May the Source be with You

I was contacted a few weeks ago by a large systems house that occasionally contracts with FMF to provide models of logic components. They got their memory models from another company that they said they were quite happy with – until recently. The other company provided compiled models that only ran in a proprietary environment. The systems house had very long product life cycles so some of the parts in their simulations were at or near end of life. The company supplying the memory models decided their own business interests were best served by discontinuing these models of obsolete parts.

This left the systems house in a bind. They had long term contracts to support and upgrade fielded hardware but their model supplier had just pulled the models out from under them. What to do?

The solution should be obvious. Models delivered as standards compliant source code can never be withdrawn. Once you have them, you can hang on to them as long as you like. No further support from the supplier is required. This is the only reliable option for systems companies with long product life cycles, such as medical electronics and defense. But there are other advantages to source models.

Source models give you complete visibility into your simulation. You can see which features and constraints of a component are modeled and which are not. When the simulation does not give the expected results, you can compare the model to the datasheet to gain and clearer understanding of the part and gain confidence in the model – or not.

Should you find an error in a source model, you have the option of making corrections on the spot. With a compiled model, you have to first, convince the vendor there is a problem, then, wait for them to confirm the problem, fix it and send you the update. It can be the difference between a delay of a few minutes versus a few weeks.

Some compiled models will work with only one version of a particular simulator.  When a new version of the simulator is released, a new model must be obtained.  If you want to use a different EDA vendor’s simulator, you must get a different model – if one is available.  With source models, this is a non-issue.  You compile the model to use with any version of any standard simulator whenever you want.  And you can run as many simulations as you have simulators.  The model has no run time license to slow you down.

Free Model Foundry was formed in 1995 by three engineers who wanted to simulate their own boards but were stymied by the lack of models.  We chose open source models because they best suited our needs as engineers and that was more important to us than maximizing a revenue stream.  We continue to believe open source models provide the most value for engineers faced with performing board-level verification.  If you have arguments to the contrary, you are invited to share by leaving a comment below.

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