1541 can write 1.2 DS\HD Floppy

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AlexVivat
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1541 can write 1.2 DS\HD Floppy

Post by AlexVivat »

hi!

1541 CAN write to 1.2MB DS\HD floppy disks.
I spent the experiment. I wrote the .d64 images several times to a floppy disk, then read it back and compared it byte-by-byte - a complete match!!!

However, probably this method can only be used to write images to floppy disks - but this is also a lot. This will free up DS\DD floppy disks for something more useful. And for demos, games or other products, where you do not need to regularly update the data, it is quite a good solution.

You need a PC with 1541 connected to them and Star Commander.
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LoneWolf33
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Re: 1541 can write 1.2 DS\HD Floppy

Post by LoneWolf33 »

I've experimented using HD disks in a 1541-II drive some years ago, but the results were disappointing for me.
The drive wasn't able to format 3M HD disks at all, but some Verbatim (or Memorex?) ones could be formatted after multiple attempts.
With the 3M HD ones the format process stopped at the very same position every time.

Writing HD disks would require different write head bias I think.
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Re: 1541 can write 1.2 DS\HD Floppy

Post by AlexVivat »

I used Budget HD - china low-cost brand.
Yes, i use multiply attempts format with ignore errors.

I used therory what the signals from the magnetic head are superimposed on one and the other on the same area of the magnetic surface, gradually magnetizing the surface to the required level. This "feint with the ears" does not work with magnetic tape, because it is almost impossible to accurately position on the tape for domestic-type magnetophone.
But, since the magnetic disk can be positioned accurately, and sooner or later, the contents of the sector after repeated attempts will become what you need.
And, yes, I turned off error checking.
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Re: 1541 can write 1.2 DS\HD Floppy

Post by AlexVivat »

LoneWolf33 wrote: Mon Aug 09, 2021 12:47 pm I've experimented using HD disks in a 1541-II drive some years ago, but the results were disappointing for me.
The drive wasn't able to format 3M HD disks at all, but some Verbatim (or Memorex?) ones could be formatted after multiple attempts.
With the 3M HD ones the format process stopped at the very same position every time.

Writing HD disks would require different write head bias I think.
i think Hungary not forget Bulgarian brand "ISOT". 'Mini-Disk" DS\HD (subbrand of ISOT) - try this disc.
different head bias - hmm maybe yes but not necessary - if disks is written.

I forced myself to go through a bunch of floppies (they were all in the same box after moving to a new place of residence) - and I found 4 high-density floppies (1541-formatted). they are still readable after 20 (or maybe more) years in the box.
By the way, I recorded in early 1541 with the mechanics of alps (maybe this factor somehow solves). .
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LoneWolf33
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Re: 1541 can write 1.2 DS\HD Floppy

Post by LoneWolf33 »

Well, I had to google the ISOT brand :)
Personally I've never heard/seen that before.
We had TDK, Sony, Verbatim, Memorex, Parrot (in many different colors), Pelikan, 3M and of course noname floppy brands here back then.
I've got some 3M DD disks and a few noname DD ones, they're seem to work OK.
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Re: 1541 can write 1.2 DS\HD Floppy

Post by AlexVivat »

oh, you probably didn’t find the Hungarian People's Republic, otherwise you wouldn’t have to google IZOT - the brand that produced floppy disks for the countries of the "Warsaw Pact" =)
but, nevertheless, unnamed floppy disks may well have quite visible traces leading to the manufacturer. how to find out the manufacturer?
now I will. there are thermal marks on the back of the plastic envelope - how the envelope is "sealed". Well, each plant has its own drawing (well, "brand", or TAURO you can also call it, because this drawing is obtained by thermal means, a hot print is made on the envelope, which melts the rear flap by gluing it). for example, for floppy disks of the Atlas(UNIMEX) brand | as a "signature" there are two dashes 5mm long at a distance of about 5mm ... IZOT has a matrix of 2x4 dots. look at your nameless floppy disks - who knows, maybe they were made by IZOT =)
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Re: 1541 can write 1.2 DS\HD Floppy

Post by AlexVivat »

AlexVivat
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Re: 1541 can write 1.2 DS\HD Floppy

Post by AlexVivat »

LoneWolf33 wrote: Mon Aug 09, 2021 12:47 pm I've experimented using HD disks in a 1541-II drive some years ago, but the results were disappointing for me.
The drive wasn't able to format 3M HD disks at all, but some Verbatim (or Memorex?) ones could be formatted after multiple attempts.
With the 3M HD ones the format process stopped at the very same position every time.

Writing HD disks would require different write head bias I think.
old C<=1541 (pcb 251830 assy 250446 with alps mechanics with vertical door) is pretty good for format and write HD.
my internal 1571 not wish format HD floppyes too... but - thanks god - he read them.

i tested this evening
3m HD (silver sticker, black letters) - the commodore 128 normally autobooted from the recorded diagnostic disk "c128 factory test",

i also have other brands (will report about them later)
maxell HD
nashua HD -
verbatim HD
nova HD (china brаnd)
AlexVivat
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Re: 1541 can write 1.2 DS\HD Floppy

Post by AlexVivat »

Lonewolf33, you are right. floppies which is goodformatted - sometimes is a fake-goodformatted.
In my collection of floppy disks only 3 diskettes 3m-branded (i.e. with brand-sticker "3M" and in branded silk paper case) floppies - and only one booting but fatum disk checker show me bad blocks on the map of the "good" 3m disk... ooops!!! =)

yes i also have "unbranded" or nonamed 3m. why i call this unnamed floppy 3m? because the thermal imprint on a "branded" floppy disk and on an "nameless" floppy disk is identical. thermal imprint - plastic envelopes of floppy disks are sealed with it.
Well, the thermal imprint is identical - on an unnamed and on a branded floppy disk (both floppy disks were released at the same plant)

unnamed 3m-floppy - diskchecker show me GOOD status... and i don't know what to think after all that.

that's all folks!
END.
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