Floppy Disk Image Format

I have file DISK1.IMG that it is image of a floppy disk. I guess it is compressed. I don't know which utility I must use to copy to floppy.
Some of its first bytes (Header ID) is: FF 18 06 44 49 53 4B 20 31 20 20 20 20 20 4F 0F
Which utility I must use to copy or uncompress it?

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Farzad AkbarnejadDeveloperAsked:
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A. Cristian CsikiSenior System AdministratorCommented:
use floppy image from
it's like *.iso that *.img so i think you should rewrite the image with floppy image on a new floppy.
see ya.
Farzad AkbarnejadDeveloperAuthor Commented:
Hello nodramas,
Thabks for your repling. I test Floppy Imgae. It didn't solve my problem.
Yes I must write the file on to floppy but I think that it is a special format.
I saw its content in a Hex Editor. It is 1.2 MB (For 5.25" Disk) that I must write to 3.5" 1.44.
Also It is compressed with a Algorithm like RLE that replace string of blanks (00, 20, FF, F6) with
this like:   FF 00 [nn],  FF 20 [nn], F6 00 [nn], ...

I tried to write a program for decompress it but I didn't succeeded because some of rules are hidden
and thre are extra bytes.

A. Cristian CsikiSenior System AdministratorCommented:
try using magiciso from http://www.free-press-release.com/news/200409/1094539467.html ....may do the trick
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Farzad AkbarnejadDeveloperAuthor Commented:
I try it. I didn't solve my problem. It can't read my IMG File.

A. Cristian CsikiSenior System AdministratorCommented:
i recently searched and found more usefull programs. You may try opening it with alcohol 120%, DEAMON-tools,
or winimage, wich i used it and found that opens *.img files

good luck

RawWrite at http://uranus.it.swin.edu.au/~jn/linux/rawwrite.htm may help - its native file extension is .IMG

Farzad AkbarnejadDeveloperAuthor Commented:
I tried WinImage. I didn't solve my problem. :-(
Are you sure about other tools?

A. Cristian CsikiSenior System AdministratorCommented:
well if it is not confidential the data, you may upload somehere, so i can search for alternatives. The other software i wrote about opened me img file made like an iso but for cd-dvds, you may try it for your problem.
Farzad AkbarnejadDeveloperAuthor Commented:
I tried rawwrite. I didn't solve my problem.

No. It isn't confidential data. You can download it from http://www.geocities.com/fao_79/DISK1.zip
In DISK1.zip you find DISK1.IMG file.

Thanks for your help.

I don't think the disk is 'compressed' as such or othrwise encoded - it just look like a simple raw dump of the source disk, with a few bytes tagged onto the front for use by what-ever program originally created the image perhaps.

I "suspect" RawWrite should be able to write the image onto the *appropriate type of disk* (possibly 5.25inch 1.2MB??) once the extraneous info at the beginning of the image file has been removed using something like AXE (http://www.jbrowse.com/products/axe/download.shtml - just Open the image file up, select the bytes to delete, delete them, and re-save as a new image, then try RawWrite)

Once the first 186 bytes are removed, this will then leave you with an image that conforms to the proper boot sectory layout; ie.

3 byte 'jump' instruction
8 byte OEM name (in this case "MSDOS5.0")

Once correct, the file should start with:   eb 3c 90 4d 53 44 4f 53 35 2e 30 . .

cheers + good luck!,

Farzad AkbarnejadDeveloperAuthor Commented:
Thanks. But It has compression.
If you see the sector 0 you find that it isn't 512 byte and the FE 00 [n] must be replaced with n 00(s).
Also the FAT must be 7 sectors that you can find that it isn't and in Directory Entry you find that reserved blanks replaced with FF 20 [nn].
I tried to decompress it and I succeeded to decode until sector 100 but another coded information is exists in it.

Download ftp://ftp.sac.sk/sac/utildisk/img2_0e.zip and run:
img e disk1.img
You will have the files extracted in the current directory.

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Farzad AkbarnejadDeveloperAuthor Commented:
Thanks a lot adi_vladut. :-))

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