Microsoft DirectX ne tarin aikace-aikace shirye-shirye musaya (APIs) domin handling ayyuka alaka multimedia, musamman wasan shirye-shirye da kuma video, a kan Microsoft dandamali. Asali, sunayen wadannan APIs duk fara da Direct, kamar Direct3D, DirectDraw, DirectMusic, DirectPlay, DirectSound, da sauransu. The sunan DirectX aka ƙirƙira a matsayin wani abbreviation lokaci ga dukan wadannan APIs (da X tsaye a cikin ga takamaiman API sunayen) da kuma nan da nan ya zama sunan tarin. A lokacin da Microsoft daga baya ya kafa wajen samar da wani caca na'ura wasan bidiyo, da X da aka yi amfani a matsayin tushen da sunan Xbox don nuna cewa na'ura wasan bidiyo da aka dogara ne a kan DirectX fasahar. A farko X da aka dauka a gaba a cikin naming na APIs tsara don Xbox X kamar Xbox da Cross-dandamali Audio Creation Tool (ACTX), yayin da DirectWrite ya ci gaba da tsari kamar yadda APIs for Windows? Tambaya: A kan abin da waɗannan dandamali suna amfani da DirectWrite?
Kamfanin Microsoft