emulator
In computers, an emulator is a hardware device or a program that pretends to be another particular device or program that other components expect to interact with. For example, using a 3270 emulator, a program written to be used with the 3270 workstation can communicate with and control a personal computer as though it were a 3270. Typically, an emulator is provided when a popular hardware device becomes outdated and no longer marketed but legacy application s exist that still need to communicate with the older device. The practice of using an emulator to make an older program work with a new end-use device is called terminal emulation .