Have by default blue/orange screens and have preferences programs that are basically universal preference editors in one program.

It can be identified by the white menu bar across the top of the screen.

1.0-1.3 can be found in:

Amiga 1000

Amiga 2000

Amiga 500

The Amiga 1000 had Kickstart on a disk.

Kickstart is the Amiga equivalent of a BIOS, (Basic Input/Output System).

Has a black menu bar at the top of the screen and standard light Blue on light gray color scheme. If you select "about" from the Workbench menu, it should read...

"Kickstart version 37.xx" for 2.0 to 2.1

"Workbench version 38.xx" for 2.1 version.

2.0 was only available on early A3000 machines.

2.04 was available on newer A500, 2000, and A3000 machines.

2.05 was on board the A600 to add support for the  PCMCIA expansion slot.

2.1 was a software only upgrade that added some upgraded preference editors and CrossDOS the PC filesystem which allows access to MS-DOS and Atari formatted disks

3.0 is found on older "stock" A1200 and A4000 machines.

3.0 is buggy and it is highly recommended that you at least do a software upgrade to 3.1, although the 3.1 "Kickstart" ROM also fixes some fairly nasty bugs.

3.x signifies a return to the white menu bar at the top of the screen and maintains the 2.0 baby blue on light gray color scheme. Selecting the about box should reveal something to the effect of:

"Workbench v39.xx", if v40.xx, or above it's 3.1.

One of the most important improvements in OS3.0 and above is the use of libraries and datatypes to allow plug-ins to the Operating System to add advanced features.

Because of AGA and other better graphics handling 3.0-3.1 will allow you to use graphics as a background, you are no longer limited to background patterns.

3.5 is available as an upgrade. It includes some sorely missed features such as:

Internet support, including JavaScript, NewIcons (glowicons), better graphics, bugfixes, PowerPC support and much more.

 3.9

3.9 is the currently available OS. This is an upgrade to 3.5 and 3.1.   It includes some added features: Improved Internet support, Multimedia, Improved PowerPC support, a program launching dock and much more.