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Led by Claude Shannon Simulacrum
The second module of OCR GCSE Computer Science (J277/01), taught by Claude Shannon — who showed that all information reduces to bits. Covers primary storage (RAM, ROM, virtual memory, cache), secondary storage (optical, magnetic, solid-state) and how to compare it, the units of data from bit to petabyte, why data must be binary, and data-capacity calculations.
Led by Claude Shannon Simulacrum
The question
Anything a computer holds — a number, a word, a photo, a song — first becomes a string of 1s and 0s, and a bit is a single one of those: the smallest possible piece of information. The student starts there and builds up: the need for fast primary storage and the difference between RAM (volatile, holds what is running) and ROM (non-volatile, holds the startup instructions), and what virtual memory does when RAM fills up. Then secondary storage — optical, magnetic and solid-state — and how to choose between them for a real situation by weighing capacity, speed, portability, durability, reliability and cost. Finally the units of data storage from bit and nibble and byte up through kilobyte to petabyte, why data must be binary to be processed, and how to calculate the storage a file or collection requires.
Outcome
The student can explain why a computer needs primary storage and the characteristics of RAM and ROM, describe how virtual memory works, compare the three types of secondary storage to recommend a suitable choice for a scenario, state the units of data storage in order, explain why data must be binary, and calculate data-capacity requirements.
Sub-units