In 1985, Steve Wozniak, while critical of the Apple III's hardware flaws, called SOS "the finest operating system on any microcomputer ever".

Examples of SOS character devices are keyboards and serial ports.

[2] When powered on, the Apple III runs through system diagnostics, then reads block number zero from the built-in diskette drive into memory and executes it.

That loader program searches for, loads, and executes a file named SOS.KERNEL, which is the kernel and API of the operating system.

The kernel, in turn, searches for and loads a file named SOS.INTERP (the interpreter, or program, to run) and SOS.DRIVER, the set of device drivers to use.