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Moore collateral effects

While I believe your fundamental point is spot-on, there are some collateral effects of Moore's Law that are less obvious and generally under-reported.

    In response to the June 11 Perspectives column by Michael Kanellos, "Myths of Moore's Law":

    I enjoyed your piece on Moore's law. As a systems architect, I deal with these issues on a daily basis. While I believe your fundamental point is spot-on, there are some collateral effects that are less obvious and generally under-reported.

    The first: While memory "speed" has increased (albeit more slowly than microprocessors), memory latency (the time that it takes to get data out of memory once it is requested) has not become significantly shorter. Further, the ratio between cycles per instruction of the CPU (central processing unit) and latency are really disproportionate, such that a "miss" in the processor's cache can make idle the processor for hundreds--if not thousands--of instructions.

    Neither Intel nor AMD has chosen to put large secondary caches on its "budget" processors (the bulk of the business). And so, for many people, the companies' system performances may be only marginally different from the 1GHz system that was mentioned in your article and a 2GHz system.

    The second: A strange symmetry once existed in which chip manufacturers made memory chips in order to "try out" new processes before they built CPUs out of them. Additionally, the same CPU innovations that were going into desktop chips were finding their way into chips that were embedded in disk drives and more. The entire "ecosystem" of the computer was thus evolving simultaneously.

    And yet, disk drives, a fundamental part of the system equation, have doubled in density faster than every 24 months but have not doubled in operations per second. In fact, in the value market, speeds have climbed from 3,600 revolutions per minute to 5,400RPM and now to 7,200RPM, a rather stately pace.

    The result is that overall system performance increases have not had nearly as much "Wow!" effect in the current generation as they have had in the past. Further, if you remove video games and their graphics cards from the equation, it might not be possible for someone to differentiate between an Excel spreadsheet that runs on a 1GHz, 2GHz or now 3GHz machine.

    Chuck McManis
    Sunnyvale, Calif.