Operating Systems – Introductory Vocabulary

A set of vocabulary flashcards covering key introductory operating-system terms and concepts discussed in the lecture.

Operating System (OS)

Program that acts as an intermediary between users and computer hardware.

Resource Allocator

OS role that decides among conflicting requests to ensure efficient and fair use of hardware resources.

Control Program

OS role that oversees program execution to prevent errors and improper computer use.

Kernel

Core program of the OS that is always running on the computer.

Bootstrap Program

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

Firmware

Bootstrap code stored in ROM or EPROM.

Interrupt

Signal from hardware that notifies the CPU an I/O operation has finished.

Interrupt Vector

Table holding addresses of all interrupt service routines (ISRs).

Interrupt Service Routine (ISR)

Code executed by the CPU to handle a specific interrupt.

Trap

Software-generated interrupt triggered by an error or user request.

System Call

User request for the OS to perform a service, often used to wait for I/O completion.

Device-Status Table

OS table containing type, address, and state information for each I/O device.

Main Memory

Volatile random-access memory used for current program data.

Secondary Storage

Non-volatile storage that extends main memory capacity (e.g., disks).

Disk

Magnetic storage medium divided into tracks and sectors.

Disk Controller

Hardware that manages logical interaction between the disk and the computer.

Caching

Copying data into a faster storage system to speed up future access.

Multiprocessor System

Computer with two or more CPUs for increased throughput, economy of scale, and reliability.

Asymmetric Multiprocessing

Multiprocessor model where each processor is assigned a specific task.

Symmetric Multiprocessing

Multiprocessor model where all processors are peers, sharing work equally.

Clustered System

Collection of linked multiprocessor systems working together.

Multiprogramming

OS feature that schedules multiple jobs in memory to improve CPU utilization.

Timesharing

Interactive computing where the CPU switches among jobs rapidly so each user perceives direct access.

Dual-Mode Operation

Hardware support that distinguishes user mode from kernel mode to protect the OS.

User Mode

CPU mode for running user applications with restricted privileges.

Kernel Mode

CPU mode for running OS code with full hardware privileges.

Privileged Instruction

Operation executable only in kernel mode.

Single-Threaded Process

Process containing one program counter and one thread of execution.

Multi-Threaded Process

Process containing multiple threads, each with its own program counter.

Protection (OS)

Mechanisms controlling access of processes or users to system resources.

Security (OS)

Defensive measures safeguarding the system against attacks.

User ID (UID)

Unique identifier assigned to each user for access control.

Group ID (GID)

Identifier that defines a collection of users sharing common privileges.