Data Representation Flashcards
Explain why computers use binary.
Computers operate using logic gates, which have only 2 states, true and false
What is a computer made up of?
Billions of switches, which have an off (0) and on (1) position - this is called binary
How would you work out the number of possible combinations per switch?
You would do 2 to the power of n - with n being the number of switches
What are the units of data storage?
Bit - 0 or 1 Nibble - 4 bits Byte - 8 bits Kilobyte - 1000 bytes Megabyte - 1000 kB Gigabyte - 1000 MB Terabyte - 1000 GB Petabyte - 1000 TB
What are the rules in binary addition?
0 + 0 = 0
0 + 1 = 1
1 + 1 = 0 carry a 1
1 + 1 + 1 = 1 carry a 1
What is an overflow error?
When the result of adding two binary numbers is greater than the number of bits allowed
What is a binary shift?
A binary shift moves all of the bits in a given binary number either to the left or the right by a given number of places
What would a shift to the left do to a binary number?
multiply the number by 2 - you do 2 to the power of n (with n being the number of shifts)
What would a shift to the right do to a binary number?
It would divide the number by 2 - you would do 2 to the power of n (n being the number of shifts)
What is a character set?
A character set consists of all the letters, numbers and special characters that can be recognised by a computer system
How many characters does the ASCII character set include?
7 bits - 128 characters
How many characters does the Extended ASCII set include?
8 bits - 256 characters
How many characters does Unicode include?
16 bits - 65,536 characters
Explain one limitation of the ASCII character set.
➜ASCII uses only 7 bits so it can only represent 128 characters
➜which is not enough to represent other languages (e.g. Russian and Arabic)
What is a bitmap image?
A bitmap image is a digital image made up of pixels
What are pixels?
Pixels represent the smallest identifiable area of an image, each appearing as a square with a single colour
What is the colour/bit depth of an image?
its the number of bits per pixel
How do you figure out the bit/colour depth?
for example: 4 colours 4 = 2 to the power of 2 so the colour depth = 2 bit per pixel (the power is the bit depth)
What are the effects of increasing colour/bit depth of an image?
➜More colours can be represented so quality of the image increases.
➜However, this increases the file size
What is the resolution?
It is the density of pixels in the same area
What are the effects of more pixels per inch?
➜It will improve the overall quality
➜Which will increase file size
➜Which makes it possible to enlarge the image without visible loss of quality
What is metadata?
Metadata is the data stored in a file alongside the actual file data identifies
What are some examples of metadata?
➜Date created
➜File type
➜GPS location
What must analogue sounds be digitally recorded in?
binary
