Learning path: Computers

No prerequisites

Computers has no prerequisite concepts: you can start here.

1. ComputersYour goal

   A computer is a device that takes in digital data, processes it by following a program of instructions, stores it and produces results. Inside, everything is represented as bits, each either 0 or 1. Most computers still follow the organisation John von Neumann described in 1945: a processing unit, a control unit, a memory that holds both instructions and data, and input and output.

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Where to go next

Concepts that build directly on Computers:

• AI basics: Artificial intelligence (AI) is the field of building machine-based systems that, for a given set of objectives, produce outputs such as predictions, recommendations or decisions. Early AI tried to write intelligence down as hand-made rules; much of modern AI instead learns patterns from data. Today's systems can be remarkably strong at some tasks and surprisingly weak at others, so knowing what an AI system was built and tested to do matters as much as knowing what it can do.
• CPU: The central processing unit (CPU) is the part of a computer that carries out a program's instructions. It repeatedly fetches an instruction from memory, decodes it, executes it and stores the result, all kept in step by a clock ticking billions of times a second. Its instruction set architecture is the contract that lets the same software run on different processor designs.
• Memory: Computer memory holds the instructions and data a processor is using, while storage keeps information when the power is off. Working memory (RAM) is usually volatile: DRAM stores each bit as a tiny charge on a capacitor that leaks and must be refreshed. Computers combine small, very fast memories near the processor with larger, slower ones further away, and measure capacity in bytes using decimal (GB) or binary (GiB) prefixes.
• Networks: A computer network links devices so they can exchange data, over copper cable, radio (wireless LANs) or optical fibre. Data travels as packets, each carrying addresses, and is handled by a stack of protocol layers from the physical link up to applications. Routers join separate networks together by forwarding each packet on its own, while the end devices keep track of reliability.