Re: [math-fun] 32-bit computers almost gone
Yes, but... 1. Memory is cheap. Even uP will have decent sized memories. Every delta in line widths produces at least O(delta^2) in memory size, if not O(delta^3). 2. SIMD-type processors are cheap and quite energy-efficient. There's really no reason for a traditional 16-bit processor anymore. 3. Most crypto codes are 1-1 functions, and therefore *reversible*. In theory, reversible functions can be computed with asymptotically zero energy dissipation. At 07:31 AM 7/6/2016, Richard Howard wrote:
BTW, there is an interesting mathy problem here--how do you do security when you have only a few microjoules and a few kB of memory in a 16 bit processor?
RSA is not even remotely feasible.
1. Cheap means something different if you are talking about ubiquitous IOT nodes. Large amount of embedded memory are very expensive and external RAM chips really break the bank for cost/size etc. Trend is to single chip solutions with MCU/radio/memory. Not compatible with large quantities of DRAM. As to delta in linewidth--the news is that the end is near because we are running out of atoms. Check the ITRS roadmap and Intel. I have a nice photo of a CMOS device with 142 atoms from source to drain and 6 atoms of oxide (you can see the dots). That was 20 years ago in research--we are there on-schedule in production. 2. Sounds wonderful, but for IOT you need a processor with a very large production run to get the cost down. Maybe someday SIMD single chip solutions will be there, but not in the near term. 3) Reversible computers are delightful ideas, but there are fundamental issues running them at room temperature. Because of the kT/q slopes in diodes, you can't actually recover the energy. Hardware was made 20 years ago and shows that nicely. Now at mK temperatures, that is a different story. --R On Wed, Jul 6, 2016 at 11:48 AM Henry Baker <hbaker1@pipeline.com> wrote:
Yes, but...
1. Memory is cheap. Even uP will have decent sized memories. Every delta in line widths produces at least O(delta^2) in memory size, if not O(delta^3).
2. SIMD-type processors are cheap and quite energy-efficient. There's really no reason for a traditional 16-bit processor anymore.
3. Most crypto codes are 1-1 functions, and therefore *reversible*. In theory, reversible functions can be computed with asymptotically zero energy dissipation.
At 07:31 AM 7/6/2016, Richard Howard wrote:
BTW, there is an interesting mathy problem here--how do you do security when you have only a few microjoules and a few kB of memory in a 16 bit processor?
RSA is not even remotely feasible.
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