Operating Systems

1. Resource management

2. extension/abstraction

1. Batch processing

   1. serial batch processing

   2. multiprogrammed batch processing

2. interactive systems

   1. main frames

   2. nondistributed systems

   3. distributed systems

3. virtual systems

   1. run time environment

   2. virtual machine

   3. hypervisor

1. processes

2. memory managment

3. managment of I/O devices

4. file system

5. (security, user and rights managment)

-Executed right after computer start

-resight at a fixed adress

-main purpose = fetch OS and prepare computer to execute OS

Is a program being executed.

Program = file

1. Program

2. new

3. ready

4. running

5. blocked

6. terminated

Cooperativ:

-Processes transfer contoll to OS voluntarily

Preemptive:

-timer is used to transfer controll

-Chaining

-old process ends, new process starts

-Forking

-old process copies itself, both run afterwards

-Creation

-old process creates new, independant process

-Merging

-process waits for subordinant process to end

-Rendezvous

-process waits for any process to end

1. privilege levels (OS mode, user mode)

2. interrupts

3. times

Systemcall = process (user mode) needs OS functionality (switch between user and OS mode)

Exception = hardware detects something unusual (caused by the process) switches to OS mode

Interrupt = hardware detects something unusual (not caused by the process) switches to OS mode

1. message based

2. memory based

1. data delimitation

2. syncronicity

3. connection orientation

4. receiver adressing

Direct Memory Access