Intro to Computer Organization

8 Great Ideas of Organization

1. Moore’s Law: Processing power doubles every few years
2. Use abstraction to simplify design; divide big problems into smaller ones
3. Make the common case fast because the common case will be used very often
4. Increase performance via parallelism; do multiple things at once
5. Increase performance via pipelining; make use of all stages and steps whenever possible
6. Increase performance via prediction
7. Implement a hierarchy of memories
8. Increase dependability via redundancy

Von Neumann Architecture

• Much of modern computer architecture is based on Von Neumann Architecture
  • Separate CPU and RAM
  • Binary instructions and program data in MIPS are stored within the RAM
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• Instructions are run in a Fetch - Decode - Execute cycle
  • All of thise stored in the memory
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Differences in Architecture

• RISC Architecture
  • Reduced Instruction Set Computers
  • Wanted to provide a minimal set of instructions that covered all necessary operations
    • Few, simple instructtions with fixed size and short execution time
    • Explicit load and store instructions for memory
  • Examples include MIPS, LC3, PowerPC, SPARC
• CISC Architecture
  • Complex Instruction Set Computers
  • Wanted to add more instructions so that programs used a smaller amount of instructions, thus reducing memory usage
    • Multiple operations per instruction
    • Many memory-related instructions
    • More information is used for each instruction due to instructions of variable length Examples include x86

Memory in Architecture

• Memory is divided into cells with each cell having an address
  • Words are 32 bits
  • Memory is byte-addressable (can access in 8 bit / 1 byte increments)