09 — How Computers and Systems Work Free Online FlashCards

What makes a computer a system?

A computer is a system of cooperating components that represents information, executes instructions, stores data, and communicates with other systems.

How do RAM and persistent storage differ?

Main memory holds programs and data currently in use, while persistent storage retains them when power is removed.

What are the main stages of the processor cycle?

The processor fetches an instruction, decodes it, executes it, and retires or writes back the result while updating processor state.

What does the program counter store?

The program counter holds the address of the next instruction to be executed.

What does an instruction set architecture define?

An instruction set architecture defines the programmer-visible instructions, registers, data types, memory addressing, encodings, and exception behavior of a processor.

Why does locality of reference improve performance?

Locality of reference is the tendency of programs to reuse nearby data or instructions, allowing caches to serve later requests quickly.

What triggers a page fault?

A page fault occurs when a referenced page is not currently available in the required physical-memory location, so the operating system must load or reconstruct it.

What does a file system organize?

A file system organizes persistent storage into files and directories and records names, contents, sizes, permissions, timestamps, and storage blocks.

What is the main role of an operating system?

The operating system manages hardware and provides applications with services for processor time, memory, files, devices, security, and communication.

What is a system call?

A system call is an application’s request for an operating-system service, such as opening a file, allocating memory, creating a process, or sending network data.

How does a process differ from a thread?

A process is a running program with resources such as a virtual address space and open files; a thread is a schedulable instruction sequence within a process.

What happens during a context switch?

A context switch saves one thread’s execution state and restores another’s, allowing a single core to alternate among threads.