17311734
Description
2.6 - Data
Representation
- How is data represented?
- Bit = 0 or 1.
- Nibble = 4 bits.
- Byte = 8 bits/ 2 nibbles.
- Kilobyte = 1000 bits.
- Megabyte = 1000 KB
- Gigabyte - 1000 MB
- Terabyte = 1000 GB
- Petabyte = 1000 TB
- Bit = 0 or 1.
- Denary --> Hex
- Divide by 16 - Whole number = the first
digit, the remainder = second digit.
- 167/16 = 10.7
- 10 = A, 7
- Therefore 167 = A7
- Therefore 167 = A7
- 10 = A, 7
- 167/16 = 10.7
- Divide by 16 - Whole number = the first
digit, the remainder = second digit.
- Binary ---> Hex
- Split the byte into 2 nibbles.
- Add up each number per
nibble and get 2 digits.
This is your answer.
- Add up each number per
nibble and get 2 digits.
This is your answer.
- You would tend to use hex because:
- Has a shorter string so
uses less storage.
- Easily converted to
binary if needed.
- Programmers find it
easier to work with.
- Has a shorter string so
uses less storage.
- Split the byte into 2 nibbles.
- Characters
- ASCII has 7 bits.
- Extended ASCII has 8 bits.
- 256 possible characters.
- 256 possible characters.
- Unicode has 2 bytes.
- giving 2^16 possibilities (65,536).
- giving 2^16 possibilities (65,536).
- To get the lower case version of a
capital letter in binary, just add 32.
- ASCII has 7 bits.
- Images
- Bitmap
- Becomes blurred when you
zoom in because each pixel is
assigned a colour.
- The page is divided into
an invisible grid.
- Every bit is mapped.
- Becomes blurred when you
zoom in because each pixel is
assigned a colour.
- Vector
- Follows a set of
mathematical instructions.
- For example:
- Draw a circle, radius = 6
pixels, centre(10,10), line
thickness =1 pixel.
- Draw a circle, radius = 6
pixels, centre(10,10), line
thickness =1 pixel.
- Doesn't blur when zoomed in.
- Follows a set of
mathematical instructions.
- Each image holds
'metadata' - data about
data.
- Resolution - the
number of pixels used.
- The higher the resolution, the
greater the quality.
- The greater the resolution,
the larger the size.
- The higher the resolution, the
greater the quality.
- Bitmap
- Compression
- Saves space, reduces the amount of
data transferred and runs quicker.
- Lossless
- No data lost, the reconstructed file is identical to
the original and not all files can be compressed
like this.
- No data lost, the reconstructed file is identical to
the original and not all files can be compressed
like this.
- Lossy
- Loses some info, acceptable
to do this with images and
vide0, but not text.
- Loses some info, acceptable
to do this with images and
vide0, but not text.
- Saves space, reduces the amount of
data transferred and runs quicker.
- Audio
- Sample frequency - the number of captured
samples per second.
- Sample size/Sample depth - the
number of bits available per second.
- Bit rate - the number of
bits used per second.
- More samples lead to better
quality but larger file size.
- Sample frequency - the number of captured
samples per second.
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