| Thompson's FPGA has 100 logic cells, and the best program has each of the cells doing something. |
| But only 32 were doing something necessary to distinguish the signals. (Note there was no fitness benefit for a smaller circuit.) |
| This is about 1/10 the number of logic cells used by the most efficient human-designed discriminators. |
| The circuit still worked if the other 68 were removed. |
| Of the reamining 32, 5 were not directly connected to the output. |
| When any one of these was removed, the circuit stopped working. |
| The program appears to have discovered a subtle inductance effect between logic cells, an effect not used by human designers. |
| This circuit is not without problems, including a very narrow operating termperature. |
| Current experiments are trying to solve this problem. |
| Others have used evolution of FPGAs to grow basic arithmetic elements, usually more efficient than human-designed circuits. |
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