Amiga Operating System

The Amiga's was an OperatingSystem well before its time. Pre-emptive multitasking in 1984, imagine that! It only took the MacOs and MicrosoftWindows about a decade to catch up. As well as this it had a fast, responsive GUI and a CommandLineInterface with commands whose names made sense. Yes, I'm a Unix guy, but saying "grep" when you mean "search" is a pathological violation of the PrincipleOfLeastAstonishment.

Of course it also had no memory protection (one misbehaved app could crash the whole OS), but the speed advantage you got from being able to pass messages right into another app's address space made this a feature, rather than a bug, on a 7Mhz M68000 processor.

See (or possibly merge with) AmigaComputer.

There are many emulators for the Amiga for Mac, Windows, and Linux. Many of the people using them hang out on http://www.amiga.org/

Although the original AmigaOS 3.x ran on a 68k processor, and essentially died in 1994 when Commodore went under, there are now a number of clones being produced:

Amiga OS4, which has essentially taken the old 3.x source code, ported it to the PowerPC processor, and added as many modern OS features as possible. Runs existing 68k apps through a novel non-sandbox process-level emulation approach, which is said to have very low latency. Commercial and likely to be released sometime in 2004 (June if you are a betting man).
MorphOS, which is (allegedly) a clean-room partial-reimplementation of the OS untop of a new PowerPC micro-kernel. Runs existing 68k apps through a standard sandbox emulation approach. Has a VERY slick looking GUI. Commercial, but various beta versions of it are already available for free if you purchase a Pegasos computer from Genesi. Sadly there is a lot of hostility between the MorphOS & Amiga OS4 user communities - and blaming either camp here is not the right place.
AROS, which is an open source clean-room reimplementation of the OS to run on standard PC (x86 processor) hardware. Unlikely to ever run existing 68k apps, except through the UAE emulator. The plus side of this is that certain parts of the OS have been redesigned to be more modern, rather like OpenBeOS has done actually. Although progress has been slow, it now duplicates most of OS 3.x, and has a growing library of programs & extensions to the OS (such as Zune which is a clone of the MUI GUI-toolkit).
Amithlon. While not strictly a re-implementation of the OS, it uses a basic Linux kernel, plus UAE emulation core, to allow the old 3.x OS to run unchanged on a standard PC. The Linux kernel is hidden after booting, and the OS has complete control of most of the hardware, so that it feels much more like a "real" OS rather than one that is actually being emulated. Sadly disagreements between the two original commercial creators of Amithlon means that it is now dead, and the previously mentioned 3 clone OSes look to have a better future.
unnamed, but let's call it MacUmilator?. One of the original authors of Amithlon (and arguably the main coder) has written a system similar to Amithlon from scratch, but this time for Apple computers. It is not yet publicly released, but apparently uses a Linux kernel, and this time will use the kernel to provide as many drivers as possible. It is probably not a real contender, but is worth mentioning for completeness.

-- ChrisHandley

There is also the AmigaSdk, an Amiga-like programming environment for Linux, Windows, and handhelds.

s As to the lack of memory protection in the Amiga OS - yes it is a problem <- Not True, well written software for the Amiga never has and never will require "memory protection", if the software is written to the standards expected of the OS and is system friendly then "Memory Protection" is meaningless as the properly written software on the Amiga using it built in memory handling structures and routines means that it already has it's own "memory protection".

... but surprisingly many Amiga users report they find it far more stable than a Windows system (especially prior to Windows XP). The lack of protection simply forces programmers to be more careful in testing, and the well-designed OS does not itself cause crashes (where-as Windows crashes are often due to kernel bugs).

The design of the OS was amazingly advanced for the 1985-1994 era it occupied, so that it is still quite compelling even today (hence the number of clone OSes), but people also ought to consider alternatives - such as BeOs, which is purportedly a "spiritual successor" to the Amiga OS as far as design goes.

IIRC the OS was designed by people from a mainframe culture, so multi-tasking was considered fundamental.

Personally I rather like SymbianOs (EPOC), which has much of the responsiveness plus elegance (simplicity & power) of the Amiga OS. -- ChrisHandley

It's worth pointing out that the 68000 did not have the capability for memory protection. This was a hardware issue; the OS didn't have any choice.

The 68010 had limited buggy ability in that direction, and required an extra expensive support chip even to do it badly (Sun worked around this with an extremely sophisticated and expensive hardware hack). It wasn't until the 68020 that these processors had the full ability to do memory protection in an uncrippled way, and not only were those not even available when the Amiga was introduced, they were also too expensive, initially, for a product like the Amiga, when they were introduced a few years later.

Of course, once they were available, and at a more reasonable cost, then backwards-compatibility was an issue, as always. Same thing happened to the Mac, and it didn't truly get fixed 100% until they changed both the processor family and the OS (to Mach). This is not true. The '020-using Mac II defined "Mac compatibility" for almost a decade.

Similarly with Windows; it took an OS swap (to NT) to fix the same problem. -- DougMerritt

CategoryOperatingSystem