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AmigaOS is the default native operating system of the
Amiga. The DOS
library and CLI were based on a Tripos port by MetaComCo written in BCPL.
| Contents |
The AmigaOS has:
AmigaOS always came divided in two parts, Kickstart and the Workbench.
Each Kickstart version is tied to a particular version of the Amigas operating system software, so users should only boot Workbench 1.3 on a machine with a 1.3 Kickstart ROM. It is possible to boot incorrect versions (Workbench 3.1 will boot on Kickstart 3.0, with some problems). The only exception is Workbench 2.1, which was a software-only update based on Kickstart 2.04. Also, the latest Workbench versions, 3.5 and 3.9, use Kickstart 3.1 and load ROM updates at boot time.
Kickstart is the name given to the bootstrap ROM. On the first Amiga model, the A1000, this was loaded from disk, although eventually Kickstarts were put on a ROM chip inside the computer. The Amiga 1000 could be modified to take these chips.
As well as containing the code needed to boot the computer, the Kickstart also contained large portions of the Amiga's operating system, such as Intuition (the Amiga's graphical user interface libraries), Exec (its preemptive multitasking microkernel), AmigaDOS (the disk handling libraries).
Later versions of the kickstart contained drivers for IDE and SCSI controllers, PCMCIA ports and various other hardware that came with Amiga.
With third party software, it is possible to have a different kickstart loaded in RAM and to use it instead of the ROM one - for example Kickstart 1.3 may be loaded in order to run old games incompatible with Kickstart 2.0 and higher. These programs are called Softkickers and they are selectable either by a switch or a keyboard shortcut when you first turn the machine on.
Workbench is the native graphical user interface for the Amiga computer. As the name suggests, the metaphor of a workbench, rather than a desktop, is used: Directories are depicted as drawers, executable files are depicted as tools, data files are depicted as projects and GUI widgets are gadgets. Most Amiga application software has pull-down menus starting "Project Edit ..." rather than the usual "File Edit ..." from other platforms. Strictly speaking, the term Workbench refers only to the main file-manager of AmigaOS, but it is commonly used in referring to all the parts of the OS non residing in the ROM.
The Workbench environment is not required for the machine to function, therefore a lot of old games can boot directly from Kickstart, without loading it. Without Workbench there is more RAM available, however the application will lose the ability to multitask with other applications. In this circumstance, the machine must be rebooted.
In many other aspects the interface resembles Mac OS, with the main desktop having the drive icons, and a single menu bar at the very top of the screen. Unlike the Mac mouse, the Amiga mouse has two buttons - the right mouse button operates the pull-down menus, with a Macintosh-style 'release to select' mechanism.
A unique feature of Workbench is multiple screens. These are conceptually similar to X Window System virtual desktops or workspaces, but are generated dynamically by application programs as necessary. Each screen can have a different resolution and colour depth. A gadget in the top-right corner of the screen allows screens to be cycled - as the OS stores all screens in memory simultaneously, redrawing is instantaneous. Screens can also be dragged up and down by their title bars, but this functionality is provided only by the custom chipsets specially designed for the platform, so it is no longer available on systems that run with a modern graphics card.
AmigaOS up to 3.1 doesn't offer any software layer to use additional graphic or audio solutions. Starting with AmigaOS 3.5, some of these solutions were bundled with the OS, allowing the use of common hardware cards other than the native chipsets, but don't include any driver solution of their own. Users are required to use third party software to supply hardware dependent drivers. Common software packages for graphics are EGS, Picasso96 and Cybergraphics. For audio support there is AHI, a widely supported freeware driver system.
The 1.x versions are the original implementation of AmigaOS. They defaulted to a distinctive blue and orange colour scheme which was designed to give high contrast on even the worst of television screens (it could easily be changed by the user). Versions 1.1 consisted mostly of bug fixes. Versions 1.0 and 1.1 were distributed only on floppy disks for the Amiga 1000.
Versions 1.2 and 1.3 were the first versions to be put in ROMs (allowing their use on models with kickstart in ROM) but were still available on floppies for Amiga 1000 owners. These versions were shipped in ROM with the A500, A1500, CDTV (1.3 only) and A2000. Version 1.2 of Kickstart fixed many bugs, greatly improving the stability of the system, and added AutoConfig (tm) support which could automatically configure expansion boards. Release 1.3 had few changes to Kickstart (mainly fixing a bug to allow autobooting hard disks) but had many more changes supplied with Workbench, including a much faster file system for hard disks, an improved CLI, and various extra programs.
Kickstart/Workbench 1.4 was a beta version of the upcoming 2.0 update and never released, but the Kickstart part was shipped in very small quantities with early Amiga 3000 computers, where it is often referred to as the "Superkickstart ROM". In these machines it is only used to bootstrap the machine and load the Kickstart that will be used to actually boot the system. The appearance is similar to that of 2.0 and higher, with just minor differences.
Kickstart/Workbench 2.0 introduced a lot of major advances to the Amiga operating system. Gone was the harsh blue and orange colourscheme, replaced with a much easier on the eye grey and light blue. The Workbench was no longer tied to the 640x256 (PAL) or 640x200 (NTSC) display modes, and much of the system was improved with an eye to making future expansion easier.
Workbench 2.04 introduced ARexx, a system-wide scripting language. Programmers could add so-called "ARexx ports" to their programs, which allowed them to be controlled from ARexx scripts. Using ARexx, you could make two completely different programs from different vendors work together seamlessly. For example, you could batch-convert a directory of files to thumbnail images with an ARexx capable image manipulation program, create and index HTML table of the thumbnails linking to the original images, and display it in a web browser, all from one script. ARexx became very popular, and was widely adopted by programmers.
Unfortunately, 2.x introduced some incompatibilities with old, badly written software, and so a lot of people were upset with this update.
2.x shipped with the A500+ (2.04), A600 (2.05), A3000 and A3000T. Workbench 2.1 was the last in this series, and only released as a software update. It included useful features such as CrossDOS, to support working with floppy disks formatted for PCs. In other words, there was no Kickstart 2.1.
3.x was another major update. Updates included:
3.x shipped with the CD32, A1200, A4000 and A4000T.
After the demise of Commodore, the later owners of the Amiga trademark granted a license to a German company called Haage & Partner to update the Amiga's operating system. Along with this update came a change in the way people referred to the Amiga's operating system. Rather than specifying "Kickstart" or "Workbench," the updates were most often referred to as simply "AmigaOS."
Updates included:
A new version of AmigaOS is being developed by Hyperion Entertainment (http://www.hyperion-entertainment.com) under license from Amiga, Inc (http://www.amiga.com). The 4.0 version will be a major update a decade after the last official release.
The new version will be PowerPC native, finally abandoning the Motorola 68k processor. Since there will be no more Amiga hardware, AmigaOS 4.0 will run on third party hardware, which currently only includes 1200 and 4000 with PowerPC accelerator boards and AmigaONE motherboards.
Amiga, Inc's distribution policies for AmigaOS 4.0 (and any later versions) require that for third party hardware, the OS must be made available only bundled with the hardware, with the sole exception of Amigas with PowerPC accelerator boards, for which the OS will be sold separately.
These policies were presented in 2002, and have since then been vividly debated among some circles of the AmigaOS community, and are subject for an ongoing petition to Amiga, Inc (http://amigapop.8bit.co.uk). Currently, as of December 2004, the only third party hardware and dealer that have acquired a licence to sell such bundles is the company that was consulted by Amiga, Inc. to create this distribution model, Eyetech (http://www.eyetech.co.uk), who currently offer Mai Logic (http://www.mai.com/)'s Teron series motherboards (http://www.mai.com/products/Mainboard.htm) under the licensed label "AmigaOne".
A developer pre-release version was sent to purchasers of AmigaOne hardware in June of 2004, and currently ships with new AmigaOne boards. This does not have all of the features planned for the full release version, but includes a full SDK based on GCC, and VBCC C/C++ compilers.
Main features planned for AmigaOS 4.0:
Although not strictly Amiga related, a recent fork of FreeBSD-4.8 called DragonFly BSD has been created by a former FreeBSD developer and Amiga programmer Matt Dillon. DragonFly BSD (although still a work in progress) aims to make the BSD core more like the Amiga architectually, featuring a message-passing kernel, allowing for a very efficient and virtually mutex-free SMP design.
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