# USB Interfaces

- **Track:** Cambridge IGCSE™ Computer Science (0478 / 0984) (CAMBRIDGE IGCSE 0478)
- **Module:** Section 2: Data Transmission
- **Estimated Duration:** 10 minutes
- **Access:** Open Theory (All-Access for Interactive IDE & Autotests)

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## Theory & Conceptual Background

Universal Serial Bus connects peripherals to a computer using a standard interface. It sends data serially. A connection may also supply power, allowing some peripherals to operate without a separate power supply.

## Establishing communication

When a device is connected, the host identifies it and establishes how to communicate. Operating-system support and a suitable device driver allow applications to use it. Plug-and-play support reduces manual configuration; it does not guarantee every device works with every computer.

## Worked decision

A photographer connects a camera using USB to copy images. The standard interface is convenient and may charge the camera. The cable restricts movement; the connector and data/power capabilities must be compatible. A connector that fits does not alone establish the transfer rate.

## Advantages and limitations

Common connectors, widespread support and automatic detection simplify use. Cable reach, available ports, compatible versions and shared bandwidth can limit it. Wire counts, speeds and cable limits differ by version: learn the trade-off rather than a universal specification number.

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## Interactive Exercises & Autotest Specifications

### Exercise 1: Application: Choosing USB (Fill in blank, 30 XP)

**Instructions:**
Work out each answer before submitting. Data travels serially or in parallel? Can the interface carry power as well as data: yes or no? Does fitting the connector guarantee a particular transfer speed: yes or no?


**Starter Code:**
```text
{"prompt":"Application: Choosing USB","template":"1. Data travels serially or in parallel? [blank_1]\n2. Can the interface carry power as well as data: yes or no? [blank_2]\n3. Does fitting the connector guarantee a particular transfer speed: yes or no? [blank_3]","blanks":[{"id":"blank_1"},{"id":"blank_2"},{"id":"blank_3"}],"word_bank":["serially","in parallel","yes","no","sometimes"]}
```