Operating System Concepts - 10th Edition

Computer System Organization

• A computer system consists of one or more CPUs and device controllers connected through a common bus, providing access to shared memory.
• Concurrent execution of CPUs and devices competes for memory cycles.
• I/O devices and the CPU can execute concurrently.

Interrupt Handling

• Interrupts transfer control to the interrupt service routine (ISR) through the interrupt vector.
• Interrupt architecture must save the address of the interrupted instruction.
• A trap or exception is a software-generated interrupt caused by a user request or error.

Interrupt Timeline

• The OS preserves the state of the CPU by storing registers and the program counter.
• The OS determines which type of interrupt has occurred and takes appropriate action.

I/O Structure

• After I/O starts, control returns to the user program either upon I/O completion or without waiting for I/O completion.
• A system call is a request to the OS to allow the user to wait for I/O completion.
• The device-status table contains entries for each I/O device, indicating its type, address, and state.

Storage Hierarchy

• Storage systems are organized in a hierarchy based on speed, cost, and volatility.
• The storage hierarchy includes main memory, secondary storage, and tertiary storage (e.g., optical storage, magnetic tape).

Caching

• Caching involves copying information from slower to faster storage systems temporarily.
• The cache is smaller than the storage being cached.

Direct Memory Access (DMA) Structure

• DMA is used for high-speed I/O devices that can transmit information at close to memory speeds.
• The device controller transfers blocks of data from buffer storage directly to main memory without CPU intervention.

Process Management

• Process management involves creating and deleting processes, suspending and resuming processes, and providing mechanisms for process synchronization and communication.
• A single-threaded process has one program counter specifying the location of the next instruction to execute.
• A multi-threaded process has one program counter per thread.

Memory Management

• Memory management determines what is in memory and when.
• Memory management activities include keeping track of memory usage, deciding which processes and data to move into and out of memory, and allocating and deallocating memory space.

File Management

• The OS provides a uniform, logical view of information storage.
• File management involves creating and deleting files and directories, and providing access control to determine who can access what.

Mass-Storage Management

• Mass-storage management involves managing free space, storage allocation, and disk scheduling.
• Tertiary storage includes optical storage, magnetic tape, and other slow, non-volatile storage media.

I/O Subsystem

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

Protection and Security

• Protection involves controlling access to resources defined by the OS.
• Security involves defending the system against internal and external attacks.
• User identities, group identifiers, and privilege escalation are used to control access to resources.

Computing Environments

• Traditional computing involves general-purpose machines connected to the Internet.
• Mobile computing involves handheld devices, tablets, and laptops with wireless networks.
• Networking is becoming ubiquitous, even in home systems.