DirectX

A set of Windows interfaces from Microsoft for programming graphics and sound. Windows developers program to the DirectX APIs, and the manufacturers of sound cards and display adapters write DirectX drivers to be included with their hardware. DirectX provides a high-level interface for accessing low-level functions "directly." It accesses the hardware abstraction layer in Windows (see HAL).

The first DirectX API was introduced in late 1995 to encourage game developers to move their software to Windows. Before DirectX, games for the PC were written in DOS in order to redraw the screen fast enough for real time animation. To obtain the speed, gaming companies had to write drivers for a variety of display adapters, which was a development headache.

A Single Graphics Interface for Windows
DirectX provides the interface to access the frame buffer and advanced features of the display adapter, which are not provided in the standard Windows GDI graphics interface. When DirectX was introduced, display adapter vendors were quick to develop DirectX drivers that would expose low-level functions of their hardware to the application.

Emulate Graphics Functions in Software
Through the Hardware Emulation Layer (HEL), DirectX is capable of emulating graphics functions in software that are not built into the display adapter (video card). See graphics pipeline.

Which DirectX Version Is Running?
To determine which version of DirectX is installed in your PC, select Run from the Start menu, type in dxdiag and click OK. Look under System Information for the DirectX Version number. See DirectX 10, GDI, video accelerator and DirectSound.

 DirectX
 Interface      Purpose

 DirectDraw     2D graphics
 Direct3D       3D graphics
 DirectSound    audio
 DirectSound3D  3D audio (gaming)
 DirectPlay     multi-player control (gaming)
 DirectInput    input device control (gaming)
 DirectVoice    players talk to each other (gaming)
 DirectShow     audio, video, streaming media
 DirectVideo    video (earlier API)

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(programming, hardware)

DirectX - A Microsoft programming interface standard, first included with Windows 95. DirectX gives (games) programmers a standard way to gain direct access to enhanced hardware features under Windows 95 instead of going via the Windows 95 GDI. Some DirectX code runs faster than the equivalent under MS DOS. DirectX promises performance improvements for graphics, sound, video, 3D, and network capabilites of games, but only where both hardware and software support DirectX. DirectX 2 introduced the Direct3D interface. Version 5 was current at 1998-02-01. Version 8.1 is included in Windows XP. Latest version: 8.1 (as of 2001-12-31). http://microsoft.com/directx/.