Terminology

• Simulation is recreating an environment in enough detail that desired effects of a ``real'' system can be observed.
• Instruction-Set Simulation is simulating a processor at the instruction-set level. Instruction-set simulation is simulation that is detailed enough to run executable programs intended for the machine being simulated. It is possible to do both a more-detailed simulation, for example timing-accurate or RTL (register transfer level) simulation are even more detailed, and bus architecture or cluster simulation are less detailed.
• Emulation is simulation that uses special hardware assistance [RFD 72], [Tucker 65], [Wilkes 69].
• The target machine is the one being simulated; the host machine is the one where the simulation runs. This terminology parallels retargetable compiler terminology. However, there is no standard terminology where the simulation framework is produced on yet a third platform. That is, a target simulator which runs on special host hardware often has the simulation software compiled on a general-purpose machine. Some have suggested ``generation host'' or ``ghost'' for the machine where the software is created, that suggests the place where the simulator runs is the ``runtime host'' or ``rhost'' (pronounced "roast").