Operating Systems Chapter 1

Vocabulary flashcards covering core concepts introduced in Chapter 1: Introduction to Operating System Concepts (definitions, roles, and architecture).

Operating System (OS)

A program that acts as an intermediary between a user of a computer and the computer hardware; goals include executing user programs, making the system convenient to use, and using hardware efficiently.

Kernel

The core component of a computer's operating system that serves as the fundamental layer between the software and the hardware. It acts as the central command center, managing critical system resources like the CPU and memory, facilitating interactions between software processes and hardware devices, and handling tasks such as process scheduling and input/output requests.

System program

Programs that ship with the operating system but are not part of the kernel.

Application program

Programs not part of the OS, such as word processors, browsers, and databases.

Middleware

Software frameworks that provide additional services to applications (e.g., databases, multimedia, graphics).

Hardware

The basic computing resources: CPU, memory, and I/O devices.

Device driver

A part of the OS that manages a specific device controller; provides a uniform interface to the hardware.

Interrupt

A signal from an I/O device to the CPU indicating an event

Interrupt service routine (ISR)

Code to handle a specific interrupt; the address is stored in an interrupt vector.

Trap/Exception

A software-generated interrupt caused by an error or by a user request.

Interrupt-driven

An OS design where the flow is controlled by interrupts and their handlers.

Dual-mode operation

Hardware feature that supports user mode and kernel mode to protect the system.

User mode

Mode in which user programs run with restricted privileges.

Kernel mode

Mode in which the OS kernel runs with privileged instructions allowed.

Mode bit

Hardware indicator that distinguishes between user mode and kernel mode.

System call

Software interrupt used by a process to request OS services; causes transition to kernel mode.

Bootstrap program

Code loaded at power-up or reboot that initializes the system and loads the kernel.

Main memory

Primary, directly accessible, volatile storage (RAM/DRAM).

Secondary storage

Nonvolatile storage that extends main memory with larger capacity (e.g., HDDs, SSDs).

Hard Disk Drive (HDD)

Nonvolatile storage with tracks and sectors; disk controller manages interaction with the computer.

DRAM

a type of volatile RAM used as a computer's main memory for temporary storage of active programs and data. It uses capacitors and transistors to store information as electrical charges, which must be periodically refreshed to prevent data loss

Cache

Smaller, faster storage that holds copies of data from slower storage to speed access

1. cache

2. main memory

3. secondary storage

What is the hierarchy of storage systems by speed, cost, and volatility;

Von Neumann architecture

Architecture where the CPU and memory are connected by a bus; programs and data reside in memory.

Direct Memory Access (DMA)

Technique allowing device controllers to transfer data directly to main memory without CPU intervention; typically yields fewer interrupts.

I/O subsystem

Manages memory buffering, caching, spooling, and provides a uniform device-driver interface.

File system

Uniform, logical view of storage as files; includes directories, access control, and primitives to manipulate files.

Mass-storage management

Management of disks and long-term storage, including mounting, free-space management, disk scheduling, partitioning, and protection.

Process

A program in execution; an active entity that requires resources and has a program counter.

Multiprogramming

Holding a subset of jobs in memory so the CPU always has a job to execute, switching when I/O waits occur.

Timesharing (multitasking)

Extends multiprogramming to allow interactive computing; frequent CPU switching with target response times (e.g., < 1 second).

Virtual memory

Technique allowing execution of processes not completely in main memory, enabling larger processes than physical memory.

Direct memory access (DMA)

(See Direct Memory Access) DMA transfers blocks of data directly to main memory without CPU intervention.

I/O structure (wait vs. non-wait)

Models for I/O: wait for completion (blocking) or continue execution and handle completion later.

Von Neumann architecture

See above.

Cloud computing

Delivery of computing, storage, and apps as a service over a network, often using virtualization and service models like IaaS, PaaS, SaaS.

Open-source operating systems

OSes whose source code is available for study and modification; examples include GNU/Linux and BSD; licenses such as GPL.

Free and Open-Source Software (FOSS)

Software that is free to use, modify, and distribute, with source code available.

Kernel data structures

Core OS data structures such as singly/doubly/circular linked lists, binary search trees, hashes, and bitmaps.