How do different components of the computer communicate with each other?

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> [!TLDR]
> All components of a computer talk over the **system bus** — a bundle of wires split into the data bus (what), address bus (where) and control bus (which operation, when) — with external devices connecting via ports.

**The idea.** The CPU, primary memory and I/O devices are separate units, yet every instruction cycle requires them to exchange information: instructions flow from memory to CPU, results flow back, keystrokes arrive from the keyboard, images go out to the monitor. Rather than wiring every component to every other, computers use a shared highway — the **system bus**, a group of parallel electrical wires over which all these transfers travel.

**The three buses inside the system bus**

| Bus | Carries | Direction |
|---|---|---|
| **Data bus** | The actual data and instructions being transferred | **Bidirectional** — data moves both to and from the CPU |
| **Address bus** | The address of the memory location or device involved | **Unidirectional** — only the CPU issues addresses |
| **Control bus** | Command/timing signals: memory read, memory write, I/O read, acknowledge | Bidirectional |

**A concrete communication, step by step** — CPU reads a value from memory:

| Step | Bus used | What happens |
|---|---|---|
| 1 | Address bus | CPU places the memory location's address on the address bus |
| 2 | Control bus | CPU asserts the *memory read* control signal |
| 3 | Data bus | Memory places the contents of that location on the data bus |
| 4 | — | CPU copies the value from the data bus into a register | …

Q.How do different components of the computer communicate with each other?

Concept understanding — Computer Bus Architecture

Bus	Carries	Direction
Data bus	The actual data and instructions being transferred	Bidirectional — data moves both to and from the CPU
Address bus	The address of the memory location or device involved	Unidirectional — only the CPU issues addresses
Control bus	Command/timing signals: memory read, memory write, I/O read, acknowledge	Bidirectional

Step	Bus used	What happens
1	Address bus	CPU places the memory location's address on the address bus
2	Control bus	CPU asserts the memory read control signal
3	Data bus	Memory places the contents of that location on the data bus
4	—	CPU copies the value from the data bus into a register

Q.How do different components of the computer communicate with each other?

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