Creating an .iso from a HFS CD-ROM in macOS 10.15 (Catalina)

[Ronald P. Regensburg]

How to create a disk image file from a HFS CD-ROM in macOS 10.15 (Catalina) and macOS 11 (Big Sur).

This procedure assumes you are logged in as Admin user.

1. Insert the CD-ROM in the CD/DVD drive (I used the Apple USB SuperDrive)
- The CD will not be mounted, wait till the drive settles down

2. Find the volume name
- Open Disk Utility (in Apps/Utilities)
- In the Device and Volumes list at the left, the CD volume is shown greyed
- Select that greyed CD volume
- Now you will see in the bottom-right corner the device name*
- Note that name and close Disk Utility
* In my test the device name was "disk5s1s2", it can be different in your case. In the command below replace disk5s1s2 with the name you found.

3. Create the disk image file
- Open Terminal (in Apps/Utilities)
- Open a bash session by typing at the prompt:

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bash

- Hit Return
- Ignore the message about the default shell now being zsh and about how to update to use zsh.
- At the prompt enter the command below, replacing disk5s1s2 with the device name you found and replacing Disk 1 with the name you want the image file to have:

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sudo dd if=/dev/disk5s1s2 of=~/Desktop/"Disk 1.iso"

- Hit Return
- Enter your password (note that you will see nothing happening while typing your password)
- Hit Return

The disk image is now being created on your desktop. It will take some time. Do not interrupt.
When the process has finished, you will see a message in Terminal window similar to this one:

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348426+0 records in
348426+0 records out
178394112 bytes transferred in 106.781745 secs (1670642 bytes/sec)

- Enter this command to eject the CD:

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drutil tray eject

- Hit Return
The CD will be ejected
- Close Terminal

[mabam]

Ronald,

As always, your guide is very clear and detailed.

There’s something I’d like to add, however:
As described under https://daoyuan.li/solution-dd-too-slow-on-mac-os-x/ and https://unix.stackexchange.com/question ... 091#189091 it will speed up things when using rdisk instead of disk and setting the block size to a multiple of 2 MB when reading a CD-ROM. That would result in the following amended command:

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sudo dd if=/dev/rdisk5s1s2 of=~/Desktop/"Disk 1.iso" bs=6m

[Ronald P. Regensburg]

Thanks. But when I try this, the whole process does not take less time:

$ sudo dd if=/dev/disk5s1s2 of=~/Desktop/"Disk 1.iso"
Password:
1333683+0 records in
1333683+0 records out
682845696 bytes transferred in 606.767548 secs (1125383 bytes/sec)

$ sudo dd if=/dev/rdisk5s1s2 of=~/Desktop/"Disk 1.iso" bs=6m
Password:
108+1 records in
108+1 records out
682845696 bytes transferred in 606.794664 secs (1125332 bytes/sec)

[Cat_7]

Hi,

Should that not be "sudo dd if=/dev/disk5" of=~/Desktop/"Disk 1.iso" to copy the whole disk?

Best,
Cat_7

[Ronald P. Regensburg]

Should that not be "sudo dd if=/dev/disk5" of=~/Desktop/"Disk 1.iso" to copy the whole disk?

When you do that, you will get a file that BasiliskII cannot read. It is the mountable HFS volume that you want for the image. For the CD-ROM that I used, it is the HFS volume named "MW 01/97" (the Macworld January 1997 disk).

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/dev/disk5 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:        CD_partition_scheme                        *784.9 MB   disk5
   1:     Apple_partition_scheme                         683.5 MB   disk5s1
   2:        Apple_partition_map                         1.0 KB     disk5s1s1
   3:                  Apple_HFS MW 01/97                682.8 MB   disk5s1s2

When Disk Utility (on pre-Catalina macOS) is used to create the image, it is also only that volume that is used for the disk image. To find the ID for that volume one can still use Disk Utility in Catalina. See instruction #3 above.

[mabam]

Thanks. But when I try this, the whole process does not take less time:

$ sudo dd if=/dev/disk5s1s2 of=~/Desktop/"Disk 1.iso"
Password:
1333683+0 records in
1333683+0 records out
682845696 bytes transferred in 606.767548 secs (1125383 bytes/sec)

$ sudo dd if=/dev/rdisk5s1s2 of=~/Desktop/"Disk 1.iso" bs=6m
Password:
108+1 records in
108+1 records out
682845696 bytes transferred in 606.794664 secs (1125332 bytes/sec)

So what is supposed to be faster theoretically, in fact is even a fraction of a second slower practically.

Sorry, should have tried it myself before posting.

[adespoton]

So if you read the entire disk, you should save it as a <filename>.bin and create a cuefile with the track sizes as indicated via diskutil.

Then you have a bin/cue pair that should work with the recent bin/cue patches for BII/SheepShaver If you don't want to go through all this effort and only need the HFS partition, then you're better off just imaging the HFS partition.

[cgecastro]

Hello,

How to create a disk image file from a HFS CD-ROM in macOS 10.15 (Catalina).



1. Make sure your shell is bash (the default shell in Catalina is zsh)
- Open System Preferences > Users & Groups
- Click the lock and enter your password to allow changes
- In the list with users, right-click (or control-click) on the current user (you) and choose Advanced Options...
- In the Advanced Options dialog see the "Login shell" menu
- If it shows "/bin/bash", you can click the Cancel button and close Preferences
- If it shows a different shell, choose "/bin/bash" in the menu (The item "/bin/bash" may not be shown at first sight, it is at the top of the menu.)
- DO NOT CHANGE ANYTHING ELSE!
- Click the OK button
- Close Preferences
- No need to restart

Instead of all this just type "bash" in the terminal and it will load a bash session.
In the end type "exit" to return to zsh
The warning about zsh being the default shell also apears.
Tested on BigSur

[Ronald P. Regensburg]

Ah, yes. Much simpler. I did not know that. I will rewrite the instructions above.
(No need to use "exit" to return to zsh. The next time a Terminal window is opened it is back to the default zsh.)