1.2.3 Units
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Units of data storage
• Bit • Nibble (4 bits) • Byte (8 bits) • Kilobyte (1,000 bytes or 1 KB) • Megabyte (1,000 KB) • Gigabyte (1,000 MB) • Terabyte (1,000 GB) • Petabyte (1,000 TB)
Converting between units:
Why must data be stored in binary format?
Because computer systems consist of billions of tiny translators which are switches that only have 2 values - on (1) off or (0). Therefore all data must be represented and processed in this way.
Why is the binary system know as base 2?
Because there are only two digits to select from (1 and 0)… …and when using the binary system, data is converted using the power of two.
Why is does having just 2 states (0 and 1), make is simple to build electronic devices?
With 2 states, electronic components are: -Easier to manufacture -Therefore cheaper -More reliable
What are some examples of using 2 states to store data?
-RAM -Hard disk -Optical disc -Flash memory
Text file size calculation
bits per character x number of characters
Sound file size calculation
sample rate x duration (s) x bit depth
Character set
-A defined list of characters that are recognised and can be stored in a computer system. -All characters are assigned a unique binary code
Unicode
A character set that uses 16 bits (2 bytes) to present characters, allowing for a wider range of characters than ASCII
Describe how an analogue sound wave is converted into digital form.
-(analogue) sound wave is sampled -… amplitude/height (of wave) is measured -… at set/regular time intervals // by example -Each sample/measurement is stored as a binary number
Describe how bitmap images are represented in binary.
-Image made of / split up into pixels -Each pixel given a binary code… -…which represents the colour of that pixel -Each colour is given a different/unique binary code. -Metadata stored alongside the image