Investigating Hardware-Software Interaction

1. Investigating Hardware-Software Interaction Neil SteinerMark Jones, ChairPeter AthanasJames ArmstrongBlacksburg, VirginiaAugust 12, 2004

2. Introduction & Motivation Foreword • Interests are hardware and software • Software will be presented as a subset of information • Statements about information are assumed to hold true for software • Not restricting this to digital computers; c.f. quantum, biological, optical, …

3. Introduction & Motivation Presuppositions • Information is non-physical • All information stems from design • Presuppositions have philosophical and physical foundations • Some of the presuppositions may not be required by the hypothesis

4. Introduction & Motivation Chronological Overview • Introduction and Motivation • Initial Literature Searches • Tentative Original Thoughts • Proposed Hypothesis • The Information Problem • Perspectives on Information • The Search for Interaction • Open Issues and Questions

5. Initial Literature Search Historical Perspective • Computational aids: • Abacus, Napier’s rods, Oughtred’s slide rule • Computing machines: • Schickard’s calculating clock, Pascal’s and Leibnitz’s mechanical calculators • Programmable machines: • Jacquard’s loom, Babbage’s analytical machine • Reconfigurable machines: • Hardware and software lines sometimes blur

6. Initial Literature Search Is Nobody Asking Questions? • It’s surprising that nobody is looking more closely at hardware and software interaction • No papers, books, or conferences on hardware-software interaction • No matches for ‘synergy’ or ‘gestalt’ or ‘interface’ or ‘boundary’ • Hardware and software typically mentioned in conjunction only in the case of co-design

7. Initial Literature Search Did We Miss Something? • Has the computer revolution been so successful that we haven’t stopped to look around? • Do we really believe that we understand everything about the foundations of hardware and software? • The absence of scholarly works seems to justify further investigation

8. Tentative Original Thoughts Similarities / Dissimilarities • Hardware-software dissimilarities • Software lacks a substrate • Hardware can not be replicated • Software affords generality and reusability • Von Neumann versus parallel • Fixed versus flexible • Tangible versus intangible • A more compatible view is desirable • Both perform functions • Can we cast hardware and software as counterparts?

9. Tentative Original Thoughts Case Study 2-input look-up table

10. Tentative Original Thoughts Case Study 2-input look-up table

11. Tentative Original Thoughts Case Study 2-input look-up table

12. Tentative Original Thoughts Case Study 2-input look-up table

13. Proposed Hypothesis Hypothesis Duality Software is persistent information; signals are non-persistent information Hardware Storage Connection Logic     Information Software Signal Operation

14. Perspectives on Information Communications Engineering Claude Shannon “A Mathematical Theory of Communication” • Seminal work on reliable communication, without wasting bandwidth • Proposed source, transmitter, receiver, and destination, in presence of noisy channel • Relation between probability and entropy: H   pi log pi • Foundations of digital computers, encoding, compression, error correction, … • Ignores any meaning in information

15. Perspectives on Information IBM Research Rolf Landauer “Information is Physical” • Shows that erasing information requires a minimum of kT Joules • Proposes reversible computing, to avoid erasing information • Arbitrarily low energy cost, but computation proceeds at its own pace and possibly with some uncertainties • Does not show that information is physical

16. Perspectives on Information Quantum Mechanics Doug Matzke “Information is Protophysical” • Suggests that information laws predate and cause the universe • Sees energy/information duality, information being more fundamental than energy • Suggests the possibility of converting between energy and information; c.f. E=mc2 • Expects that unified field theories will have to include computational and informational perspectives

17. Perspectives on Information Computer Science Federico Flückiger “Unified Concept of Information” • Dissertation on information • Surveys semiotics, cybernetics, and cognition • Explains syntax, semantics, and pragmatics • Believes information to be a construction of the human brain, and takes time and individual into account • Builds formalism out of ‘a priori atoms’ • Model is open ended, c.f. Gödel

18. Perspectives on Information Philosophy Andrzej Chmielecki “What is Information?” • “Any detectable difference of physical states” • Information definition built from ‘collection’, ‘alphabet’, ‘code’, and ‘repertoire’ • Information levels: Level 0: code Level 1: parainformation Level 2: structural information Level 3: metainformation • Applicable to broad range of physical applications

19. Perspectives on Information Quantum Mechanics, Quantum Gravity Other Physicists Uncertainty or Determinism? • Copenhagen Interpretation – what is reality?: Bohr, Heisenberg, Pauli • Determinists: Schrödinger, Einstein, Bohm, Bell (and computation advocates: Zuse, Fredkin, Wolfram, Feynman) • Planck scale determinism: ’t Hooft • Black hole information: Wheeler, Beckenstein

20. The Search for Interaction Attributes • Hardware is physical, fixed, tangible, able to function on its own • Software is non-physical, flexible, intangible, unable to function on its own (requires a substrate) • Effects of software on hardware are tangible • Hardware is already capable of anything the software tells it to do – I think

21. The Search for Interaction Boundaries • Boundary conditions help us analyze specific problems, c.f. electromagnetics • What is the nature of the interface? Can we describe or quantify it? Is there any “energy” or “force” at the boundary? • Is the boundary flexible or rigid, gradual or abrupt? Is it smooth? Can we cheat? • Questions are relevant whether or not information is physical

22. The Search for Interaction Structure • An ordering of parts – relational information • May be spatial, temporal, or logical • Formation requires energy – runs counter to 2nd law of thermodynamics • Randomness is absence of structure • Structure is fragile, randomness is not • Structure is compressible, randomness is not • Structure requires finer grained interaction – without forces we would have no structure

23. Open Questions and Issues Miscellaneous Thoughts • Storage may simply be a cache and interface to information • Maybe a computer is just a device that links and synchronizes hardware and information – match the topologies and enforce the symmetries – symmetries give rise to forces • How about virtual hardware or emulation? Structure can exist in both hardware and software – physical and non-physical forms

24. Open Questions and Issues Concluding Questions • What do we really know? Not much • What might we do differently? • Where do we start looking? At the interface – at the underlying “forces” • Is this a worthwhile pursuit?

25. Conclusion Questions