Target Disk Mode

Instead, the Mac's firmware enables its drives to behave as a SCSI, FireWire, Thunderbolt, or USB-C external mass storage device.

A unique system control panel on the PowerBook was used to select a non-conflicting SCSI ID number from the host Mac.

When Apple dropped the SCSI interface, starting with the AGP Power Mac G4 and “Pismo” PowerBook G3, FireWire Target Disk mode replaced the earlier disk mode implementation, also receiving official support beyond laptops to all subsequent Macs with built-in FireWire.

[1] The host computer may run Microsoft Windows, but with some possible shortcomings: to read a Mac's HFS-formatted partitions, extra drivers such as MacDrive, TransMac, MacDisk, or HFSExplorer are necessary.

Users also must ensure their computer possesses appropriate interface hardware in order to physically connect to a Mac in Target Mode.

Host computers running Linux are also able to read and write to a Mac's HFS or HFS+ formatted devices through Target Disk Mode.