Operating System Concepts - Boot Process

Computer System Organization

• A computer system consists of one or more CPUs, device controllers, and shared memory, connected through a common bus.
• Concurrent execution of CPUs and devices competing for memory cycles.

Interrupt Handling

• Interrupts transfer control to the interrupt service routine through the interrupt vector.
• The operating system preserves the state of the CPU by storing registers and the program counter.
• Interrupt handling involves determining the type of interrupt, and taking separate actions for each type.

I/O Structure

• I/O operations can be synchronous or asynchronous.
• In synchronous I/O, the CPU waits for I/O completion before returning to the user program.
• In asynchronous I/O, the CPU continues executing other tasks while waiting for I/O completion.

Storage Hierarchy

• The storage hierarchy consists of main memory, secondary storage, and tertiary storage.
• Caching is a technique that copies information from slower storage to faster storage, temporarily.

Process Management

• A process is a program in execution, and it requires resources to accomplish its task.
• Process management involves creating, deleting, suspending, and resuming processes.
• Process management also involves providing mechanisms for process synchronization, communication, and deadlock handling.

Memory Management

• Memory management involves keeping track of which parts of memory are currently being used and by whom.
• Memory management also involves deciding which processes and data to move into and out of memory.

Storage Management

• Storage management involves providing a uniform, logical view of information storage.
• Storage management involves organizing files into directories, and providing access control mechanisms.

Mass-Storage Management

• Mass-storage management involves managing disk storage, including free-space management, storage allocation, and disk scheduling.

I/O Subsystem

• The I/O subsystem is responsible for managing I/O operations, including buffering, caching, and spooling.
• The I/O subsystem also provides a general device-driver interface, and drivers for specific hardware devices.

Protection and Security

• Protection involves controlling access to resources defined by the operating system.
• Security involves defending the system against internal and external attacks.

Computing Environments

• Traditional computing environments have evolved into client-server computing, and distributed systems.
• Clustered systems are multiple systems working together, providing high-availability services.

Operating System Structure

• Multiprogramming is needed for efficiency, and it involves organizing jobs to keep the CPU and I/O devices busy.
• Timesharing is a logical extension of multiprogramming, where the CPU switches jobs so frequently that users can interact with each job.

Operating-System Operations

• The operating system is interrupt-driven, and it responds to hardware interrupts, software errors, and requests.
• The operating system operates in dual-mode, with a mode bit provided by hardware, to distinguish between user code and kernel code.