Neuristor (bio-transistors) one of those great Rapture tecnological feats :
The electronic Synapse & Axon - the making of.
Engineering the Technology was greatly short-cutted by utilizing existing biological mechanism (nerve cell structures) instead of creating it from scratch (largely impossible genetically). ((Just about all geneic engineering done EVEN TODAY is still just recombining existing genetic material))
Made possible by ADAM manipuation of cell genetics to do a process of growing/forming the desired semi-natural nerve structure groupings of cells to do the complex electronic function required for the computing/logic ). This would be outgrowth of Plasmid research, which modified human body structures (which is much more complicated and harder to do *In Situ*). It would(should) initially have been based around Seaslug nerve cells, which got ALOT of investigation in Rpature (as you might expect).
Real Nerve Cells interconnect potentially with hundreds of other cells with very small fibers (features which could only be partially fabricated in the Real World 40 years later). Inducing natural nerve cells to form grids to facilitate usefull logic interconnects was an early achievement (childs-play compared to making Bees (or whatever) come out of your hands).
This technology uses the natural 'learning' nerve feedback, shaping/training the arrays of cells while 'alive' to build/shape/force the desired interconnection 'logic' to process binary/analog input patterns in complex ways, which generate expected 'programmed' outputs (thus computing the desired useful logic functions).
Then there would be 'baking' process to fix the function permanently into a post-biological circuit, after 'doping' conductive chemicals (like metal ions) so the cell structure will function electronically afterwards. The 'baked' cell functions would then operate using normal transitor/electronic physics in a pattern similar to the original 'trained' living neuro-functioning cell. Electronic signals going into the circuit are processed and appropriate electronic signals then come out of the circuit.
Finding a way to translate/convert the natural cell into working electronics was the 'trick' and once that was found all kinds of opportunities became possible. ADAM modified the cell's genetics to form useful interconnections and train easily, and to then be triggered to start absorbing various chemicals which on 'baking' would make the 'fixed' cell function electronically. The natural cell's inbuilt/original 'learning' mechanism was not needed, so THAT complexity could be ignored/lost (a simplification).
Attempts to use continuously 'living' cells as components failed because they continue to change (and even die eventually) and were not easily/practically able to be connected to standard electronic circuits.
Pre-Planar process transister electonics are used to interface with this hardened Bio-Electronic circuitry.
These circuits usually have alot of excess cells involved because of the fundamental way Neuro-Nets operate. But because they are small (ie- 10 microns, 10000 per square millimeter), all those extras cells dont take up that much space (thousands of functioning 'gates' in the space of a typical discrete transister of that time). Each cell also can actually perform the function of hundreds of transisters.
Simple vision functions takes millions of cells and a structuring of different patterns of Neuristors mimicing a real brain's overall structure, with a progression of different functions (optical feature processing, pattern detection/interpretation, situational conclusion).
An important second generation of development used the production(growing) of reuseable 'molds' which once formed (trained correctly) and 'baked' could be used in a process to stamp out/replicate various circuitry patterns. This facilitated faster and easier (cheaper) mass production of certain useful logic patterns (ex- computer memory which utilized millions of replications of the same simple circuit)
(ex- "R-34 Wire Cluster" which on having a simple Neurister feed back mechanism added became 9000% more reliable).
Brain Boost greatly accelerated the development of this technology (one of those meta level collaboration accelerations of technology). It took just a few Manic researchers, who couldn't sleep, who delved into all kinds of odd things (some of which turned up some astounding Tech). Hmm, Brain Boost (or a derivative) could help accelerate the learning process employed to 'Train' the Neurister nerve cells, Later, the resulting Computer Tech sped up cell training by magnitudes -- lowering costs to develop this technology for Consumer Products (the Business of Rapture is Business -- after all). Voila (behold!), even more money for further tech developments, and enabling more complex uses ...
The Thinker's system employed third generation neuro-electronics and the independant work with N-Gram Big Daddy Conditioning combined to create that Artificial Intelligence. (NOTE- Porters memories of his wife 'made her' real to him, so that N-Grams recorded/taken from HIM were utilized to create that artifical personality (in effect he saw what he remembered).
Interesting sidebar - use of human tissues in this Research - Ethics in Rapture - cutting open the brains of "Experimental Subjects" and extracting tissues to be use for this eletronic stuff (to make money - not just to 'save lives', as much Medical research purports to do). As in Persephone - if you sign the Waiver and sign up for the 'Experimental' Program (and it spells out reasonably honestly whats involved and what the risks are). (Alot of the Bioshock Players probably dont know that this was actually common practice in the US in the 40s and 50s - use of prison/jail inmates for various experimentation).
But then, alot of the research was based on the less 'legally entwined' Seaslug tissues which were simpler and more robust than human tissues.
Idea - if the Thinker could mimic Porter then have it mimic Ryan (in a "Twist" Ryan arranges it to make believe he's alive - but is really the Thinker - but then (wheels within wheels) actually HE IS still alive (not great, but better than the stupid/lame/illgical suicide 'twist' we got).
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