Aug 95

Vendors: OPTi, Intel, Dell, CompuDox, Novell

Muscle Processors

By Bruce Gavin

Special to Government Technology

Just like yesterday's muscle cars, the new 133 MHz Pentium processor (P133) delivers copious amounts of power. This newest member of Intel's racing team came onboard in mid-June and has already taken its position in first place. And unlike its high-powered cousins, the P133 won't leak oil on your desktop.

The P133 is the next step in Pentium processors. It breaks new ground as the first Pentium to use the new 0.35 micron BiCMOS* fabrication technology. The resulting 50 percent reduction in wafer size allows more system components to be integrated onto a single chip. Simply put, on-chip components run faster. For example, the internal (L1) cache runs at the full 133MHz processor clock speed. This 16K cache consists of a pair of 8K caches, one for code and the other for data. Dedicating each cache to a single purpose increases performance. The separation helps prevent potential conflicts between instruction prefetching and data access.

Although the external (L2) cache runs at the slower 66MHz processor bus speed, it will still deliver very high performance. This bus is a full 64 bits wide, twice the width used in 486 systems. It yields burst transfer rates up to 528 MB/second, a fivefold increase over the 486/DX4 processor.

The Bug

What about the well publicized math bug? It's gone. Similar to its flying cousins, swatting it created a much bigger mess than the bug itself. The actual chip problem was a software error in a look up table used for floating point division. Historically, this obscure problem was similar to lesser advertised math bugs in previous generation processors.

The messy part came from Intel's complete failure to handle this problem properly from the onset. Instead of stepping up to the problem, they stonewalled. When the bug went public, a few vendors demonstrated grace and class by declining to comment about it. Others were more opportunistic, trying to profit from it by pushing the panic button and grandstanding with the media. Mostly, it was a tempest in a teapot.

Not fixing the bug in a timely fashion was Intel's real problem. After they finally took ownership of the problem, they took extra steps toward restoring the public's confidence in the Pentium. A toll-free number (800/628-8686) for customer support was set up and heavily staffed. Any customer who believed they had a faulty chip could obtain a free replacement, no questions asked. Intel went the extra mile for customers doing their own replacements by taking their systems down only long enough to replace the chip. They did this by sending out the replacement chips in advance. A customer's credit card provided the guarantee for returning the defective chip. When the old chip was returned within the specified period, the customer was not billed for the new one.

Intel is taking both communications and bug prevention very seriously. They are now publishing the errata documents for their new processors. Additional quality assurance programs and testing methods are now in place to prevent this problem from occurring again. Management says they have a very high level of customer satisfaction with the replacement program and preventive measures.

The Pentium is serious about parity checking for data integrity. It checks parity on both the external processor pins, and the internal data structures. Cache, buffers, and microcode ROM are all parity checked. Additionally, the Pentium supports Functional Redundancy Checking (FRC). This requires two Pentium chips, one operating as the master, and the other as the watchdog. Both chips run in tandem, comparing their outputs for errors. FRC provides a very high degree of error checking. Additionally, every Pentium processor has a built-in self-test function that checks out 70