Unit 3: Digital Systems and Data
What you must understand
Unit 3 builds the technical vocabulary that the rest of the course assumes. Be fluent in the relationship between data, information, knowledge and wisdom: data are raw symbols, information is data given context and meaning, knowledge is applied understanding, and wisdom is judgement about when to act. Know the characteristics of data (accuracy, completeness, timeliness, relevance, validity, reliability) and be able to argue which characteristic is most at risk in a scenario.
Understand hardware and software layers, input–process–output models, and the role of the operating system. For networks, know topologies (star, bus, mesh), transmission media, bandwidth versus throughput, protocols and the client–server versus peer-to-peer distinction. For data, know the difference between structured, semi-structured and unstructured data, and be able to choose an appropriate data type and field constraint in a relational design.
Traps
- Confusing bandwidth (capacity) with throughput (actual achieved rate).
- Calling any organised collection of data "information" without stating the context added.
- Describing a topology's advantages without linking them to the scenario's constraints.
- Ignoring non-functional requirements (security, usability, maintainability) when asked to justify a design.
Worked example
A school wants attendance recorded at the gate. A weak answer lists "use a database". A strong answer identifies the entities (Student, AttendanceEvent), keys (StudentID as primary key, StudentID + Timestamp as composite key), data types (Boolean for present, DateTime for timestamp), a validation rule (timestamp must fall within school hours) and a justification tied to accuracy and timeliness.
Rule of thumb
Every technical choice must be justified by a stated requirement. If your answer names a technology without naming the requirement it satisfies, it is incomplete.