AQA A Level Computer Science Unit 6 Latest Exam Fully Solved 2024.

Serial data transmission - Answer Bit are sent one after another along the same data line. Only one line is needed to transmit data in one direction. Parallel data transmission - Answer Several bits are sent simultaneously along separate lines or channels. This means that an 8-bit block of data will require 8 data channels. Problems with parallel data transmission - Answer Skew: - As each individual wire has different properties, bits travel at slightly different speeds and produces skew. Crosstalk: - Electromagnetic interference between two adjacent channels. It gets more pronounced as the frequency increases Serial vs Parallel transmission - Answer Parallel transmission can be used only over very short distances whereas serial transmission is reliable over very long distances at very high frequencies Synchronous transmission - Answer All data transfers are time to coincide with an internal clock pulse. The data is sent as one long stream with no gaps. The receiver counts the bits and reconstructs bytes Asynchronous transmission - Answer Each byte is sent separately the moment it is available instead of waiting for a clock signal Latency - Answer The time delay between the moment the first byte or packet of a communication starts when it is received at its destination Protocol - Answer Set of rules relating to communication between devices. Protocols define the standards for physical connections, data format and error checking procedures