7-8 Digital Technologies: Representing data with binary Hangman

The 19 key terms

1data

Raw facts and values, like names or scores. When data is organised so it has meaning, it becomes information, like a table showing each class's average score.

2numeric data vs text data

Numeric data is numbers you can calculate with, like 12 or 3.5. Text data is words and characters, like cat or a phone number, which you never add up or average.

3file

A named chunk of stored data. Pictures, sounds and videos are all data that a digital system saves as files, such as photo.jpg, song.mp3 or clip.mp4.

4digital data

Computers store text, pictures and sound as numbers. Data is converted into number codes so a digital system can store it and work with it.

5bit

A bit is a single binary digit that is either 0 or 1, like a switch that is off (0) or on (1). A group of 8 bits is called a byte.

7Add the place values that have a 1

To read a binary number, add up the place values (1, 2, 4, 8...) that have a 1 under them and ignore the 0s. For example, 1011 is 8 + 2 + 1 = 11.

98-bit binary: 128 64 32 16 8 4 2 1

A byte has 8 bits with place values 128 down to 1. Add the place values that are 1s. The smallest number is 0 and the largest is 11111111 = 255, so a byte stores 0 to 255.

10subtract place values

To write a number in 8-bit binary, go from 128 down to 1. If the place value fits in what is left, write 1 and subtract it. If not, write 0. Check by adding the place values.

12character code

A number the computer uses to stand for one letter or symbol. It stores the number, then turns it back into the character on screen. In one A=1 code, A is 1 and B is 2.

14ASCII

A standard table that gives every character a number, such as A = 65 and a = 97, so computers can store text as binary. Lowercase codes are 32 more than capitals.

15Unicode

A system that gives every character a unique number, including letters from many languages and emoji, so it covers far more than the small ASCII table.

16pixel

A pixel is one tiny square in a grid that makes up a digital image. Each pixel is stored as a number, such as 0 for white or 1 for black.

18resolution

The number of pixels in an image, given as width x height (like 1920 x 1080). More pixels give more detail but make a bigger file.

19Sampling

Measuring a sound wave thousands of times per second and storing each measurement as a binary number.

20sample rate

The number of sound measurements taken each second, in hertz (Hz). CDs use 44,100 Hz. A higher rate gives better quality but makes a bigger file.

21KB, MB, GB, TB

Units of storage size built on the byte. Each unit is about 1000 times bigger than the one before: 1 KB, then 1 MB, then 1 GB, then 1 TB. Use them to check if files fit on a drive.

22width x height x bits per pixel

The size of an uncompressed bitmap image in bits. Multiply width by height by the bits used for each pixel, then divide by 8 to get bytes.

23File size

How much storage a file needs, based on how much data (text, image, audio) it contains.

24Compression

Reducing file size by removing or simplifying data, sometimes losing quality.