with were HD not DD. I tried with DD and it works! Thank YOU!

The hub ring is not the problem. It's used to strengthen the media at the center so it doesn't slip or tear easily. The real problem is the magnetic coercivity of the media itself. Commodore drives are only designed to recognize and work with DSDD Diskettes. IBM PC and compatibles could do both because the mechanism itself compensates with the extra tracks and different coercivity. When you format a 1.2M Diskette as 360K, the drive just uses less tracks. The coercivity is automatically adjusted. Edit: oh you said this in the video

loved the Micadon ad at the end. that brought up some memories! and i did NOT know that there was an issue with HD floppies, very informative Robin, thanks!

Thanks for your research. I just ordered some HD disks for my 64. Without your video I would probably pulling out my hair wondering what is wrong with my disks or the 1541. Thanks again. 🖖- Live long & prosper.

I've run into this issue too and just thought I had some bad disks. And now we know the rest of the story...

My 1541 would occasionally eat hub rings. I don't know what kind of material that stuff was, but man, you pretty much needed scissors to get it out. Some tough plastic. I can't remember if I ever had success with HD disks or not. I know I had encountered them, but can't recall if they ever worked for me. They probably never worked.

Similar experience here with HD disks. My dad brought home a number of used 5.25" disks for me to use on my C64. I found they wouldn't format on my 1541 -- BUT after rubbing them on a rather strong magnet, quite often they would work! I wound up using them for years, but they were unreliable in the sense that if you wrote to them there was a chance of corruption. However, once data was written successfully I never had trouble reading it back, even 30 years later. My theory as a 12-year-old was that the magnetic field on the disks needed to be "reset" for them to work on the 1541. After making this discovery, I began using the magnet as a bulk disk eraser. This eventually cost me a brand new copy of Test Drive, when my little brother took the game disk out of the drive and decided the magnet looked like a perfect place to store it.

The reason why the HD floppy disks required a higher magnetic flux was so that they could support the higher density of data. If you try to "squash" data bits too close together on a disk, the magnetic field used to write the bits will tend to "spill over" to adjacent bits, possibly overwriting them. When the magnetic coating won't take the data as easily, then the bits can be placed closer together without the magnetic field from the write head adversely affecting nearby bits, even though the magnetic field needs to be stronger to write each bit.

HD floppies do not work in a DD drive because the properties of the magnetic material are different. The amount of energy required to write and read HD disks is different than DD disks and the data rate used to write the disk is also different. also the track width of a HD disk is narrower than for DD disks. Some single sided double density disks will not work when the disk is flipped. This happened in the early days because it was too expensive to test and format the second side. Later, the quality of DD floppies was much better and the same media was used for single sided floppies. This allowed floppies to be flipped.

I just got my first ever 1541! Unfortunately it did not come with the serial cable, so I need to find one of those. But I'm excited to finally have disk access for my VIC-20!

Embassy Gold! Awesomes memories! 1-3 disks per box failed in the first 3 months of use. All I could afford at the time. I remember getting it in multi colour packs.

Hi, found your channel I while ago, and just started to go through to watch all the videos on it. re high density disks working in your C128D, i had a C128D back in the day too which I used for many years, and I had the same experience, HD disks would format perfectly fine (both sides) and even save stuff to them without issue, whereas a 1541 drive I obtained later on would not work with them at all. Being that the C128D had a 1571 drive, it must be because of that, the 1571 is more tolerant or higher build quality, to have a better ability to use a wider range of disks or something. Which is why I would have liked to see you try on your external 1571 drive to see if the HD disks worked on that too (but you didn't use it in the video). Even before I got my own 1541 though, I already knew about HD disks being totally unreliable when used as a DD disk, so I never used them anyway, and on the occasion someone else sent me stuff on a HD disk (it did happen) I immediately copied it to a blank DD disk in my 128D before loading the stuff contained on it. Utility cartridges are nice too. I had an Action Replay back in the day, with many similar features to the Super Snapshot (just accessed and used in slightly different ways). Love the fast format the AR offered, formatted disks in just 10 seconds, no messing around waiting for it to finish there.

I remember going there and buying the same diskettes. I also went to Honest Ed's to get no name diskettes. Thanks for the memories

I`m C128 owner. Someday i bought Polaroid`s DataRescue diskettes 2S/4D (Quad Density) 96TPI. Never had any issues with formating or writing/reading. My disk drive is a liitle difrent than yours, with Alps drive mechanism. BTW one of my 10 diskette pack still folied...

back in the day i used to have some dshd diskettes too... i've had games on some of them and i couldn't read or write them with most of my drives, only my 1571 could decently write and read from the ones thta worked (and most of them didnt). I had 4 drives and copied tons of diskettes (literally thousands) one time i had a batch of hd disks used, and the guy who bought those disks from me couldn't read them at all. Since then i banned ALL hd diskettes, i even lost some data as some diskettes i had couldn't be read anymore, not even with the 1571. (my collection was over 2000 diskettes). In case you're wondering, i used the superdisk toolkit to copy all of my disks as it could copy from one to multiple drives at high speed

Nobody: Basic: "AAAAAAAAAAAAAAAAAAAAAAAA"

I remember this shit. There was a variation of disk that could do both and that was one of the differences between expensive disks and cheaper or earlier disks. The brands that are around for later 3.5" floppies exist because of that feature. The 1571 in the 128D is an example of the upgrade. Counting the tracks written is key, the drives that format a HD always format with the correct strength for the media. If it's still a 35 track disk format, the 1541 would probably read it. I wouldn't try and write it with a 1541 after the fact. It would probably mess up the disk.

I'm impressed with how well this media holds up. For some reason (perhaps it was just too soon) I never came in contact with the HD disks for my c64. Luckily I never had a problem reading disks because of their density. Having seen your video, I know I never will.

The reason why the HD disks have a coating that requires stronger magnetic fields is because the tracks are closer together. So when one track is written to, it must be ensured that the tracks next to it are not also written to. By making the coating less sensitive to magnetic fields, a strong magnetic field writing to one track will already be too weak to write to the adjacent tracks. This is not a problem with DD disks because the tracks are further apart and the magnetic field decreases greatly with distance. An alternative would have been to make the coating even more sensitive and simply work with weaker magnetic fields, but this approach would have had the disadvantage that the disks would then become much more sensitive to magnetic fields from external sources, and magnetic fields always occur around a computer and TV, even every power supply generates some.

Happened to me as well. I used the HD disks to watch the 1999 Total Eclipse with them.

I found out that the 1541C (Mitsumi drive) has problems with HD Disks, but the 1541 II (Chinon drive) and the 1571 can handle HD disks, i even could backup original copyprotected disks and they work. The brand i use is "db boeder". Maybe i was just lucky to have good working disk drives.

Ok 1541 does not work with HD disks and 128d drive does. But does anybody tests 1541-II or 1571 ?

The reason why the 1541 failed to format the high density disk is not because the disk is bad, but because the 1541 wasn't designed to deal with such disks. High density disks were meant to be formatted in IBM compatible systems that had 5.25" floppy drives that supported those disks. Also, they spin at 360 rpm, and they need a much stronger magnetic field to write to them and were often pre-formatted. The manual for 1541 states that only double density disks should be used. The rotational speed is 300 rpm. Formatting a disk takes 80 seconds which is slow compared to other drives. The rattling sound you hear when you format a disk is the head being banged against the stop. The reason for this is that the drive has no way of knowing where Track 0 is located, which is why it does that. It also does that when it encounters an error and can be caused by disk protection.

Intresting video. 👍 On my Enhancer 2000 disc drive HD floppys seems work fine, even after 20 years!

One thing to note is that commodore never produced the actual disk drives. The drives were made by alps, then mitzumi...but after that it might have been made by teac or some of the more modern manufactuerers. This would mean that the drives being manufactured would likely end up in a wide range of machines. Its just possible that the newer drives were meant to handle both DD AND HD. Just as youd find in an IBM or compatible AT.

HD also didn't work on the Amiga, if you had no modified PC drive ... was so bad and sad one said, he swapped the drive from a 541 to a pc hardware drive, but I can't believe it - because the electronik is for a DD disk somehow like with audio tapes (ferro and chrome / metal)

And i reccomend, always before hit RETURN close command, i mean write all full command with OPEN and CLOSE, and after each format try to Initialize each disk, best regards.

Interesting! I have a 1541 too, and I have some imation DS, HD disks, that format normally and are usable...

Several years ago when a Radio Shack in the area was closing down, I went there and bought them out of 5.25" floppies which I was surprised they still had. I got a ton of them for maybe $5. But it wasn't until after I got them home that I discovered they were all HD, and HD floppies aren't compatible with the 1541! I was so disappointed. I still have them and don't know what to do with them. BTW, I love Fast Hack'em format: 9 seconds and done. JiffyDOS is pretty fast, too.

Your pronunciation of 'ørsted' is quite fine for a non-Danish speaker, don't worry.

I believe it is because high density floppy need a higher bias due to the difference in magnetic material composition. Similarly to not being able to record on a chrome audio tape with a cheap tape recorder.

I absolutely agree. I recently bought a mix of different floppies on eBay. All the 2D floppies formatted in my 1571. None of the HD ones did.

Holy cow! I worked at Mikadon (County Fair) for a while when I was 14 --up until it folded (don't blame me!). Missed the days when that was *the* store to get Amiga stuff...

Tryed this on my 128d back in the day. HD disks were a no go for it

My Clone Oceanic Drive seems to be quite happy reading and formatting HD Disks, perhaps they are using 1570/1571 or similar mutiple format capable drives

After formatting with the 1571 or copying a DSDD disk to a DSHD, can you read that disk in the 1541?

The inner ring hub was quality, some disk makers added them some did not.

Atari worked with my HD diskettes in DD drive. But there was an issue - they was not read on second DD-drive, and vice versa.

Well he did 'hammer it home', and that was painful viewing indeed. First he stamps the notch ON the delicate floppy drive, then he does it again, sending a shock wave through the 1541 drive, whilst it's formatting a disk/disc! 😂 🖋

There were about 4 versions of the 1541, and these were not marked, so some of the later ones may have had different mechanisms then the early ones... The fact the drives were "smart" meant that a change of mechanism could be accomodated with a change in the ROMS.

I remember reformatting HD floppies on the ZX spectrum. I dont remember how well they worked, but as I dont remember issues either, I think they were fine :)

Squeeze the puncher within your hand, much easier that trying to push it down on a flexible housing...

In the early 90ies some compatible (but not original) floppy drives appeared. They had a standard PC floppy drive and a microcontroller emulating the 1541 behaviour. They´ve been much cheaper than the originals. Probably these could handle HD disks. I had one of these and it worked.

This is the first time I've heard about this. Back in 1995 or so, when I was still regularly using a C64, I bought a couple boxes of 5.25" disks, which were still readily available. They were ordinary 3M brand if I recall, and IBM formatted, but not sure if they were HD but assume they were (they're in storage) or if DD were still even regularly sold anymore at the time. I never had trouble with any of them, this with using a 1571, and saved quite a bit of stuff back then but have barely touched them since the late '90s and not all since 2004 or so. What I'm concerned with now is, assuming they're HD, if the recordings are still viable, assuming they weren't adequately magnetized back then.

What about the shutter on the drive.The drive with a flap is a different sort.Alps and newtronic and there's a jumper on the board for the different drives,you can swap them but you need to look at the jumper setting.I think the jumper j6 is to do with the current to the read write head.J6.

Interesting. I own a C128 with 1541 and 1571, I'm pondering to try it myself. Here's an idea. Put one of those HD floppies in an old regular PC and format it with the parameter for 360k or 720k, and see what happens. Then try to format again on the 1541.... By the way: I have the exact same floppy puncher as you do, over here in Europe!

I use HD Disks in my 1571 for ober 20 years, without issue. Also I have no issue with HD Disks on my 1581. But I havent testet this for so long. I got it for 2 years now.

I wouldn't expect the reverse side of any single sided disk to work (at 10:20) because the pilot hole is now on the wrong side, thus it would not be able to detect rotational speed. I remember having some double sided disks for the BBC Micro (they were actually double sided as you could flip them over) and they had 2 pilot holes either side of the main spindle hole. The notch(es) on the side(s) are used to control if the disk is writable or not for that side, similar to the notches on audio cassette tapes.

Playing catch-up on your most recent videos. Informative video, yet again, Robin. Man, I always wanted a notcher -- I was always eyeballing them in the magazines when I was a kid. Wasn't that a movie, Godzilla Vs Mikadon? ;)

we have to make a fix for the 1541 :-) a kind of calibration run when formating would be cool and writing the power information on a reserved space if there is one. if there is no reserved space available, then the drive would have to make a check after each new write

The 1571 drive can write HD floppies. As I read the C128D has a 1571 drive built in. It's interesting that 1541 can not even READ a successfully written HD disk, I don't know exactly why.

an old school disk. Do you know the double density can convert to high density floppy disk you must remove the tape at the middle of the circle but it makes badsector if you format from 360kb to 1mb disk

As new DD diskettes are getting harder and harder (and expensive) to find here in Hungary, I'm planning to do a mod on my 1541, to make it able to save on HD disks. I'll put a switch on it somewhere, which will adjust the recording current to match the different formulation. Reading the disks saved on this modded drive with other 1541 should be fine, only saving to them is a problem. I'll probably put a reed switch behind the case, somewhere far away from the disk, and this way I will be able to switch between modes by putting a strong external magnet to the right spot. I don't like the idea of drilling holes for mod switches on my 1541. There might be a fatal trap for this plan: if the head can't handle the doubled recording current, and saturates. I *probably* won't go so far to transplant a HD capable drive's head into my 1541...

Lucky you finding 50 boxes of DSHD Diskettes... Need some myself for my AT

PLEASE RECAP your Monitor or cut it off while talking!!!! I'm 51 years old and can still hear that CRT Squeal!!! Love The Videos!

Nope, they cannot work in 90% of cases. The magnetic elements are just too small on the HD discs. I even tried with my SFD-1001 (requires a quad density disc), but could not format any of them. (I tried 3M and Verbatim HD discs, should be in great quality).

I have Commodore 128D too, and put it into C64 mode and tried to format it using the 1571's 1541 mode and it still would not work with HD disks, and neither worked in C128/1571 mode also... oh well...

I got a disk drive recently and I can't format any of my disk. and I don't know what to do..... I use DD disk. the drive start format like 3 sector. a'd after the delay betwen sector are long. and at the end I got a error. a'd I got a vic-20 not à C64..... I cleaned the head. to a'd nothing.

I am curious if in 128 mode, the high density disk gets the 1328 blocks. Oddly, my 128D always formats just one side of my DD disks, even in 128 mode using the HEADER command. I have to put in a sort-of cryptic command to force to format both sides. It could be the custom JiffyDOS that the seller installed on it or if all 128D machines do that.

This gives me a few thoughts: 1) If you save data to a HD disk in DD format on a drive that can write correctly, I assume you can read that data on a drive that can only read DD disks. In this case, you could use it as a sort of "read only" disk. You can't accidently erase your data without deliberately moving back to the drive that can write to HD disks. 2) Imagine a proprietary formula of disk for commercial software (even higher coercivity than HD disks so that NO normal drive can write to them). You write the disk with a custom drive that can write with stronger magnetic fields, then sell the disk to customers. Customers can't erase your disk because their drive can't write. SO...first thing you try to do when starting the software up after loading is write to overwrite your software. If the disk has been pirated...OOPS! the disk is now blank. If the disk is too high coercivity (authentic), then you can't write anyway, so the software runs and doesn't self destruct. 3) Different regions of the disk surface could be different chemistry. You can have regions that you can't write to, like game code and resource files, and regions you can write to, such as save game data. 4) You can modify the disk drive to increase the current going to the write head (or replace the head with a higher power one), thus enabling you to safely and reliably write to HD disks (and with proper signal strength that doesn't degrade and become unreadable after a while). 5) In theory, a higher temperature medium will have a lower coercivity. How high in temperature can you drive go before it becomes damaged? Can you heat up the disk drive (and the disk inside it) somehow and make it able to write to the disk? I imagine any temp high enough to sufficiently weaken the magnetic coercivity of the disk would be very close to the curie point (where magnetic materials break down and lose their magnetic properties). This would certainly destroy the motors in your drive, and probably cook the electronics to death too. I guess this idea is terrible.

I had similar experiences with my Amiga. Over the hears, I had 4 Amigas, and multiple external drives. Some would read and write to HD disks without an issue. Some would only read, and some didn't touch them at all. It was a bit of a nightmare. Back to the c64, I don't think the plastic hub guard made much of a difference, as you know the reverse of the disks don't have them, and you can still use the 2nd side of the disk fine.

have the same isue, back in 1990, wen i bougth a floppy disck, and dont work on my 1541 drive, but find a way around to makeit work, letme take out my drive to show you, how i fix it..

I wonder if anyone has ever sold or trashed their drives because the only disk they had to test the drive was a high density.

This is interesting, I didn't know there was a difference between the drive heads on the 1541 and 1571/1571CR (barring the fact the 1571 has dual heads, of course). I don't recall you addressing it in this video - since HD disks appear to work in the 1571CR (the one inside your 128D), did you try handling them in the standalone 1571 as well?

Hi Robin, I am a fellow French Canadian from Montreal region. Your videos are part of the reason I jumped into the retro 64 adventure my self. I recently found my self a functional 1541 disk drive and I was wondering if You knew where I could find new DD floppy disks, either on the web or among yours subscribers. Thanks for your videos and knowledge sharing. Best regards.

I wonder why that 1541 has a square led... I remember it round like the power led.

Die alten Computer hören sich wie ein Elektro Schreibmaschine

Hm.. I didnt pay attention to my disks when using my Commodore 1541.. not sure if it was DD or HD... alas.. most of the disks worked for me, not sure which types, maybe they were DD.

I had plenty of HD-disks for my C64 and 1541 back in the early 90s and I never thought about it because it never troubled me. And after 30 years, these diskettes still work fine. How can that be? :D However, half a year ago I discovered that I wasn't able to format new HD-discs so I googled it and found out that they shouldn't work. Although now again they all work fine. Very strange!

When I started shipping Loadstar, I got a good deal with HD 3.5 disks. Never had a problem since I used an FD drive - or PC > 1581 copy (on the PC). But immediately got many who used real 1581s writing to me. Didn't work! Had to go to DD 3.5s for them.

The ring that you see on the DSDD was a reinforcement ring. Also did you try to format it on the 1571 that was below the 1541? The 128D has a 1571 built in.

You forgot to close command, or try OPEN15,8,15,"N0:DISK NAME,01":CLOSE 15

I don't recall ever having this issue with my CoCo2 and its drive. I had a PC with 1.2Mb floppy and the disks seemed interchangeable. Am I imagining this? Is this only a C64 drive peculiarity? I wonder if you could simply bump up the write power of the drive to around 400 or 450 and start to get reliable reads on both?

Can the 1541 read HD floppies even though it can't format them?

It is double density compatible external floppy drive

I have some of these hd disks. WOrked fine. A few with ekstra ring around hole like the dd. On some of the dd it says hardhole and sector soft. What is that?

Hi, I got a question: I bought a c64 used and got a big stack of flopys free. They are supposed to be emoty, but some still contain data. On most of the disks my comodore frezes loading with the 1541-2 doing nothing. Could it be bit rott from questionable storage conditions?

using HD disks in a DD drive is and has always been a crap shoot.

Did you try it in the 1571 drive?

Wow, i was having this same issue

why didnt you try using the external 1571 disk drive to format the HD disk? perhaps you can try doing so and show results?

If you want check my program to test 1541 speed: github.com/Zibri/C64-1541-Speed-Test I just released it a few days ago.

I had the same issue with Atari computers.

What's the memory difference of DD and HD? They all should be 180kb per side yes?

this rattling of the head hurts again and again ... back in the days no one tok this seriously, but today we know, it is bad :D