A hardware, software, or firmware system that (a) emulates another different hardware, software, or firmware system and (b) appears to have all the same characteristics of another system, such as (i) accept identical data, (ii) accept and execute the identical programs, and (iii) produce an identical set of outputs for the same set of inputs when running the same programs as the imitated system, although the system configuration and the internally stored programs, computer routines, or supervisory routines run by each system may be different. Note: A computer system might be designed to emulate another computer system. See  device emulator,  integrated emulator,  stand-alone emulator,  terminal emulator. See also  characteristic,  clone,  computer program,  computer routine,  computer system,  configuration,  data,  hardware,  input,  internally stored program,  network,  output,  problem time,  run,  simulator,  software,  supervisory routine,  set.