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© 1997-2006
Gareth Knight
All Rights reserved



Commodore Amiga Operating System (CAOS)

Developer: Amiga Corp/Commodore
Year of Development: 1983/4

The story of the early Amiga Corp. has been distributed widely and openly debated. One of the issues raised about this period was that AmigaDOS (as we know it) was a replacement for another project in development. The CAOS project had fallen behind schedule. The result of this was the contracting of  MetaComco, a British company based in Bristol, commissioned to port TripOS to the Amiga hardware and integrate it into EXEC. At the time TripOS was an experimental system used on 'Computer Laboratories' 68000 and Z80 based system. At the time the AmigaOS was still missing high-level functions needed for a consumer OS. However, this has forced many Amiga users to question what the AmigaOS would have become if CAOS development had continued. While details are sketchy, an article by Andy Finkel (Software Manager at Commodore-Amiga) reveals some of the major differences between the cancelled CAOS and its replacement, AmigaDOS. This article indicates that the AmigaOS would have been more Unix-like in its structure. Commands would have also used Unix syntax. This would have made it easier for potential users to transfer from larger operating systems to the Amiga. It would also have made Unix emulation more transparent when porting applications to the AmigaOS. Unlike Unix, however, it was geared towards an end-user system that would be enjoyable to use, rather than frustrating to use. The draft specifications highlighted this aim, stating the main aims of the operating system:

"It is a small, full-bodied operating system, functioning on a small (but great) machine bound for the consumer market-place. Its primary purpose is not to provide a sophisticated software development environment - rather is provides a foundation for pleasant and useful application programs. This is not to say that it neglects the programmer's needs. Externally it is meant for end users; internally, however, it is designed to support the complex demands of most applications. It provides extra rich functionality for an operating system of its class.
An examination of the system specification reveals that the 'extra rich functionality' move beyond consumer operating systems, to incorporate features only found in high-end systems at the time. The most notable difference for Amiga user is resource tracking. This would have enabled the OS to track the resources in use and free them if the application crashed. While this is possible to an extent under AmigaDOS, the CAOS method was more effective and promised to do it cleanly. It is this part that was delayed and would most likely require a significant redesign to incorporate the code into the existing AmigaDOS.

The TripOS code was written in BCPL, a forerunner to C. This code continued to exist in the Dos.Library until v36 when it was replaced with assembler and C. However, a small percentage of the code lives on in the latest Amiga models to retain compatibility.


Last Update: 1/11/2001

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