What's In The Sytstem Folder?
This article gives brief descriptions of the files and folders you'll find in
the System Folder of a Macintosh computer installed with system software
version 7.0. The article indicates how the 7.1 System Folder differs.
The Macintosh stores system software in two types of memory: Read Only
Memory (ROM) and Random Access Memory (RAM). Sections of the operating system
are contained permanently in ROM. This type of system software, which is built
into the hardware, is called firmware.
The system software that you install provides updates (new routines and
corrected versions of old routines) between major ROM revisions. These updates
are provided in System and Finder files, device drivers, and other resources
found in the System Folder. When a system boots up, it loads the data from the
System Folder and places the data in RAM, where it's stored until you shut down
You can't open many of the files in the System Folder because most of them
are resource files, not applications. Their use is restricted to the system.
But you can remove or copy them, and you can add files to the System Folder.
The exact content of a System Folder depends on the Macintosh model and other
equipment used with the Macintosh. At the top level, the System Folder
generally contains these items:
* The System file
* The Finder file
* The System Enabler (System 7.1)
* Clipboard file
* Note Pad File
* Scrapbook File
* Apple Menu Items folder
* Control Panels folder
* Extensions folder
* Fonts folder (System 7.1)
* Preferences folder
* PrintMonitor Documents folder
* Startup Items folder
The following sections describe the top-level files in the System Folder.
This is the most important file on a startup volume, and it's the first file
loaded during the boot process. It contains the RAM-based portions of the Mac
ToolBox and operating system, ROM extensions and patches, fonts, and sounds.
All applications and the operating system share the System file's collection of
resources. Every Macintosh startup disk requires this file to start up and run
the Macintosh computer.
The Finder is the application that presents and maintains the Macintosh
desktop. The Finder keeps track of what files belong in which folders and
where they appear on the desktop. It manages disks and files, and it launches
other programs. Every Macintosh startup disk requires this file to start up
and run the Macintosh computer.
Ordinarily, the operating system designates the Finder as the startup
application. This means it's the application that takes control when you first
start the system. With System 7, the Finder stays open while you're running
All new Macintosh models shipping after the release of version 7.1 include a
System Enabler specific for that model or a particular family of models, like
the Macintosh PowerBook family. System Enablers provide compatibility between
Macintosh CPU hardware and system software. You add a System Enabler rather
than reinstalling a new system. System Enablers are located at the top level
of the System Folder -- not in the Extensions folder.
The Clipboard stores data that you have cut or copied.
The Notepad desk accessory uses resources found in this file.
This file stores graphics and text for the Scrapbook desk accessory. The
Scrapbook retains information even after the system shuts down.
Note: If you delete the Clipboard, Notepad, or Scrapbook files, the system
will recreate them.
Apple Menu Items Folder
You install files in the Apple menu by dragging them into the Apple Menu
Items folder. You can put any file or alias that opens when double-clicked
(applications, documents, server volumes) in the Apple menu. When you install
System 7, the Alarm Clock, Calculator, Chooser, Key Caps, and Scrapbook desk
accessories and a Control Panels folder alias appear in the Apple menu.
Control Panels Folder
The Control Panels folder contains resources that allow you to set features
for your computer. The system draws upon data and instructions provided in
these control panel files, sometimes called Control Panel Device Resource files
(cdev files). The specific control files included with the Macintosh system
depends on configuration requirements and user preferences. Here are some of
the control panels you may find in this folder:
If you have a color monitor, the Color control panel lets you select
highlight and window colors.
* Date & Time
This control panel allows setting the computer system date and time.
* Easy Access
Easy Access supports features the Macintosh provides for disabled people:
* Mouse Keys - a substitute for using the mouse
* Sticky Keys - a way to input complex key sequences more easily
* Slow Keys
* File Sharing Monitor
The File Sharing Monitor control panel lets you observe file sharing
activity. It shows you the name of any connected users, and it lets you
disconnect any connected users.
* General Controls
This control panel allows changing features like desktop pattern and rate of
insertion point blinking.
This lets you select keyboard layout, and key repeat and delay rates.
The Labels control panel provides the colors and names for the Finder Label
menu. You can change the label names and colors corresponding to the label
The Map control panel lets you type in a city name to see geographic
This is where you set the disk cache size, and turn on or off virtual memory
and 32-bit addressing.
The Monitors control panel is where you select monitor characteristics
(number of grays or colors). You can also set monitor orientation when you have
more than one monitor connected to your computer.
The Mouse control panel lets you select tracking and double-click speeds for
your Mouse device.
The Network control panel shows the available data links (LocalTalk,
EtherTalk, TokenTalk). These resources are called AppleTalk Devices (adev
files). You select which data link to use for network operations. Switching
data links causes a temporary loss of network connections.
Here is where you set number display format.
* Sharing Setup
In this control panel you can start File Sharing or Program Linking. And you
enter information here to identify your computer on the network.
This is for specifying the type and volume of sound for your computer.
* Startup Disk
If you have more than one volume attached to your computer, you can specify
the startup disk in this control panel.
* Token Ring
This is used to set transmission speed of the Apple Token Ring 4/16 NB
card, to set other operational timers, and to assign a locally administered
address used for network management instead of the default hardware address.
* Users & Groups
This control panel allows you to designate who has access privileges to your
Here you select the font, icon arrangement, and list information shown on
The Extensions folder contains:
* System extensions, called INITs in System 6 (for example, network drivers)
* Chooser extensions, sometimes called Remote Devices (rdev files) (for
example, AppleShare, CD-ROM, and printer drivers)
* System applications (for example, PrintMonitor)
* PostScript fonts
When you start your computer, the Extensions folder is the first place the
system looks when loading system extensions.
Printer drivers, sometimes called printer resources, provide the interface
to specific printers. You indicate your choice of printers in the Chooser.
When you select a printer with the Chooser, the system draws upon the resources
in these files. A system must have the resource files corresponding to the
printers used with the system.
Here's a list of some printer drivers included with system software version
* AppleTalk ImageWriter
This is for all LaserWriter printers except the LaserWriter Pro series.
* LQ AppleTalk ImageWriter
* LQ ImageWriter
* Personal LaserWriter SC
* Personal LW LS
* Laser Prep
LaserWriter driver versions 6.0 and earlier, and AppleShare Print Server 2.0
require the Laser Prep file. This file works with the LaserWriter driver to
provide PostScript, the language the LaserWriter uses to print text and
graphics. The Laser Prep file is rolled into LaserWriter driver version 6.1
* Printer Share
Printer Share is part of GrayShare, and the extension allows sharing
StyleWriter II, Apple Color Printer, LaserWriter Select 300, and Personal
LaserWriter 300 printers.
Other Chooser Extensions
If you have a CD-ROM drive, you need the appropriate software to access it,
like the Apple CD-ROM file. Foreign File Access handles the conversion of File
Manager calls to High Sierra or ISO 9660 discs.
Network software provides the interface to network data links (for example,
EtherTalk, or TokenTalk).
A/ROSE stands for Apple Real-Time Operating System Environment. It's a
system extension that allows communication between the Macintosh main logic
board and Macintosh Coprocessor Platform (MCP) based NuBus cards that run the
Apple Real-Time Operating System.
A/ROSE runs as a driver under the standard Macintosh operating system. It
downloads, starts, stops, sets priorities, and communicates with real-time
processes that run on any A/ROSE-compatible NuBus card.
* EtherTalk Phase 2
EtherTalk software allows communication with AppleTalk network services over
Ethernet networking interface cards and media.
* Network Extension
The Network control panel uses resources in this extension.
* TokenTalk Phase 2
TokenTalk software allows communication with AppleTalk network services over
Token Ring networking interface cards and media.
* File Sharing Extension
This allows other users on a network to see information you designate for
This application runs in the background to send spooled information to the
printer. When printing is complete, PrintMonitor empties the PrintMonitor
Documents folder. System 6 also requires Backgrounder for background printing.
If you install system software version 7.1, you'll have a Fonts Folder that
provides a single location for fonts, including TrueType, Adobe Type 1, and
bitmapped fonts. System software earlier than version 7.1 stores TrueType and
bitmapped fonts in the System file.
The Preferences Folder stores preference files that keep default or current
settings for programs. Examples include these preference files created by
Microsoft word processing applications: Word Settings, MsWorksPref, and Excel
Settings. It also contains dictionary and help files. System 7-compatible
applications create and maintain these files automatically.
PrintMonitor Documents Folder
From your Macintosh computer, you can print to a LaserWriter or a
StyleWriter printer while you do other work. For instance, you can print and
continue working on a document at the same time. This is called "background
When you turn on background printing for printers in the Chooser,
PrintMonitor temporarily stores files waiting in the print queue in the
PrintMonitor Documents folder until the printer is ready to print them. This is
all done in the background.
Startup Items Folder
Place in this folder the aliases of all applications and documents that
you'd like to have opened automatically when you start up your Macintosh
computer. Don't put system extensions in this folder.
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