Glossary of computer hardware terms

This glossary of computer hardware terms is a list of definitions of terms and concepts related to computer hardware, i.e. the physical and structural components of computers, architectural issues, and peripheral devices.

A

Accelerated Graphics Port (AGP) A dedicated video bus standard introduced by INTEL enabling 3D graphics capabilities; commonly present on an AGP slot on the motherboard. (Presently a historical expansion card standard, designed for attaching a video card to a computer's motherboard (and considered high-speed at launch, one of the last off-chip parallel communication standards), primarily to assist in the acceleration of 3D computer graphics). Has largely been replaced by PCI Express since the mid 2000s.

accelerator A microprocessor, ASIC, or expansion card designed to offload a specific task from the CPU, often containing fixed-function hardware. A common example is a graphics processing unit.

accumulator A register that holds the result of previous operation in ALU. It can be also used as an input register to the adder.

address The unique integer number that identifies a memory location or an input/output port in an address space.

address space A mapping of logical addresses into physical memory or other memory-mapped devices.

Advanced Technology eXtended (ATX) A motherboard form factor specification developed by Intel in 1995 to improve on previous DE factor standards like the AT form factor.

AI accelerator An accelerator aimed at running artificial neural networks or other machine learning and machine vision algorithms (either training or deployment), e.g. Movidius Myriad 2, TrueNorth, Tensor Processing Unit (TPU), etc.

Advanced Configuration and Power Interface An open standard for operating systems to discover, configure, manage, and monitor status of the hardware.

B

Blu-ray Disc (BD) An optical disc storage medium designed to supersede the DVD format. Blu-ray Disc is capable of storing about 5 times as much data as a standard DVD. Most computers do not come shipped with Blu-ray drives, however they can be purchased and added as a separate upgrade. Blu-ray won a format war against HD DVD and for a time drives offering both formats were sold.

bus A common path shared by multiple subsystems or components to send / receive signals. It is a low cost option in mini and micro computers compared to multiple dedicated non-shared paths in main frame computers.

Bottleneck An occurrence where a certain component compromises the way another component works.

C

cache A small and fast buffer memory between the CPU and the main memory. Reduces access time for frequently accessed items (instructions / operands).

cache coherency The process of keeping data in multiple caches synchronised in a multiprocessor shared memory system, also required when DMA modifies the underlying memory.

cache eviction Freeing up data from within a cache to make room for new cache entries to be allocated; controlled by a cache replacement policy. Caused by a cache miss whilst a cache is already full.

cache hit Finding data in a local cache, preventing the need to search for that resource in a more distant location (or to repeat a calculation).

cache line A small block of memory within a cache; the granularity of allocation, refills, eviction; typically 32–128 bytes in size.

cache miss Not finding data in a local cache, requiring use of the cache policy to allocate and fill this data, and possibly performing evicting other data to make room.

cache thrashing A pathological situation where access in a cache cause cyclical cache misses by evicting data that is needed in the near future.

cache ways The number of potential cache lines in an associative cache that specific physical addresses can be mapped to; higher values reduce potential collisions in allocation.

cache-only memory architecture (COMA) A multiprocessor memory architecture where an address space is dynamically shifted between processor nodes based on demand.

card reader Any data input device that reads data from a card-shaped storage medium such as a memory card.

channel I/O A generic term that refers to a high-performance input/output (I/O) architecture that is implemented in various forms on a number of computer architectures, especially on mainframe computers.

chipset Also chip set. A group of integrated circuits, or chips, that are designed to work together. They are usually marketed as a single product.

Compact Disc-Recordable (CD-R) A variation of the optical compact disc which can be written to once.

Compact Disc-ReWritable (CD-RW) A variation of the optical compact disc which can be written to many times.

Compact Disc Read-Only Memory (CD-ROM) A pre-pressed compact disc which contains data or music playback and which cannot be written to.

computer case Also chassis, cabinet, box, tower, enclosure, housing, system unit, or simply case. The enclosure that contains most of the components of a computer, usually excluding the display, keyboard, mouse, and various other peripherals.

computer fan An active cooling system forcing airflow inside or around a computer case using a fan to cause air cooling.

computer form factor The name used to denote the dimensions, power supply type, location of mounting holes, number of ports on the back panel, etc.

control store The memory that stores the microcode of a CPU.

Conventional Peripheral Component Interconnect (Conventional PCI) Also simply PCI. A computer bus for attaching hardware devices in a computer.

core The portion of the CPU which actually performs arithmetic and logical operations; nearly all CPUs produced since the late 2000s decade have multiple cores (e.g. "a quad-core processor").

core memory In modern usage, a synonym for main memory, dating back from the pre-semiconductor-chip times when the dominant main memory technology was magnetic core memory.

Central Processing Unit (CPU) The portion of a computer system that executes the instructions of a computer program.

D

data cache (D-cache) A cache in a CPU or GPU servicing data load and store requests, mirroring main memory (or VRAM for a GPU).

data storage A technology consisting of computer components and recording media used to retain digital data. It is a core function and fundamental component of computers.

device memory local memory associated with a hardware device such as a graphics processing unit or OpenCL compute device, distinct from main memory.

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