computer science

Multidrop bus

Multidrop bus 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 Multidrop bus rather than just read about it. In short: A multidrop bus (MDB) is a computer bus able to connect three or more devices. A process of arbitration determines which device sends information at any point.

Key takeaways

Multidrop bus 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 Multidrop bus to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Multidrop bus from memory before moving on to harder problems.

Reference excerpt

A multidrop bus (MDB) is a computer bus able to connect three or more devices. A process of arbitration determines which device sends information at any point. The other devices listen for the data they are intended to receive. Multidrop buses have the advantage of simplicity and extensibility, but their differing electrical characteristics make them relatively unsuitable for high frequency or high bandwidth applications.

In computing Since 2000, multidrop standards such as PCI and Parallel ATA are increasingly being replaced by point-to-point systems such as PCI Express and SATA. Modern SDRAM chips exemplify the problem of electrical impedance discontinuity. Fully Buffered DIMM is an alternative approach to connecting multiple DRAM modules to a memory controller.

In automotive One of the first widespread multidrop serial buses available is CAN bus designed by engineers at BOSCH starting in 1983, released in 1986. CANbus is widely considered to be replaced by SPE in the near future. Starting in 2019, the IEEE defined multiple multidrop-bus ethernet standards, namely in 802.3cg and 802.3da, called 10BASE-T1S, and 10BASE-T1M respectively, the latter being an improvement in terms of noise resistance, power delivery and collision avoidance. Both 10BASE-T1S and 10BASE-T1M directly compete with Can XL.

For vending machines

MDB/ICP

MDB/ICP (formerly known as MDB) is a multidrop bus computer networking protocol used within the vending machine industry, currently published by the American National Automatic Merchandising Association.

ccTalk

The ccTalk multidrop bus protocol uses an 8 bit TTL-level asynchronous serial protocol. It uses address randomization to allow multiple similar devices on the bus (after randomisation the devices can be distinguished by their serial number). ccTalk was developed by CoinControls, but is used by multiple vendors.

See also Bus network topology EIA-485 1-Wire Open collector I2C

References

External links IBM Journal of Research and Development

Worked examples

Example 1 — a first encounter with Multidrop bus

Start with the simplest possible case. Write down what Multidrop bus 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 Multidrop bus 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 Multidrop bus 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 Multidrop bus

In research: Multidrop bus 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 Multidrop bus 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: Multidrop bus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer buses, so understanding it makes those chapters shorter.
In everyday life: Look for Multidrop bus 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 Multidrop bus in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Multidrop bus 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 Multidrop bus out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Multidrop bus in simple terms?

A multidrop bus (MDB) is a computer bus able to connect three or more devices. A process of arbitration determines which device sends information at any point.

Why does Multidrop bus 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 Multidrop bus?

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 Multidrop bus.