There are many benefits of emulators and there are many benefits of simulators. I'll let Erik discuss the advantages of emulators. :-)

Some of the benefits of simulation are:

Simulation is great when there is no hardware or when you want to determine what the hardware should actually look like.

Simulation is very fast. It enables you to concentrate on the problem rather than on hooking stuff up.

A simulator works great for testing the logic in the program. Good simulators let you go beyond simple logic testing and allow you to test the entire application.

There are some things that can't easily be tested WITHOUT simulation. For example, single bit failures are very difficult to test in hardware.

With a simulator, you control time. When you stop the simulation, you stop everything, the program counter, the oscillator, interrupts -- everything. Nothing is running in the background.


OK, enough of the benefits. Here are a few things to look for in a simulator:

* Instruction set simulation. This should be obvious but I think this is one of the main points in simulation.

* Accurate Instruction Timing. This is important so that you know what you simulate is what you'll see on the actual device.

* On-chip Peripheral Simulation. This allows you to setup on-chip peripherals and see what's happening. The timers, counters, A/D, D/A, PWM, CAN, I2C, UARTs, and so on can all be simulated.

* Extensible simulation capabilities with either a script language or DLLs or something. This allows you to simulate stuff that is outside the chip. You'll need to have some way to inject signals (input) into the simulated device and some way to analyze signals (output) coming out of the device.


So, back to the original question, Who has the best simulator? That really boils down to what you mean by best. If best means most features and it simulates lots of devices, the Keil Simulator is best (of course that's what I think, I work there).

Jon