What is computer architecture ?

• Amdahl, Blaauw and Brookes, 1964 (IBM 360 team):
  • The structure of a computer that a machine language programmer must understand to write a correct (timing independent) program for that machine
• Loosely speaking, it is the science of designing computers “leading to glorious failures and some notable successes”

Architect’s job

• Design and engineer various parts of a computer system to maximize performance and programmability within the technology limits and cost budget
• Technology limit could mean process/circuit technology in case of microprocessor architecture
• For bigger systems technology limit could mean interconnect technology (how one component talks to another at macro level)

Slightly outdated data

58% growth rate

• Two major architectural reasons
  • Advent of RISC (Reduced Instruction Set Computer) made it easy to implement many aggressive architectural techniques for extracting parallelism
  • Introduction of caches
• Made easy by Moore’s law
• Two major impacts
  • Highest performance microprocessors today outperform supercomputers designed less than 10 years ago
  • Microprocessor-based products have dominated all sectors of computing: desktops, workstations, minicomputers are replaced by servers, mainframes are replaced by multiprocessors, supercomputers are built out of commodity microprocessors (also a cost factor dictated this trend)