AmigaOS is the proprietary native operating system of the Amiga and AmigaOne
personal computers, introduced with the launch of the first Amiga, the Amiga
1000, in 1985.

The most recent release is AmigaOS 4.1, developed by Hyperion Entertainment,
which received in 2009 by Amiga Inc. an exclusive, perpetual, worldwide
license to AmigaOS 3.1 in order to develop and market AmigaOS 4 and subsequent
versions.

AmigaOS is a single-user operating system based on a preemptive multitasking
kernel, called Exec. It includes an abstraction of the Amiga's hardware, a
disk operating system called AmigaDOS, a windowing system API called Intuition
and a desktop file manager called Workbench.
A command-line interface, called AmigaShell, is also integrated into the
system, though it also is entirely window based. The CLI and Workbench
components share the same privileges. Notably, AmigaOS lacks any built-in
memory protection.

AmigaOS is formed from two parts: a firmware component called Kickstart and a
software portion usually referred to as Workbench. Up until AmigaOS 3.1,
matching versions of Kickstart and Workbench were typically released together.
However, since AmigaOS 3.5, the first release after Commodore's demise, only
the software component has been updated and the role of Kickstart has been
diminished somewhat. Firmware updates may still be applied by patching at
system boot.

In 2006 AmigaOS 4.0 was rewritten to become fully PowerPC compatible.

The screens became draggable in any direction, drag and drop of Workbench
icons between different screens was possible, new version of Amidock,
TrueType/OpenType fonts and movie player with DivX and MPEG-4 support were
added.

In AmigaOS 4.1, a new Start-up preferences feature was added which replaced
WBStartup drawer. Additional enhancements were a new icon set to complement
higher screen resolutions, new window themes including drop shadows, AmiDock
with true transparency, scalable icons and AmigaOS with auto-update feature.