Computer System Structures

1. I/O Structure

1.1. Synchronous I/0 Structure

1.1.1. After I/O starts,control returns to user program only upon I/O completion

1.1.2. At most one I/O request is outstanding at a time,no simultaneous I/O processing

1.1.2.1. After I/O starts,control returns to user program without waiting for I/O completion

1.2. Asynchronous I/O Structure

2. Interrupt Handling

2.1. The fixed location contains the starting address of the interrupt service routine

3. Memory Protection

3.1. Memory outside the defined range is protected

4. Modes of Operation

4.1. User Mode

4.2. Kernel Mode

4.2.1. Monitor Mode

4.2.2. Privileged Mode

4.2.3. System Mode

5. Storage Structure

5.1. Main memory(volatile storage)

5.2. Secondary storage(non-volatile storage)

6. CPU Protection

6.1. Load-timer is a privileged instruction

7. Computer-System Operation

7.1. Each device controller is in charge of a specific type of device

7.2. The occurrence of an event from either the hardware or software

8. Dual-Mode Operation

8.1. Mode bit is added to computer hardware to indicate the current mode : kernel(0) or user(1)

9. I/O Protection

9.1. All I/O instructions are privileged instructions

10. Hardware Address Protection

10.1. The load instructions for the base and limit registers are privileged instructions