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Joined: 2011 Jul 21
Opening a compressed DMG file

I downloaded a DMG file that contains a bunch of platform/version independent audio VST files.

Of course it wouldn't open on my 9.2.2 system.

So I went looking for a way to "mount" the file. I found a couple of ways to open an uncompressed DMG but came up dry for compressed ones.

Suggestions?

Gary

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Joined: 2009 Apr 18

IIRC the Classic handles early un-compressed DMGs which gives alternatives:
– Re-route over Windows; apps like 'Alcohol120%', 'ISOBuster' can convert into something suitable,
– Re-route over OS X; well, the most obvious I´d say. Use Toast to mount and save an 'Disc Image'
All is IIRC btw Smile HTH!

Protocol 7's picture
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Joined: 2010 Aug 7

On Windows I use TransMac for all of my HFS volume access. It can also expand dmgs.

On the freeware side there's dmg2iso and dmg2img which should also work, though I haven't used either since switching to TransMac.

In OS X you can just use Disk Utility to convert it to a CD/DVD Master which will be a plain uncompressed .cdr (.iso) file.

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Joined: 2011 Jul 21

My further investigation hints that 7-ZIP can decompress DMG files. Is there a Mac OS 9 version of 7-ZIP available?

Gary

MikeTomTom's picture
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Joined: 2009 Dec 7

7-Zip on OS 9? - Only in a wish-list somewhere. Not at this point in time AFAIK.

Other suggestions?

On a Windows PC I have PearPC running Panther (10.3) it handles DMG files nicely. I also share a drive file between PearPC & SheepShaver running OS 9. One reason for this is so I can access DMG files via Mac OS X and if they have files that are compatible with OS 9, I can access them.

One thing you could try, is putting up a link to the DMG file and someone here can access it and re-upload it in an OS 9 friendly format for you.

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Joined: 2011 Jul 21

Thanks for the offer. But I'm looking for a general way to open the DMG since I have a bunch of them I've collected over the years.

I will likely set up an X system on a spare computer and put it on my network.

Gary

MikeTomTom's picture
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Joined: 2009 Dec 7

I will likely set up an X system on a spare computer and put it on my network.

That would be the way to fix your problem.
In the meantime I'd try Protocol 7's suggestions above, for expediency sake (assuming you have a Windows box, here).

On Windows I use TransMac for all of my HFS volume access. It can also expand dmgs. On the freeware side there's dmg2iso and dmg2img which should also work...

I've also had good success with the freeware dmg2iso in the past.

Balrog's picture
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Joined: 2009 Apr 24

dmg2img should work — it converts DMG files to raw images (which Disk Copy 6 should see as "read/write" images).

MikeTomTom's picture
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Joined: 2009 Dec 7

I just tried dmg2img on Windows using its suggested basic command line argument:
dmg2img -i [input.dmg] -o [output.img]

It worked really well.

However it does not create a "read/write" image that is mountable in Disk Copy. The image file it creates is more ".iso" than ".img" and the result using the command above was read only, not read/write or mountable in Disk Copy.

In a Classic Mac OS system, it mounts OK using the free Virtual CD/DVD Utility from here. Fantastic! Laughing out loud

The resulting image files are HFS+ so keep that in mind too. Mountable in Mac OS 8.1 or newer only.

[Edit] A further test; I converted a largish ".dmg" (271 MB) in dmg2img on Windows. The resulting expanded 590 MB ".img" file, I renamed as ".iso" and burnt it to CD using ImgBurn on Windows. Taking the resulting CD to a PPC Mac (both OS 9 & Tiger), it mounts immediately onto the Mac's desktop and all files were intact and accessable. On Tiger it was just as though I had mounted the ".dmg" file itself (indistinguishable).

A great result, but strengthens my impression that the ".img" files that dmg2img creates are in fact ".iso". Changing the filename's suffix ".img" to ".iso" certainly doesn't harm the output from dmg2img anyway. And that they are now both burnable & mountable in a Classic Mac OS too is also a plus.

[Edit 2] Changing the command line instruction to: dmg2img -i [input.dmg] -o [output.iso]
results in a perfect ".iso" file from the expanded ".dmg" file.

I'm appreciating this dmg2img application even more so.

Balrog's picture
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Joined: 2009 Apr 24

The ".img" files that dmg2img produces are raw images, as you would get if you mounted the .dmg on an OS X Mac and used the dd command to copy all the data to a file. They are equivalent to most isos, indeed.

IIGS_User's picture
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Joined: 2009 Apr 8

The resulting image files are HFS+ so keep that in mind too. Mountable in Mac OS 8.1 or newer only.

Could expect that, because .dmg has been introduced in Mac OS X.

MikeTomTom's picture
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Joined: 2009 Dec 7

Could expect that, because .dmg has been introduced in Mac OS X.

Yet not everybody has used Mac OS X (tho' may be dabbling in Classic Mac emulation for 1st time) so bear that in mind too, and not expect what might be obvious (to you) Wink

Protocol 7's picture
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Joined: 2010 Aug 7

Well, you could make a dmg of a HFS volume just as easily. It's just a compressed disk image after all. So it can be HFS as well as HFS+.

IIGS_User's picture
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Joined: 2009 Apr 8

MikeTom is true, ...

Euryale's picture
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Joined: 2009 Jul 22

Just change the .dmg suffix for .nrg (nero)
and then use UltraIso.

that worked for me long time ago when I had so much trouble with these kind of files

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Joined: 2011 Jul 21

I tried changing the file extension but UltraIso still said that I had an invalid format file.Nice try though.

MikeTomTom's picture
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Joined: 2009 Dec 7

@Gary:

I tried changing the file extension but UltraIso still said that I had an invalid format file.Nice try though.

You haven't discovered a solution yet? Hmm you were given a better hint or two back up in the thread.

You have a PC running Windows of some version? If so this method is fairly painless (and it works). Hope you have a Windows box handy (oh the irony).

1). Download dmg2img.exe. Scroll down page to "download latest [win32 binary]" to DL, Its a zipped archive, so once DL'd extract it to somewhere convenient.

2). If dmg2img is not in your PATH (it doesn't matter then), move "yourfilename.dmg" into the same folder or directory as where you extracted the dmg2img.exe app to.

3). Fire up Windows' Command-line app, cmd.exe. If you are unsure of where this might reside, go the "Start" menu, click onto "Run" and enter cmd into the Run dialog to fire it up.

4). Navigate to where dmg2img.exe was extracted to.
To do this in the cmd shell type: cd "foldername1"\"foldername2" etc etc and press the enter or return key to execute the command - if you need to go backwards in the shell type cd .. (2 dots) and press the enter key. To see where you are at any time(and what files are there) in the shell , type dir /w [enter]

5) once in the correct location (where dmg2img.exe is located), type:
dmg2img -i yourfilename.dmg -o yourfilename.img [enter]
Or:
dmg2img -i yourfilename.dmg -o yourfilename.iso [enter]

Your choice, and the result is the same (only the file name suffix differs here, not the data content), dmg2img will extract & decompress the contents of yourfilename.dmg to yourfilename.img - note; .iso is more universal amongst computer OS's (and if its a large file you can burn it to CD/DVD on the spot, regardless of OS (and you can mount the burned CD in a Classic Mac OS system, afterwards).

6) To open the resulting ".img" (or ".iso") on Mac OS 9 if you move it over as a raw file, you will need a software that can mount this type of image file. The Virtual CD/DVD Utility app from here will do it. Toast would likely do it as well but the CD/DVD Utility is ultra light-weight and fast.

HTH.

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Joined: 2011 Jul 21

My PC is dedicated to a single task: Internet phone. So it isn't really an option. Instead I've taken a spare computer and installed X on it. That way I can open the DMG and copy its contents anywhere I want.

Gary

Balrog's picture
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Joined: 2009 Apr 24

.cdr is equivalent to .iso.
.dmg is not.

Euryale's picture
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Joined: 2009 Jul 22

I just found a program I have (and I forgot I had it until yesterday) cuz I haven´t used it yet,
it´s called -AnyToISO- and this is what it does (copy/paste from the manual):

"1.1. AnyToISO Features Convert to ISO or extract all most popular CD/DVD/Blue-ray images found in Internet today Make ISO images from CD/DVD/Blue-ray disks Make ISO images from local folders Extract all kinds of ISO images Extract DMG files (Apple disk image files) Extract DEB and RPM Linux images Command line support (batch mode) Available for Windows and Mac"

You might wanna try it out

Balrog's picture
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Joined: 2009 Apr 24

I dunno if it will convert from a dmg...

dmg2img most definitely does work. I've used it.