UserDoc:Introduction to AmigaOS

AmigaOS, the flexible operating system

AmigaOS is an operating system - a collection of efficient programs written to start the computer, let the user control the computer and to present feedback to the user.

AmigaOS is designed with ease of use and flexibility in mind. To begin with, AmigaOS provides a clear view of your computer, your applications and files. A number of methods are available to let your computer serve you - whether it is graphically with a mouse, by using the "Shell" command line or by some other means the user configures.

AmigaOS strives to avoid stupid limitations that can be found on other systems. An AmigaOS user can organise their files the way they like. There are few limits on file hierarchy, locations and file names - drives don't have to named with a letter or cryptic names (C:, sda1), your files don't have to reside in your "Documents" folder and your hard drives aren't hidden from you. If you're not writing to drives and you want "shut down", why do you have to wait for the OS to allow you? With AmigaOS, just hit the power switch.

An Amiga does not start with pre-installed applications serving some sales conglomerate, marketing organization or their big brother. AmigaOS does not do actions behind the user's back. As unique as it is today, the AmigaOS computer serves the user and not the other way around. With one of the largest proportions of user-programmers around, the trustworthy AmigaOS ethic is mirrored in AmigaOS applications

Since the first versions twenty-five years ago, AmigaOS has also been designed to serve efficiently. Developers of this operating system and programs have always strived to optimize their applications. The result is an operating system and applications that take less space on your hard drives, waste less time loading, consume less memory, require less processing power and respond quickly to the user.

Every update AmigaOS doesn't demand you must buy newer, more powerful hardware. AmigaOS currently runs on twenty year old 200MHz computers or brand new dual core 1,800MHz computers - it's the user's choice how they want to enjoy AmigaOS.

AmigaOS platform targets

While the original versions of AmigaOS would run on computers of the eighties on the Motorola 68k series CPU chips, the current AmigaOS runs on computers using the PowerPC processor chips hardware. These can be the old Amiga computers (also called Classic Amigas) with PPC "accelerator cards" or the new generation Amiga PPC computers.

In this guide, we will concentrate on the current AmigaOS running on the supported hardware.

How to use AmigaOS?

You can use the AmigaOS system with a mouse and/or a keyboard but also by some other input devices the system can support. Another way to perform actions and get their result is to execute command scripts. They are a list of commands that will be executed. Each command will do an action.

Using the mouse

On AmigaOS, you can use a mouse to act on graphic elements. The left mouse button is used to click on graphic objects, to select them or operate them. The right mouse button is used to display the menus of the current program. The middle mouse button (also called the mouse wheel) is used to scroll the viewable area. To select an icon, you just have to click once on it. To open the associated program, you need to double-click it. This is done doing two clicks one after the other in a short time.

Using the keyboard

Of course the keyboard is used to enter text but it can be used to execute some actions by using shortcuts. There are special keys that allows this. They are called qualifier keys. Here is a list:

• the Amiga keys
• the Ctrl keys
• The Alt keys

Shortcuts are written with the qualifier key and the value key next to it. See below. The most famous shortcuts are the copy, cut and paste operations that you can perform on selected text:

• copy is done with the Amiga-C shortcut
• cut is done with Amiga-X
• paste is done with Amiga-V

With the Shell

The Shell is a command line interface. You will need to enter commands using the keyboard. When a command is executed by the system, you will get the result of it.

With the Workbench

The Workbench is the first thing you see when AmigaOS is fully started. It is the main place where you can control AmigaOS from. It will allow you to use your mouse to open programs, do actions or just to examine your disks and your data you stored on them. The Workbench is graphical interface between the user and the computer. Please see the section about the AmigaOS Workbench to learn more about it.

With scripts

Scripts contain a list of commands written in a specific language. There are different languages you can choose from: the AmigaDOS language, Arexx, Python or many others. Each of these language as its rules and you'll have to learn the one that suits better the actions you want to do. You can create a script using a text editor. Then you will be able to run such script from the Workbench or from the shell (or from any other script).

What do you see in AmigaOS?

When AmigaOS is started, you see several graphical elements. Let's see what they are and how they are called in AmigaOS.

Icons

Icons are a small image which represents a disk, a directory or a file. The user can select these icons, open them with the mouse or delete them or move them around in the system.

Windows

Windows are graphic areas which can contain different elements. There are drawer windows where you can see icons or other drawers. There are shell windows you can use to type commands. There are also program windows that contain the graphic objects which represent a program.

Screens

Screens are areas that contain windows. The one you see first is the Workbench screen which show you the Workbench. Some programs can open either windows on the Workbench screen or its own screen. On AmigaOS you can move screens around and see other screens without the need to select them or to switch completely to them.

Menus

Menus are lists of items that will allow you to control a specific program. The Workbench uses a menu you can use to perform actions on the Workbench. In AmigaOS menus are always displayed at the top of the current screen. This way you always know where to find them.

Graphic gadgets

Buttons

Buttons are elements you can click to perform actions.

Text fields

Text fields are graphic areas where you can enter some text, either alphabetic or numeric.

Cycle gadgets

Cycle gadgets allow you to select one value between several.

Checkmark gadgets

You can click on checkmark gadgets to enable/disable an option. A visual checkmark image is shown when this option is enabled.

Tabs

Tabs are used in programs to organise graphic elements in independant pages.

How is my data stored?

Files

Executable files

Programs you can start are stored in executable files. These are files with an executable bit, a flag that shows AmigaOS that such file will do something when started. An example is a music player. When you start this executable, the player opens and you can start playing music files.

AmigaOS can run two different kinds of executable files: the AmigaOS native programs made for the PowerPC processor and programs created for the Motorola 68k processors. The laters are executed inside an emulation that transcripts them into PowerPC code.

Data files

Files that are not executable are data files. These contain some data that will be manipulated by programs. Some examples are a music file, a video file or a text document.

Directories/Drawers

In order to organise things a bit, files are not all of them in the same place. We create directories which like drawers of a cabinet will store different files of the same kind. The graphical interface of AmigaOS being called the Workbench, directories are often called drawers.

Disks, partitions and volumes

Disks

Disks are storage medium you can purchase on a computer store. We use them to store our files. They can be internal hard disks, external ones or a USB disk drive.

Partitions

A disk is often very big and many users prefer to make it more organised. This is done virtually splitting the disk into several smaller parts. This operation is known as creating partitions on a disk.

TODO: insert a disk image with partitions

Volumes

A partition is a physical area on a disk. To access it with AmigaOS we could read the physical data off the partition but it's not an easy way. To make it easier AmigaOS uses the concept of volumes. These are virtual representations of a partition. The volumes have a name so AmigaOS and therefore the user can access all files/directories stored on it in a very practical way: just by using its name.

AmigaOS components

AmigaOS is made of different components which have their own job in the system. The most important ones are mandatory. Without them the system does not even start. Other components are less important and the user can choose to use them or not. This is the case of drivers. For instance, a device driver may be omitted. If so, the corresponding device will just not work as AmigaOS will have no driver that allows it to know what to do with this device.

Kickstart modules

These components are the heart of AmigaOS. Their duties is to do graphics, to handle discs or to handle all reads/writes to files. Also one of them is the AmigaOS kernel which is some kind of director handling the work of all other components. You can find all these modules in the Kickstart directory in the system volume. Here is a list:

Mandatory modules

The following modules are required in any AmigaOS system. Without one of these, the system will not start.

• kernel - The kernel works like a conductor in an orchestra. Its job is to make everything works together. It creates processes, handle memory usage, defines the way other components will access peripherals...etc. Note that the AmigaOS kernel is not based on any other kernel. It is a self made kernel that works since 1983.
• loader - this component handles the loading of all other kickstart modules
• battclock.resource.kmod - this module handles reading/writing the battery backed up clock which is used on all computers to keep the date and time
• bootimage - this is the boot picture. It is displayed during the start sequence of AmigaOS
• bootmenu.kmod - this component handles the Early Startup Menu the use can use to define some settings before starting AmigaOS
• con-handler.kmod - it directs the read and write requests to the console window, to a serial AUX: device or any other supported interface
• console.device.kmod - it opens a window and reads/writes text to and from that window
• diskboot.kmod - handles the booting of AmigaOS from a supported disk
• diskboot.config - this is a text file experienced users can modify to change the boot behaviour of AmigaOS
• dos.library.kmod - this module is a collection of functions that any program can use to perform actions on disks, files and directories
• elf.library.kmod - handles the loading of executable programs
• env-handler.kmod - handles the read/writes of environment variables
• FileSystem.resource.kmod - handles the use of the different filesystems
• gadtools.library.kmod - collection of functions used to create all graphic objects like gadgets, sliders, menus...
• gameport.device.kmod - handles the read/writes of game pads and joysticks
• graphics.library.kmod - collection of functions used to draw graphic elements on the monitor
• hunk.library.kmod - set of functions to read a data stream into memory
• input.device.kmod - handles of input events like keyboard events or mouse clicks
• intuition.library.kmod - collection of functions to create and handle all graphic elements (screens, windows, the mouse pointer...)
• layers.library.kmod - set of functions to be used to handle different layers in graphic operations
• keyboard.device.kmod - driver for the keyboard
• keymap.library.kmod - functions to handle different keymaps
• newlib.library.kmod - collection of functions to perform memory operations (allocating memory, copying memory areas... )
• nonvolatile.library.kmod - provides a simple means for an application developer to manage nonvolatile storage
• nvram.resource.kmod - handles the read/writes to the EEPROM chip present on many AmigaOS computers
• PCIGraphics.card - driver that supports the use of different graphic cards
• ram-handler.kmod - functions that handles the Ram disk: special disk
• ramdrive.device.kmod - device that allows the usage of the ramdrive device RAD: disk
• ramlib.kmod - loads disk based libraries and devices for exec.library
• rtg.library - library of functions perform lowlevel graphic operations on graphic cards
• shell.kmod - the AmigaOS command line interface
• strap.kmod - module that handles booting on different disk devices
• timer.device.kmod - driver to give access to timing functions

Filesystem support

These kickstart modules can be loaded or left aside. If you want to use a particular filesystem on your disk partitions, you need to load the corresponding filesystem module.

• CDFileSystem - handles the CD-ROM disks with data stored in different formats: ISO9660, HFS...
• SmartFilesystem - allows to store data on partitions in SFS0 and SFS2
• JXFileSystem - allows to create partitions in JXFS
• FastFileSystem - allows the usage of partitions in FFS and FFS2 layouts
• diskcache.library.kmod - component required by the SmartFileSystem and JXFileSystem modules

Hardware drivers

Graphic cards drivers

• 3dfxVoodoo.chip
• 3DLabsPermedia2.chip
• ATIRadeon.chip
• RadeonHD.chip
• siliconmotion502.chip

Disk drivers

Each of these drivers allow the use of disks connected to a disk controller. These files are named with the name of the controller they support. As an example, the sii3114ide.device.kmod allows to use disks connected on a Silicon Image SiI3114 controller chip.

• it8212ide.device.kmod
• lsi53c8xx.device.kmod
• sam460sata.device.kmod
• sii3112ide.device.kmod
• sii3512ide.device.kmod
• sii3114ide.device.kmod
• sii0680ide.device.kmod
• sii3132ide.device.kmod

USB drivers

• hub.usbfd
• usbsys.device
• usbresource.library
• ehci.usbhcd
• ohci.usbhcd
• uhci.usbhcd
• massstorage.usbfd

Other drivers

• bootkeyboard.usbfd - allows a USB keyboard to be used even before the USB stack is loaded
• bootmouse.usbfd - allows a USB mouse to be used even before the USB stack is loaded
• fpga.resource.kmod - allows to use the FPGA components which are present on some Amiga computers
• i2c.resource.kmod - allows to use the i2c interface present on some Amiga computers
• xena.resource.kmod - provides access to the Xena chip on the AmigaOne X1000

Misc modules

• petunia.library.kmod - this module contains the Just-In-Time emulator that allows AmigaOS to run programs made for the Motorola 68k processor

System components

Beside the kickstart modules, AmigaOS uses many different components that can be loaded only when used. These files are stored in different directories in the system volume. Here is described a default AmigaOS installation.

• C

This directory contains AmigaDOS Commands

• Classes

contains different object elements easy to be used in any program: gadgets, requesters, graphic table, windows...

• Devs

contains definition for Devices

• Emulation

contains files used for the 68k emulation (though E-UAE)

• Fonts

contains various systems fonts

• Internet

contains a dialer to connect to Internet

• Kickstart

contains the kickstart modules

• L

contains handlers and filesystems

• Libs

contains dynamic Librairies of functions

• Locale

contains all files used to localise the system (catalogs, keymaps...)

• MUI

contains the needed files for programs that use the MUI third party graphic interface

• Prefs

contains the preference programs used to customise AmigaOS

• S

contains the Scripts

• SObjs

contains .so shared object library files

• Storage

contains other optional files

• System

contains some programs used by the system itself (i.e. you don't need to run them yourself) or low-level programs like disk tools

• Utilities

contains several utilities

AmigaOS boot procedure

Basically a computer with AmigaOS does the following when the power button is pushed:

• the BIOS of the computer initialises the hardware
• the BIOS looks on the harddisk and finds a file called the Second Level Booter (SLB)
• the SLB will then analyses all Amiga partitions and read each system configuration it finds. It shows all available configurations to the user.
• the SLB loads the kickstart files of the selected configuration
• the kickstart files are executed, AmigaOS becomes alive
• the file Startup-sequence is executed and with it all commands it contains
• the Workbench is started

At this point the user can use his/her computer.