Emulator in the context of Terminal emulation

A personal computer game, or abbreviated PC game, also known as a computer game, is a video game played on a personal computer (PC). The term PC game has been popularly used since the 1990s referring specifically to games on "Wintel" (Microsoft Windows software/Intel hardware) which has dominated the computer industry since.

Mainframe and minicomputer games are a precursor to personal computer games. Home computer games became popular following the video game crash of 1983. In the 1990s, PC games lost mass market traction to console games on the fifth generation such as the Sega Saturn, Nintendo 64 and PlayStation. They are enjoying a resurgence in popularity since the mid-2000s through digital distribution on online service providers. Personal computers as well as general computer software are considered synonymous with IBM PC compatible systems; while mobile devices – smartphones and tablets, such as those running on Android or iOS platforms – are also PCs in the general sense as opposed to console or arcade machine. Historically, it also included games on systems from Apple Computer, Atari Corporation, Commodore International and others. Microsoft Windows utilizing Direct3D become the most popular operating system for PC games in the 2000s. Games utilizing 3D graphics generally require a form of graphics processing unit, and PC games have been a major influencing factor for the development and marketing of graphics cards. Emulators are able to play games developed for other platforms. The demoscene originated from computer game cracking.

Direct3D is a graphics application programming interface (API) for Microsoft Windows. Part of DirectX, Direct3D is used to render three-dimensional graphics in applications where performance is important, such as games. Direct3D uses hardware acceleration if available on the graphics card, allowing for hardware acceleration of the entire 3D rendering pipeline or even only partial acceleration. Direct3D exposes the advanced graphics capabilities of 3D graphics hardware, including Z-buffering, W-buffering, stencil buffering, spatial anti-aliasing, alpha blending, color blending, mipmapping, texture blending, clipping, culling, atmospheric effects, perspective-correct texture mapping, programmable HLSL shaders and effects. Integration with other DirectX technologies enables Direct3D to deliver such features as video mapping, hardware 3D rendering in 2D overlay planes, and even sprites, providing the use of 2D and 3D graphics in interactive media ties.

Direct3D contains many commands for 3D computer graphics rendering; however, since version 8, Direct3D has superseded the DirectDraw framework and also taken responsibility for the rendering of 2D graphics. Microsoft strives to continually update Direct3D to support the latest technology available on 3D graphics cards. Direct3D offers full vertex software emulation but no pixel software emulation for features not available in hardware. For example, if software programmed using Direct3D requires pixel shaders and the video card on the user's computer does not support that feature, Direct3D will not emulate it, although it will compute and render the polygons and textures of the 3D models, albeit at a usually degraded quality and performance compared to the hardware equivalent. The API does include a Reference Rasterizer (or REF device), which emulates a generic graphics card in software, although it is too slow for most real-time 3D applications and is typically only used for debugging. A new real-time software rasterizer, WARP, designed to emulate the complete feature set of Direct3D 10.1, is included with Windows 7 and Windows Vista Service Pack 2 with the Platform Update; its performance is said to be on par with lower-end 3D cards on multi-core CPUs.

In computing, a virtual machine (VM) is the virtualization or emulation of a computer system. Virtual machines are based on computer architectures and provide the functionality of a physical computer. Their implementations may involve specialized hardware, software, or a combination of the two.Virtual machines differ and are organized by their function, shown here:

• System virtual machines (also called full virtualization VMs, or SysVMs) provide a substitute for a real machine. They provide the functionality needed to execute entire operating systems. A hypervisor uses native execution to share and manage hardware, allowing for multiple environments that are isolated from one another yet exist on the same physical machine. Modern hypervisors use hardware-assisted virtualization, with virtualization-specific hardware features on the host CPUs providing assistance to hypervisors.
• Process virtual machines are designed to execute computer programs in a platform-independent environment.

Some virtual machine emulators, such as QEMU and video game console emulators, are designed to also emulate (or "virtually imitate") different system architectures, thus allowing execution of software applications and operating systems written for another CPU or architecture. OS-level virtualization allows the resources of a computer to be partitioned via the kernel. The terms are not universally interchangeable.

The term digital card can refer to a physical item, such as a memory card on a camera, or, increasingly since 2017, to the digital content hosted as a virtual card or cloud card, as a digital virtual representation of a physical card. They share a common purpose: identity management, credit card, debit card or driver's license. A non-physical digital card, unlike a magnetic stripe card, can emulate (imitate) any kind of card.

A smartphone or smartwatch can store content from the card issuer; discount offers and news updates can be transmitted wirelessly, via Internet. These virtual cards are used in very high volumes by the mass transit sector, replacing paper-based tickets and the earlier magnetic strip cards.

Speedrunning is the act of playing a video game, or section of a video game, with the goal of completing it as fast as possible. Speedrunning often involves following planned routes, which may incorporate sequence breaking and exploit glitches that allow sections to be skipped or completed more quickly than intended. Tool-assisted speedrunning (TAS) is a subcategory of speedrunning that uses emulation software or additional tools to create a precisely controlled sequence of inputs.

Many online communities revolve around speedrunning specific games; community leaderboard rankings for individual games form the primary competitive metric for speedrunning. Racing between two or more speedrunners is also a popular form of competition. Videos and livestreams of speedruns are shared via the internet on media sites such as YouTube and Twitch. Speedruns are sometimes showcased at marathon events, which are gaming conventions that feature multiple people performing speedruns in a variety of games.

A terminal emulator, or terminal application, is a computer program that emulates a video terminal within another display architecture. Though typically synonymous with a shell or text terminal, the term terminal covers all remote terminals, including graphical interfaces. A terminal emulator inside a graphical user interface is often called a terminal window.

A terminal window allows the user access to a text terminal and all its applications such as command-line interfaces (CLI) and text user interface (TUI) applications. These may be running either on the same machine or on a different one via telnet, ssh, dial-up, or over a direct serial connection. On Unix-like operating systems, it is common to have one or more terminal windows connected to the local machine.

A video game console emulator is a type of emulator that allows a computing device to emulate a video game console's hardware and play its games on the emulating platform. More often than not, emulators carry additional features that surpass limitations of the original hardware, such as broader controller compatibility, timescale control (such as fast-forwarding and rewinding), easier access to memory modifications (like GameShark), and unlocking of gameplay features. Emulators are also a useful tool in the development process of homebrew demos and the creation of new games for older, discontinued, or rare consoles.

The code and data of a game are typically supplied to the emulator by means of a ROM file (a copy of game cartridge data) or an ISO image (a copy of optical media). While emulation software itself is legal as long as it doesn't infringe copyright protections on the console, emulating games is only so when legitimately purchasing the game physically and ripping the contents. Freely downloading or uploading game ROMs across various internet sites is considered to be a form of online piracy, and users may be sued for copyright infringement.

DOSBox is a free and open-source MS-DOS emulator. It supports running programs – primarily video games – that are otherwise inaccessible since hardware for running a compatible disk operating system (DOS) is obsolete and generally unavailable today. It was first released in 2002, when DOS technology was becoming obsolete. Its adoption for running DOS games is relatively widespread, partly because of its use in commercial re-releases of games.

Mind uploading is a speculative process of whole brain emulation in which a brain scan is used to completely emulate a person's mental state in a digital computer. The computer would then run a simulation of the brain's information processing, such that it would respond in essentially the same way as the original brain and have a sentient conscious mind.

Substantial mainstream research in related areas is being conducted in neuroscience and computer science, including animal brain mapping and simulation, development of faster supercomputers, virtual reality, brain–computer interfaces, connectomics, and information extraction from dynamically functioning brains. Supporters say many of the tools and ideas needed to achieve mind uploading already exist or are under active development, but they admit that others are as yet very speculative, though still in the realm of engineering possibility.

In computer science, dynamic recompilation is a feature of some emulators and virtual machines, where the system may recompile some part of a program during execution. By compiling during execution, the system can tailor the generated code to reflect the program's run-time environment, and potentially produce more efficient code by exploiting information that is not available to a traditional static compiler.

A system virtual machine (also called SysVM) is a virtual machine (VM) that provides a complete system platform and supports the execution of a complete operating system (OS). These usually emulate an existing architecture, and are built with the purpose of either providing a platform to run programs where the real hardware is not available for use (for example, executing on otherwise obsolete platforms), or of having multiple instances of virtual machines leading to more efficient use of computing resources, both in terms of energy consumption and cost effectiveness (known as hardware virtualization, the key to a cloud computing environment), or both. A VM was originally defined by Popek and Goldberg as "an efficient, isolated duplicate of a real machine".

A hypervisor, also known as a virtual machine monitor (VMM) or virtualizer, is a type of computer software, firmware or hardware that creates and runs virtual machines. A computer on which a hypervisor runs one or more virtual machines is called a host machine or virtualization server, and each virtual machine is called a guest machine. The hypervisor presents the guest operating systems with a virtual operating platform and manages the execution of the guest operating systems. Unlike an emulator, the guest executes most instructions on the native hardware. Multiple instances of a variety of operating systems may share the virtualized hardware resources: for example, Linux, Windows, and macOS instances can all run on a single physical x86 machine. This contrasts with operating-system–level virtualization, where all instances (usually called containers) must share a single kernel, though the guest operating systems can differ in user space, such as different Linux distributions with the same kernel.

The term hypervisor is a variant of supervisor, a traditional term for the kernel of an operating system: the hypervisor is the supervisor of the supervisors, with hyper- used as a stronger variant of super-. The term dates to circa 1970; IBM coined it for software that ran OS/360 and the 7090 emulator concurrently on the 360/65 and later used it for the DIAG handler of CP-67. In the earlier CP/CMS (1967) system, the term Control Program was used instead.

The Quick Emulator (QEMU) is a free and open-source emulator that uses dynamic binary translation to emulate a computer's processor; that is, it translates the emulated binary codes to an equivalent binary format which is executed by the machine. It provides a variety of hardware and device models for the virtual machine, enabling it to run different guest operating systems. QEMU can be used with a Kernel-based Virtual Machine (KVM) to emulate hardware at near-native speeds. Additionally, it supports user-level processes, allowing applications compiled for one processor architecture to run on another.

QEMU supports the emulation of x86, ARM, PowerPC, RISC-V, and other architectures.