This page is a wiki. Please login or create an account to begin editing.


10 posts / 0 new
Last post
Protocol 7's picture
Offline
Joined: 2010 Aug 7
How to make a PROPER copy of a CD for sharing here (or anywhere else).

Unlike other systems, Mac OS doesn't treat CD images as read-only. A HFS or HFS+ volume is treated the same whether it's on a floppy, hard disk, CD, zip etc. Unless the media is write-protected, it's fair game for writing to. And Mac OS (especially OS X) loves writing things to volumes.

From a software preservation point-of-view this is a nightmare and it's sadly all too common to find valuable CDs imaged incorrectly. Yes it all might sound a bit anal, but really if it's not hard to do it right, why do it wrong?

So here's a couple of quick pointers on how to image a CD correctly and not mess it up afterwards. The key to this last part is to ensure than the image file is read-only before attempting to mount it. This has all been covered before in different parts of the forum but it may be buried too deep for some to find.

OS X

To image a CD in OS X you just need the built-in Disk Utility. This will also handle Mac/PC "hybrid" discs (but not CDs with audio).

Pop in your CD and launch Disk Utility. Click on your CD/DVD drive (not the volume) in the drive list (Fig.1) and then click on the "New Image" button on the toolbar. Set the output type to "DVD/CD Master" with no encryption and save it out (Fig.2).

Once the image is created, right-click on the image (or click and go to the File menu in the Finder), choose "Get Info" and tick the "Locked" option (Fig.3). Now the image is read-only and won't be modified if mounted (Fig.4).

A DVD/CD Master .cdr file is just a plain flat disc image, so you can change the file extension to .iso if you like.

Mac OS

Toast is the weapon of choice for imaging CDs in the classic Mac OS. You will need at least version 5 if you wish to image Mac/PC hybrid discs (but not CDs with audio).

Pop in the CD and run Toast. Click on the Copy button (Fig.5). From the File menu choose "Save as Disc Image" (Fig.6) pick your destination and filename and click Save (Fig.7).

Once completed, right-click on the toast image (or click and go to the File menu in the Finder) and choose "Get Info" and then "General Information" from the options (Fig.8 ). In the Info dialog box, tick the "Locked" option (Fig.9). Now the image can be safely mounted without being modified by Mac OS (Fig.10). If the disc was a hybrid, Toast will mount both "sessions" on the image as seen here (Fig.11).

Windows / Linux etc

Pretty much any CD tool on these platforms will be able to successfully image a Mac CD. Just because Windows can't mount a Mac volume (without third-party software) doesn't mean it can't be copied. ImgBurn, Alcohol, Nero etc can all make a proper ISO image of a Mac CD.

On Linux the situation should be the same (you could even do a device copy using dd from the terminal).

As a precaution it's good to make the iso image read-only before compressing it to share. In some cases it will remain read-only when extracted on a Mac and thus will not be modified if mounted. Though it's good practice to always check if an image is locked before mounting.

CD Audio

To get a proper 1:1 copy of a CD with audio tracks you need to use a tool that can create multisession images. In OS X 10.4+ you can use SimplyBurns or FireStarter FX. For older versions of OS X there's MissingMediaBurner. These tools will create a bin/toc image (the bin file contains the raw data and the toc file contains the necessary track info). It's the linux equivalent to the more widespread bin/cue format that's commonly used in Windows. There are no tools to create these in the classic Mac OS.

For Windows you can use a tool such as Alcohol for bin/cue or burnatonce for bin/toc. In Linux any tool that's based on the cdrdao engine will output a valid bin/toc file that can be burned on OS X by SimplyBurns, FireStarter FX or MissingMediaBurner. For more info check out the discussion here.

Comments

Thundersock's picture
Offline
Joined: 2010 May 20

This is incredible, nicely done. It looks like "Figure 8" was changed to a smiley.

About locking and modifying:
You lock the image after it's created? What would that protect against? Couldn't you do that yourself after download if its important?

Protocol 7's picture
Offline
Joined: 2010 Aug 7

Yep. Locking it is to prevent the image from being modified by the OS when it's mounted. There are plenty of images out there that have been modified because they were mounted while still writable. And yes you can also do it with an image you have downloaded. Unless you have a reason not to, you should always do it with any disk images.

24bit's picture
Offline
Joined: 2010 Nov 19

Very comprehensive manual indeed. What about us regular folks running SheepShaver on a low end X86 host? Smile

Protocol 7's picture
Offline
Joined: 2010 Aug 7

Thanks!

You can just use a tool native to the host OS. There's tons that can make a plain iso image from a CD. The main reason I wanted to put this together was to try to cut down on "bad" CD images coming from the Mac side.

Thundersock's picture
Offline
Joined: 2010 May 20

Oh, I think I get it now: You lock the disk image because the IMAGE gets modified when you mount it as a disk, which messes it up the next time anyone mounts it.

Protocol 7's picture
Offline
Joined: 2010 Aug 7

Yep that's it Smile

IIGS_User's picture
Offline
Joined: 2009 Apr 8

Great hints, thank you very much! Smile

Offline
Joined: 2012 Apr 1

Ugh, in 10.4.11 I have to click "Session 1" to create a CD/DVD master. Selecting the drive itself (disk1) won't work, so disk1s1 does fine.

Technically, Disk Utility is just a front end for select Terminal stuff...like $ dd... and $ unmount...so it may be appropiate to cover all bases with your writeup on how to do it in Terminal (especially if someone is doing a lot of them, but then other software usually steps in at that point). If you were doing it in batch Terminal mode, you could just press the up arrow, edit the of= name and press Enter.

Wash, lather, rinse and repeat.

Protocol 7's picture
Offline
Joined: 2010 Aug 7

It's mostly just a guideline. If you look at the screenshot when I saved out the drive the filename was Session 1, so it defaults down to that anyway. The main thing it to image "all" of the disc.

There's many different ways to do it, I just went through a couple. I still do all my imaging on Windows (with ImgBurn usually) as that's my daily driver.