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On Superfloppies and their Images

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#151
jaclaz

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Yes. The new version works beautifully! You may remove the previous one. :yes:

Good :), I am removing BOTH 001 AND 002 :w00t:, please meet 003 ;).
(I forgot "Current_head" field in previous ones, and have now added a clearer - hopefully :unsure: - view)

jaclaz

P.S. File updated, small typo, I had "lost" a "%" in the %Volume_Label% of first view.

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Edited by jaclaz, 29 January 2012 - 02:06 PM.



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#152
jaclaz

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In an attempt to better the little batch, I actually seemingly bettered it. :w00t:
Now:
  • it can run on 2K too (no need for fsutil)
  • it can run on read-only media (no more temp file)
  • can process files larger than 512 bytes (like whole floppy or super-floppy images)
  • values are now right-aligned
  • it is a tadbit slower in first screen coming up, though :blushing:

Verson 0.05 attached.

(don't try finding version 0.04, it was for internal use only)

In order to remove the temp file I had to introduce a possible bug, that along the good old tradition I will call "feature" ;).
If the bootsector starts with "::" i.e. with 3A3A the first two bytes will be reported as 0000.
I'll see if I can later remove this "feature".


jaclaz

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#153
jaclaz

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For NO apparent reason :w00t:, view_bs_008 :yes: .

It should be almost working, still a couple options missing :blink: .

Still no kids willing to play with me though :(.

jaclaz

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#154
jds

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OK, I'll dump the 1232K and 1280K formats. :thumbup
More generally only 512 Bytes/Sectors will be included (besides the booting aspect, I suspect that non 512 bytes/sector formats would have anyway problems in VM's and/or Virtual Drives).
For the record there are the 8.00" floppy formats:
http://support.micro.../kb/75131/en-us
that do have a different sector size, and they will be ignored also.

Hey, great find, jaclaz! I didn't realize these olde 8" floppies had 128 byte and 1024 byte sectors!

I have a working 1KB Sector Floppy Disk with only a few additional mods needed.
As I expected the BIOS will not boot the Disk, but a slightly non-standard format may make it possible to boot, if I can solve an internal Disk Geometry problem.

Well, the 128 byte and 1024 byte sectors in the above KB are from the time of MS-DOS 1.0 and 2.0, which was pretty much (if not completely) the pre-hard-disk era. So the BIOSes of the time (especially the original IBM one) must have been able to boot with these now-obscure/defunct sector sizes.

Joe.

#155
rloew

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[


I have a working 1KB Sector Floppy Disk with only a few additional mods needed.
As I expected the BIOS will not boot the Disk, but a slightly non-standard format may make it possible to boot, if I can solve an internal Disk Geometry problem.

Well, the 128 byte and 1024 byte sectors in the above KB are from the time of MS-DOS 1.0 and 2.0, which was pretty much (if not completely) the pre-hard-disk era. So the BIOSes of the time (especially the original IBM one) must have been able to boot with these now-obscure/defunct sector sizes.

Joe.

I assume so.

Modern BIOSes do support these formats. They can't be booted because the Boot code does not scan for them. It only tries 512 Byte Sectors. I did create a Bootable 1K Sector Floppy by slipping in one 512 Bytes Sector.
Ye who enter my domain. Beware! Lest you become educated in the mysteries of the universe and suffer forever from the desire to know more.

#156
jaclaz

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Before I forget about this, I'd better make a note.

Nice :unsure: experiment (that should be done "mentally" before actually replicating in practice).
  • Take a floppy.
  • Format it under DOS 7.x, give it not a label.
  • Copy to it a single file (whatever smallish file, let's say 2048 bytes or less, like an AUTOEXEC.BAT for example, would do)
  • Make a dd-like copy of the floppy.
  • Format the copy under the same DOS 7.x, still not giving it a label, but this time using the /q switch.
  • Make another dd-like copy of the floppy made in points #1-3
  • Format it from XP command line, stil not giving it a label and use as well the /q switch
  • Compare the two latter floppies with the first one in a hex editor or similar.
Of course the same can be done in a VM and/or using a virtual disk drive with floppy images instead of real floppies.

Questions:
Q1. How many different sectors there are between first and second disk?
Q2. How many different sectors there are between first and third disk?
:angel

jaclaz

#157
dencorso

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Questions:
Q1. How many different sectors there are between first and second disk?
Q2. How many different sectors there are between first and third disk?
:angel

Q1: 4, of course!
Q2: 5 ?!? :blink:
Posted Image

Note added later:
Just for the record, I used the excellent freeware DiskImage, by Mike Brutman, to generate the floppy images under plain MS-DOS 7.10, and the equally excellent freeware NTRawrite, by Blake Ramsdell, to generate the floppy image at the XP SP3 DOS Box.

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#158
jaclaz

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Good. :thumbup
Now, what could have been the reason the good MS guys did that change? :unsure:

The chances of this phenomenon actually "changing something" is in practice virtually 0, as it is actually very rare to have a floppy filled "up to the brim", but I find it "queer".
Could it be some form of "preparation" for NTFS formatting? (that was however removed since day 1, because of the size of the metadata, and was it not for the good Mark Russinovich :yes: - and for the good memory of you know who ;) it would have been deemed as impossible).
Compare with:
http://www.msfn.org/...ize-of-bootsdi/
http://code.google.c.../wiki/Tiny_NTFS

It would be interesting if a simialr experiment would be repeated on a NT 4.0 and on a Win2K machine ... :rolleyes:

jaclaz

#159
tomasz86

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This is an image created after using "format /q" in Windows 2000. I used a virtual floppy drive and I'm not sure if everything was done correctly but please check it.

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post-47483-1123010975.png
Unofficial Service Pack 5.2 for MS Windows 2000 <- use this topic if you need help with UURollup, Update Rollup 2 and other unofficial packages

#160
jaclaz

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This is an image created after using "format /q" in Windows 2000. I used a virtual floppy drive and I'm not sure if everything was done correctly but please check it.


You NEED to start from a "fully formatted" under DOS floppy image, as in steps 1-2-3 of the instructions.
I haven't checked the image you posted, but if it was not made like the above and if there are NOT 3 (three) images done EXACTLY as the given instructions, the experiments makes no sense/gives no results you can observe.
You can re-use the files dencorso provided, though, making a copy of 1STIMA.IMA naming it 3rdima2K.ima and formatting it with /q on Windows 2000.

jaclaz

Edited by jaclaz, 02 October 2012 - 04:55 AM.


#161
dencorso

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tomasz86 used my 2NDIMA.IMA as the starting image, because I actually asked him to do so.
While it's not exactly what you asked, after reviewing the image tomasz86 attached, I'm confident the result is equivalent.
And, from tomasz86's attached image you can confirm, as I just did, that the quirck you found out first appeared on Win XP (or: after Win 2k).

#162
jaclaz

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And, from tomasz86's attached image you can confirm, as I just did, that the quirck you found out first appeared on Win XP (or: after Win 2k).

Good :thumbup .
So it's just another of the stupid senseless changes made in XP, not entirely unlike the one that made a lot of people throw away otherwise "good enough" floppies :ph34r: :
http://www.msfn.org/...post__p__971266
http://www.denispetrov.com/?page_id=3

It is very possible that the MS geniuses which had the fantastic idea of volume tracking on Windows 9x :w00t: :
http://en.wikipedia....ble#Boot_Sector
http://homepage.ntlw...name-field.html
were later promoted and managed to worsen the otherwise OK 2K FORMAT executable.

jaclaz




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