



But their aim is to devise a new generation of fast and flexible computers that can work out for themselves how to solve a problem, rather than having to be told exactly what to do.

Professor Bill Ditto, at the Georgia Institute of Technology, is leading the project and says he is amazed that today's computers are still so dumb.





Bill Ditto views his computer wetware

Well connected

The device the team has built can "think for itself" because the leech neurons are able to form their own connections from one to another. Normal silicon computers only make the connections they are told to by the programmer.

This flexibility means the biological computer works out it own way of solving the problem. "With the neurons, we only have to direct them towards the answer and they get it themselves," says Professor Ditto.

This approach to computing is particularly suited to pattern recognition tasks like reading handwriting, which would take enormous amounts of power to do well on a conventional computer.





Each neuron's electrical activity corresponds to a number

These features can be used to make each neuron represent a number. Calculations are then performed by linking up the individual neurons.

Leech neurons are used because they have been extensively studied and are well understood.

Though much simpler, the neuron computer works in a similar way to the human brain. Professor Ditto says a robot brain is his long-term aim, noting that conventional supercomputers are far too big for a robot to carry around.





However, in the immediate future, the team from Georgia Tech and Emory University are working on enabling their computer to do multiplication.

The biological computer is featured on BBC One's Tomorrow's World at 1930 BST on Wednesday 2 June 1999.