1. 1 Pertemuan 3 Konsep Sistem Operasi Matakuliah: T0316/sistem Operasi Tahun: 2005 Versi/Revisi: 5

2. 2 Learning Outcomes Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu : menjelaskan istilah dan konsep sistem operasi (C2)

3. 3 Outline Materi Konsep –Processes –Deadlock –Memory management –I/O –File –Shell –System call Struktur –Monolithic –Layered –Virtual machine –Exokernels –Client-Server

4. 4 Process  Program in execution  Consist of: o Executable program, data, stack o Program counter, stack pointer, registers  Process table  array or linked list of structure of the process in execution  Process has: o Address space (core image) o Attribute/information in the process table  OPERATING SYSTEM CONCEPT

5. 5  A process tree:

6. 6  Condition in which interacting process cannot be continued and there is no process that can get out of that condition. Deadlock (a) A potential deadlock. (b) an actual deadlock.

7. 7 Input/Output  Independent I/O software  Device dependent, eg. device drivers Memory Management  Multiple program dalam memory  needs: o Protection o Address space management

8. 8  Files  Directory  Pathname  Protection mode  rwx bits  File descriptor

9. 9  Mounted file system Before mountingAfter mounting  Special file o Block o Character  Pipe

10. 10  Shell  Unix command interpreter  Prompt Example: date date > file sort file2 cat file1 file2 file3 | sort > /dev/lp cat file1 file2 file3 | sort > /dev/lp &  Security  Protection, eg. rwx bits  Intruders, from human or non-human (eg. virus)  Background job

11. 11 SYSTEM CALLS Interface between user program and operating system Steps in Making a System Call

12. 12  Example of system calls: o Process Management

13. 13 o File Management o Directory and file system management

14. 14 o Miscellaneous

15. 15 Monolithic system  The big mess  No structure  OPERATING SYSTEM STRUCTURE Simple structuring model

16. 16 Generalisation of layering concept at MULTICS  concentric ring Layered System  Hierarchical layer, each layer is built on top of the layer below it.  Eg: THE system

17. 17 Virtual Machine  Virtual machine monitor  not an extended machine, but an exact copy of the bare hardware  CMS (Conversational Monitor System)  JVM (Java Virtual Machine) Structure of VM/370 with CMS

18. 18 Exokernels  Designed for a system that gives each user clone of the actual computer, but with a subset of resources  Program run on the bottom layer to allocate resources to virtual machine

19. 19 Client-server model  Mikrokernel  Client process  Server process  Mechanism vs policy The client-server model

20. 20 Advantages of distributed system model:  Smaller parts are easier to maintain  No direct access toward hardware  Adaptability The client-server model in a distributed system