X-Message-Number: 26325 From: Date: Mon, 13 Jun 2005 01:13:56 EDT Subject: Uploading technology (1.iii.0) What technologies ? Uploading technology (1.iii.0) What technologies ? The Blue Brain Project and the CCortex project [ http://www.ad.com/tech.html ] both, look at building a brain on a computer. The CCortex seems to concentrate on "classical" neural networks, so it would be a brain scale neural net with elementary neuron far more simple that the biological ones. The BBP is more ambitious and could ultimately represent the computer part of the uploading system I have described before. These projects are based on general purpose computers, the CCortex would use 500 linked workstations and the BBP is based on a version of the Blue Gene computer from IBM. This is a multiprocessor system. Given some raw computing power, it has been demonstrated by experience that, with a good interconnecting scheme such the hypercube, the more we divide the pover into smaller processor the best the overal performance. T. Donaldson has championed this idea with the concept of one neuron on one processor. It must be pointed out neverthless that this is true only for general purpose computer. When a system is built for a particular task, be brain simulation or astronomical "experiments", this is no more true. A single processor or a small number of them is best. Whatever the issue, that remains limited at the simulation part worked out on the computer. for fast processes, that technologiy is far too slow and other solutions must be sought. As pointed before, FPGA seems the best contender, even if specialized parts must be worked out by TRACs, their analogic equivalent. General purpose computers with one or many processors are readily available, FPGA too and TRACs can be ordered as ASIC products with low mask cost. There is yet another possibility, the use of neurons on a chip. These are very special circuits built to emulate biological neurons. Kwabena BOAHEN call them neuromorphic microchips in the Scientific American May issue. The retina, may be the best understood part of the central nervous system, has been wired with its five layers, now the work is moving to the visual cortex six layers, the number IV has been worked out. [www.neuroengineering.upenn.edu/boahen ]The corresponding chips are not on the market but could be ordered from the inventors for research purpose. Some organizations such MOSIS [www.mosis.org ] can handle the process of interfacing with a silicon foundry for small batch, down to 50 items. One possibility is then to create a circuit on computer and FPGA and then to move it, or at least the FPGA part, to a TRAC-neuromorphic chip. Today works concentrate on simple neuron models, far from what is asked for in a uploading project. So it is not possible for that use to simply pass a phone call to a research lab a buy some chips added to their next batch order. K. BOAHEN gives the following scale in processing power and efficiency : The brain uses 10 Watts for 10^16 synapse events per second. The common computer today uses at least 100 W for One billion operations per second. The energy efficiency is 10 millions worst in the computer. But: Transistors are working 25,000 times faster that ion channels, if they worked at the same electric potential, they would be 3,600 faster than the neuron ion channels. This give the order of magnitude of the time sharing re-use of a given circuit. Yvan Bozzonetti. Content-Type: text/html; charset="US-ASCII" [ AUTOMATICALLY SKIPPING HTML ENCODING! ] Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=26325