British firm claims Pentium "bug"

The alleged glitch appears to have been identified and documented years ago by Intel engineers.

3 min read
A British software company says it has found a flaw that negatively impacts the performance of Pentium processors, but the alleged glitch appears to have been identified and documented years ago by
Intel engineers.

An article by the U.K.-based Intelligent Firmware has also been posted at Intel Secrets, a site which tracks inside information on the world's leading chipmaker.

Intelligent Firmware claims that the performance issue occurs on 486, Pentium, and Pentium MMX processors any time information is passed from a system's main memory to the processor and that Intel has yet to disclose all the necessary details of this performance issue.

The "problem" is also said to occur when information is passed from a Pentium Pro or Pentium II processor's secondary cache memory to the processor. Secondary cache memory is a separate high-speed memory chip. Its use speeds the amount of data that can be fed to the processor, thereby improving overall system performance.

The upshot of the claim is that a computer's performance is unnecessarily slowed.

Upon a cursory examination of the issue, Michael Slater, principal analyst at MicroDesign Resources, said he would characterize the issue not as a bug but as an "idiosyncracy" of the Pentium architecture.

Intel says the same in essence: That it was a design decision and is not a flaw. Intel also says the issue was first noted "years ago," according to a company spokesperson, and is described on page 43 of a technical document called the Intel Architecture Optimizations Manual.

Software vendors were alerted shortly after the issue arose, Intel adds, in 1993, when the Pentium chips were first introduced.

"This issue is known--has been for years--and we of course worked with [software developers] and compiler vendors years ago as when this was an issue. It is a documented behavior of Pentium based systems," the Intel spokesperson said.

"It is not a calculation bug, but a performance error. It would be no problem if Intel admits there is a problem and says there is this workaround," said Michael Krech, director of Intelligent Firmware, who noted he has Intel's manual and claims there is no description of the specific problem he is addressing. "This penalty is an undocumented flaw and continues to exist. It affects every computer," he insisted.

Intelligent Firmware says on its Web site that a Pentium processor with EDO (extended data out) memory and a recent chipset should be able to transfer data from the main memory to the processor at about 185 megabytes per second. But when one measures the transfer rate with the software the company offers, the transfer rate is only around 119 megabytes per second.

"This is not a magical program someone would put in and they would automatically get better performance," because the problem requires all software to work differently, according to Krech. "We are not trying to sell software really--we want to be publicly known as experts in our field," he said. The program the company is selling includes what is referred to as "source code," which basically shows every programmer how to work around these performance issues, he said.

Intel says that there are a number of ways of measuring the flow of data in between a system's various components, and that measurements can therefore vary when using different benchmarks.