Cosc 2p13

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.

hardware

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

application program

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.

Moore's Law

A law predicting that the number of transistors on an integrated circuit would double every eighteen months.

kernel

The operating system component running on the computer at all times after system boot.

system program

A program associated with the operating system but not necessarily part of the kernel.

middleware

A set of software frameworks that provide additional services to application developers.

bus

A communication system; e.g., within a computer, a bus connects various components, allowing them to transfer data and commands.

device driver

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

interrupt

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

interrupt vector

An operating-system data structure indexed by interrupt address and pointing to the interrupt handlers.

interrupt-request line

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

interrupt-handler routine

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

interrupt-controller hardware

Computer hardware components for interrupt management.

nonmaskable interrupt

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

maskable

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

interrupt chaining

A mechanism by which each element in an interrupt vector points to the head of a list of interrupt handlers.

interrupt priority level

Prioritization of interrupts to indicate handling order.

random-access memory (RAM)

Rewritable memory, also called main memory; most programs run from RAM.

dynamic random-access memory (DRAM)

The common version of RAM, which features high read and write speeds.

bootstrap program

The program that allows the computer to start running by initializing hardware and loading the kernel.

volatile

Describes storage whose content can be lost in a power outage or similar event.

firmware

Software stored in ROM or EEPROM for booting the system and managing low level hardware.

bit

The basic unit of computer storage. A bit can contain one of two values, 0 or 1.

byte

Eight bits.

word

A unit made up of one or more bytes.

kilobyte (KB)

1,024 bytes.

megabyte (MB)

1,024² bytes.

gigabyte (GB)

1,024³ bytes.

terabyte (TB)

1,024^4 bytes.

petabyte (PB)

1,024^5 bytes.

von Neumann architecture

The structure of most computers, in which both process instructions and data are stored in the same main memory.

secondary storage

A storage system capable of holding large amounts of data permanently; most commonly, HDDs and NVM devices.

hard disk drive (HDD)

A secondary storage device based on mechanical components.

nonvolatile memory (NVM)

Persistent storage based on circuits and electric charges.

tertiary storage

A type of storage that is slower and cheaper than main memory or secondary storage.

semiconductor memory

The various types of memory constructed from semiconductors.

memory

Volatile storage within a computer system.

nonvolatile storage (NVS)

Storage in which data will not be lost in a power outage or similar event.

direct memory access (DMA)

A performance-improving operation for device controllers allowing devices to transfer large amounts of data directly.

core

Within a CPU, the component that executes instructions.

multiprocessor systems

Systems that have two or more hardware processors (CPU cores) in close communication.

symmetric multiprocessing (SMP)

Multiprocessing in which each processor performs all tasks equally.

multicore

Multiple processing cores within the same CPU chip.

heterogeneous multiprocessing (HMP)

Multiprocessing in which processor cores are differentiated by power consumption and clock speed.

P-core

A performance core used for high performance and consumes more power.

E-core

An efficiency core used for less demanding tasks and consumes less power.

system-on-a-chip

A computer system that combines multiple components on the same integrated circuit chip.

graphics processing unit (GPU)

The specialized hardware to run computer graphics.

shared system interconnect

A bus connecting CPUs to memory allowing all CPUs to access all system memory.

non-uniform memory access (NUMA)

An architecture aspect of computer systems where memory access time varies based on the core.

blade server

A computer with multiple processor boards and I/O boards in the same chassis.

clustered system

A system that gathers together multiple CPUs and joins them together.

high-availability

Describes a service that will continue even if one or more systems in the cluster fail.

graceful degradation

The ability of a system to continue providing service proportionate to the level of surviving hardware.

fault-tolerant system

A system that can suffer a failure of any single component and still continue operation.

asymmetric clustering

A configuration in which one machine in a cluster is in hot-standby mode while the other is running applications.

hot-standby mode

A condition in which a computer in a cluster monitors the active server.

symmetric clustering

A situation in which two or more hosts are running applications and are monitoring each other.

high-performance computing

A computing facility designed for use with a large number of resources for parallel operation.

parallelization

The process of dividing a program into separate components that run in parallel.

distributed lock manager (DLM)

A function used by a clustered system to supply access control and locking.

storage-area network (SAN)

A local-area storage network allowing multiple computers to connect to one or more storage devices.

big data

Extremely large sets of data; distributed systems are well suited to working with big data.

MapReduce

A big data programming model and implementation for parallel processing across nodes.

system daemon

A service provided outside the kernel by system programs that run continuously.

trap

A software interrupt, caused either by an error or a specific request from a user program.

exception

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

system call

Software-triggered interrupt allowing a process to request a kernel service.

multiprogramming

A technique that increases CPU utilization by organizing jobs so that the CPU always has a job to execute.

process

A program loaded into memory and executing.

multitasking

The concurrent performance of multiple jobs, allowing user interaction.

response time

The amount of time it takes the system to respond to user action.

CPU scheduling

The process by which the system chooses which job will run next.

virtual memory

A technique that allows the execution of a process that is not completely in memory.

logical memory

Memory as viewed by the user; usually a large uniform array.

user mode

A CPU mode for executing user processes wherein some instructions are limited.

kernel mode

A CPU mode in which all instructions are enabled, used by the kernel.

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 kernel mode.

protection rings

A model of privilege separation consisting of a series of rings.

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.

resource manager

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

program counter

A CPU register indicating the main memory location of the next instruction.

file

The smallest logical storage unit; a collection of related information.

caching

The use of temporary data storage areas to improve performance.

cache management

The management of a cache's contents.

cache coherency

The coordination of the contents of caches to ensure updates are reflected.