Below your program

A simplified view of hardware and software

• Applications software
  • Written in high-level language
• Systems software
  • Compilers: translate high-level language to machine language
  • Operating Systems
    • Handle input/output operations
    • Manage resources (e.g., storage, memory)
    • Schedule tasks (processes)
• Hardware
  • processors memory, I/O devices

Execution of programs

Step 1: Translating language

• From high-level language
  • Designed for specific domain
  • Provides for productivity and portability
• To hardware machine language
  • Binary digits
  • Encoded instructions

Step 2: Inputting, outputting, processing, and storing data

4 Fundamental HW components

• Processor
  • Datapath + control, our primary focus
• Memory
• Input device
  • Keyboard, mouse, ...
• Output device
  • Screen, speaker

8 STEPS

1. Loading: programs are stored in memory
2. Inputting: input device write data to memory
3. Fetching: processor fetches instructions and data from memory
4. Decoding: processor (control) decodes the instructions and determine what to do
5. Executing : processor (datapath) executes the instructions & stores the computation result to memory
6. Outputting: output device sends the result by reading output data from memory

Understanding program performance

• Algorithm
  • Determines the number of operations executed
• Programming language, compiler, and instruction set architecture (ISA)
  • Determine the number of machine instructions executed per operation
• Processor and memory system
  • Determine how fast instructions can be executed
• I/O system (including OS)
  • Determines how fast I/O operations are executed

What is ISA (Instruction Set Architecture)

• An interface between SW snd HW (includes a set of machine instruction)
  • SW is translated into the machine instructions included in the ISA
  • HW is designed to support the instructions in ISA

8 great ideas for designing better computer architecture

• Design for Moore's Law
  • Anticipate where the technology will be when the design finishes
• Provide abstraction to simplify design
  • Hide low-level details for the ease of SW development
• Make the common case fast
  • Enhance performance of the common case instead of optimizing the rare case.
• Perform via parallelism
  • Perform operations in parallel
• Performance via pipelining
  • Use a particular patten of parallelism, called pipelining
• Performance via prediction
  • Start working with prediction, stead of waiting until you know for sure
• Hierarchy of memories
  • Use the fastest, smallest, and most expensive memory at the top of the hierarchy and the slowest, largest, and cheapest memory at the bottom
  • cache > RAM > Large SSD
• Dependability via redundancy
  • Include redundant components that can take over when failure occurs