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General Concepts


Most important are:

Before Startup

Your Mac consists of these major components:

  1. A central processor: this does all the work.  It is like a robot in a workshop and it can't do anything without being programmed.  Your Mac has an Intel processor, older models may have an Apple/IBM/Motorola G4 or an Apple/IBM G5 processor.
  2. Memory, also referred to as "RAM".  This is used for storing temporary data, or intermediate results.  There is nothing in memory when the machine is switched on, and whatever was in it when you switched it off is lost.  It is like a note pad of scrap paper that is used for jotting down some things to remember and is thrown away at the end of the job.  Your Mac has probably 2GB or more.
  3. Hard disc.  This is where all stuff that needs to be preserved is kept as recordings in magnetic form.  The recordings survive switching on and off of the machine.  Two important categories of objects are recorded:  application programs and documents.  The application programs are the tools in the robot's workshop and the documents are the products made with the tools.
  4. A set of communication ports.  They are used to ship data between the machine and printers, network lines, scanners, digital cameras etc. that are attached to it.  Your Mac has at least several USB ports, two Firewire ports, a fast Ethernet port, a speaker and microphone port, and it it is an older model perhaps an analog modem port.
  5. A keyboard, a mouse and a screen which are the means to get data shipped between the machine and a human being.  They are the means to control the robot and to observe what it does.  Your Mac comes standard with an Apple optical mouse with four buttons and a scrollwheel.

Starting Up

When you switch on your Mac it goes through a sequence of steps before it lets you work:

  1. Electric power is supplied to the processor, memory and disc.
  2. The processor obeys a list of commands that it finds in the "ROM", a fixed piece of memory that cannot be erased and is only used at this stage.  This startup program tells the processor what type of machine it is on, what the machine's hardware can do and cannot do.
  3. The processor then looks in another piece of memory that has some specific preferences, the PRAM (Preferences RAM). This memory holds:
  4. The processor then starts the startup system from the startup disc.  The system will be Mac OS X.  "Startup" just means the computer loads its memory with the set of general services in the same manner that the robot in the workshop has to be programmed for quite a few basic jobs before you can tell it to do anything meaningful.  It's like priming the robot so it already knows how to use a drill, a screwdriver, where to find the nails and wood, etc., i.e. it becomes functional and acquainted with its workshop.
  5. Finally the computer is ready:  the screen displays some objets, and one basic application runs and listens to the keyboard and the mouse.  This basic application is called the Finder.  The Finder is like the program in the robot that would listen to your commands.  See "Finder".

Memory, Disc, Server

Memory is a scratch pad for the processor.  In Mac OS X, memory is allocated to applications as needed (so you will no longer "run out of memory" as you did in older operating systems).  The more memory your machine has, the better for speed.  The new machines have at least 2GB of RAM installed.  This is sufficient to work with all the usual applications at the same time.

The hard disc is your permanent storage.  The newer machines all have at least 200GB of disc space.  The system and the applications take 10 to 15 GB of this space.  The rest is more than ample for your documents!  Only if you start to do video-editing will you come close to occupying the remaining disc space.

Doing Work

You produce documents using applications.

Examples of applications are:  Safari (web browsing), Pages or Word (texts), Numbers or Excel (spreadsheet calculations), iPhoto or Photoshop (image handling), Finder (filing), Mail or Eudora (e-mail), Preview or Acrobat (pdf files), FileMaker (data bases), ...

Handling Applications

You tell applications what to do via four visible objects:

menus These are always at the top of the screen.  They are always in the order:
1= = system menu;
2=application name=application menu;
5 =other menus.
windows These contain your work.  Each window has a name.  A single application can have many windows each holding a document, or no windows at all.
tool palettes These group icons representing frequently used operations.  They can be hidden, moved around, grouped etc.
dialog boxes These appear only when the application needs more information from you.  There is always a row of buttons at the bottom, and there is always one of those highlighted:  the "default" response.  You can choose the default response by pressing the return key.  Pressing -. (command-full-stop) is equivalent ot Cancel.

Application, Document, Folder

There are only three kinds of object in your computer: documents, applications and folders.  Keeping the distinction in mind is extremely important for understanding what is going on and solving problems!

The basic object you want to work with is a document.  It is a file on your hard disc where it will be recorded until you throw it away.  Documents are the result of your work on the computer.  Your documents are the most precious things on your machine, so you should ensure that you have a backup.  The icons of documents usually looks like a sheet of paper with the top-right corner folded (dog-ear)
To produce and modify documents, you need tools. These tools are the applications. Applications are programs, pieces of software.  The icons of applications usually have an oblique look and show an instrument (the icon of the script editor shown on the left has a pen as instrument).
After you have created a number of documents, you want to file them in categoriesFolders are for organizing your documents in a systematic way that corresponds to the kind of work that you do.  Use folders as much as you can to keep order on your hard disc or server.  The icons of folders usually look like a blueish cover with a tab.

Type, Creator, Extension

To work on a document you can double-click it to open it on your screen.  Or you can use the File-->Open menu to select a document from within an application.  In either case an application is active on your document.  A document is always worked on by using an application.  You should know which application is being used, and this depends on the document's type, creator and extension as well as on whether you double-clicked it or used an application's File-->Open menu.

There are several categories of document:  text, spreadsheet, web pages, data bases, images, drawings etc.  Each has its type.  The type is about the content format, not about the purpose.

But each type of content may potentially be operated upon by more than one application, just like in a workshop you can use more than one tool on a type of material:  you normally use a hammer on nails and a screwdrive on screws, but you could use a pair of pliers on either.  It is the purpose of the document that decides which application you use on it.  A text document containing lists may be worked upon by a data base program, another text document may be a web page and need a web editor, a third text document may be a book and be used with a word processor.  The application that is normally used to work on a document is called its creator.  Thus we can think of a whole matrix:

Application  Tex-Edit PhotoShop Illustrator Acrobat Word Excel FileMaker Golive QuickTime Eudora
Word document
Excel document
FileMaker data base
Golive Site
MPEG movie
Word template

The table above is of course not complete, but you can see:

When you double-click a document, it will open with the application that is considered to be its creator:  Word for word templates, QuickTime player for QuickTime movies etc.  But you may also be able to open that same document with another application.  However, to use Word to work on a text document that was created with Tex-Edit, you obviously cannot double-click the document: you must open it from within Word.  Thus we have these two essential ways of opening a document:

  1. double-click:  --> use the normal application associated with the document (its creator)
  2. start the application first, then use the File->Open menu, navigate to the document and open it (you may have to tell the application to show also documents created by other applications).

Unfortunate note:

In the Unix and DOS world, it was thought that the file type was sufficient to relate a document to an application.  In the time before icons and desktops, file names were therefore given an "extension", usually three letters, to indicate the type of document.  Hence such file names as "report.txt" or "minutes.doc".  Of course this is not really enough, and the 1984 Mac introduced type & creator and also relegated both attributes to the system, leaving the file name free of any extensions.  Type and creator were visibly encoded in the file icon (as in the matrix above).  The Unix/DOS system has more or less caught up by (a) using different extensions for the same type to indicate the creator: e.g. "home.html" really is a text file but indicates it is used as a web page; and (b) using longer extensions such as ".jpeg".  Because Mac OS X runs Unix at its base, the file extensions have crept in and disturb the type-creator system.  This may sometimes be confusing.

Shutting Down

When you shut down the Finder orders all applications to quit.  Each application will see if there are open documents that have been changed and ask you to save these changes first.

Then all data volumes (connected external discs) are closed, all network connections are closed, peripherals shut down and finally power is switched off.  Whatever information was in the memory is now lost, but whatever you saved to disc is still there.

Organising Files

After a short while of using your computer, you will have a fair number of files, and that means you need a way of organising them.  This is what you do with folders and it is the subject of the page "Files and Folders".


You communicate with your computer through three devices:

These devices constitute the interface.

Text that you type will go to the active application only, while all the others are waiting.


It is a good idea to keep duplicates of your documents somewhere, i.e. make a backup.  Backups are made by you onto CDROMs, external discs or other devices, OR they are made automatically by Time Machine onto a second hard disk (usually outside your computer).

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next planned revision: 2009-01