In modern computers the operating system consists of the system software that "makes the hardware usable" and provides shared components to application software. The operating system normally "comes with" the computer. In the Amiga, like on other computers, the operating system consists of a part that is loaded from disk (floppy disk or hard disk), and a part which is stored in higher speed and/or read only memory (e.g. ROM or PROM chips on the computer motherboard).
CAOS, Tripos, AmigaDOS and Intuition
According to the original plans, the Amiga hardware was to be accompanied by CAOS, which stood for "Commodore Amiga Operating System", and was to be built on top of lower-level components like Exec. Instead of CAOS, which never made it to a shipping version, a British research project known as Tripos (named after the chair where Cambridge University exam candidates had to sit), designed by Tim King, was ported to the Amiga, and became "AmigaDOS".
When the Amiga was launched, in 1985, operating systems, and the word "operating system" itself, while well known to computer science students, did not have as strong an identity and recognition to the broad audience as they would have in the following decades. Even for the 1985 Byte Magazine Amiga article (included in Amiga Forever), which introduced the Amiga to the masses, the Amiga and its operating system were simply... the "Amiga". (The article also uses terms like "disk operating system" and "desktop", but not "AmigaDOS" or "operating system".)
By the 1985 launch event the Amiga code was still unfinished. The then-current ROM ("Kickstart") version was 0.7, and did not include a desktop user interface, but rather booted into a command line window titled "AmigaDOS", while the screen title bar displayed the capitalized name "INTUITION". "Intuition" was also a part of the 1985 New York Amiga launch presentations. Later it was repositioned into a more technical role, not exposed in the screen title, but remaining documented for developers as the Amiga component providing user interface functionality (windows features and user interface elements like menus, buttons and other controls).
From AmigaDOS to Amiga OS
At some point it must have become clear that the "DOS" part of "AmigaDOS" was somewhat of an understatement for an operating system which comprised not only a "disk" part, but also substantial multitasking, multimedia and other components. Also, "DOS" brought to mind IBM and Microsoft's much less sophisticated "DOS". So it comes that at Cloanto we have both original "AmigaDOS" documentation from 1985 and 1986 stating that "AmigaDOS is a multi-processing operating system designed for the Amiga", and written developer's documentation by Commodore saying that "AmigaDOS" should not be used to refer to the name of the Amiga operating system.
Slowly, "Amiga OS" became used to refer to the Amiga operating system as a whole, while "AmigaDOS" and "DOS" became used more specifically for the disk subsystem. Computer users in general became better aware of what an "operating system" was, and recognized "OS" as its abbreviation.
In light of the historical roots of the Amiga operating system (neither "CAOS" not "Tripos" had a "disk" part in them), and of subsequent official company decisions and popular use, we consider the brief use of "AmigaDOS" a small distortion of DOS-dominated times more than the official operating system name meant to last in the eyes of "Classic" Amiga history. Therefore "Amiga OS", which is both generic and formally correct, appears to be a better name to use in the context of the "Classic" Amiga operating system, as used since 1985.
From Amiga OS to AmigaOS
While other companies too use "OS" as a stand-alone word in their operating system names (e.g. Apple, for "Mac OS"), somebody possibly decided that "OS" in itself, meaning "operating system", was too generic. It so occurred that Amiga OS 4.0 officially became... AmigaOS 4.0, and a new name and distinctive trademark was born.
The name "Workbench" was originally not meant to express the concept of an "operating system" as in "OS" or "DOS". Neither Commodore-Amiga nor any of its successors ever used the word "Workbench" to refer to an operating system. Nevertheless, perhaps also because of the lack of branding clarity about what ought to have been the "real" name of the Amiga operating system, and because of Cloanto's increasing use of this word in Amiga Forever, "Workbench" kept receiving an increasing preference by the public.
One of the many unique points of the Amiga Forever project is its consistent use of the name "Workbench" for the operating system, which as such has become a Cloanto "trademark". Neither "Amiga OS" (with a space between "Amiga" and "OS") nor "AmigaOS" (without spaces) are used in Amiga Forever for this purpose.
Cloanto's use of the "Workbench" name for the operating system also helps avoid confusion with projects like AmigaOS 4.0, as Amiga Forever focuses entirely on "Classic" Amiga systems.
Historically, there are two other uses of the name "Workbench" within the Amiga family:
- One of the floppy disks that shipped with early Amiga computers was called "Workbench", while other disks in the same set were named "Kickstart", "Extras", "Fonts", etc.
- "Workbench" was also a name used for the desktop user interface
Never, however, was the operating system itself called "Workbench", or did Commodore try to use the term "Workbench" as a broader operating system brand.
The first Amiga, i.e. the Amiga 1000, had an additional floppy disk, named "Kickstart". The Kickstart disk was needed because when the Amiga 1000 shipped, the ROM-based part of the operating system was not stable enough, so the machine was manufactured with only enough code to boot into the operating system from the Kickstart disk. After that, the Amiga 1000, like other Amiga models (which had a "real" ROM chip on their motherboard), could continue loading from other floppy disks (e.g. games), or from hard disk. Interestingly enough, the Amiga 3000 had a similar problem (i.e. the hardware was finished before the new operating system was ready), so that early versions of it loaded their operating system ROM code from a "kickstart" file (located on hard disk).
Interviewed by Cloanto in 2015, Intuition developer RJ Mical described the names used by the Amiga team in the early development days. While individual Amiga OS components had prominent recognition and were referred to by name, e.g. "Exec" or "Intuition", the set as a whole, and as such what was seen as the Amiga operating system, was referred to as "Kickstart" for a long time.