Cambridge O Level Computer Science · Syllabus 2210 · Data Transmission
Full-Duplex
What is Full-Duplex?
Full-duplex transmission is data transmission in both directions at the same time, so both devices can send and receive simultaneously.
This definition is part of the Data Transmission chapter in Cambridge O Level Computer Science.
Full-Duplex in context
These three describe which directions data is permitted to travel, and whether both directions can be active at the same moment. In simplex transmission, data travels in one direction only. In half-duplex transmission, data can travel in both directions, but not at the same time. In full-duplex transmission, data can travel in both directions at the same time. Two words decide every question in this area: direction and simultaneously.
A scenario question never wants a memorised list. It wants you to find the features of the situation that decide the answer, and then say which property of the method each of those features points to. Two independent questions have to be answered every time: how do the bits travel? (serial or parallel) and which directions are needed, and when? (simplex, half-duplex or full-duplex). Answering only one of them leaves half the marks on the table.
Common mistakes with Full-Duplex
- Trap. Every one of the three definitions turns on direction and, for the last two, on at the same time. Leave out “at the same time” and half-duplex and full-duplex become indistinguishable.
Questions students ask about Full-Duplex
What is the difference between simplex, half-duplex and full-duplex transmission?
These describe which directions data may travel and whether both directions can be active at once. Simplex transmission sends data in one direction only, such as a keyboard sending keystrokes to a computer. Half-duplex allows data both ways, but not at the same time. Full-duplex allows data to travel in both directions at the same time, so both devices can send and receive simultaneously. The two words that decide every question here are direction and simultaneously.