9618 Chapter 6: Security, privacy and data integrity
9618 Chapter 4: Processor fundamentals
A* 9618/9608 Chapter 3: Hardware
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5 System Software
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5.1
What is an OS?
A software platform that provides facilities for programs to be run which
are of benefit to a user.
An operating system is a low-level piece of software that manages the
computer’s hardware & software, and provides an interface between the
user and the computer. The operating system is the software that
controls, manages and runs all of the applications on the computer.
Explain why a computer system requires an OS
The computer hardware is unusable without an OS
… because it provides the visual user interface
… which allows the user to communicate with the computer system.
Explain the key management tasks carried out by the OS : Memory
management
Memory management
There are two broad tasks to be accomplished when managing
memory :
1. Each process must have enough memory to execute, and it can
neither run into the memory space of another process nor be
run into by another process (fair memory allocation)
a. Ensuring that different processes cannot access the same
memory location at the same time
b. Managing virtual memory and page files
5 System Software 1
, 2. Different types of memory in the system must be used properly
so that each process can run most effectively.
a. Allocating memory locations to processes that are running
on the computer
File management
The operating system is responsible for maintaining the file system.
The tasks include:
1. File naming conventions
2. Directory (folder) structures
3. Access control mechanisms
This is done through:
1. Find, move, edit and delete files
2. Inspect files to find out their properties (e.g. creation date, size,
type)
3. Organise files into a series of folders and sub-folders
4. View directory trees
5. Formatting disks
Security management
Part of the role of the operating system is to manage security of the
devices, file system and memory. The management includes:
1. Provision for recovery when data is lost (backup)
2. Prevention of intrusion (user accounts)
3. Ensuring data privacy
This is done by :
1. Denying write access to protected files and folders (access
rights)
2. Scanning memory and hard drives to ensure file integrity
5 System Software 2
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