Computer science

• Computer


  A machine that processes data
• Computer


  • Consists of hardware and software
• Hardware


  Physical stuff - CPU, motherboard, etc.
• Software


  Programs or applications - video games, printer drivers, etc.
• Embedded systems


  Computers built into other devices
• Embedded systems are computers inside a larger system
• CPU


  • Control unit
  • Arithmetic/Logic unit
  • Registers
• Fetch-Execute Cycle


  1. Fetch the instruction

  2. Decode the instruction

  3. Execute the instruction
• The CPU accesses memory to fetch instructions and data
• The CPU has a control unit, arithmetic/logic unit, and registers
• The cache is a small, fast memory that stores frequently accessed data and instructions
• Von Neumann's Design


  1. Program counter - holds the memory address the instruction for each cycle

  2. Accumulator - Stores results of the calculations from the ALU

  3. MARholds any memory address about to be by the CPU

  4. MDR-holds the actual date/instruction
• Network Protocol
• Network Protocols


  • TCP
  • IP
  • HTTP
  • HTTPS
  • FTP
• Network Prascos are divida


  Layer
• Fetch - Execute Cycle

  1. Copy memory address from the program court to the th

  2. Copy the instruction Stored in the MAR addres to the MDR

  3. Increment the program counter to point to the address of the next instruction recidy for the next cycle
• Decode


  The instruction in the MORIS decoded by the W. The Cu may then prepire for the next step
• Execute


  The instruction is perponed. This could be load data from memory write data to memory.do a calculation or logic opencer on
• Controlling data down
• Memory


  Twin rou mache but feeker than secondary
• Compression


  • Lossy
  • Lossless
• Lossy


  • Greatly reduced resize
  • Take up less bandwidth so can be downloaded and savetimed quaker
  • Commonly used
  • Loses dauka
  • cant be used on text or software Ates
  • Worse quality lat this is usualls unnaiceable
• Lossless


  • no reduction in quality, files can be decompress
  • can be used ontext or Software files
• Analogue digital


  process called Samping
• Samping


  vent we sample the amplitude of the wave it can only taxke certain thrin. Once it has
• Sound


  Sampled and stored digitally
• Factors affecting Size + Quality of Sound cing

  • Sample rate is how many Samples you take in second and it measured in Hertz
  • Bit depth is the number of bits arcerate
  • File Size=Sample rate xbit depth x lengh
  • Increasing sample rate means the analogue recording is sampled more often
  • Increasing the sample rate or bitdoph will increase the file size
• Protocols


  • HTTPS
  • FTP
• Sampling sound
• Sound is sampled and stored digitally
• Analogue digital is done by an converter this. process is called samping...


  1. To convent we sample the amplitude of the wave regular intervals, it can only take Certain values depending on the bit depth. Once it has been sampled it creates the curve digitally

  2. The digital data is about the same shape but it's not continuous and has lost a-lot of data. This can be improved by taking more regular samples
• bring Images
• Images


  Stored as a series of Pixels
• Increasing colour depth + resolution


  • Increases the file size an file size image resiction=colour depth <= width x height colour depth
• Devices need metadata to display the image
• is usually includes the images Bile format, height with Colour depth and resoluti
• Network Pracco


  • HTTP
  • FTP
• Construing d
• 2 Mating forrige
• NCHORS MAIN