1 Effect of Increasing Chip Density on the Evolution of Computer Architectures R. Nair IBM Journal of Research and Development Volume 46 Number 2/3 March/May 2002

2 International Roadmap for Semiconductors (1999)

3 A Billion Transistors on a Chip “What functions will be expected of billion- transistor chips, and how will they be organized?” Move Memory closer to the processors (physically speaking) System on a Chip – integration on the same chip of varied structures such as processors, DRAM, sensors, and transducers

4 Processor Evolution New generations depending on prediction algorithms Performance benefit decreasing Sometimes simpler is better!

5 The Current Techniques (Benchmarks) Increasing pipeline depth and frequency Fewer applications responding well

6 Cellular Architectures Little communication overhead between threads Connectionist architecture – large number of processors with little memory Advantages –Off-the-shelf commodity parts –Use existing compilers –Possibilities of redundancy

7 System-on-a-Chip Integrate functions that are outside processor Reduce communication costs between elements Current state – performance decrease when combining technologies on one die Help with clock skew

8 Conclusions Convergence of processors Less focus on more computation power Scalable, distributed computing