Even though the final cognitive computers will have billions of neurons, they will only consume power when a neuron fires, which happens at the incredibly slow clock speed of 10 Hz. As a result, an entire brain-sized cognitive computer could fit into a shoebox and consume less than a thousand watts.
IBM showed two working prototype chips, both completely digital, which it hopes will serve as the cores of future cognitive computers where thousands will be integrated on multi-core chips.
"A key intellectual step forward was that our chips are all digital, allowing us to simulate on a supercomputer and then implant the results on a silicon chip, resulting in predictable, deterministic behavior," said Modha.
Its two prototypes each use a few million transistors to implement a single core housing just 256 neurons and consuming less than four square millimeters in area using IBM's 45-nanometer silicon-on-insulator (SOI) complementary metal oxide semiconductor (CMOS) process. The only difference between the two test cores was in their use of the interconnecting crossbar array, either as 256k pre-programmable synapses, or as 64k learning synapses. The chips were fabricated at IBM's facility in Fishkill, N.Y., and are currently being testing at the T.J. Watson Research Center in Yorktown Heights, N.Y. and at IBM Research in San Jose, Calif.
In operation, IBM's chips learn from experience, after several learning parameters are set. For instance, one parameter is the threshold level at which neurons fire after integrating over their multiple inputs, allowing faster but cruder operation when set low, or slower but more refined operation when set high. Then as the neurons fire, the learning synapses adapt by changing their weights as they are used. IBM implements the (Donald) Hebb rule, whereby the more a synaptic connection from one neuron to another is used, the more conductive it becomes by virtue of lowering its synaptic weight. Seldom used pathways, on the other hand, inherit higher weights that virtually prune them from the neural network.
IBM envisions its cognitive computers solving a wide variety of applications in navigation, machine vision, pattern recognition, associative memory and classification. So far it has taught one to recognize a cursive letter "7" regardless of in whose handwriting. The other has learned to play (and win against humans) at the game "Pong."
PCM brings nothing to the so-called cognitive chip. Even if the cognitive chip made sense (which it does not), its value would be in the connectivity per sq inch (i.e., number of "synapses"), not the storage/counting media.
Just to keep things straight, almost all neurons send OUT only one signal along one axon. The axon branches at the end and connects to the dendrites of many other neurons. Neurons may have thousands of dendrites receiving signals from other neurons (or receptors) Axons and synapses are like PCM, there is no possible way they could actually work :-)
I can't help but find it a bit odd that IBM is still trying to duplicate probabilistic, over-complete, non-orthogonal, impulse integration systems using perfectly ordered and organized grids of binary devices. Might as well write the whole thing in software at that point. Biological neurons don't send signals in one or two defined routes, rather many directions randomized from neuron to neuron often including back to the neurons that originated the signal. It is interesting to note, though, that their learning algorithm does strengthen or "prune" pathways based on use.
Mr rbtbob-I am aware, and I tried to cover at least one application of a programmable resistance device, the PCM, in neural applications with the work I reported in:-
Here is my quote from PCM PR#4 that I think is applicable in light of the present stagnant state of commercial PCM product development
“If, going forward, the dreams of neural network emulation are to be fully realized, the challenges to PCM device designers in terms of precision, discrimination and scaling will exceed, by far, anything that has been accomplished to date.”
A quote that is also applicable to all programmable resistance devices, including, CBRAM and ReRAM. Also, with respect, I think you should also be reminded that for the synapse, timing between pre- and post-synaptic pulses as well as conduction change as a function of usage is important.
Naah, even Apple II's 1Mhz processor could beat humans at "Pong" and read a written letter 7! This is just another scam on the taxpayer, and IBM should be ashamed! The so-called cognitive computer is nothing more than an underpowered curve-fitting device that gets stuck in local extrema, as IBM knows very well. A multi-core CPU with enough DRAM beats IBM's monstrosity in any task, any time.
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