Java Reference
In-Depth Information
1.15
What is an interpreter?
1.16
What is a compiler?
1.17
What is the difference between an interpreted language and a compiled language?
High-Level Source File
Output
...
area = 5 * 5 * 3.1415;
...
Interpreter
(a)
High-Level Source File
Machine-Code File
...
0101100011011100
1111100011000100
...
Output
...
area = 5 * 5 * 3.1415;
...
Compiler
Executor
(b)
F
IGURE
1.4
(a) An interpreter translates and executes a program one statement at a time. (b) A compiler translates the
entire source program into a machine-language file for execution.
The
operating system (OS)
is the most important program that runs on a computer.
The OS manages and controls a computer's activities.
Key
Point
operating system (OS)
The popular
operating systems
for general-purpose computers are Microsoft Windows, Mac
OS, and Linux. Application programs, such as a Web browser or a word processor, cannot
run unless an operating system is installed and running on the computer. Figure 1.5 shows the
interrelationship of hardware, operating system, application software, and the user.
User
Application Programs
Operating System
Hardware
F
IGURE
1.5
Users and applications access the computer's hardware via the operating system.
The major tasks of an operating system are as follows:
Controlling and monitoring system activities
■
Allocating and assigning system resources
■
Scheduling operations
■
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