Data Representation Flashcards
How many inputs and outputs do NOT gates have?
One Input
One Output
Put these units in order of size (smallest to largest):
Terabyte, Byte, Kilobyte, Gigabyte, Megabyte
Byte, Kilobyte, Megabyte, Gigabyte, Terabyte
Convert 17 (decimal) to binary
10001
Convert 17 (decimal) to hexadecimal
11
Convert 0011 1000 (binary) to decimal
56
What effect do left and right shifts have on binary numbers?
Left shifts multiply a binary number. For every place shifted left, the number is doubled
Right shifts divide a binary number. For every place shifted right, the number is halved
Convert 1001 1111 (binary) to decimal
159
Convert 1001 1111 (binary) to hexadecimal
9F
Convert 10 1011 (binary) to decimal
43
Convert 10 1011 (binary) to hexadecimal
2B
Convert 4A (hexadecimal) to decimal
74
Convert 4A (hexadecimal) to binary
1001010
Convert 75 (hexadecimal) to decimal
117
Convert 75 (hexadecimal) to binary
1110101
Convert 148 (decimal) to binary
10010100
Convert 148 (decimal) to hexadecimal
94
Convert 240 (decimal) to binary
11110000
Convert 240 (decimal) to hexadecimal
F0
Convert BD9 (hexadecimal) to decimal
3033
Convert BD9 (hexadecimal) to binary
101111011001
Encode this string using run-length encoding:
PPPPQQRRRSSSSSSPPPPPQQQ
(4,P), (2,Q), (3,R), (6,S), (5,P), (3,Q)
Calculate the number of bits need to store this string if it was encoded with ASCII:
PPPPQQRRRSSSSSSPPPPPQQQ
23 x 8 = 184 bits
Why do programmers prefer hexadecimal over binary and decimal?
It is simpler to remember large numbers in hex - they’re far shorter than binary numbers
Due to them being shorter, there’s less chance of input errors
It’s easier to convert between binary and hex than binary and decimal
What is the definition of a character set?
A collection of characters that a computer recognises from their binary representation
What are the four types of characters that are included in a character set?
- Uppercase letters
- Lowercase letters
- Digits
- Symbols
What are the two main character sets?
ASCII
Unicode
Define the term pixel?
One of the individual units that make up an image
Define the term bitmap?
An image made up of pixels
Define the term colour depth?
The number of bits used for each pixel
Define the term image resolution
The number of pixels in the image
What are the effects of choosing a greater image resolution or colour depth for an image?
Using a grater image resolution or colour depth mean that there are more bits in the image. This can give a higher quality image, but also increases the file size.
How does audio sampling work?
- Sound is recorded by a microphone as an analogue signal
- The analogue signals are converted into digital data by analogue to digital converters so that the computers can read and store sound files
Define the term sample rate
How many samples you take in a second
What happens when you increase the sample rate?
Increasing the sample rate means the analogue recording is sampled more often.
The sampled sound will be better quality and will more closely match the orignal recording.
However, increasing the sample rate will also increase the file size
Define the term sample resolution
The number of bits available for each sample
What happens when you increase the sample resolution?
Increasing the sample resolution means the digital file picks up quieter sounds, even if they’re happening at the same time as louder ones.
This will also result in a sampled sound that is closer to the quality of the orignal recording.
However, increasing the sample resolution will increase the file size
Why might you want to compress data?
Smaller files take up less storage space on a device
Streaming and downloading files from the internet is quicker as they take up less bandwidth
It allows webpages to loads more quickly in web browsers
Email services normally have restrictions on the size of the attachment you can send - compressing the file allows you to send the same content with a much smaller file size.
What is the difference between lossy compression and lossless compression?
Lossy compression works by permanently removing data from the file - this limits the number of bits the file needs and so reduces its size
Lossless compression makes the files smaller by temporarily removing data to store the file and then restores it to its orignal state when its opened
Why might you want to use lossy compression?
Greatly reduced file size, meaning more files can be stored
Takes up less bandwidth so can be downloaded and streamed more quickly
Commonly used - lots of software can read lossy files
Why might you want to use lossless compression?
Data is only removed temporarily so there is no reduction in quality - the compressed file should look or sound like the original
Can be decompressed - turned back into the original
Can be used on text and software files
What is the formula used to calculate the size of a sound file
File size (in bits) = sample rate (in Hz) x sample resolution x length (in seconds)
Define the term number base
A number base is the number of digits or combination of digits that a system of counting uses to represent numbers
Explain the purpose of hexadecimal
It can be used to write large binary numbers in just a few digits
Describe the ASCII and Unicode character sets
ASCII is a character encoding that uses numeric codes to represent characters
Unicode is a universal character encoding standard that assigns a code to every character and symbol in every language in the world
