The Ndoli Jewel is a device from the Ndoli Universe created specifically to run sapient algorithms.
In its first incarnation (Learning To Be Me, Closer), it ran in parallel, first learning to emulate the creature's behaviour by tweaking its algorithms steadily to match input to output until the electronic system matched the biological one completely - then, once that point has been comfortably reached, people could choose to have their biological neurology removed, to run purely on the Ndoli Jewel to achieve de-facto immortality.
Fifty years after the invention of the Jewel, it instead replaced the host brain in a seamless transition, simply replacing the biological neurons with the sturdier technology.
- In the early days, the jewel was a separate device that learnt its task by mimicking the brain, and it had to be handed control of the body at one chosen moment. It took another fifty years before it could be engineered to replace the brain incrementally, neuron by neuron, in a seamless transition throughout adolescence.
- - taken from Border Guards