Architectural Trends
Greatest trend in VLSI generation is increase in parallelism
- Up to 1985: bit level parallelism: 4-bit -> 8 bit -> 16-bit
- slows after 32 bit
- adoption of 64-bit now under way, 128-bit far (not performance issue)
- important inflection point when 32-bit microprocessor and cache fit on a chip
- Mid 80s to mid 90s: instruction level parallelism
- pipelining and simple instruction sets, + compiler advances (RISC)
- on-chip caches and functional units => superscalar execution
- greater sophistication: out of order execution, speculation, prediction
- to deal with control transfer and latency problems
- Next step: thread level parallelism