Purchasing A Computer

• Parts of a computer.
  • The most important part is the CPU
    • This is the central processing unit
    • Or the "processor"
    • This is what does all of the computation
  • Memory is next
    • Two types,
      • main memory
      • Cache
  • Secondary Storage
    • Disk Drive
    • Floppy Drive
    • Other drives as well (CDROM, ...)
  • I/O devices
• The Fetch-Decode-Execute Cycle
  • This is how everything gets done.
  • The CPU asks memory for the next instruction to execute
  • Memory transfers this to the CPU
  • The cpu decodes the instruction.
  • This usually requires it to fetch some additional information from memory.
  • The CPU then executes the instruction.
• The problem:
  • Memory is MUCH slower than the CPU
  • Secondary Storage is MUCH slower than the Memory
• Cache, memory close to the CPU
• Register/Word size
  • This is the size of data that the computer deals with.
  • This is always a power of two. (8, 16, 32, 64 for now)
• So the choices in the Intel world:
  • A real Intel machine or a clone? (AMD)
    • What does reverse engineering mean?
  • 32 bits or 64 bits?
  • Cache or no cache?
  • Xeon, Pentium, Celeron (Intel)
  • Athelon, Sempron (AMD)
• Hyper threading, dual core