What Does `Real Time' Mean

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Argues that real time means tying computation to physical time and gives concrete work: clock sync with CERN White Rabbit to ~80 picoseconds, a Bosch Rexroth press with hundreds of Etherneted controllers that uses synchronized clocks to avoid packet loss, and a RISC‑V PRET processors line that enforces bounded execution time. Presents TIDES as an existence proof: timestamped event streams plus assumptions of bounded clock error, bounded network latency and bounded execution time yield deterministic cyber‑physical behavior.

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" chapters (23)

1. 0:00Intro
2. 0:47Background: The TerraSwarm Research Center (2013-2018) The Sponsors
3. 4:18The Large Hadron Collider does actually have real-time problems.
4. 8:01On the Cyber Side of CPS: Real-Time Computation
5. 9:22Fast Computation
6. 15:07Key Challenge: Timing is not part of the semantics of programs
7. 18:28Abstraction Layers
8. 24:18Performance Cost?
9. 24:42Benefits of PRET
10. 28:26Example of the benefits of embracing temporal semantics
11. 30:45Determinacy
12. 32:28Schematic of a simple CPS
13. 35:00Models vs. Reality
14. 35:31Engineers often confuse the model with its target
15. 37:01Software is a model
16. 37:41Software relies on another deterministic model that abstracts the hardware
17. 38:57Deterministic models for the physical side of CPS
18. 39:21A major problem for CPS: Combinations of deterministic models are nondeterministic
19. 39:52Determinism? Really?
20. 42:06A Physical Realization
21. 42:27For CPS, we need to Change the Question
22. 43:20Determinism? What about Resilience? Adaptability?
23. 49:27Existence proof. Ptides: Time stamped streaming models