DOSBox is a DOS emulator for the x86 architecture, optimized for running DOS games and applications. It emulates older x86 processors, but is focused more on game compatibility than on exact emulation of Pentium processors.
DOSBox can be used for old applications that ran on Pentiums, but is not intended for complex hardware emulation or more modern applications that require more accurate hardware-level emulation.
Some DirectX games are reported to work on a patched versionof DOSBox [1]