Cambridge O Level Computer Science · Syllabus 2210 · Data Transmission
USB
What is USB?
USB, the universal serial bus, is a standard interface used to connect devices to a computer and transmit data between them using serial transmission.
This definition is part of the Data Transmission chapter in Cambridge O Level Computer Science.
USB in context
USB stands for universal serial bus. It is an interface — an agreed standard for connecting a device to a computer and transmitting data between them. It uses serial transmission: the bits travel one after another along the connection. Because both ends follow the same agreed communication standard, a device made by one manufacturer can be plugged into a computer made by another and the two can exchange data. The name describes the design: universal (one widely supported standard for many kinds of device), serial (bits one after another) and bus (a shared connection system carrying data and power between the computer and the connected devices).
Common mistakes with USB
- Trap. Do not answer this by describing what a USB flash drive stores. The question is about the interface.
Questions students ask about USB
What is the difference between serial and parallel transmission?
In serial transmission, bits are sent one after another along a single data line. In parallel transmission, several bits are sent at the same time, each along its own separate data line. Parallel can move more bits per unit of time over a short link, but over a longer distance the separate lines lose their timing alignment and interfere with one another, which is why long-distance links, such as USB, almost always use serial transmission instead.