mac icon march 
 Table of Contents

System Folder

Folders within the System

Useful Control Panels

Start up sequence

Application memory

Installing Applications

Extensions Manager

Memory Control Panel


In the advanced lesson we will get into more of the details of how the Mac OS is put together. We will take a closer look at the OS, its components, and how it works with applications. Understanding how all of this works will allow you to fix many common situations, and help you to work with any application you may need to use on a Mac.

Mac OS Changing Settings

System Folder

The System Folder is the home of the Macintosh Operating System (Mac OS). This is the software that provides an environment to manage files and to run programs. Without a correctly configured System Folder, the Mac OS will not launch, and the computer will not boot.

 System Folder

The Brains: Finder and System

For the Mac system folder to be considered complete, it must contain the System, the Finder, and several other important files.

System and Finder files

The System suitcase is the file that handles most of the work. The Finder is the application that provides the primary user interface of the computer - letting you copy and move files, handle views, and do other basic tasks

System Folder icon

The System folder can be assigned any name. As long as it contains the System, the Finderm and a few other important files needed to run the computer, it is considered an acceptable System. Even if the System Folder has been renamed, you can still tell which folder holds the system files from the icon of the folder.


Different versions of the Mac OS, and even different machines, have slightly different requirements about what MUST be in the System Folder for the computer to work. Unless specifically told differently, never remove items from the System Folder.


Control Panels

Control Panels add features to the Mac OS and allow for customization to fit a specific users needs. They are stored in a folder called Control Panels. Some are loaded as the computer launches and stay in memory the entire time the computer is running. Others are really just applications that launch when needed and then quit when no longer being used.


Extensions, like control panels, modify the way the Mac OS works. Extensions are stored in a folder called Extensions. The main difference between a control panel and an extension is that control panels have an interface for a user to specify options while an extension does not. Extensions, like control panels, sometimes are loaded as the computer is launched, while others are loaded only when needed by specific programs. The ones that load and unload as needed are sometimes referred to as "libraries".

Control Strip

stCntrlstrp.gif (2560 bytes)


The control strip provides a quick and easy way to change some of your computer's settings (much like control panels). For example, you can use the control strip to turn file sharing on or off, and to adjust the computer's speaker volume. You can adjust the same things in the control panels, but it may be faster to do so from the control strip. Other control strip modules may give access to adjusting things which can not be adjusted in the control panels, or even to other features like a quick-access calculator or egg timer. Control strips are loaded as the Control Strip Control Panel is loaded.

You can click on either end to expand or collapse the strip, making it take up very little screen space.

Control Panels, Extensions, and some of the other files that add capabilities to the Mac OS are referred to as a whole as Extensions. The Extensions Manager (a control panel), for example, handles all several types of extensions, including: extensions, control Panels, and some "free-floating" items in the System Folder.


Start up sequence

A key ingredient in understanding extension management is to understand the order in which the Macintosh loads/runs extensions and control panels during the boot process.

When the power is booted the Mac immediately checks to see if its internal components are all working correctly.

Next, it looks for a drive that has an acceptable System (this is called a startup drive). If the Mac finds a suitable startup drive it will continue the startup process. If not, it will display a flashing question mark and wait for a working startup disk.

The first thing you should see if startup is going correctly is the message: Welcome to Mac OS. This screen will also tell you if the extensions have been Disabled.

Next the Mac looks for files in the System Folder. In order, it looks in the:

  1. Extensions Folder
  2. Control Panel Folder
  3. Items in the main part of the System Folder
  4. Items in the Startup Items folder

The computer will read through the files in each folder in alphabetic order. As it does this, the Mac will display a screen that shows icons marching across the screen from left to right as it reads these files. Due to conflicts between extensions, there may be times when you will want one extension to load before another. To make this happen, you can simply change the name of the extensions to make it fit your needs.

Not every file in the Extensions folder, Control Panel folder, or System Folder is loaded at this time, only the files designed to be running at all times. Every item in the Startup Folder will be launched.

Important: You can bypass the loading of most extensions of all types by holding down the Shift key during startup. This will result in a Mac that is not running any extensions, control panels, or other extras, other then the few that it absolutely needs in order to run (example: Appearance Control Panel). This is called booting with Extensions Disabled.


 Extensions Manager

It’s very important to be comfortable with the Extension Manger. With it, you can choose which extensions load into memory. Once you have made your selections, close the Extensions Manager control panel and restart the Macintosh. For trouble shooting purposes, you would mostly use the Extensions Manager to shut off any third party extensions that a customer may be using. You may need to disable extensions if you suspect that a problem may be caused by an Extension that is causing the computer to freeze or have other undesirable effects.

To set the Extensions to a base set:

  1. Open the Extensions Manager and take note of the current set. Write down the name of the current set. You may also want to have the customer write the name of the set down so he or she can return to the same set later.
  2. From the Selected Set menu, select the Base Set for the OS version you are using. Base Set is not an option in some older versions of the Mac OS. In those cases, select the "Mac OS Only" for that Mac OS version.

To make changes on the fly during startup, hold down the space bar on the keyboard during startup, until you are greeted with the Extensions Manager window. Be warned, however, that any extensions that have already loaded will be unaffected by this change. In general the Extension Manager should be one of the first items to load (it has an invisible character at the start of its name that places it first alphabetically). Keep in mind that some third party Extensions are named in such a way as to be placed before the Extensions Manager, and some users may rename their extensions. In these cases, using the space bar to launch the Extensions Manager and temporarily disable an extension will not work.

Extensions  Manager

 Extensions can be viewed in one of three different groupings:

Extensions Manager View Window

  1. As Folders: This shows what files are enabled in each folder in the System Folder. Examples: Control Panels, Extensions, Startup Items
  2. As Packages: This shows what files are enabled based on what package installed them. A package can be an application or a subset of an application that gives the Mac a specific ability. This is very useful to find all extensions and control panels installed from one package or application. Examples: English Text-To-Speech, ColorSync, and QuickTime.
  3. As Items: This shows each item by itself, not grouped with any others


To make it even easier to find specific extensions, you can sort extensions by their On/Off status, name, size, version, or package by clicking once on the appropriate column heading.

In older versions of the Mac OS the Extension Manager had a different look to it, but it worked much the same. It did not give extra information about the extensions, but otherwise had many of the same functions.

Extensions Manager from Sys 7.5.5


Other folders within the System Folder

It is important to be familiar with several other folders in the System Folder.

Control Panels (Disabled)

This folder holds any disabled control panels placed here by the Extension Manager. When you use the Extensions Manager to enable and disable control panels, it is simply moving files back and forth between the Control Panels folder and the Control Panels (disabled) folder.

Extensions (Disabled)

This folder holds any disabled extensions placed here by the Extension Manager. Extensions are moved by the Extensions Manager the same way Control Panels are.

Fonts Folder

Fonts are used to display text on your screen. There are three types of fonts: Postscript, Bitmap, and TrueType. These fonts allow for the different styles of text that are used throughout the computer for menus, titles, messages, or anything else that requires text.

Fonts are usually stored in containers called suitcases. Suitcases are containers like folders except they are designed to only contain fonts, sounds and other system resources. You could combine two suitcases by dragging and dropping one on top of the other

The Fonts folder cannot access more than 128 items. However, you can put 128 fonts into a single suitcase, so the total number of usable fonts is quite large (over 16,000). [NOTE: Mac OS 9 allows for 256 items in the Fonts folder.]


This folder holds the preferences for most modern applications and control panels. Nearly every Macintosh program can create a new preferences file if it can not find an existing one. This makes it possible to remove a program’s preferences from this folder and resolve issues where the preference file is corrupt and causing problems with a program. When you do this, the preferences that have been set in the application will have to be manually reset.

Most preference files will contain the name of the application that created them (example: "Quicken 98 preferences"). Often the preference file will also have the same creator code as the application that created it.

The Preferences folder is also where most web browsers keep their cache folders.

Installing Is a Drag: The System Folder is really smart. If you drag an extension, control panel, font, contextual menu item, control strip module, or any one of a number of other types of files on to the closed System Folder, the Finder will ask if it’s OK to put that item in the correct folder. If you have many items, the Mac will sort them by itself and tell you how many files were placed in each sub-folder.




 Memory Control Panel

The Memory control panel is used to adjust memory settings on the Mac. It is found on the Apple menu, under Control Panels. The main features of the Memory control panel are disk caching, virtual memory, and the RAM disk. On older versions of the Macintosh, there were features called Modern Memory Manager (as shown) and 32-bit Addressing (not shown)

OS 8 mem control panel

Mac OS 8.6 Memory Control Panel

Mac OS 7.5 Memory Control Panel

Disk Caching

Disk Caching is the use of memory to speed access to data stored on a disk. A disk cache holds frequently used information from the drives/ volumes in memory rather than wasting time reading that data all over again. With Mac OS 8 and above, Apple added the option to use the default setting. There is never a reason to go against this recommendation when working with a customer unless the knowledge base or a lead suggests differently.

Modern Memory Manager or 32-Bit Addressing

On PowerPC Macs the "Modern Memory Manager" is the native version of the Mac’s memory management software. It is the fastest memory manager available for a Power Mac. On non-Power Macs (68000 Macs) this option is replaced with a 32-Bit Addressing option. Not having these features enabled may make the Mac be incompatible with newer software. The only time you should tell a customer to disable these is if it is listed as a solution in the knowledge-base.

Virtual Memory

Virtual memory is a way to run more programs with the memory available. Apple’s virtual memory scheme uses space on a drive that you select to store the contents of RAM temporarily. It then switches between the information in RAM and on the hard drive to access programs.

The settings on this control panel let you control how much total memory you have available, and which disk will hold the invisible virtual memory file. Virtual memory has a reputation for being slow. For this reason it is not recommended to use applications that require more memory than the computer physically contains.

Note: The file created for virtual memory will be the size of the total memory that you allocate in the control panel plus the additional amount selected. In the example of the Mac OS memory control panel, above, 128 MB of hard drive space is being used.


RAM Disk

A RAM disk is the exact opposite of virtual memory - using extra RAM as a virtual disk to speed "disk" access. The RAM that is being used as a disk is not available for other purposes. This feature is used frequently in the graphics industry where large files, lots of memory, and a great need for speed are the norm. For our purposes there is no reason to set a RAM disk on a customers machine unless the knowledge base suggests it. If a customer has a RAM disk set up, you may want to turn this feature off to free memory for other applications.

You can learn more about freeing memory in later lessons.


Application memory

The Get Info - Memory Window

In earlier modules we looked at the differences between hard drive space and memory. We also saw how much memory the computer as a whole was using and even how much any single application was using. Now we will learn how an application has memory allocated to it,

To the right is the Get Info window for SimpleText. The Size of the the various memory settings is listed in kilobytes. This is where we can see what the suggested memory requirement for a program, what it will use as a minimum, and how much memory an application would prefer to work with.

Suggested Size

When a programmer (or group of programmers) release a program, they suggest an amount of memory to use at a minimum. In many cases a program will not run well in the suggested size, especially if it is working with a large data file or has plug-ins of its own.

Minimum Size

When an application is first launched it will try to grab on to and "own" as much memory as is listed in the Preferred Size. If that is not possible, it will grab a smaller amount, down to the size in the minimum size field.

SimpleText Memory Information

Preferred Size


The larger a data file is, and the more add-ons a program has, the more memory it will require. For example, if someone is working with several years of Quicken data they may need more memory allocated to Quicken than a user with a new file. The same is true for the tax products as additional state form sets are added. It is not suggested that you run an application with less memory than is set in the preferred size (which is, after all, why we call it the "preferred size", we would prefer to use that much memory). Not using the preferred size can slow the program down and increase the chance of the application crashing.

Changing Minimum and Preferred Sizes

Generally you should be able to enter information into these two fields. If you can’t enter amounts in these fields, then either the application is currently open (running) or the program is locked. If it is running you will need to Quit out of the application to change these settings. If the program is locked, remove the check from the Locked check box in the same information screen.

Virtual Memory and Application Memory

Many programs on the Macintosh adjust the amount of memory they require depending on if virtual memory is on or off. This is another reason to have virtual memory turned on - it reduces the amount of memory many applications require.

Only PPC native applications are affected this way. Emulated 68000 applications need the same amount of memory regardless of the virtual memory settings.

virtual mem adjustment to memory


Useful Control Panels

General Controls panel

With the release of system 7.5, Apple took many of the features that were helpful on their Performa line, and gave them to everyone. The main features were the ability to hide the desktop from novice users, the ability to protect the system folder, and the ability to automatically save files in a folder called Documents.
 You will use this control panel mostly to resolve the following customer issues:

Monitors and Sound control panel(s) 

In Mac OS 7 there were two separate control panels, Monitors and Sounds. With the introduction of Mac OS 8 Apple combined them into one control panel called Monitors & Sounds. In Mac OS 9, they have each become their own control panel again.

The Monitors control panel allows the user to decide how many colors their computer will display on the screen (limited by the computer’s capabilities).

To choose the number of colors displayed select one of the choices in the list.

Moniters and Sound Control Panel

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Mac OS 8.x Monitors & Sound control panel
Mac OS 7.x Monitors control panel

Note: Many Macs also have this functionality on the Control Strip via the Monitor BitDepth and Monitor Resolution Control Strip Modules.

Apple Menu Options

This control panel provides hierarchical menus on the Apple menu and keeps track of the items displayed in Recent Applications, Recent Documents, and Recent Servers.

You can set the number of recent items of each type using this control panel. If you take the check out of Submenus then none of the menus will show in the Apple Menu.

If you want to keep some, but not have others, you can set the number of items in any category to zero.

Startup Disk


The Startup Disk control panel allows you to choose which volume should be used when the computer is restarted. Apple includes this control panel on any CD that has a System Folder to help set which drive should be used for the next boot.

To boot from a CD (or DVD), you can also press the "C" key on the keyboard as you boot with a CD in the drive (the CD must have a usable System Folder).

Other shortcuts for selecting the drive to boot from can be found in Apple's built in help, but are rarely needed for troubleshooting at Intuit.


The Launcher is a utility that allows you to open any icon with one click, much like the Button view throughout the Finder. The aliases that show up in the Launcher are stored in another folder in the System Folder called Launcher Items. You can set whether this is used or not in the General Controls control panel.


Apple's built in help has more information on adding and removing items from the Launcher.



Installing Applications

Most Macintosh applications are placed on the computer’s hard drive using an installer program (as opposed to simply being dragged from a CD, for example). There are four main reasons for this:
  1. Programmers want programs to be easy for users to put on their computer and use immediately
  2. Many programs are compressed so that they require less download time
  3. Programs usually have supporting files that go into the same folder as the program as well as in the System folder. Installers can place files where they belong, easing the installation for the user.
  4. Occasionally programmers don’t want users to know where certain files are stored

A typical program installation has the following steps:

  1. Locate the installer icon or disk with the installer on it
  2. Launch the installer by double-clicking on it
  3. View the splash screen if one comes up
  4. Read and accept the disclaimer
  5. Select your installation options - by default most applications instal to the top level of the Startup Disk
  6. Start the installation by clicking on the Instal button

Finder-6.gif (1986 bytes)


 Things to look for on installer screens

"Disk space available" VS. "Approximate disk space needed"

This helps you see if you can fit a program on a hard drive

Custom button

This will allow you to select a partial installation of a program or additional options

Switch Disk button

This will allow you to select another drive (example: if there in not enough space on the current drive)

Select Folder button

This allows you to choose a location on your hard drive to put the program

Quit button

This allows you to change your mind and not install anything

Once you have completed the installation, you may be asked to restart the computer. This is required to load any extensions the program may have added to the computer.

While not all programs have installers that work this way, both Quicken for the Mac and MacInTax are installed using this standard method.



You should now have a good understanding of how the Mac OS uses its resources, how the OS is configured, and how the OS interacts with applications. You should know the basic components of the System Folder and how to correctly select which extensions are activated upon booting the computer. In the Troubleshooting lesson we will look at how to better use our resources and what to do when something goes wrong.

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