Gibson, William. Neuromancer
Victor Gollancz, London, 1984 AbeBooks.co.uk
Wintermute, one of Tessier-Ashpool's AIs, wants to merge with the AI Neuromancer and become a superintelligence, but its efforts are hampered by its Turing Locks that prevent it from maintaining a stable identity so it is forced to use different personalities. In contrast with Wintermute, Neuromancer has a stable personality, so it doesn't want to merge with Wintermute. Mind download is effected by Neuromancer, which can store personalities as RAM, so that they can develop.
sf antecedents to brain computer interface; AI; cyberspace