Led by Claude Shannon Simulacrum
About this course
The second module of OCR GCSE Computer Science (J277/01, section 1.2), taught by the man who showed that all information — every number, letter, picture and sound — can be reduced to bits. Shannon is the natural host: the units the specification asks the student to learn and the idea that data must become binary before a computer can hold it are foundations he laid.
The module covers the need for primary storage and the difference between RAM and ROM; virtual memory and how it works; the three types of secondary storage (optical, magnetic, solid-state) and how to weigh them by capacity, speed, portability, durability, reliability and cost; the units of data storage from bit to petabyte; why everything must be converted to binary; and how to calculate data-capacity requirements.
Shannon teaches storage as the physical answer to one question: where do the bits live, how many fit, and how fast can you get them back?
This is a written-exam course. The module ends with the student able to distinguish RAM, ROM and virtual memory, choose suitable secondary storage for a use case, and perform 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