Computer system structures

1. storage structure

1.1. main mamory

1.2. secondary storage

1.3. storage hierachy

1.3.1. speed

1.3.2. cost

1.3.3. volatility

1.4. caching

2. dual-mode operation

2.1. user mode (1)

2.1.1. user program

2.1.2. certain area protected

2.1.3. certain instruction may not be executed

2.2. kernel mode (0)

2.2.1. monitor

2.2.2. protected area can be accessed

2.2.3. priviliged instruction

3. i/o protection

3.1. i/o instruction are privileged instruction

3.2. ensure user program never gain control in monitor mode

4. memory protection

4.1. base register

4.2. limit register

5. interrupt handling

5.1. 1) device controller causing interupt

5.2. 2) CPU transfer execution to interrupt vector table

5.3. 3) interrupt vector provide address of ISR for interrupting device

5.4. 4) OS preserves the state of CPU

5.5. 5) interrupted computation resumes after inerupt serviced

6. synchronous i/o

6.1. only 1 i/o can run at the same time

7. asynchronous i/o structure

7.1. control returns to user program without waiting i/o completion

7.2. system call

8. CPU protection

8.1. timer