Unit 2: Data Representation Flashcards
Which numbers are stored in one bit?
0 and 1
How many bits are there in a nibble and a byte?
Nibble = 4 bits
Byte = 8 bits
What are the units after a kilobyte?
Megabyte, Gigabyte, Terabyte, Petabyte
What is zero as an 8 bit Binary number
0000 0000
What is 255 in Binary?
1111 1111
What is 39 as an 8 bit Binary number?
0010 0111
Convert C in hexadecimal to denary
12
What’s 2B hexadecimal in Binary?
2B = 162 + 1B = 32 + 11 = 43
0010 1011
What’s 1010 0011 in hexadecimal?
A3
Calculate
1001 0101
+ 0010 0110
1001 0101
+ 0010 0110
________________
1011 1011
Explain what effect a left and right shift have
Left shift doubles the number
The right shift halves the number
Calculate the left shift of 0110 1011
1101 0110
How many bits are in the extended ASCII?
8 bits
How many characters does ASCII allow for?
256
How many bytes are in Unicode?
16-bit has 2 bytes
32-bits has 4 bytes
If ‘f’ has the ASCII code 102, what is the ASCII code for ‘g’?
103
How many bytes are needed to store “Hello everyone.”?
15 (remember to include space and the full stop)
A bitmap graphic is made up of…
Individual pixels
Each … is represented in Binary
Pixel
The … determines the number of available colours for an image
Number of bits per pixel
Image … holds data about the image, such as …
Metadata
Colour depth, resolution, date created, author
The greater the … of the image, the greater the file size
Resolution
The sample rate is measured in what unit?
Hertz (Hz)
The number of bits available to store each sample is known as what?
Bit depth
What is the formula for calculating the size of an uncompressed music file?
Sample rate x bit depth x duration
Track1.wav uses a sample rate of 20 kHz, Track2.wav uses a sample rate of 10 kHz. Which file is the higher quality? Which is the larger file size?
Track1 is higher quality and a larger file size
Explain the need for compression
Compression reduces the size of files, which makes them smaller to store and transmit – this enables services such as streaming music and video
Explain Lossy compression
The compression technique will lose some of the original information
Explain some of the effects of lossy compression on images and sound files
Noise at edges and blocks are digital artefacts from lossy compression
Explain Lossless compression
No data is lost by using a lossless compression algorithm
