Is any Mac software incompatible with the iMac G3 models?

The iMac G3 models are compatible with all Mac software that runs on a PowerPC G3 processor, that is compatible with OpenFirmware, and that is compatible with a version of the MacOS that is supported by the iMac G3 models.

All iMac G3 models are capable of booting MacOS 9 and running MacOS 9 applications either natively or within the "Classic Environment" provided by compatible versions of MacOS X (MacOS X "Panther" 10.3.9 and lower on models with a 350 MHz or slower processor and MacOS X "Tiger" 10.4.11 on models with 400 MHz or faster processors). The iMac G3 models are not capable of running later versions of MacOS X.

Can the iMac G3 run Windows?

The iMac G3 models are capable of running Windows through emulation using a program like Microsoft Virtual PC 6.1, but they cannot boot Windows or run Windows via virtualization like the Intel-based Macs.

If you need a system capable of running Windows, you would be best served with an Intel-based Mac or a Windows PC.

For more on running Windows on Intel-based Macs, please also check out the Windows on Mac Q&A.

Can the iMac G3 run Linux?

Yes. Adelie Linux is supported on the iMac G3.

Does software that requires an ADB-based "dongle" work with the iMac G3?

For readers who may not be familar with the term "dongle" -- a dongle is a small cable that ships with some high-end, expensive page layout and CAD software packages. Upon starting the software, the computer searches for the dongle and makes sure that it is plugged into the applicable port on the back of the computer. If it is not found, then the software will not operate. Since hardware is considerably more difficult to copy and distribute than software, the dongle provides a fairly high-level of copy protection, discouraging casual software piracy.

According to the "iMac Read Me" file that was included on the hard drive of the original iMac G3, ADB dongles will not work with the iMac, but a USB dongle should work, and to "contact the vendor for further information". USB dongles that are designed to work with the iMac G3 do indeed operate properly. Fortunately, this became less and less of an issue as companies that sold software requiring a dongle started providing USB-based dongles with the software.

Typically, ADB-to-USB based adapters do not work with dongles, so for legacy use, those who continue to need software with an ADB-based dongle would be wise to maintain an old Mac with ADB ports. The "Blue & White" Power Macintosh G3 models might be of particular interest as these are the only Macs to offer both an ADB port and USB ports onboard.