Understanding System Programs: Categories and Functions

in this lecture we'll be studying about system programs in the previous lecture we studied about system calls and we saw

how system calls work now in this lecture we'll be seeing what are system programs and what are they used for

so an important aspect of a modern system is the collection of system programs so in order to understand what

the system programs are and in order to understand where the system program resides in our computer system hierarchy

let us look at the diagram of our computer system hierarchy that we discussed in the very first lecture of

this lecture series so as we see this is a diagram of our computer system hierarchy that we discussed in the very

first lecture of this lecture series so if we look at this we find that in the lowest level we have our computer

hardware which comprises of resources like the CPU memory and input/output devices and just on top of that we have

the operating system and on top of this operating system we have the system programs and on top of the system

programs we have our application programs like the word processors spreadsheets compilers text editors web

browsers and so on then we have the users here who are interacting with the system's so what we are going to discuss

today is about this system programs so we see that system programs are just above the operating system now we will

see what are the system programs and what are they useful and we'll also see some examples of system programs and we

will also study how we can categorize our system programs into different categories based on the kind of task

that they perform so system programs they provide a convenient environment for program development and execution so

the system programs what they do is they are going to provide you with a particular environment which is

convenient for program development and execution so you will understand this when we take the examples and some of

them are simple user interface to system calls while others are considerably more complex now we will see how we can

categorize these system programs into different categories based on the kind of task that they were

so system programs can be divided into the following categories so we will see the categories one by one the first one

being file management so the system programs that helps in managing your files they fall under the category of

file management system programs for example they helps to create files delete files copy files rename print or

dump files or list files and in generally we can say that they help in manipulating files and directories so

the system programs that help in manipulating files and directories they fall under the category of file

management system programs all right now let's see what is the next one so the next one is status information so the

system programs that fall under this category are those system programs that ask the system for its status

information like for example it can ask the system for the system's date and time it can ask for the amount of

available memory or disk spaces and it can also ask for the number of users and also it can ask for other detail

performance and also other complex informations like logging and debugging informations etc so all the system

programs that are dealing with the status information of your system they fall under this category of status

information system programs and then the next one is file modification so these are the system programs that helps in

modifying your files so you may be thinking what is the difference between file management and file modification

because we have just discussed the file management in the first point now file management they deal with the outer

layer of your file that means like creating your files deleting your files renaming copying moving and so on but

file modification it deals with modifying the inner content of your file alright so if you want to modify the

inner content of your file for that you use the system programs which fall under the category of file modification so we

have several text editors which may be available to create and modify the contents of files stored on disk or

other storage devices and there may also be special commands to search contents of files or perform transformations of

the text so we see that if you want to modify the contents of your file like modifying or transforming the text or

anything like that for that we have the system programs which fall under this category of file modification which

helps us to accomplish this task now coming to the next one the next one is programming language

support so these are the system programs that provide you with programming language support so there are different

programming languages like C C++ Java Visual Basic Perl and so on now your system may have to compile and run

programs that are written in this kind of different languages so your system must have support for these programming

languages otherwise it will not be able to compile or run this kind of programs so in order to give you support for

these programming languages there are system programs that helps in providing you with this programming language

support so there are things like compilers assemblers debuggers and interpreters for common programming

languages such as this which are often provided to the user with the operating system so these things are provided

usually with the operating system so that your system will be able to compile the codes that are written in these

languages so that your system works flawlessly even if it have to compile some source code related to some

programming languages so the programs which gives you the support for these programming languages they fall under

this category of programming language support system programs now the next one is program loading and execution so in

the previous point we saw that our programs were compiled and assembled using those system programs which fall

under the programming language support category now after your program is compiled it has to be loaded and

executed so in order to do that there are some system programs that allows you or helps you

do that so those are the system programs that fall under this category of program loading and execution so it says once

the program is assembled or compiled it must be loaded into memory and executed so once your compilation and assembly is

complete you need to load that program to the memory so that it can be executed so the system may provide you different

kind of loaders in order to accomplish this task like the absolute loaders relocatable orders linkage editors and

overlay loaders and also sometimes debugging system for higher level languages or machine languages are

needed as well so debugging means whenever there is a problem in your code or in anything you need to find out what

is the problem and you need to solve that problem so that is what we mean by debugging and the program's responsible

for this task is known as debuggers so debuggers also may be necessary so all these programs that helps in loading the

programs and executing the programs they fall under this category of program loading and execution system program now

coming to the last one we have communications so these are the system programs that helps in communications so

even when we discuss our system calls we had the system calls that helped in communications so in the same way the

system programs that helps in communication between processes or users or allows users to surf the web and so

on these system programs they fall under this category of communications so these programs they provide the mechanism for

creating virtual connections among processes users and computer systems and they also allow users to send messages

to one another screens to browse webpages just an electronic mail messages that is your email and to log

in remotely or to transfer files from one machine to another so we see that all the tasks that are related to

communications there are the things that we are talking about here so the system programs that help you in this

communication processes they are the ones that fall under this category of communications

programs so these are the main catagories unto which you can divide your system programs based on the kind

of tasks that you perform now apart from the system programs there are also other programs that are provided by the

operating system in order to perform certain tasks so as I told you in addition to system programs most

operating systems are supplied with programs that are useful in solving common problems or performing common

operations so some examples of those are like your web browsers you have web browsers like Mozilla Firefox Google

Chrome and all which helps you to browse the web so these web browsers may be provided with your operating system I'm

not saying that specifically Mozilla Firefox and Google Chrome will be provided with your operating system but

based on the operating system that you are using one or more of the web browsers may be provided along with it

like for example in your Windows operating system you have your Internet Explorer that is provided with your

Windows operating system so that you can browse your web using that browser so in the same way there are word processors

so depending again depending on the kind of operating system that you use and kind of the office tools that is

installed in your system you may have the word processors installed in your system which is used for processing your

word documents like for example in Windows you have your Microsoft Word and if you are using Linux and if you are

having Libre Office installed in it you have your libera office writer which is the word processing software or

application in libre office and then you have spreadsheet programs like your Microsoft Excel in your windows and in

libreoffice in Linux you may have the LibreOffice calc see ALC so those are spreadsheet

programs and then you may have database systems so you can have database systems that helps in managing your databases so

they also can be of different types like you have Oracle database MySQL database and so on and then you may have games

for your entertainment purposes exit so these are some other programs that are provided along with the operating

system for the users to perform certain tasks so keep in mind that these are not system programs but they are application

programs so once again I repeat these are not system programs but these are application programs which are provided

along with the operating system for the users to perform certain tasks all right so let us just have a quick recap of the

system programs which was the main focus of this lecture so what were the categories of system programs that we

discussed so the categories of system programs are we discussed in this lecture our file management status

information file modification programming language support program loading and execution and communications

so these are the categories into which we can divide our system programs so I hope this lecture was played to you

thank you for watching and see you in the next one [Music]

[Applause] [Music]