Data Representation Flashcards
What base system is binary?
Binary is a base 2 system
What base system is denary?
Denary is a base 10 system
What base system is hexadecimal?
Hexadecimal is a base 16 system
What is a bit?
A bit is the smallest unit of all computing memory storage terms
How many bits is each ASCII character represented by?
7 bits
How many bit is each Unicode character represented by?
16 bits
How do you convert from denary to hexadecimal?
Divide the number by 16 and whatever that value is write that in hex, then add the remainder as the second digit (if the number is too large use the powers of 16)
How do you convert from binary to hexadecimal?
Divide the byte into 2 nibbles and then write each nibbles value in hex and join the values
What is a computer register?
A computer register is a small, but very fast piece of memory. It can have 8,16 or 32 bits (all calculations in computers are performed by registers)
Why do computers use binary to represent data?
As binary is stored as 1’s and 0’s it offers a simple and efficient way to control logic circuits
Why is hexadecimal used by programmers instead of binary?
It is used as it is easier to write and remember and people are less likely to make errors when using it
What is ASCII used for?
ASCII is used to represent characters (it does this through encoding 128 characters into 7 bit binary codes)
What are 4 types of variables?
Integers, chars, strings, booleans
What are bitmap images made up of?
Bitmap images are made up of pixels
What is a pixel?
A pixel is the smallest identifiable area of an image
How are bitmap graphics created?
Bitmap graphics are created using a grid of pixels where each pixel is given a colour value
What is resolution?
The concentration of pixels within a specific area ( it is measured by the image height and width in pixels)
What is colour depth?
Colour depth is the number of bits used to represent each colour (to the find the number of colours you do 2 to the power of the the colour depth)
How do you calculate the file size of a bitmap image in bits?
Width X height X colour depth
What is metadata?
Metadata is data about data. It is information other than image data that is stored with a file such as it’s colour depth and date created
How does lossy compression work?
Lossy compression reduced the file size by permanently removing some of the original data and recreating the file using the remaining data by using algorithms to guess the removed content, this greatly reduces the file size but reduces the image quality
How does lossless compression work?
Lossless compression works by removing unnecessary metadata and averaging out pixel colours. This leads to less file size reduction but greater image quality
How is sound digitized?
Sound is digitised by sampling the sound wave thousands of times per second and converting the samples to binary
How can recording quality be increased?
By increasing the frequency of samples taken and measuring the waves amplitude more accurately
