Topic 3: Units and Data Representation Flashcards
Why must data be stored in binary form
Data must be stored in binary from because in a computer the processor can only recognize 1s and 0s
How do you calculate file sizes of sound
sound file size= sample rate x duration x bit depth
How do you calculate the file size of an image
image file size = colour depth x image height x image width
How do you calculate the file size of a text file
text file size = bits per character x number of characters
Where do you find the “most significant bit”
The most significant bit is found on the furthest left as it holds the most value
Where do you find the “least significant bit”
The least significant bit is found on the furthest right as it holds the least value
What happens when you complete a binary shift to the left once
The number doubles
What happens when you complete a binary shift to the left twice
The number doubles twice- quadruples
What happens when you complete a binary shift to the right once
The number halves
What happens when you complete a binary shift to the right twice
The number divides by two twice causing it to divide by four
Carry out a binary shift to the left on 01110101
11101010
Carry out a binary shift to the right on 01110101
00111010
What is a limitation of ASCII
It only has 7-bit so can only represent 128 characters so can only represent one language
What is a limitation of Extended ASCII
This is an additional bit meaning it can represent 256 characters meaning they ca include special characters in different languages however doesn’t account for all global languages
Why is unicode better than ASCII and Extended ASCII
Unicode represents over 65000 characters as it has 16-bit. As a result it will account for all global language and symbols
If A in ASCII is represented by the code 46 then what is E
50
What are digital images made up of
Digital images are made up of pixels. Each pixel is represented by a binary number.
What is color depth
To add color, more bits are required for each
pixel. The number of bits determines the range of colors.
How do you calculate image size
image height x image width
How do you calculate image file size (answer in kilobytes)
(image height x image width x color depth) / 8000
What is the resolution of an image
The resolution of an image refers to how tightly packed the pixels are. If an image has a high resolution it tends to a higher file size
What is metadata
Information about the file itself
What is the sample rate
The number of samples recorded in any given time- measured in hertz
What is the duration of a sound file
How long the file lasts
What is bit depth
Bit depth refers to the number of bits used to record each sample.
How do you calculate the bit rate
sample rate x bit depth
What happens in lossy compression
With lossy compression, some data is removed and discarded, thereby reducing the overall amount of data and the size of the file.
What happens in lossless compression
With lossless compression, files are reduced in size without the loss of data. However, lossless compression does not usually achieve the same file size reduction as lossy compression.
Which type of files would be suitable for lossless compression
Text files, spreadsheets, financial records and emails
How do you convert from bits to bytes
8 Bit = 1 bytes
How do you convert from bytes to kilobytes
1024 Bytes = 1 Kilobyte
How do you convert from kilobytes to megabtes
1024 Kilobytes = 1 Megabyte
How do you convert from megabytes to gigabytes
1024 Megabytes = 1 Gigabyte
How do you convert from gigabytes to terabytes
1024 Gigabytes = 1 Terabyte
How do you convert from terabytes to petabytes
1024 Terabytes = 1 Petabyte
