An operating system is a system software which enables you to perform system functions and also provides a platform to perform other application softwares.
There are many functions which are provided by the operating system:
The Os provides a interface for the user to be able to communicate or command applications softwares to perform specific tasks
The recent interface used is the Graphical user interface which uses graphics to represents commands.
Command line interface is know outdated as it doesn't use an graphics but it has a very fast execution.
Both of these interfaces must be remembered
The Os provides a platform for the application softwares to communicate with the system hardware. In other words, the programs requires the Os to use the system hardware.
This is very important function done by the Os as it allocates the memory for each program making sure that the memory locations don't cross and be used by a different program. This maintains security
Also it controls the usage of memory for each program making sure the system is running efficiently
It stores a list of all the hardware and peripherals connected to the computer and also controls the signals sent or received by them.
When a program is executed we call it a process.
Different processes may require different requirements such as the usage of memory and the GPU power.
Also during a process it will be interrupted as there will be many process running and so the Os manages the CPU time slices and allocates a time for each process.
The Os controls the creation and the management of file properties.
The path of a file or where is has been stored and how it can be accessed is controlled by the Os
Also the Os manages the file structure - This means a file could contain many subfolders.
The Os controls the access rights for each user by using passwords and usernames.
Also the Os contains sofwares such as the firewall to prevent hacking.
Usually they ask you to state a use. So we usually don't need to explain it much.
It too is considered as a system sofware as it is a softwares which perfoms a specific system function such as the examples below:
These are Utiltiy softwares which are usually used to recovery accidental loss of data or to fully erase a disk.
Also there are applications which are called disk checkers or repairs. These scan the disk for any problems such as hardware or software bugs and identifies them and sometimes fixes them.
Usually over a long use of a hard disk, we may delete and add data. Sometimes these could lead to holes in the storage - meaning unused free spaces which are not able to be used directly
So the disk defragmentation software make sures that data is stored in the most efficient form without any spaces unnecessarily left out.
These softwares perfom automated backup at regular intervals and also perform daily incremental backups.
The most famous example is the Winrar software which compresses the file so it uses less storage.
This uses less storage space and thus can be easily copied or transmitted
Performs regular scans and checks for malwares and viruses on the system
Make sure the database of the Antivirus software is up to date.
Quarantines or deletes any detected malware
Subroutines is the general name for a function or a procedure.
So modules or subroutines are block of code which are able to perform a specific task.
Usually they are tested and can be used more than once in a computer code.
Program liabries are documents or files which contains a collection of modules or subroutines which a program can refer or call
These files are usually called dll (dynamic linked liabries).
So this make the code more reliable as these modules are already tested.
Also it reduces the size of the code as they are written once and called.
Makes it easier to build a program
All programs and websites are written using programming languages and script languages.
Revisezone is built using 3 Languages
HTML,CSS & JS - however html and css are not programming languages
There are two types of translators - interpreter and compilers
Programming languages are broken down to two types:
Usually the source code of a program is written by the programmer in high level language. This must be converted to a form which can be understood by the computer.
These are programming languages which are closely related to machine code.
Machine code is another word for binary code.
Compilers and Interpreters only translate high level languages and not assembly language.
The translator first translate the source code into a intermediate code and the code is compiled as a whole.
If there are errors present at the end of the process it will display an error diagnostics but it will not produce any final machine or compile code.
If no errors are detected the intermediate code is then converted to a machine executable code.
This compiled code is in binary and so it runs directly on the proccesor.
An executable code is produced which can be distributed. This is also more secure as the users will not receive the source code.
Doesn't require the translator software to run the compiled code
Executes very fast and directly on the processor
Compiled programs can have viruses
The compilation process is quite long and resourceful and also provides a compiled code after all the errors have been corrected
Higher chance of system crashing
This type of translator executes the code line by line and not the whole code at once
It produces an object or machine code for each line and executes it.
If an error is identified the execution stops and thus alerts the user to correct the error
Best for debugging and testing purposes as it produces an alert as soon as the error is found
The whole code doesn't have to be written as the code is translated line by line
The execution of the procces is very slow
The source code is seen by the user so it less secure
The translator is used everytime the program is executed
The main use of interpreters is for building a program
This topic will be covered in the practical section as it talk about the features which an IDLE editior
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