29-09-2012, 12:53 PM
INTRODUCTION TO OPERATING SYSTEM
operating_systems.ppt (Size: 401 KB / Downloads: 26)
DEFINITION
AN OPERATING SYSTEM IS AN INTEGRATED SET OF PROGRAM THAT IS USED TO MANAGE THE VARIOUS RESOURCES AND OVERALL OPERATION OF A COMPUTER SYSTEM.
A COMPUTER SYSTEM CAN BE DIVIDED ROUGHLY INTO FOUR COMPONENTS: THE HARDWARE, THE OPERATING SYSTEM, THE APPLICATION PROGRAMS AND THE USERS.
HARDWARE: PROVIDES THE BASIC COMPUTING RESOURCES.
APPLICATION PROGRAM: DEFINE THE WAY IN WHICH THESE RESOURCES ARE USED TO SOLVE THE COMPUTING PROBLEMS OF THE USERS.
OPERATING SYSTEM: IT CONTROLS AND CO-ORDINATES THE USE OF THE HARDWARE AMONG THE VARIOUS APPLICATION PROGRAMS FOR THE VARIOUS USERS.
BATCH SYSTEMS
BATCH PROCESSING IS ALSO KNOWN AS A SERIAL, SEQUENCIAL, OFF LINE OR STACKED JOB PROCESSING.
USER PREPARES HIS PROGRAM AND LEAVE THEIR PROGRAMS WITH THE OPERATOR.
THE OPERATOR WOULD SORT PROGRAMS INTO BATCHES WITH SIMILAR REQUIREMENTS AND RUN EACH BATCH.THE OUTPUT FROM EACH JOB IS SEND BACK TO THE PROGRAMMER.
MULTIPROGRAMMING SYSTEM
MULTIPROGRAMMING SYSTEMS KEEP SEVERAL JOBS IN MEMORY SIMULTANEOUSLY.
THE OPERATING SYSTEM PICKS AND BEGINS TO EXECUTE ONE OF THE JOBS IN MEMORY.
WHEN THAT JOB NEEDS TO WAIT, THE CPU IS SWITCHED TO ANOTHER JOB. EVENTUALLY, THE FIRST JOB FINISHES WAITING AND GETS THE CPU BACK.
ADVANTAGE AND LIMITATIONS OF MULTIPROGRAMMINGSYSTEM:
MULTIPROGRAMMING INCREASES CPU UTILIZATION BY ORGANISING JOBS SO THAT THE CPU ALWAYS HAS ONE TO EXECUTE.
THIS SYSTEM REQUIRES LARGE MEMORY TO WORK SATISFACTORILY, TOGETHER WITH FAST SECONDARY STORAGE DEVICES LIKE DISK AND FAST CPU.
IT REQUIRES PROGRAM STATUS PRESERVATION.