computer science

Headless computer

Headless computer 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 Headless computer rather than just read about it. In short: A headless computer is a computer system or device that has been configured to operate without a monitor (the missing "head"), keyboard, and mouse. A headless system is typically controlled over a network connection, although some headless system devices require a serial connection to be made over RS-232 for administration of the device.

Key takeaways

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

Reference excerpt

A headless computer is a computer system or device that has been configured to operate without a monitor (the missing "head"), keyboard, and mouse. A headless system is typically controlled over a network connection, although some headless system devices require a serial connection to be made over RS-232 for administration of the device. Headless operation of a server is typically employed to reduce operating costs.

PC BIOS limitations During bootup, some (especially older) PC BIOS versions will wait indefinitely for a user to press a key before proceeding. If some basic device, such as a video card or keyboard, are not installed or connected, this could effectively halt an unattended system. On more modern systems, the BIOS factory setting will typically be configured to behave this way as well, but this setting can be changed with a BIOS setup utility to proceed without user intervention. Even in cases where a system has been set up to be managed remotely, a local keyboard and video card may still be needed from time to time; for example, to diagnose boot problems that occur before a remote access application is initialized.

Hardware remote control Some servers provide for remote control with an internal network card and hardware that mirrors the console screen. For example, HP offers a system called Integrated Lights-Out (iLO) that provides this function. Remote access to the system is gained using a secure web connection to an IP address assigned to the iLO adapter, and allows for monitoring of the system during start-up, before the operating system is loaded. Another hardware solution is to use a KVM-over-IP switch. Such a switch is a traditional Keyboard-Video-Mouse device with the added ability to provide remote control sessions over IP. Connection to the KVM device is gained using a web browser, which allows for remote monitoring of the connected system console port.

Software remote control

Administration of a headless system typically takes place with a text-based interface such as a command line in Unix or in Linux. These interfaces, often called "virtual terminals" or "terminal emulators", attempt to simulate the behavior of "real" interface terminals like the Digital Equipment Corporation's VT100, but over networks, usually using protocols such as Secure Shell. One can also use systems such as X Window System and VNC combined with virtual display drivers - this setup allows remote connections to headless machines through ordinary graphical user interfaces, often running over network protocols like TCP/IP.

See also Xvfb x11vnc Headless software Embedded systems Emergency Management Services (EMS) Serial over LAN (SOL) Console redirection CTTY (DOS command) Shell shoveling Keyboard computer

References

Illustrations

Worked examples

Example 1 — a first encounter with Headless computer

Start with the simplest possible case. Write down what Headless computer 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 Headless computer 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 Headless computer 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 Headless computer

In research: Headless computer 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 Headless computer 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: Headless computer is common in secondary-school and first-year university syllabi. It links to neighbouring topics Classes of computers, System administration, so understanding it makes those chapters shorter.
In everyday life: Look for Headless computer 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 Headless computer in 20 minutes

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

Frequently asked questions

What is Headless computer in simple terms?

Why does Headless computer 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 Headless computer?

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 Headless computer.