Emerging Technologies of Computation

1. Emerging Technologies of Computation Montek Singh COMP790-084 Oct 4, 2011

2. Today: Probabilistic Design • Basics of probabilistic design • energy-correctness tradeoff • probabilistic Boolean logic • approximate arithmetic • applications • Next class: • architectures and design tools • case studies • challenges and benefits • open questions

3. Basics of probabilistic design • Operate at reduced voltage • more noise but lesser energy consumption • Where is this acceptable? • Where could this be even desirable?

4. Probabilistic Boolean logic • Logic values have associated probabilities • p: probability that the value is correct • introduces non-determinism

5. Probabilistic CMOS switch • Thermal noise makes any switch noisy • probability of error depends on thermal noise vs. operating voltage

6. Probabilistic CMOS switch • Thermal noise makes any switch noisy • probability of error depends on thermal noise vs. operating voltage • higher supply voltage (Vdd) w.r.t. noise (sigma) implies higher probability of correct logic

7. Energy-Correctness Tradeoffs • Everything else remaining fixed: • energy required goes up exponentially with prob. of correctness • energy required goes up quadratically with noise

8. Energy-Correctness Tradeoffs • energy required goes up exponentially with prob. of correctness

9. Applications? • Probabilistic Cellular Automata • Random Neural Networks • Hyper Encryption • Bayesian Inference