computer science

Timed

Timed is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Timed rather than just read about it. In short: timed (time daemon) is an operating system program that maintains the system time in synchronization with time servers using the Time Synchronization Protocol (TSP) developed by Riccardo Gusella and Stefano Zatti. Gusella and Zatti had done earlier related work on their TEMPO algorithm.

Key takeaways

Timed belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Timed to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Timed from memory before moving on to harder problems.

Reference excerpt

timed (time daemon) is an operating system program that maintains the system time in synchronization with time servers using the Time Synchronization Protocol (TSP) developed by Riccardo Gusella and Stefano Zatti. Gusella and Zatti had done earlier related work on their TEMPO algorithm. The Time Synchronization Protocol specification refers to an election algorithm and a synchronization mechanism specified in other technical reports listed as "to appear". With the release of macOS High Sierra in 2017, timed in macOS has subsumed all time synchronization responsibilities including those of the former ntpd and timed.

See also Network Time Protocol (NTP) Precision Time Protocol (IEEE 1588 PTP)

References

External links timed(8) man page Timed Installation and Operation Guide, System Manager's Manual (SMM:11) The Berkeley UNIX Time Synchronization Protocol, System Manager's Manual (SMM:12)

Worked examples

Example 1 — a first encounter with Timed

Start with the simplest possible case. Write down what Timed claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Timed before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Timed ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Timed

In research: Timed appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Timed in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Timed is common in secondary-school and first-year university syllabi. It links to neighbouring topics Network time-related software, Operating system stubs, so understanding it makes those chapters shorter.
In everyday life: Look for Timed outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Timed in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Timed means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Timed out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Timed in simple terms?

Why does Timed matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Timed?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Timed.