ITEC 55: Operating System (OS) Fundamentals

Comprehensive vocabulary flashcards based on the lecture on Operating System Fundamentals, covering the OS as a resource manager and abstraction layer, the kernel, memory and process abstractions, system calls, and major OS families.

Resource Manager

A system function of an operating system that controls how limited hardware resources—such as CPU time, RAM, storage, and I/O devices—are allocated among competing users or programs while preventing conflicts and unauthorized access.

Abstraction

The process of hiding unnecessary internal implementation details while exposing a simpler, consistent interface for software and users, enabling programmers to interact with hardware without managing low-level operations.

File Abstraction

An OS abstraction that allows programs to interact with stored data through a logical interface using high-level operations (such as open, read, write, and close) rather than directly managing physical disk sectors, storage structures, and metadata.

Process Abstraction

An OS abstraction that represents a running program as a managed execution environment, hiding CPU scheduling details, memory mapping, and hardware state while establishing resource boundaries.

Virtual Memory Abstraction

An OS abstraction that grants each process an independent virtual address space, translating virtual memory addresses into physical RAM locations or disk mappings to provide isolation and simplify software memory access.

Page Table Address Translation

The mechanism by which the operating system and hardware map virtual addresses generated by the CPU to physical memory addresses in RAM or swap space on secondary disk storage.

Protection

Mechanisms enforced by the operating system that restrict how programs and users access system resources, preventing one process from arbitrarily accessing another process's memory or critical hardware.

Isolation

The separation of programs or resources using memory protection, privilege boundaries, and process separation so that a failure or unauthorized action in one area does not compromise the rest of the system.

Kernel

The privileged core of an operating system that operates with elevated permissions to manage physical hardware resources and provide foundational services like process management, memory tracking, and system call handling.

CPU Management

The kernel function that coordinates with the CPU scheduler to decide which programs get access to the processor and how much execution time they receive.

Device Driver

Specialized software that enables the operating system to communicate with and control a specific hardware device by translating OS-level requests into hardware-specific instructions.

Kernel Space

The protected, privileged execution environment in which the OS kernel and select privileged code execute with access to all system resources; faults here can crash the entire system.

User Space

The restricted execution environment where standard user applications and non-kernel services run with limited privileges, requiring approved interfaces to access protected resources.

System Call

A controlled programmatic interface through which a user-space application requests a privileged service from the operating system kernel, causing a transition from user mode to kernel mode.

Dual-Mode Operating System Architecture

A structural design that separates execution into User Mode (running applications, libraries, and shells) and Kernel Mode (running system calls, process management, memory management, filesystems, and device drivers) over the underlying hardware.

Process

An instance of an executing program managed by the OS that contains allocated resources including a virtual address space, execution state, and references to OS-managed objects.

Thread

The smallest unit of execution scheduled by the OS within a process; threads in the same process share its code, data, and address space while maintaining an individual stack, registers, and program counter.

Single-Threaded Process

A process model containing exactly one thread of execution, where the process's code, data, and files are tied to a single set of registers, program counter, and stack.

Multi-Threaded Process

A process model containing multiple concurrent threads of execution that share the same code, data, and files, while each thread maintains its own independent registers, stack, and counter.

Memory Management

The OS function responsible for allocating, tracking, protecting, and reclaiming physical RAM and virtual address spaces to ensure safe, isolated, and efficient memory usage across running programs.

File System

The structure and set of rules utilized by an OS to organize, store, name, access, and retrieve data and metadata on storage media.

NTFS

The default, proprietary file system utilized by modern Microsoft Windows operating systems on storage drives like SSDs.

APFS

Apple File System; the default file system used on modern installations of Apple's macOS operating system.

ext4

The fourth extended filesystem; a common journaling file system widely used across Linux distributions.

Operating System Family

A group of operating systems that share significant architectural design, historical lineage, kernel heritage, or system interfaces (e.g., Windows NT, Unix, Linux).

Windows NT

The architectural foundation of modern desktop and server Microsoft Windows, featuring a hybrid kernel, executive services, hardware abstraction layer, security subsystems, and Win32 APIs.

Linux Kernel

A monolithic, open-source operating system kernel created by Linus Torvalds that implements POSIX-compliant system interfaces and manages core hardware resources.

Linux Distribution

A complete, packaged operating system constructed around the Linux kernel that incorporates system utilities, package management tools, system libraries, and desktop environments.

UNIX

An operating system family originating at Bell Labs known for establishing foundational design philosophies such as composable command-line tools, file/process models, and POSIX standards.

macOS

Apple's desktop operating system built on the Darwin core and XNU kernel, featuring the APFS file system, POSIX compliance, and tight integration with Apple hardware and graphical frameworks.

Darwin

The open-source Unix operating system base developed by Apple that forms the core underlying environment of macOS, incorporating the XNU hybrid kernel.

XNU Kernel

The kernel component utilized in Apple's Darwin operating system architecture that powers macOS, combining Mach microkernel concepts with BSD components.