Introduction to computer science dessalegn Mequanint Yehuala Foreword

Operating system
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Language software
Operating System
Operating system coordinates the activity between the user and the computer. An operating
system has three major functions.
• Controlling operations (control program)
• Coordinates, or supervises the activity of the computer system.
• Decides where programs and data should be stored in the computer memory.
• Handles communications among the computer components, applications
software and the user.
• Controls the saving and retrieving of files to and from disks in the disk drive.
• It performs all its controlling tasks without the involvement or awareness of the
user.
• Input/output Management
• The I/O manager coordinates the computers communication with outside world,
flow of data to the display screen and other output devices (printers/ plotters) and
from the keyboard or other input devices.
• Handles the flow of data to and from the disk drives (file management).
• Handles the process of preparing a disk for use, the copying, renaming, erasing
task of a file.
• Command Processing ( command Interpreter)
– It interprets the commands or what you enter using the keyboard or
other input devices

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Computer System
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Types of operating Systems
Operating systems can be classified by:
a. The number of programs or tasks they can handle at a time and
b. The number of users they serve at once at one or different stations.
Single tasking operating systems
– With single tasking operating systems: only one program can be run on
a computer at a time.
– In order to run another program, one must remove the first program
loaded in the computer’s main memory and load the other one(i.e. it
can’t handle two or more programs at a time)
– These types of operating systems are single user or can serve only one
user at a time.