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EnglandComputer Science

1.2 Memory and storage

7 dot points across 7 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How do you convert between denary and binary, add binary numbers and use binary shifts?

Converting between denary and binary (up to and including 8 bits), binary addition and the detection of overflow, and binary shifts and their effect.
An OCR J277 1.2.4 answer on converting between denary and binary up to 8 bits, adding binary numbers and detecting overflow, and binary shifts and their effect on a value.
10 min answer →

How are characters, images and sound represented in binary, and what affects their file size?

Representing characters with ASCII and Unicode; representing images with pixels, colour depth, resolution and metadata; representing sound with sample rate, sample resolution and bit rate; and the effect on file size and quality.
An OCR J277 1.2.4 answer on representing characters (ASCII, Unicode), images (pixels, colour depth, resolution, metadata) and sound (sample rate, sample resolution, bit rate), and the effect of each on file size and quality.
11 min answer →

Why is data compressed, and what is the difference between lossy and lossless?

The need for compression and the difference between lossy and lossless compression, with their typical uses.
An OCR J277 1.2.5 answer on the need for data compression and the difference between lossy and lossless compression, including how each works and their typical uses.
8 min answer →

Why is hexadecimal used and how do you convert between binary, denary and hex?

Why hexadecimal is used to represent numbers, and how to convert between binary, denary and hexadecimal.
An OCR J277 1.2.4 answer on why hexadecimal is used in computing and how to convert between binary, denary and hexadecimal, with worked conversions in both directions.
9 min answer →

What is primary storage and why does a computer need RAM, ROM and virtual memory?

The need for primary storage, the purpose and characteristics of RAM and ROM, the differences between them, and the need for virtual memory.
An OCR J277 1.2.1 answer on the need for primary storage, the purpose and characteristics of RAM and ROM, the differences between them, and why virtual memory is needed.
9 min answer →

Why does a computer need secondary storage and how do you choose the right type?

The need for secondary storage, the common types (optical, magnetic, solid state) and how to choose a suitable device using capacity, speed, portability, durability, reliability and cost.
An OCR J277 1.2.2 answer on the need for secondary storage, the three common types (optical, magnetic, solid state), and how to choose a suitable device by capacity, speed, portability, durability, reliability and cost.
9 min answer →

How is the amount of data measured, and why is binary used?

Why data must be represented in binary, the units of information (bit, nibble, byte, kB, MB, GB, TB, PB) and how to convert between them.
An OCR J277 1.2.3 answer on why computers use binary, the units of information from bit and nibble up to petabyte, and how to convert between units of data capacity.
8 min answer →