Chapter 4 - CDEV's, INIT's and DA's
The definitions that follow are appropriate for system 7.x.
The system on the Macintosh can be modified by the addition of programs to the system that load into memory when the computer is booted. These programs are similar to each other, and are called apple menu items, control panels and extensions. In previous systems these programs are called DAs, or desk accessories, CDEVs, or control panel devices, and INITs respectively. Some authors continue to use the older names.
An apple menu item (in older terms a DA, or desk accessory) is a program that loads into memory when the computer is booted and can be accessed through the ð symbol on the menu. The one DA always available is the control panel. Any program can now be made an apple menu item.
A control panel (in older terms a CDEV, or control panel device) is a small program that carries on some function whenever the computer is on. For example, one control panel keeps track of the day and the time. When you save a document the computer also saves information about the day and the time the document was created or modified. Another control panel keeps track of how fast the mouse moves.
An extension (in older terms an INIT) is similar to a apple menu item or control panel devise, but usually can not be modified while the system is in use.
The next series of exercises show you how to change the computer to fit you needs or wants.
1) Changing the desktop background pattern, the cache, the time, and the loudness of the computer by the use of control panels.
Open the system folder (the icon is shown below) and next open Control Panels.
2) Open General Controls to see the following box:
There are programs you can add to the system to make it more functional. For example, one of the most common CEDV's is a screen saver. This program puts a constantly changing picture on the screen when the computer is not is use. Because the picture is constantly changing, the picture will not by burned into the screen.
1) Use the Calculator DA
a. Pull down the menu under the ð and select Calculator. The basic calculator will appear.
b. Use the keypad or the number keys to work the calculator. The advantage of using a calculator that is in the computer is that the result displayed on the screen can be copied and pasted into your document You may wish to add a scientific calculator to your system like the one shown below:
2) Determine the System Number and Memory
a) Go to the upper right hand corner of the screen to select finder. You will know you are at the desktop level when you can see the trash can in the lower right hand portion of the screen or an icon like the one shown on the left.
b) Under the menu on the extreme left hand side of the menu bar select About this Macintosh. You will see a dialog box that looks something like this:
This dialog box tells you the name of the computer that is in use (in this case, a Centris 610), the number of the System Software (in this case, System 7.1) the total RAM Memory in the computer (in this case, 8,192 Kilobytes or about 8 Mbytes), and the amount of RAM Memory allocated to each open application (in this case, for example, the System Software takes up 3,592 Kilobytes of RAM).
3) Determine the storage capacity of a disk.
a) To determine the storage capacity of a disk or other storage device, click on the icon of the device to make it active. A window similar to the one below will appear:
b) Below the title bar the computer displays the number of items in the storage device (in this case, 14), the amount of storage these items occupy (in this case, 685 Kilobytes), and the storage capacity available (in this case, 82 Kilobytes).
Determine the following information for the computer you are using:
The name of the computer: _______________________________
The System in use: _____________________________________
The total amount of RAM: _______________________________
The amount of RAM used for the System: ___________________
The storage capacity of the hard drive:______________________
The storage capacity of a floppy disk _______________________
