Universal Serial Bus (USB) (Cambridge International IGCSE Computer Science)

Spec point — 2.1.3 · "3 Understand the universal serial bus (USB) interface and explain how it is used to transmit data"

Universal Serial Bus (USB)

What is USB?

• The Universal Serial Bus (USB) is a widely used standard for transmitting data between devices

• It is a serial communication method , and it operates asynchronously

• Many devices use USB such as:

  • Keyboards
  • Mice
  • Video cameras
  • Printers
  • Portable media players
  • Mobile phone
  • Disk drives
  • Network adapters

• Different USB connector types exist for different devices

• The letters refer to the physical shape and design of the USB connector:

  • USB-A - Commonly used for flash drives, mice, keyboards, external HDD
  • USB-B - Found in printers, scanners, and older external storage devices
  • USB-C- Latest standard, known for it's small size, transfer speeds, and it's ability to carry power

• The term USB can also be followed by numbers (USB 2.0, 3.0, 4 etc.)

• The numbers refer to the generation of USB technology, which determines the speed and performance:

  • USB 1.1 - 12 Mbps (very slow)
  • USB 2.0 - 480 Mbps (very common but slower compared to modern versions)
  • USB 3.0/3.1/3.2 - 5 Gbps to 20 Gbps (much faster, used for external HDDs and gaming devices)
  • USB4/ USB4 2.0 - Up to 80 Gbps (the latest and fastest, used for high speed data transfer)

• When a device is connected to a USB port the computer:

  • Automatically detects that the device has been connected

  • Looks for the correct driver:

    • If the driver is already installed, the appropriate device driver is loaded so that the device can communicate with the computer
    • If the device is new, the computer will look for a compatible device driver
    • If one cannot be found, the user must download and install an appropriate driver manually

Advantages and disadvantages of USB

Worked Example Julia uses a USB connection to transfer data onto her USB flash memory drive.

One benefit of using a USB connection is that it is a universal connection.

(i) State two other benefits of using a USB connection.

[2]

(ii) Identify the type of data transmission used in a USB connection.

[1]

Answers

(i) Any two of:

• It cannot be inserted incorrectly [1] - Supports different transmission speeds [1]
• High speed transmission [1] - Automatically detected [1]
• **Powers the device for data transfer [1]

(ii)

-** Serial [1]