Year 10 work (COMPUTER SCIENCE)

Year 10 work (COMPUTER SCIENCE)

1. Data representation

   • Binary
     • Base 2 - 0 and 1
     • Only language a computer can understand - on and off switches
   • Hexadecimal
     • Base 16 - 0 to F
     • Used by humans as it is easier to read and write (because it is shorter)
   • Denary
     • Base 10 - 0 to 9
     • Used by humans as default number system
   • ASCII
     • 7-bit
     • American Standard Code for Information Interchange
     • 128 characters
     • Numbers, lowercase, uppercase, punctuation and space
     • Takes up less storage space
   • Unicode
     • 16-bit
     • 65,536 characters
     • Used for foreign communication as it has the potential to store all characters in one character set
     • Takes up a lot of storage space
   • Bitmap images (.bmp)
     • Represented in binary easily
     • file size = width x height x depth
     • Each colour has a specific binary code
   • Sound
     • Analogue
       • All sounds heard by ear
       • Continuous
       • Converted by repeatedly measuring and recording sound wave
     • Digital
       • Sounds heard by computer
       • Discrete
     • ADCs and DACs used
     • Sample rate (Hz). Number of times a sample of sound is taken every second.
     • Sample resolution - size of the numbers used to write sound samples.
     • file size = sample rate x sample res x seconds
   • Compression
     • Lossy
       • Data is lost in the process of compression
       • e.g Reducing the quality of an image by decreasing the resolution
     • Lossless
       • No data is lost in process of conversion - can be converted back to it's original form
       • e.g Huffman trees, Run-Length Encoding

2. Networks

3. Computer systems

4. Cyber-security

5. Ethics