22-01-2013, 02:30 PM
Operating Systems (For EDUSAT)
Operating Systems.ppt (Size: 116 KB / Downloads: 343)
Application Software
Spreadsheets: The spreadsheet packages are designed to use numbers and formulas to do calculations with ease. Examples of spreadsheets include:
Budgets
Payrolls
Grade Calculations
Address Lists
The most commonly used spreadsheet programs are Microsoft Excel and Lotus 123.
Graphic Presentations:
The presentation programs can be easier using overhead projectors. Other uses include:
Slide Shows
Repeating Computer Presentations on a computer monitor
Using Sound and animation in slide shows
The most recognized graphic presentation programs are Microsoft PowerPoint and Harvard Graphics.
Database Management System (DBMS):
A DBMS is a software tool that allows multiple users to store, access, and process data into useful information.
Database programs are designed for these types of applications:
Membership lists
Student lists
Grade reports
Instructor schedules
All of these have to be maintained so you can find what you need quickly and accurately.
Example:Microsoft Access, dBASE, Oracle.
What is OS?
Operating System is a software, which makes a computer to actually work.
It is the software the enables all the programs we use.
The OS organizes and controls the hardware.
OS acts as an interface between the application programs and the machine hardware.
Examples: Windows, Linux, Unix and Mac OS, etc.,
Evolution of OS:
The evolution of operating systems went through seven major phases.
Six of them significantly changed the ways in which users accessed computers through the open shop, batch processing, multiprogramming, timesharing, personal computing, and distributed systems.
In the seventh phase the foundations of concurrent programming were developed and demonstrated in model operating systems.
Batch Processing:
In Batch processing same type of jobs batch (BATCH- a set of jobs with similar needs) together and execute at a time.
The OS was simple, its major task was to transfer control from one job to the next.
The job was submitted to the computer operator in form of punch cards. At some later time the output appeared.
The OS was always resident in memory. (Ref. Fig. next slide)
Common Input devices were card readers and tape drives.
Multiprogramming:
Multiprogramming is a technique to execute number of programs simultaneously by a single processor.
In Multiprogramming, number of processes reside in main memory at a time.
The OS picks and begins to executes one of the jobs in the main memory.
If any I/O wait happened in a process, then CPU switches from that job to another job.
Hence CPU in not idle at any time.
Time Sharing Systems:
Time sharing, or multitasking, is a logical extension of multiprogramming.
Multiple jobs are executed by switching the CPU between them.
In this, the CPU time is shared by different processes, so it is called as “Time sharing Systems”.
Time slice is defined by the OS, for sharing CPU time between processes.
Examples: Multics, Unix, etc.,
Single User Systems:
Provides a platform for only one user at a time.
They are popularly associated with Desk Top operating system which run on standalone systems where no user accounts are required.
Example: DOS