Error Checking | Computer for GCSE/IGCSE - Year 11 PDF Download

Introduction

• When data is received, it may contain errors and corruption.

Why check for errors?

• Computers rely on data being in specific formats for smooth operations. 
• A format organizes data for clear human and machine understanding, ensuring efficient system functionality and minimizing misunderstandings. 
• Example of Date and Time Formats:
  • Formats for date and time, such as DD/MM/YY, MM/DD/YYYY, and MMM/DD/YY, illustrate how information can be structured differently.
  • For instance, 13/04/14 can represent April 13, 2014, or January 4, 2013, depending on the format used.
• Computers rely on data formats for accurate processing; deviations can lead to errors.
• An error occurs when received data does not align with expected formats, hindering processing and potentially causing confusion.

How is data represented?

All information is stored in binary form, using 1's (representing high voltage) and 0's (representing low voltage).

• For instance, the decimal number 67 is expressed in binary as 01000011.
• If an error occurs, one of the bits might change from 1 to 0 or vice versa.
• By way of example, if the sixth most significant bit is altered from 0 to 1, 01000011 would become 01000111, transforming 67 into 71.
• The ASCII representation of 67 corresponds to the uppercase letter 'C', while 71 corresponds to 'G'.
• A single bit flip can entirely modify the meaning of the binary sequence.
• In a scenario where a book is sent over a network and numerous bits are flipped, the original text could become challenging to decipher.

How can errors cause problems?

• Certain errors are minor and insignificant, like a single swapped letter within extensive text.
• However, errors in critical data such as postage addresses, aerospace coordinates, or bank transfers can be challenging to rectify and may lead to severe consequences.
• Any computer-reliant task involving highly sensitive or secure processes necessitates robust error-checking and correction methods.

How do errors occur?

Errors in technology can stem from various sources, both wired and wireless, often due to interference.

• Interference in Wired and Wireless Technology: Errors can manifest in both wired and wireless setups as a result of interference.
• Interference examples involve wire wear and tear or alterations in electrical fields affecting the signal.
• Interference can result in different outcomes:
  • Data loss occurs when information is not transmitted correctly.
  • Data gain refers to the reception of extra data during transmission.
  • Data change indicates alterations or flips in bits of data.
• Wireless technology employs radio or electromagnetic signals for data transfer, facing specific hurdles.
  • Physical Barriers: Buildings, walls, vehicles, and other objects can obstruct wireless signals.
  • Interference Sources: Interference may arise from weather conditions like rain or clouds, as well as competing wireless signals or electromagnetic radiation.
• Compared to wireless, wired technology carries distinct error risks mainly due to physical components.
  • Component Vulnerability: Physical components in wired systems can degrade, sustain damage, or be affected by external signals.
  • Transmission Interruptions: Data loss can stem from signal blockages or intermittent transmission issues in wired setups.