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CHAPTER 1 by Mind Map: CHAPTER 1

1. WHAT IS OPERATING SYSTEM?

1.1. A PROGRAM THAT ACTS AS AN INTERMEDIARY BETWEEN A USER OF COMPUTER AND COMPUTER HARDWARE.

1.2. GOALS

1.2.1. EXECUTE USER PROGRAMS AND MAKE SOLVING USER PROBLEMS EASIER

1.2.2. MAKE THE COMPUTER SYSTEM CONVENIENT TO USE

1.2.3. USE THE COMPUTER HARDWARE IN AN EFFICIENT MANNER

1.3. OS FUNCTIONS

1.3.1. RESOURCE ALLOCATOR

1.3.1.1. MANAGE ALL RESOURCES

1.3.1.2. DECIDES BETWEEN CONFLICTING REQUESTS FOR EFFICIENT AND FAIR RESOURCE USE.

1.3.2. CONTROL PROGRAM

1.3.2.1. CONTROLS EXECUTION OF PROGRAMS TO PREVENT ERRORS AND IMPROPER USE OF THE COMPUTER.

2. COMPUTER SYSTEM

2.1. HARDWARE

2.1.1. PROVIDES BASIC COMPUTING RESOURCES

2.2. OPERATING SYSTEM

2.2.1. CONTROLS AND COORDINATES USE OF HARDWARE AMONG VARIOUS APPLICATIONS AND USERS

2.3. APPLICATION PROGRAMS

2.3.1. WORD PROCESSORS, COMPILERS, WEB BROWSERS, DATABASE SYSTEM, VIDEO GAMES

2.4. USERS

2.4.1. PEOPLE, MACHINES, OTHER COMPUTERS

2.4.2. PEOPLE, MACHINES, OTHER COMPUTERS

3. KERNEL IS THE ONE PROGRAM RUNNING AT ALL TIMES ON THE COMPUTER.

4. INTERRUPT

4.1. DEVICE CONTROLLER INFORMS CPU THAT IT HAS FINISHED ITS OPERATION.

4.2. TWO TYPES OF INTERRUPT

4.2.1. POLLING

4.2.1.1. NOTIFIES THE PART OF THE COMPUTER CONTAINING THE I/O INTERFACE THAT A DEVICE IS READY TO BE READ OR OTHERWISE HANDLED BIT DOES NOR INDICATE WHICH DEVICES.

4.2.2. VECTORED

4.2.2.1. TELLS THE PART OF THE COMPUTER THAT HANDLES I/O INTERRUPT IS AN I/O INTERRUPTS AT THE HARDWARE LEVEL THAT A REQUEST FOR ATTENTION FROM AN I/O DEVICE HAS BEEN RECEIVED AND ALSO IDENTIFIES THE DEVICE THAT SENT THE REQUEST.

4.3. OS IS INTERRUPT DRIVEN

4.3.1. HARDWARE

4.3.1.1. INTERRUPT BY ONE OF THE DEVICE

4.3.2. SOFTWARE

4.3.2.1. DIVISION BY ZERO

4.3.2.2. REQUEST FOR OPERATING SERVICE

4.3.2.3. INFINITE LOOP

4.3.2.3.1. HOW TO PREVENT IT?

5. I/O STRUCTURE

5.1. SYSTEM CALL

5.1.1. REQUEST TO THE OS TO ALLOW USER TO WAIT FOR I/O COMPLETION

5.2. DEVICE-STATUS TABLE

5.2.1. CONTAINS ENTRY TO DETERMINE DEVICE STATUS AND TO MODIFY TABLE ENTRY TO INCLUDE INTERRUPT.

6. STORAGE STRUCTURE

6.1. MAIN MEMORY

6.1.1. ONLY LARGE STORAGE MEDIA THAT THE CPU CAN ACCESS DIRECTLY

6.1.2. RANDOM ACCESS

6.1.3. TYPICALLY VOLATILE

6.2. SECONDARY STORAGE

6.2.1. EXTENSION OF MAIN MEMORY THAT PROVIDES

6.3. HARD DISKS

6.3.1. RIGID METAL OR GLASS PLATTERS COVERED WITH MAGNETIC RECORDING MATERIALS

6.4. SOLID STATE DISKS

6.4.1. FASTER THAT HARD DISKS, NONVOLATILE

7. CACHING - COPYING INFORMATION INTO FASTER STORAGE SYSTEM; MAIN MEMORY CAN BE VIEWED AS A CACHE FOR SECONDARY STORAGE

8. DEVICE DRIVER - PROVIDES UNIFORM INTERFACE BETWEEN CONTROLLER AND KERNEL

9. DIRECT MEMORY ACCESS STRUCTURE

9.1. USED FOR HIGH SPEED I/O DEVICES ABLE TO TRANSMIT INFORMATION AT CLOSE TO MEMORY SPEEDS.

9.2. DEVICE CONTROLLER TRANSFERS BLOCKS OF DATA FROM BUFFER STORAGE DIRECTLY TO MAIN MEMORY WITHOUT CPU INTERVENTION

10. COMPUTER SYSTEM ARCHICTECTURE

10.1. MOST SYSTEM USE A SINGLE GENERAL PURPOSE PROCESSOR

10.2. MULTIPROCESSORS

10.2.1. ALSO KNOWN AS PARALLEL SYSTEM, TIGHTLY COUPLED SYSTEM

10.2.2. ADVANTAGES

10.2.2.1. INCREASED THROUGHTPUT

10.2.2.2. ECONOMY OF SCALE

10.2.2.3. INCREASED RELIABILITY

10.2.3. ASYMMETRIC

10.2.3.1. EACH PROCESSOR IS ASSIGNED A SPECIFIC TASK

10.2.4. SYMMETRIC

10.2.4.1. EACH PROCESSOR PERFORM ALL THE TASKS

11. OPERATING SYSTEM STRUCTURE

11.1. MULTIPROGRAMMING (BATCH SYSTEM)

11.1.1. JOB SCHEDULING

11.2. TIMESHARING (MULTITASKING)

12. USER MODE AND KERNEL MODE

13. PROCESS MANAGEMENT ACTIVITIES

13.1. CREATING AND DELETING BOTH USER AND SYSTEM PROCESSES

13.2. SUSPENDING AND RESUMING PROCESSES

13.3. PROVIDING MECHANISMS FOR PROCESS SYNCHRONIZATION

13.4. PROVIDING MECHANISM FOR PROCESS COMMUNICATION

13.5. PROVIDING MECHANISMS FOR DEADLOCK HANDLING

14. MEMORY MANAGEMENT

14.1. KEEPING TRACK OF WHICH PARTS OF MEMORY ARE CURRENTLY BEING USED AND BY WHOM

14.2. DECIDING WHICH PROCESSES AND DATA TI MOVE INTO AND OUT OF MEMORY

14.3. ALLOCATING AND DEALLOCATING MEMORY SPACE AS NEEDED

15. STORAGE MANAGEMENT

15.1. FILE SYSTEM MANAGEMENT

15.1.1. FILES USUALLY ORGANIZED INTO DIRECTORIES

15.1.2. ACCESS CONTROL ON MOST SYSTEMS TO DETERMINE WHO CAN ACCESS WHAT

15.1.3. OS ACTIVITES

15.1.3.1. CREATING AND DELETING FILES AND DIRECTORIES

15.1.3.2. PRIMITIVES TO MANIPULATE FILES AND DIRECTORIES

15.1.3.3. MAPPING FILES ONTO SECONDARY STORAGE

15.1.3.4. BACKUP FILES ONTO STABLE STORAGE MEDIA

16. PROTECTION - ANY MECHANISM FOR CONTROLLING ACCESS OF PROCESSES OR USERS TO RESOURCES DEFINED BY THE OS

17. SECURITY - DEFENSE AGAINST SYSTEM AGAINST INTERNAL AND EXTERNAL THREATS