D686 - Operating Systems - Chapter 1

WGU D686 Operating Systems, bold words and quizzes from zybooks (following instructor notes)

operating system

A program that manages a computer's hardware, provides a basis for application programs, and acts as an intermediary between the computer user and the computer hardware.

Instructor note: A software that manages a computer’s hardware, helps applications work, and lets users interact with the computer .

hardware

The CPU, memory devices, input/output (I/O) devices, and any other physical components that are part of a computer.

application programs

A program designed for end-user execution, such as a word processor, spreadsheet, compiler, or Web browser.

ease of use

The amount of difficulty and complexity involved in using some aspect of computing.

resource utilization

The amount of a given resource (hardware or software) that is being used.

touch screen

A touch-sensitive screen used as a computer input device.

voice recognition

A computer interface based on spoken commands, which the computer parses and turns into actions.

Siri

The Apple voice-recognition system.

embedded computer

A computer system within some other, larger system (such as a car) that performs specific, limited functions and has little or no user interface.

resource allocator

An operating system or application that determines how resources are to be used.

control program

A program that manages the execution of user programs to prevent errors and improper use of the computer. It is especially concerned with the operation and control of I/O devices.

Moore’s law

The idea that the number of parts on a computer chip doubles about every 18 months.

kernel

The main part of an operating system that starts running as soon as a computer turns on.

system program

A Software related to the operating system but designed for smaller and more specific tasks.

bus

A communication system; e.g., within a computer, a bus connects various components, such as the CPU and I/O devices, allowing them to transfer data and commands.

instructor note: a pathway that moves data and instructions between parts of a computer, like the CPU and devices 

device driver

An operating system component that provides uniform access to various devices and manages I/O to those devices.

instructor note: software that helps the operating system talk to and control hardware like printers or keyboards 

interrupt

A hardware mechanism that enables a device to notify the CPU that it needs attention.

instructor note: a signal from a device telling the computer’s brain (the CPU) that something important needs attention right away 

interrupt vector

An operating-system data structure indexed by interrupt address and pointing to the interrupt handlers. A kernel memory data structure that holds the addresses of the interrupt service routines for the various devices.

instructor note: a list that shows where the computer should go to handle different kinds of interruptions 

interrupt-request line

The hardware connection to the CPU on which interrupts are signaled.

instructor note: a wire or circuit that lets devices send signals to the CPU to ask for attention  

interrupt-handler routine

An operating system routine that is called when an interrupt signal is received.

instructor note: a special program that the computer runs when it gets an interrupt signal  

interrupt-controller hardware

Computer hardware components for interrupt management.

instructor note: parts of the computer that manage when and how interrupts are handled  

nonmaskable interrupt

An interrupt that cannot be delayed or blocked (such as an unrecoverable memory error)

instructor note: an urgent signal that the CPU must deal with immediately, like a major error 

maskable

Describes an interrupt that can be delayed or blocked (such as when the kernel is in a critical section).

instructor note: describes an interrupt that the CPU can choose to ignore briefly, usually when it’s busy doing something very important  

interrupt chaining

A mechanism by which each element in an interrupt vector points to the head of a list of interrupt handlers, which are called individually until one is found to service the interrupt request.

instructor note: a method where the computer checks a list of programs to find the right one to handle an interrupt  

interrupt priority level

A way of deciding which interrupts are most urgent, so that the computer can handle them in the right order

random-access memory (RAM)

A computer's main memory that can be used quickly to run programs

dynamic random-access memory (DRAM)

A type of RAM that is fast and used a lot in computers

volatile

Describes memory that loses its information when the computer turns off

electrically erasable programmable read-only memory (EEPROM)

A type of nonvolatile memory that can be electrically erased and reprogrammed to store data

bootstrap program

The first program that starts a computer by getting everything ready for the main software to run when the computer is turned on

bit

The smallest unit of data storage containing one of two values, 0 (off) or 1 (on)

byte

Consists of 8 bits, the smallest addressable storage units in most computers

word

A unit of data representing multiple bytes, such as 4 bytes in a 32-bit system or 8 bytes in a 64-bit system

hard disk drive (HDD)

A storage device that uses spinning disks and read/write heads to store and retrieve data

nonvolatile memory (NVM)

Memory that retains data even when power is turned off

nonvolatile storage (NVS)

Storage that keeps data without needing power, such as hard drives and SSDs

solid state drive (SSD)

a storage device that uses flash memory to store data with no moving parts 

user mode

A CPU mode for executing user processes in which some instructions are limited or not allowed.

kernel mode

A CPU mode in which all instructions are enabled. The kernel runs in this mode.

supervisor mode

A CPU mode in which all instructions are enabled. The kernel runs in this mode.

system mode

A CPU mode in which all instructions are enabled. The kernel runs in this mode.

privileged mode

A CPU mode in which all instructions are enabled. The kernel runs in this mode.

mode bit

A CPU status bit used to indicate the current mode: kernel (0) or user (1).

privileged instructions

Instructions that can execute only if the CPU is in in kernel mode.

protection rings

A model of privilege separation consisting of a series of rings, with each successive ring representing greater execution privileges.

virtual machine manager (VMM)

The computer function that manages the virtual machine; also called a hypervisor.

timer

A hardware component that can be set to interrupt the computer after a specified period.

batch operating system

executes similar jobs in batches to optimize CPU use without user interaction 

multiprogramming

keeps multiple programs in memory to maximize CPU usage by switching between them

main memory management

the process of handling the system's primary memory (RAM) to ensure efficient use by programs 

CPU scheduling

the method used by an operating system to decide which process gets to use the CPU and for how long 

time-sharing system

an operating system that allows multiple users to share computer resources simultaneously 

multitasking

the ability of an operating system to run multiple tasks or programs at the same time 

real-time system

ensures tasks are completed within defined time limits, including hard (strict) and soft (flexible) real-time systems

hard real-time

handles critical tasks that must meet strict, predefined time constraints without virtual memory or time-sharing 

soft real-time

handles tasks with deadlines that are more flexible than hard real-time systems, allowing for some timing variability 

multiprocessor system

a computer system with more than one CPU working together to process tasks 

parallel systems

systems with multiple CPUs sharing memory and communicating directly, enabling simultaneous task execution for improved performance 

virtual memory systems (VMS)

a memory management technique that extends the apparent amount of RAM by using disk space 

distributed operating system

handles networked processors that collaborate on tasks, enabling resource sharing and high-speed processing 

loosely coupled systems

systems where each component or computer is independent and communicates over a network 

local area network (LAN)

a network that connects computers and devices within a small geographic area, like a building 

wide area network (WAN)

a network that connects computers and devices over large geographic distances, such as across cities or countries 

fault tolerance

the ability of a multiprocessor system to handle the failure of a processor by redistributing its tasks to other processors, ensuring continuous operation 

resource manager

The role of an operating system in managing the computer's resources.

instructor note: part of the operating system that controls and assigns computer resources like CPU time, memory, and devices

I/O subsystem

The I/O devices and the part of the kernel that manages I/O.

instructor note: part of the operating system that handles input and output tasks, managing devices and data transfers  

program counter

A CPU register indicating the main memory location of the next instruction to load and execute.

file

The smallest logical storage unit; a collection of related information defined by its creator.

context switching

the process of saving and restoring the state of a process or thread

paging

memory management technique where data is stored and retrieved in fixed-size blocks (pages) to optimize memory use

segmentation

memory management method dividing memory into variable-sized segments for flexible allocation

malware

malicious software designed to disrupt, damage, or gain unauthorized access to computer systems 

ransomware

malware that encrypts files and demands payment for decryption, often causing data loss or operational disruption 

emulator

software or hardware that enables one computer system to mimic another to run incompatible software or use different peripherals 

protection

system functions that control access to computer resources to ensure only authorized users can use them 

security

systems and measures to protect a computer from attacks and threats, both from outside and within 

What is the role of an operating system in modern computing?

Managing hardware resources and providing a user interface

How do operating systems enhace the efficiency of computer systems?

By managing and coordinating hardware and software resources

Which components are managed by an operating system?

CPU, memory, and device controllers 

What is the role of the operating system in handling I/O operations? 

Managing data flow between hardware components 

What does dual mode operation in operating systems enable?

Differentiation between user mode and kernel mode operations

How does an operating system prevent a single program from monopolizing the CPU?

By using a timer to interrupt programs

Which type of operating system is suited for handling multiple programs running simultaneously? 

Multiprogramming

Which type of operating system allows multiple users to share resources effectively? 

Distributed

What is a significant limitation of operating systems in managing computer resources? 

Susceptibility to security vulnerabilities

How do operating systems protect data and maintain system integrity?

By isolating processes and controlling access to resources