Operating
Systems
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Notes for operating system, Study notes of Operating Systems
Introduction to operating system
Typology: Study notes
2016/2017
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Operating
Systems
Application Software
(contd…):
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.
Application Software
(contd…):
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.
Contents
(^) Today's Topic: Introduction to Operating Systems
(^) We will learnWe will learn
- What is Operating System?What is Operating System?
- What OS does?What OS does?
- Structure of OSStructure of OS
- Evolution of OSEvolution of OS (^) Batch Processing, Multiprogramming, Time sharingBatch Processing, Multiprogramming, Time sharing systems systems
- Operating System FunctionsOperating System Functions
- Main Funtions of OSMain Funtions of OS
- Types of OSTypes of OS (^) Single User, Multi User systemsSingle User, Multi User systems
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.,
What OS does?
An operating system performs basic tasks such as,
(^) controlling and allocating memory, (^) prioritizing system requests, (^) controlling input and output devices, (^) facilitating networking and (^) managing file systems.
Structure of Operating System
(Contd…):
(^) The structure of OS consists of 4 layers:
1. Hardware Hardware consists of CPU, Main memory, I/O Devices, etc, 2. Software (Operating System) Software includes process management routines, memory management routines, I/O control routines, file management routines.
(Contd…)
Structure of Operating System
(Contd…):
3. System programs This layer consists of compilers, Assemblers, linker etc. 4. Application programs This is dependent on users need. Ex. Railway reservation system, Bank database management etc.,
Evolution of OS (contd..):
Major
Phases
Technical
Innovations
Operating
Systems
Open Shop The idea of OS^ IBM 701 open shop (1954)
Batch Processing
Tape batching, First-in, first-out scheduling.
BKS system (1961)
Multi- programming
Processor multiplexing, Indivisible operations, Demand paging, Input/output spooling, Priority scheduling, Remote job entry
Atlas supervisor (1961), Exec II system (1966)
(Contd…)
Evolution of OS (contd..):
Timesharing Simultaneous user interaction,
On-line file systems
Multics file system (1965), Unix (1974)
Concurrent Programming
Hierarchical systems, Extensible kernels, Parallel programming concepts, Secure parallel languages
RC 4000 system (1969), 13 Venus system (1972), 14 Boss 2 system (1975).
Personal
Computing
Graphic user interfaces OS 6 (1972) Pilot system (1980)
Distributed Systems
Remote servers WFS file server (1979) Unix United RPC (1982) 24 Amoeba system (1990)
Batch Processing (Contd…):
(^) Common output devices were line printers, tape drives,
and card punches. (^) Users did not interact directly with the computer
systems, but he prepared a job (comprising of the program, the data, & some control information). OS
User program area
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.,
Operating Systems functions:
(^) The main functions of operating systems are:
- Program creation
- Program execution
- Input/Output operations
- Error detection
- Resource allocation
- Accounting
- protection