Operating System Concepts: Multiprogramming, Dual-Mode Operation, and Process Management

Vocabulary flashcards covering core operating systems topics including CPU scheduling, dual-mode operation, timers, memory management, and process management.

Fast switching

The mechanism where the CPU switches between tasks so quickly that users feel everything happens at the same time.

Interactive computing

A computing setup in which users can interact with running programs in real time.

Response time

The time required for the system to react in an interactive system, which should be $< 1\,\text{second}$.

CPU scheduling

Deciding which ready process runs next when multiple processes are ready.

Swapping

The technique of moving processes in and out to disk if they do not fit in physical memory.

Virtual memory

A feature that allows the execution of processes that are not completely loaded into physical memory.

Dual-mode operation

An architecture feature that protects the operating system and other programs from bad or wrong code by providing separate execution modes.

User mode

The mode of execution where normal user programs (like apps or browsers) run with limited access.

Kernel mode

The mode of execution where the core OS runs with full access to everything in the system.

Mode bit

A special bit in hardware that indicates which execution mode (user or kernel) is currently active.

System call

An interface that switches the mode from user mode to kernel mode when an application needs hardware or operating system services.

Privileged instruction

Important hardware commands that can only be executed in kernel mode.

Timer

A hardware device used to prevent a program from running forever by interrupting the computer after a designated time period.

Process

A program in execution; an active entity running in memory that serves as a unit of work in the system.

Program

A passive entity, such as a file saved on disk, that is not currently running.

Process resources

The system components required by a process to perform its work, including CPU-time, memory, I/O devices, files, and data.