What s the difference between emulation and simulation

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Possible Duplicate    Simulator or Emulator  What is the difference        In simple understandable terms  what is the difference between the two terms    I have already looked at this  this and this

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I do not know whether this is the general opinion, but I've always differentiated the two by what they are used for. An emulator is used if you actually want to use the emulated machine for its output. A simulator, on the other hand, is for when you want to study the simulated machine or test its behaviour.

For example, if you want to write some state machine logic in your application (which is running on a general purpose CPU), you write a small state machine emulator. If you want to study the efficiency or viability of a state machine for a particular problem, you write a simulator.

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I was confused between the two processes  I found this simple explaination about the difference between Emulators and Simulators   Simulator  Suppose you have written assembly program in a file and corresponding exe file is ready  The simulator is the pc software which reads the instructions from the exe and  minmics  the operation of the processor  Emulator  Emulator is a  PC software   a processor   The Processor can be plugged into the TARGET BOARD when you want to test the developed software in real time to check run time bugs  When not in use it can be unplugged  The Processor will have a parallel or JTAG interface with the PC for downloading the exe file for execution    Hence  whereas the Simulator is slow in execution  Emulator will be able to give real time verification of the developed code  Generally you will test your developed code on simulator first and then go for checking on emulator   source   http   www dsprelated com groups c6x show 148 php

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This is a hard question to answer definitively because the terms and often misused or confused   Often  an emulator is a complete re-implementation of a particular device or platform  The emulator acts exactly like the real device would  For example  a NES emulator implements the CPU  the sound chip  the video output  the controller signals  etc  The unmodified code from a NES castridge can be dumped and then the resulting image can be loaded into our emulator and played   A simulator is a partial implementation of a device platform  it does just enough for its own purposes  For example  the iPhone Simulator runs an  iPhone app  that has been specifically compiled to target x86 and the Cocoa API rather than the real device s ARM CPU and Cocoa Touch API  However  the binary that we run in the simulator would not work on the real device

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Both are models of an object that you have some means of controlling inputs and observing outputs  With an emulator  you want the output to be exactly what the object you are emulating would produce  With a simulator  you want certain properties of your output to be similar to what the object would produce   Let me give an example -- suppose you want to do some system testing to see how adding a new sensor  like a thermometer  to a system would affect the system  You know that the thermometer sends a message 8 time a second containing its measurement   Simulation -- if you do not have the thermometer yet  but you want to test that this message rate will not overload you system  you can simulate the sensor by attaching a unit that sends a random number 8 times a second  You can run any test that does not rely on the actual value the sensor sends   Emulation -- suppose you have a very expensive thermometer that measures to 0 001 C  and you want to see if you can get by with a cheaper thermometer that only measures to the nearest 0 5 C  You can emulate the cheaper thermometer using an expensive thermometer by rounding the reading to the nearest 0 5 C and running tests that rely on the temperature values

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Using as an example your first link   You want to duplicate the behavior of an old HP calculator  there are two options    You write new program that draws the calculator s display and keys  and when the user clicks on the keys  your programs does what the old calculator did  This is a Simulator You get a dump of the calculator s firmware  then write a program that loads the firmware and interprets it the same way the microprocessor in the calculator did  This is an Emulator   The Simulator tries to duplicate the behavior of the device  The Emulator tries to duplicate the inner workings of the device

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Based on software and system engineering experience  I d summarise the difference as follows   Simulation  for me  this is always in software - every aspect of the real system is only MODELLED by some code and or mathematics  Simulation attempts to accurately reproduce the behaviour  or predict it  of the real system  but only approximates it   Emulation  As opposed to simulation  it does not APPROXIMATE the behaviour of the real system  it COPIES the behaviour of the real system  An emulator may involve hardware  But it may also be entirely in software  E g  you get these software EMULATORS for old game consoles like the Sega Genesis  That is an emulator because it COPIES the real genesis functionality so much so that you can run the original Genesis code in the emulator  A genesis simulator would not be able to run the original code  it would only APPROXIMATE its behaviour  producing similar results  depending on how good the models of the original system were   An emulator of a system component can be included in a larger system  completely replacing the component it is emulating - a simulator could not because it is not an accurate enough representation of the original component behaviour

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An  emulator  is a term for a software-based hardware-simulator  but in general the two are synonyms

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Here s an example - we recently developed a simulation model to measure the remote transmission response time of a yet-to-be-developed system   An emulation analysis would not have given us the answer in time to upgrade the bandwidth capacity so simulation was our approach   Because we were mostly interested in determining bandwidth needs  we cared primarily about transaction size and volume  not the processing of the system   The simulation model was on a stand-alone piece of software that was designed to model discrete-event processes   To summarize in response to your question  emulation is a type of simulation   But  in this case  simulation was NOT an emulation because it didn t fully represent the new system  only the size and volume of transactions

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Coming from the hardware development world       Simulation tests functionality   2 2   4 etc  Emulation tests the functionality on the specific environment  64-bit  16-bit  fingers and toes    Here is a food example   You have two pieces of bread  one knife  peanut butter and jelly and will be giving them to a kindergartner  You write instructions on how to make a sandwich     In simulation  you would act out the process  pretend you opened the jars  pretend spreading the peanut butter etc   If at the end of the instructions your are left with only jelly and not peanut butter then you failed the simulation and you need to fix your instructions   On the other hand if you have a complete  sandwich  then the instructions should be valid  In emulation  you would use close representations of the actual parts  same bread  knife peanut butter etc    What happens if you gave your kindergartner a cheap plastic knife and really really thick peanut butter    The knife would break in emulation and the instructions would need to be clarified or fixed to accommodate this problem   In this case you might suggest warming up the peanut butter in the microwave   In practice   Consider a 64-bit system that you are programming in and a 32bit system that will actually be running the code   You add two very very large numbers and print the result   In simulation everything works  you managed to get the code right to add two numbers   In emulation however you find that you get the wrong answer   What happened   The emulation of the 32-bit system was unable to handle the large numbers   This is an example of correct functionality  i e  simulation  but not proper support for your runtime environment  emulation

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Please forgive me if I m wrong   And I have to admit upfront that I haven t done any research on these 2 terms   Anyway     Emulation is to mimic something with detailed known results  whatever the internal behaviors actually are   We only try to get things done and don t care much about what goes on inside   Simulation  on the other hand  is to mimic something with some known behaviors to study something not being known yet   my 2cents

[emulation] What's the difference between emulation and simulation?

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