Operating Systems

Operating System (OS)

System software that manages computer hardware and software resources, providing service/platform for programs.

Process

A running program that the OS manages, including ways to create, run, terminate, and suspend.

Virtualization

The act of giving each process the illusion that it has exclusive access to the computer's resources.

Latency

The time it takes between a request being sent and the first data received in response.

Context Switching

The process of saving the state of a running process and restoring the state of another process.

Kernel Mode

A mode where the CPU can access and modify memory locations containing OS code or data.

Direct Execution

A technique where a process is executed directly on the CPU without intermediate interpretation.

System Call

A user process that calls a function related to the operating system.

Cooperative Scheduling

A method of process scheduling where the OS relies on processes to voluntarily yield control of the CPU.

Non-Cooperative Scheduling

A method of process scheduling where the OS actively preempts running processes to ensure CPU time distribution.

File System

Responsible for how the OS interacts with storage devices, enabling file management and access.

Memory Virtualization

An abstraction that presents each process with its own virtual address space to run independently.

Paging

Divides memory into fixed-size blocks: pages (virtual) and page frames (physical) to manage memory allocation.

Address Translation

The process of converting virtual addresses used by programs to physical addresses used by RAM.

Page Faults

Occur when a process tries to access a page not currently in physical memory, prompting the OS to load it from disk.

Directory File

Contains file descriptors for each file within it, enabling organized data storage.

Inodes

Metadata structures for each file, containing pointers to data blocks and file attributes.

Master Boot Record (MBR)

Contains system boot code and partition information for disk organization.

Multilevel Pointers

File allocation technique that allows efficient point access for data blocks, including direct and indirect pointers.

Turnaround Time

The difference between completion and arrival time; smaller values indicate better efficiency.

Shortest Time to Completion First

A CPU scheduling algorithm that prioritizes jobs with the shortest required CPU time.