Intelligent RAM (IRAM): Chips that remember AND compute

Dave Patterson

UC Berkeley

Two trends call into question the current practice of microprocessors and DRAMs being fabricated as different chips on different fab lines: 1) the gap between processor and DRAM speed is growing at 50% per year; and 2) the size and organization of memory on a single DRAM chip is becoming awkward to use yet size is growing at 60% per year.

Intelligent RAM, or IRAM, merges processing and memory into a single chip to lower memory latency, increase memory bandwidth, improve energy efficiency, and reduce size. Surprisingly, the integration of the processor/cache/memory of IRAM with with high-speed serial I/O lines may also lead to very good I/O performance.

This talk explores some of the opportunities and challenges for IRAMs, suggests that conventional microarchitectures do not exploit IRAM's potential, and proposes an initial architecture that is a better match.

I conclude by speculating on applications for a DRAM-size chip in 2-3 years that consumes 1 watt of power, contains 24 MBytes of memory, has about 1 GByte/sec of I/O, and crunches at the rate of 5 GFLOPS (64-bit floating point) and 40 GOPS (8-bit fixed point).

Today, the semiconductor industry is sharply segregated into processor and memory camps. If IRAM proves successful, integration will come to the semiconductor industry. In such a future, will historically DRAM-oriented companies still ship the most memory? Will historically processor-oriented companies still ship the most processors?

Back to LESS

Last modified: April 6, 1997
Mike Dahlin