1. CSI 400/500 Operating Systems Spring 2009 Lecture #2 – Functional Parts of an Operating System Monday January 23, 2009

2. The Manager

3. Device Manager  Communicates with devices  Maintains drivers  Allocates ports  Passes data and signals between device and task  Discussed in detail in Lecture 14

4. Process Spooler  Schedules tasks  Allocates resources  Maintains process isolation while providing contact with system  Our next topic

5. Memory Manager  Allocation of resources across system  Separates memory  Translates virtual addresses  Discussed in Lectures 8 and 9

6. File Manager  Maintains links to external storage devices  Maintains internal files and maps  Handles data transfer between tasks and files  Discussed in Lectures 10 and 11

7. Interrupt Handler  Analyzes errors  Pauses action to prevent further problems  Fixes error or terminates action  Communicates with Process Manager  Discussed in Lecture 14

8. System Calls  Stored library of functions  Passes messages between functionary parts  Available system-wide  Some available to user-defined tasks

9. OS Concerns

10. Security Concerns  Within system  Between tasks and processes  From outside  Discussed at end of course

11. OS Components

12. Central Processing Unit  Called “ Processor ”  Performs calculations and operations  Two parts:  Arithmetic-logical unit  Control unit and program counter

13. Registers  Local to processor  Holds single value or address  Types:  Memory address register  Memory data register  Command register  Instruction register  Operation data registers

14. Instruction Stack  Held in local memory  Holds instructions and related operands  Sequential  One instruction at a time loaded into CPU for processing

15. Buses  Used to transfer info:  Between tasks  Between units  Between systems  High-speed  Dumb

16. Input/Output Controllers  Device drivers  Connected by ports, channels, or bus lines  Controls flow  DOES NOT handle data transfer  Handled by task  Managed by device

17. Interrupt Library  Catalog of interrupts  Available to all units  Common and categorized  Recognized by Interrupt handler