operativsystemsavbildningar

An operating system (OS) is system software that manages computer hardware and provides services for computer programs. It acts as an intermediary between applications and the hardware, enabling a stable environment for execution.

Key responsibilities include process management (scheduling, creation, and termination of processes), memory management (allocation, paging, virtual memory), storage and file systems (organizing data on disks), device management through drivers, networking, and security (permissions, authentication, isolation).

Architecturally, most OSs consist of a kernel core that runs in privileged mode, plus system libraries and user applications. The kernel handles low-level tasks; user-space programs interact via system calls. OSs vary in architecture, such as monolithic kernels, microkernels, or hybrid designs. Common components include the bootloader, kernel, system services, and a user interface (command line or graphical).

Types and examples include desktop and server OSs (Windows, macOS, Linux distributions, BSD), mobile OSs (Android, iOS), and embedded or real-time systems (RTOS). File systems include NTFS, ext4, APFS, FAT32. Modern OSs support multitasking, multiprocessing, virtualization, and containers.

History and evolution cover the shift from early batch systems to time-sharing and multitasking, with milestones such as UNIX, Windows NT, Linux, and the rise of open-source and mobile platforms. Security models have evolved from simple user accounts to more advanced approaches like mandatory access control and sandboxing.