Macs can read and write to many Windows formatted disks right out of the box, without any extra software. This includes flash drives – those little solid state thumb drives – and larger capacity USB and Firewire drives. Macs use different disk formats, though that doesn’t stop them from reading Windows disks.
But there are a few exceptions; it depends on how the Windows disk was formatted, and more on that below. And that’s why you will sometimes you’ll get an error that says the disk you have doesn’t have any OS X readable files, or must be formatted before you can use it. But if you know there are Windows files on it, don’t toss it or erase it. There are several things you can try.
First, when I mean “read,” I mean that you can transfer files from the disk to the hard drive of your Mac. When I mean “write,” I mean you can copy files from your hard drive in your Mac to the flash or USB drive.
And when I say format, I mean the way the structure of the disk is arranged. Windows computers use disks formatted in either DOS, FAT 32 and NTFS, with (basically) DOS being the oldest and NTFS being the newest, and Macs will read from most of those formats, most of the time.
Now, disk format doesn’t have much to do with the actual files on the disks; dealing with the files themselves is a different issue than just being able to read and write from the disk. For example, Microsoft Office file formats are mostly transferable between OS X and Windows, and because of that, you might not know that the files themselves can be a problem.
So, if you can’t see a Windows disk on the desktop of your Mac to copy files from it, or you can copy files from it but can’t save files to it, there are a few things that are going on.
Disk permissions might be the problem. If you get an error that says you don’t have sufficient permissions to do what you want to do, then it is a permission error. Highlight the disk icon on the desktop and select “Get Info” from the File menu, or hold down the Apple key and type an “I.” You’ll get an info box that will allow you to check and change disk permissions. Look for “Ownership and Permissions,” and select You Can “Read and Write.”
If you can’t even see the Windows disk on the desktop, it might be NTFS format. I mentioned FAT32 and DOS disk formats for Windows and how OS X can read from them, but NTFS formated disks can be a problem. According to the Apple Knowledge Base article: How to transfer data from a PC to a Macintosh“NTFS formatted drives cannot be used in a Macintosh (except as read-only with Mac OS X 10.3 and 10.4 as noted above). If you attempt to use a NTFS formatted disk, upon starting up the Mac OS will prompt you to format the drive. Do not format the drive, doing so will erase the contents of the drive. If you have an NTFS formatted disk, you must use another method to transfer the data from the PC to the Macintosh.”
If you can see the disk on the desktop, but can’t read from it, another method to get to the files is using a USB or Flash drive you know is formatted – or one that you format for Windows – and copy the files from the Windows PC to that other drive. Then, use the drive to move the files to your Mac. You can use Disk Utility on a Mac to format a disk in Windows FAT32, and then use that drive to move the files to your Mac.
As for CDs and DVDs, optical disks burned on a Windows PC – and manufactured by music and software companies – can be read by OS X because the format of the CD is what is known as ISO 9660 [wikipedia], which stands for International Organization for Standardization, and 9660 is the standard. That standard (one of any for CDs and DVDs) means Windows PCs don’t have problems reading the discs either.
If you can’t read a CD on your Mac that was burned under Windows, it might have been burned in a different format called UDF Universal Disk Format [wikipedia]. That’s the format mostly used by a program called DirectCD or Drag-to-Disc, now made by Roxio. You’ll need that software for OS X to read those discs, as UDF is not yet a universal format and not all operating systems will read and write it.
You won’t be able to write to a CD or DVD originally burned with Windows, unless they are “multi-session” and you have a Superdrive that burns discs.
And never use one of those mini CDs or DVDs in a slot drive Mac, or use an adapter to play one; more than likely it will get stuck and you’ll be lucky not to damage your Mac.