Architecture

Architecture

1. CPU

   • CONTROL UNIT
     • Completes fetch-decode-execute cyle
       • hertz = amount of cycles executed per second
     • tells the rest of the CPU what to do
   • Arithmetic Logic Unit (ALU)
     • DOes basic calculations e.g baddition, subtraction, multiplication and division
     • performs logic operations such as AND, OR, WHILE, etc.
     • Accumulator
       • stores intermediate results of calculations in ALU
   • Von Neumann Architecture
     • REGISTERS
       • Memory Address Register (MAR)
         • Holds memory address about to be used by CPU
       • Memory Data Register (MDR)
         • Holds actual data or instruction. May have been fetched from memory or waiting to be written
     • Cache
       • Very fast memory
       • not much storage and very expensive

2. CPU Performance

   • clock speed
     • number of instructions a processor can do in one second (measure in hz)
       • 1 GHz is 1 billion Hz
     • higher the clock speed, faster the computer runs
   • Cache Size
     • Cache is expensive, however the morte cache you won the more frequently used data stored wqhich means the faster your account runs

3. GCSE Computer Science

4. GCSE Computer Science

   • Protocols TCP/IP Layers
     • Protocols
       • HTTP(S)
         • Used to access the a website using a web browser. HTTPS is the secure version
       • IMAP/POP3
         • Downloading mail to your computer
       • FTP
         • Transmitting a file from a client to a server
       • SMTP
         • Sending an email from one mail server to another
     • Layers mean that a layer can be changed or removed without affecting any other layers