What is an operating system?
An operating system is a collection of programs and utilities which manage the computers hardware and software, they look after the basic functions of the computer.
What is the kernel
central part of the operating system. it is loaded into memory when the computer is first booted up and stays in the memory until the computer is powered down
What are the jobs of operating system?
Memory Management
Multitasking
File management
Management of Input/Output devices
Explain how the kernel does memory management
Ensures that all the programs and data have appropriate space allocated
ensures that programs and data don’t occupy the same memory locations
Explain How The kernel does multitasking
Ensures that multiple programs use CPU efficiently and don’t interfere with each other
When multiple programs are open the OS ensures that they look like they are running simultaneously
Explain how the kernel manage Input/Output Devices
Communicates and sends data to output devices
manage network communication
communicates and receives data from input devices
Explain how the kernel does File Management
Manages the backing store
The kernel manages secondary storage by finding empty space to save data and locating stored files for retrieval. It also enforces security by checking if a user or program has the correct permissions to access specific files.
it does this by creating a FAT(File allocation table)
The kernel maintains an index, often called a FAT, to track the physical location of data across various disk clusters. This “map” allows the OS to correctly reconstruct files that may be fragmented or split across non-contiguous parts of the disk.
it organises the files in hierarchical directory structure
The kernel organizes files into a logical “tree” of folders and subfolders to make data easy for humans to navigate. By using pathnames, the kernel can efficiently locate specific files without having to search the entire disk drive.
C:/Users/Documents/Revision.pdf)
What are some utility programs in the operating systems include
Disc Defragmentation
Compression(zipping)
Anti-virus Software
Firewall
Task management
disk scanning and repair
Backup
What are the two parts of a file
Filename.extension
What does metadata include
When the file was created
the author of the file
when the file was last modified
the size of the file
S ize
C reator
A uthor
M odified
What are Transcaction files
Transaction files use serial(chronological) organisation and all records in the files are stored chronologically. They store the most recent transactions for the client
What are master files
Master files use sequential(by primary key) organisation and all records are stored in order using a key feild.it stores descriptive data and current status information about a set of entities.
Explain Transaction file and Master file using the example of Payroll
Transaction file keeps the hours worked by the staff and master file contains the employees details
Explain Transaction file and Master file using the example of Utility Bill
Transaction file keeps the meter readings of the customers and the master
file contains the customers details
Explain Real Time control
This system means that data is processed and results are acted on as quickly as possible
the computer maintains a complete up-to-date picture of a real world environemnt
Explain Real time transaction
The system aims to keep as up to data as possible , but in a real time transaction system aim is to have the most up to date information available to the user
Example of Real time control
Rocket thrusters
Examples of Real time transaction
Airline reservations
Advantages of Real time transactions
Completed immediately
provides an instant confirmation of the transaction, with users being able to check feedback
online database is not necessary
data is validated and verified as it is entered, this means errors are identified and corrected immediately
Disadvantages of Real time transaction
Network maintenance under real time pressure. If the network breaks or needs an update, you have to fix it while it’s running. If the system goes down for even five minutes, thousands of transactions could fail, leading to lost money and angry customers.
expensive compared to batch processing, need high speed servers,and staff availaive 24/7 to monitor
procedures necessary in ensuring all transaction of the same type are handled in the same way
Define Human computer Interface
The HCi of a system is the means by which the machine and the person using it are communicating with each other
What are the types of human computer interface
Text -based interface
Graphical user interface
Speech Recognition
Speech Synthesis
Handwriting Recognition
Define text based interface
user generally inputs using only the keyboard, the output is in the form of text or patterns of ASCII characters to create line or images
Advantages of Text based interface
simple
no complex graphics, suitable for low spec machines
very fast
Can be learned very quicky
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Hardware and Communication70
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Software Engineering6
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Data transmission28
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Operating System45
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Data Security and Integrity processes22
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The need for different types of software systems and their attributes12
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Data Protection act9
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Economic, Moral, Legal, Ethical and Cultural issues relating to Computer Science8
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Data Transmission2
