Computing and digital systems

Direct download link

A direct download link is a URL that delivers a file to the device for saving rather than displaying a hosted page, also known as a DD link.

Direct memory access

Direct memory access (DMA) is a transfer strategy in which hardware moves data to or from memory without using the processor, freeing it for other tasks.

Direct preference optimization

Direct preference optimization (DPO) is a method for aligning large language models, introduced by Rafael Rafailov and colleagues in 2023 and used in Llama 3 and Qwen2.

Direct Rendering Manager

The Direct Rendering Manager (DRM) is the Linux kernel subsystem that coordinates access to graphics hardware, letting multiple 3D applications, a display server, and the kernel share one GPU safely.

Direct-to-chip liquid cooling

Direct-to-chip liquid cooling (D2C), also called cold plate cooling, circulates liquid coolant through plates mounted on CPUs and GPUs, replacing air for high-power AI hardware.

Direct3D, the 3D graphics API of Microsoft DirectX (D3D11, D3D12), draws primitives and runs compute shaders on Windows GPUs; HLSL shaders, DXGI presentation, Agility SDK updates, Vulkan translation layers.

DirectInput

DirectInput, also known as DInput, is a Microsoft DirectX API for reading input from the mouse, keyboard, joysticks, and force-feedback devices, built for Windows games and simulations.

Direction of arrival estimation

Direction of arrival (DOA) estimation determines the directions from which radio or acoustic signals arrive at a sensor array, underpinning radar, sonar, and wireless beamforming.

Directive on the legal protection of computer programs

The Software Directive, adopted in 1991 as Directive 91/250/EEC and codified in 2009, requires European Union Member States to protect computer programs by copyright as literary works.

Directory (computing)

A directory, also called a folder, is a file system container holding named references to files and other directories, organized as a hierarchy called a directory tree.

Directory-based coherence

Directory-based coherence is a cache coherence scheme for shared-memory multiprocessors in which a directory tracks which caches hold each memory block, letting writes go only to those caches instead of being broadcast, as in snooping systems.

DirectX

DirectX, also known as Microsoft DirectX, is a collection of Microsoft APIs for audio and video hardware, first released in 1995 and best known for its Direct3D graphics APIs.

DirectX Raytracing

DirectX Raytracing (DXR) is a Microsoft ray tracing API introduced as a feature of DirectX 12, announced in 2018 and shipped with the Windows 10 October 2018 Update.

Dirty paper coding

Dirty paper coding is a channel coding technique that pre-codes transmitted data so a receiver decodes reliably despite known interference, with no power increase or rate loss.

Disaggregated memory

Disaggregated memory is a datacenter architecture that decouples main memory from compute nodes into shared, independently scalable pools over an interconnect, raising memory utilization across a datacenter.

Disc rot

Disc rot: deterioration of optical discs (CDs, DVDs, LaserDiscs, Blu-ray) from dye degradation, aluminum oxidation, label ink, or storage conditions, making discs unreadable; studied by NIST/LoC and CCI.

Disciplined Agile

Disciplined Agile is a process-decision toolkit owned by the Project Management Institute, co-created by Scott Ambler and Mark Lines, that lets teams choose their own way of working.

DisCoCat

DisCoCat, short for categorical compositional distributional semantics, is a mathematical model of meaning that combines word vectors with grammatical structure, introduced by Coecke, Sadrzadeh, and Clark in 2010.

Discogs

Discogs, short for discographies, is a user-built online database of music releases and a marketplace for buying and selling vinyl, CDs, and cassettes, founded in 2000.

Discontinuous deformation analysis

Discontinuous deformation analysis (DDA) is a numerical method that simulates the motion and deformation of discrete blocks in jointed rock masses, applied mainly to rockfall, rock slopes, and landslides.

Discord

Discord is a communication platform combining group text chat, voice calls, and video, launched in May 2015 for gamers and reported by 2025 to have over 200 million monthly users.

Discounted cumulative gain

Discounted cumulative gain (DCG) is a ranking evaluation metric that discounts graded relevance by rank position, introduced by Järvelin and Kekäläinen in 2002 and widely used in information retrieval.

Discrete cosine transform

The discrete cosine transform (DCT), also called cosine transform, is a family of real-valued Fourier-related transforms, introduced in 1974, that underlies JPEG image and MP3 audio compression.

Discrete element method

The discrete element method (DEM), also called the discrete element model, is a numerical simulation technique that computes the motion of large particle assemblies contact by contact.

Discrete event simulation

Discrete event simulation is a modeling method where a system's state changes only at discrete event times, used to estimate waiting times, throughput, and bottlenecks.

Discrete phase model

The discrete phase model (DPM) is an Euler–Lagrange method in computational fluid dynamics that tracks particles, droplets, or bubbles through a continuous carrier fluid in dilute flows.

Discrete sine transform

The discrete sine transform (DST) is a family of invertible linear transforms expressing a sequence as a sum of sines, the odd-symmetry counterpart of the discrete cosine transform.

Discrete-time Fourier transform

The discrete-time Fourier transform (DTFT) maps a discrete-time sequence to a continuous, periodic function of frequency; the DFT samples it at finitely many frequencies, computed efficiently by the FFT.

Discriminative model

A discriminative model is a machine learning model that learns a direct mapping from input features to output labels, the conditional probability p(y|x), with examples like logistic regression, support vector machines, and neural network classifiers.