Operating System Concepts

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hash map

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In computing, a hash table (also hash map) is a data structure used to implement an associative array, a structure that can map keys to values.

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host

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a computer or other device connected to a computer network. A network host may offer information resources, services, and applications to users or othernodes on the network. A network host is a network node that is assigned a network layer host address.

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host-standby mode

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A method of redundancy in which the primary and secondary (i.e., backup) systems run simultaneously. The data is mirrored to the secondary server in real time so that both systems contain identical information.

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interrupt driven

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they start down the list of computer instruction s in one program (perhaps an application such as a word processor) and keep running the instructions until either (A) they can't go any further or (B) an interrupt signal is sensed. After the interrupt signal is sensed, the computer either resumes running the program it was running or begins running another program.

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interrupt vector

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is the memory location of an interrupt handler, which prioritizesinterrupts and saves them in a queue if more than one interrupt is waiting to be handled.

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Amazon Elastic Compute Cloud ( EC2)

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provides scalable computing capacity in the Amazon Web Services cloud

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apple ios

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an easy to use interface

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Application Programs

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Word processors, spreadsheets, compilers, and web browsers

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application-specific integrated circuit (ASIC)-

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a kind of integrated circuit that is specially built for a specific application or purpose.

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Asymmetric Clustering-

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one machine is in hot-standby mode while the other is running applications

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Asymmetric Multiprocessing

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each processor is assigned specific tasks by a "Master processor

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balancing binary search tree

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any node-based binary search tree that automatically keeps its height small in the face of arbitrary item insertions and deletions.

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bit

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basic unit of computer storage (0 or 1)

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binary search tree

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abinary tree where each node has a Comparable key and satisfies the restriction that the key in any node is larger than the keys in all nodes in that node's left subtree and smaller than the keys in all nodes in that node's right subtree

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binary tree

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a data structure in which a record is linked to two successor records, usually referred to as the left branch when greater and the right when less than the previous record.

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bitmap

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a representation in which each item corresponds to one or more bits of information, especially the information used to control the display of a computer screen

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blade servers

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multiple processor boards, I/O boards, and networking boards are placed in the same chassis

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Bootstrap program

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automatic procedure whereby basic OS is reloaded following a complete shutdown or loss of memory

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BSD Unix

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started in 1978 as a derivative of AT&T's unix

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byte

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8 bits, smallest convenient chunk of storage

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Cache Coherency-

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Makes sure that an update of a value of A in one cache is immediately reflected in all other caches where A resides

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Cache Management-

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-Makes sure that the cache size and replacement policy can result in greatly increased performance

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Caching

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storing data in a cache memory

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Central Processing Unit (CPU)

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Main Processor

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client-server

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denoting a computer system in which a central server provides data to a number of networked workstations.

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Client System

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A computer used to access the maestro HUB or LUI components

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Closed-Source-

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made available as compiled binary code

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cloud computing

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is a type of computing that delivers computing, storage , and even apps as a service across a network

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Clustered System

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composed of two or more individual systems or odes joined together over a LAN or faster interconnect (Infiniband)

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Compute-Server System

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provides an interface to which a client can send a request to perform an action

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Computer Core

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multiprocessor chips, can be more efficient than multiple chips with single cores because on-chip communication is faster than between-chip communication

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Control Program-

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manages the execution of user programs to prevent errors and improper use of the computer

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copy protection-

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is any effort designed to prevent the reproduction of software, films, music, and other media, usually for copyright reasons.

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CPU Scheduling-

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if several jobs are ready to run at the same time, the system must choose among them

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Device Driver-

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Understands device controller and presents a uniform interface to the device to the rest of the OS

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digital rights management (DRM)

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a class of technologies that are used by hardware manufacturers, publishers, copyright holders, and individuals with the intent to control the use of digital content and devices after sale

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Direct Memory Access (DMA)-

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When a device controller transfers an entire block of data from its own buffer storage to memory without CPU intervention

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disk blocks

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medium-sized disk drive might be divided into several thousand individual units

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Distributions

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system is a software system in which components located on networked computers communicate and coordinate their actions by passing messages.

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Distributed Lock Manager-

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to provide shared access to data, system must supply access control and locking to ensure that no conflicting operations occur

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Dynamic random-

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access memory(DRAM)-a type of random access memory that stores each bit of data in a separate capacitor within an integrated circuit.

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Ease of Use

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how convenient it is for a user to use a PC

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-EEPROM

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electrically erasable programmable read only memory

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Effective User ID

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-user id with extra privileges

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​Electronic Disk

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-can be either volatile or nonvolatile, it stores data in large DRAM array

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Escalate Privileges

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changing privileges to gain extra permissions for an activity

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​Emulation

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is hardware or software or both that duplicates the functions of one computer system in another computer system , different from the first one, so that the emulated behavior closely resembles the behavior of the real system

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Fault Tolerant

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-can suffer a failure of any single component and still continue operation

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file-server system

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-provides a file-system interface where clients can create, update, read and delete files

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firewalls

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protects the network from security breaches

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firmware

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same thing as EEPROm

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Free Software Foundation (FSF)-

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encourages the free exchange of software source code and the free use of software

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files

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are links or shortcuts to an executable located elsewhere on the Windows operating system.

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FIFO(first in,first out)

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-is an acronym for First In, First Out, a method for organizing and manipulating a data buffer, or data stack, where the oldest entry, or 'bottom' of the stack, is processed first.

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GNU General Public License (GPL)-

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codifies copylefting and is a common license under which free software is released. Requires that the source code by distributed with any binaries and that any changes made to the source code be released under the same GPL license

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GNU/Linux

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example of an open-source operating system (produced many UNIX-compatible tools, including compilers, editors, and utilities - never released a kernel)

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Graceful Degradation

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Ability to continue providing service proportional to the level of surviving hardware

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​Group ID-

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group functionality that can be implemented as a system-wide list of group names

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Hardware

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-CPU, Memory, I/O devices which provide basic computing resources for the system

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High-Availability Service

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service continues even if one or more systems in the cluster fail

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High-Performance computing

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​supply significantly greater computational power than a single-processor or even SMP systems because they are capable of running an application concurrently on all computers in the cluster

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Input/Output devices

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-devices that are used to input to a computer (keyboard, mouse) or output (monitor)

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Instruction Register

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Used to hold the current instruction that is being executed

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Interactive Computer

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-provides direct communication between the user and the system

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Job Pool

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consists of all processes residing on disk awaiting allocation of main memory

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Job Scheduling-

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if several jobs are ready to be brought into memory and if there is not enough room for all of them - system must choose among them

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Kernel

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the one program running at all times on the computer

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Kernel Mode

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when a user application requests a service from the operation system

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Local-Area Network (LAN)

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connects computer within a room, a floor or building

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Magnetic Disk

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provides storage for both programs and data

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Mainframe

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-large and powerful data processing system

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Memory

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-Dynamic data storage unit

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Minicomputer-

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-Middle range of computing systems, between mainframes and PCs

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Mode Bit-bit

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added to the hardware of the computer to indicate the current mode: kernel(0) or user (1). Distinguishes between a task that is executed on behalf of the OS and one is that executed on behalf of the user

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Multi-processor system

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parallel systems that have more than one processor in close communication

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Multiprogramming-

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increases CPU utilization by organizing jobs (code and data) so that the cpu always has one to execute

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Network

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a communication path between two or more systems

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Network operating system

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OS that provides features such as file sharing across the network and includes a communication scheme that allows different processes on different computers to exchange messages

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Non-Uniform Memory Access (NUMA)-

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, in which some parts of memory take longer to access than other parts

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Nonvolatile storage

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storage that does not lose its contents when power is removed

NVRAM-nonvolatile storage which is DRAM with battery backup power

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Open-Source operating systems

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OS's made available in source-code format rather than as compiled binary code

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Operating System

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Program that manages computer hardware

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Parallelization

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consist of dividing a program into separate components that run in parallel on individual computers in the cluster

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Privileged Instruction

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A computer instruction that can be executed only by a supervisory program - can only be executed only in kernel mode

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Process

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a program loaded into memory and executing

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Random Access Memory (RAM)

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memory that is erased as soon as the computer is turned off

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Read-only memory (ROM)

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memory that cant be removed

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Real-Time operating system-

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an OS intended for real time applications --> almost always used in embedded systems

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resource allocator

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job of the operating system, allocates and manages hardware resources

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Resource Utilization

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-how various hardware and software resources are shared

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Response Time-

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-time it takes for the computer to give results

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Protection-

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any mechanism for controlling the access of processes or users to the resource defined by a computer system

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Interrupt

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signal sent from hardware or software to CPU to transfer execution to some other instructions