1. USER CENTRIC VIEW AND SYSTEM CENTRIC VIEW OF SYSTEM SOFTWARE
PREPARED BY :
S. G. RAVANI
ASST. PROFF.
SSASIT, SURAT

2. Views of System software

3. Views of System software
Figure shows typical uses of system software of computer system.
User1 uses language processor that helps her in developing and executing a program .
Each of these language processor interacts with only one user.
On the other hand User2 and User3 are using multiuser software which could be either system software or application software which deal with one or more user simultaneously.
OS arranges execution of language processor used by user1 and multiuser software used by user 2 and user3.
The view would be expanded horizontally if we show more users uses the programs

4. User Centric View of System software
This view includes system programs that provides user convenience by permitting a user to specify his/her computational needs in a manner of his/her choice and permitting her to use several programs together to implement a complex task.
Vertical slices of figure contains two kind of system software..language processor and operating system
language processor contributes to translating user’s need in to a program form that a computer system can understand and execute
A system program in OS setup execution of program and allocates resources such as memory and input-output devices to it.
Language processor takes different form depends on nature of computational activity of user.

5. User Centric View of System software
If activity aimed to developing a program that is to be used repeatedly , the language processor can be a compiler that translate a program written in high level language to a machine level program, an assembler that translates program written in low level language like assembly language in to machine language program.
Linker/loader helps in execution of machine language program or debugger helps in checking present bugs in the program.
If activity aimed at developing a program for small number of uses, the language processor can be interpreter of programming language that performs computation described in a program.
If user is interested in a single use of program, he/she may have coaded program in a scripting language so language processor would be interpreter for scripting the language.

6. User Centric View of System software
Situation would be different if user’s activity simply involves use of an application program.
The application program itself developed by language processor. However language processor would not appear in user centric view if the program was compiled and stored in library.
If the code of application program interpreted would appear in user centric view.

7. System Centric View of System software
This view includes system programs that provides effectiveness in the simultaneous servicing of many user’s computational needs by interleaving services of many programs and ensuring non interference.(efficient use of computer resources by sharing them among several programs)
This programs also provides facility for interleaving of user’s request in a multiuser software.
Thus we can say that system centric view of system software has system programs that achieve effective utilization of computer system.
This view spans horizontal dimension in figure.
The system programs in this view provides user convinience through, by allocating resources to programs and interleaving their execution so that all programs make good progress , by providing facility for short and long term storage of programs and data in files, scheduling of resources and resource partition.

8. System Centric View of System software
Sharing of resources among programs leads to need for ensuring non interference between programs. hence system centric view also has some program, that implements security and protections measures

9. Difference between user centric view and System Centric View of System software
SR. NO
USER CENTRIC VEW
SYSTEM CENTRIC VIEW 1
User centric of system software includes system programs the assists an user in fulfilling his/her computational needs
The system centric view of system programs achieve efficient utilization of computer system by resource sharing 2
Here user uses language processing kind software which are single user software
Serves multiple users simultaneously and ensuring non interference 3
Software programs in user centric system software are, language processor : compiler (in repeated use of same computation), interpreter(small use of same computation), linker, loader, debugger
System centric view system software programs : device drive, bus, boot, scheduler, memory allocator and de allocator, short term and long term storage for program and data in file, 4
In case of application software (implemented using compiler) is already compiled and stored in library would not appear in user centric view but if code of application program through interpreter would appear in user centric view.
Provides security and protection measure to ensure non interference