A SEQUENCE OF INFORMATION GIVEN TO A COMPUTER TO PERFORM A PARTICULAR TASK IS CALLED A PROGRAM , AND A SET OF PROGRAMS WRITTEN FOR A COMPUTER BY COMPUTER LANGUAGE IS CALLED A SOFTWARE .
THE TERM SOFTWARE REFERENCE TO A SOFT OF COMPUTER PROGRAM PROCEDURES AND ASSOCIATED DOCUMENTS DESCRIBING PROGRAMS AND HOW THEY ARE TO BE USED.
AND THE TEAM OF SOFTWARE PACKAGE IS A GROUP OF PROGRAMS THAT SOLVE A SPECIFIC PROBLEM OR PERFORM A SPECIFIC TYPE OF JOB .
TYPE OF SOFTWARE
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SOFTWARE CAN BE CATEGORIES INTO TWO TYPE
- SYSTEM SOFTWARE
- APPLICATION SOFTWARE
IN GENERAL A COMPUTER SYSTEM SOFTWARE PERFORMS ONE OR MORE OF FOLLOWING FUNCTION .
- SUPPORTS DEVELOPMENT OF OTHER APPLICATION SOFTWARE .
- SUPPORTS EXECUTION OF OTHER APPLICATION SOFTWARE .
- MONITOR EFFECTIVE USE OF VARIOUS HAND WARE RESOURCES ,SUCH AS CPU ,MEMORY, PERIPHERALS ETC.
- COMMUNICATION WITH AND CONTROLS OPERATION OF PERIPHERAL DEVICE ,SUCH AS PRINTER, SCANNER ETC.
- OPERATING SOFTWARE ( OPERATING SYSTEM) :- OPERATING SYSTEM SOFTWARE TAKE CARE OF EFFECTIVE AND EFFICIENT UTILIZATION OF ALL HARDWARE AND SOFTWARE COMPONENTS OF A COMPUTER SYSTEM.
- PROGRAMMING LANGUAGE TRANSLATOR:- PROGRAMMING LANGUAGE TRANSLATORS TRANSFORM THE INSTRUCTIONS PREPARED BY PROGRAMMED INTO A FORM THAT CAN BE INTERPRETED AND EXECUTED BY A COMPUTER SYSTEM .
- COMMUNICATION SOFTWARE :- COMMUNICATION SOFTWARE ENABLES TRANSFER DATA AND PROGRAMS FROM ONE COMPUTER TO AND THEIR COMPUTER SYSTEM.
- UTILITY SOFTWARE:- UTILITY SOFTWARE OR PROGRAMS ARE A SET OF PROGRAM THAT HELP THE USER IN SYSTEM MAINTENANCE
OPERATING SYSTEM IS AN INTERRED SET OF PROGRAM THAT CONTROLS THE RESOURCE OF A COMPUTER SYSTEM AND PROVIDES ITS USERS WITH INTERFERE OR VIRTUAL MACHINE THAT ARE EASIER TO USE.
AN OPERATING SYSTEM A COLLECTION OF PROGRAMS THAT CONTROLS THE OVERALL OPERATION IN A COMPUTER .
TWO PRIMARY OBJECTIVES OF AN OPERATING SYSTEMS ARE
- MAKE A COMPUTER SYSTEM EASIER TO USE.
- MANAGE THE RESOURCES OF A COMPUTER SYSTEM.
MOST OF THE OPERATING SYSTEM PERFORM THE FOLLOWING FUNCTION
- PROCESS MANAGEMENT
- MEMORY MANAGEMENT
- FILE MANAGEMENT
- DEVICE MANAGEMENT
- SECURITY
- COMMAND INTERPRETATION
SOME PROCESS MANAGEMENT TECHNIQUES ARE
- MULTIPROGRAMMING :- MULTIPROGRAMMING IS THE INTER LEVEL EXECUTION OF TWO OR MORE DIFFERENT AND INDEPENDENT PROGRAMS BY COMPUTER.
- MULTI TASKING :- MULTI TAKING IS A SINGLE USER VARIATION OF MULTIPROGRAMMING CONCEPT . MULTI TASKING MEANS CONCURRENT EXECUTION OF MULTIPLE JOB TASK /PROGRAMS IN A SINGLE USER SYSTEM . FOR EXAMPLE PERSONAL NOTE BOOK ,LAPTOP .
- MULTI PROCESSING :-MULTI PROCESSING IS THE USE OF TWO OR MORE CPU LINKED TOGETHER TO OPTIMIZE DATA PROCESSING. IN MULTI PROCESSING SYSTEM THE PROCESSORS MANY SIMULTANEOUSLY EXECUTE DIFFERENT INSTRUCTION FROM THE SOME PROGRAM.
- MULTI THREADING :- THREADING ARE A POPULAR TO IMPROVE APPLICATION PERFONMANCE .IN THOSE OPERATING SYSTEM THE BASIC INIT OF CPU UTILISATION IT THREADS , THE PROCESS CONSIST IN THOSE OPERATING SYSTEM OF ADDRESS SPACE AND ONE OR MORE THREAD OF CONTROL.EACH THREAD OF A PROCESS HAS OWN PROGRAM COUNTER , IT IS OWN REGISTER STATE AND IT IS OWN STRACK.
- TIME SHARING:- THE TIME SHARING IS THE ABILITY OF A COMPUTER TO BE USED BY MORE THAN ONE USER FOR MORE THAN ONE APPLICATION AT THE SOME TIME.
TIME SHARING IS A MECHANISM TO PROVIDE SIMULTANEOUS INTERACTIVE USE OF A COMPUTER SYSTEM BY MANY USERS IN SUCH A WAY THAT ALL USER FOR THAT HE/SHE IS THE SOLE USER OF THE SYSTEM.IT USE . MULTI PROGRAMMING WITH A SPECIAL CPU SCHEDULING ALGORITHM TO ACHIEVE THIS.
MEMORY MANAGEMENT:- THE MEMORY MANAGEMENT PLAYS AN IMPORTANT ROLE IN OPERATION SYSTEM. ITS JOB IS TO KEEP LINK OF FREE AND ACCUSED PART OF MEMORY. IT ALSO ALLOCATED MEMORY TO PROCESS.WHEN THEY NEED IT AND DEALLOCATES WHEN THEY NO MORE NEED.
SOME DIFFERENT MEMORY MANAGEMENT SYSTEM ONE MODULE GIVEN BELOW .
- UNIPROGRAMMING MEMORY OR SINGLE CONTIGUOUS ALLOCATION.
- MULTIPROGRAMMING MEMORY MODEL OR PARTITIONED ALLOCATION.
B) MULTIPROGRAMMING WITH VARIABLE NUMBER OF MEMORY PARTITIONS.
FILE MANAGEMENT:- A FILE IS A CALLCETION OF RELATED INFORMATION.EVERY FILE HAS A NAME , ITS DATE AND ATTRIBUTES, FILE MANAGEMENT MODEL OF AN OPERATING SYSTEM TAKE CARE OF FILE RELATIVE ACTIVITIES ,SUCH AS STRUCTURING ACCESSING ,NAMI NA SHARING AND PROTECTION OF FILES.
SOME FILE MANAGEMENT SYSTEM METHOD ARE :-
1. FILE ACCESS METHODS.
a) SEQUENTIAL ACCESS FILES.
b) RANDOM ACCESS FILES.
SEQUENTIAL FILE :- A FILE IN WHICH RECORDS AND STORED ONE AFTER ANOTHER IN AN ASCENDING OR DESCENDING ORDER DETERMINED BY THE VALUE OF THE KEY FIELD OF RECORDS.
RANDOM ACCESS FILE:- A FILE ORGANISATION IN WHICH A RECORD CAN BE DERECTLY LOCATED BY ITS KEY FILED VALUE WITHOUT HAVING TO SEARCH THROUGH A SEQUENCE OF OTHER RECORDS.
DEVICE MANAGEMENT:- PERIPHERALS AND ALL THE DEVICE MANAGEMENT MODULE OF AN OPERATING SYSTEM TAKES CARE OF CONTROLLING ALL I/O USER DEVICE OF A COMPUTER SYSTEM AND PROVIDE A SIMPLE AND EASY TO USE INTERFACE TO THESE DEVICES.
COMPUTER USERS DEVICE CONTROLLER TO CONTROL EASY I/O AND OTHER PERIPHERAL DEVICE OF THE SYSTEM.
DEVICE CONTROLLER TAKES CARE OF THE DATA TRANSFER BY THE FOLLOWING TWO METHODS
1 ) NON DMA TRANSFER
2) DMA TRANSFER
SECURITY :- COMPUTER SECURITY DEALS WITH PROTECTING VARIOUS RESOURCES AND INFORMATION OF A COMPUTER SYSTEM AGAINST DESTINATION AND UNAUTHORIZED ACCESS .IT INVOLVES BOTH EXTERNAL AND INTERNAL SECURITY.
EXTERNAL SECURITY MEANS FIRES FLOODS .AS LIKE EARTHQUAKE STOLEN DESK, BACK COPIES ETC.
INTERNAL SECURITY
1) USER AUTHENTICATION
2) ACCESS CONTROL
COMMAND INTERPRETATION:- COMMAND INTERPRETATION MODULE KNOWN COMMAND INTERPRETERS OF AN OPERATING SYSTEM PROVIDES A SET OF COMMANDS WHICH USERS USE TO GIVE INSTRUCTION TO A COMPUTER FOR EXECUTION OF THEIR JOB.
TWO DIFFERENT COMMEND INTERPRETER ARE 1) COMMAND LINE INTERFACE 2 ) GRAPHICAL USER INTERFACE.
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