September 01, 1997, Issue: 809
Section: WinLab Reviews
Cyrix 6x86MX Processor -- Cyrix 6x86MX Keeps Socket 7 Full
By Jonathan Blackwood
It's happened again. Just when you got a grip on the bewildering array of microprocessor choices, out come two new chips from the Lone Star State: Cyrix Corp.'s 6x86MX processor (formerly called M2) and new player Centaur Technology's IDT-C6 (see sidebar "C6 Promises New Value"). We recently benchmarked an early engineering sample of the Cyrix processor at the company's headquarters in Richardson, Texas. It's still too early to benchmark Centaur's C6, designed at its facility in Austin, Texas. Both the 6x86MX and the IDT-C6 are MMX-enabled, Socket 7 processors that will fit handily into existing motherboards with current chipsets.
SIDEBAR: C6 Promises New Value
Glenn Henry is either tilting at windmills, or he's ready to become the king of discount microprocessors. The founder of Centaur Technology is launching an effort to build a simpler, smaller, cheaper Intel Pentium-compatible processor. Dubbed the IDT-C6, it will sell in lots of 1,000 for much less than $200-perhaps as low as $100-it will fit into standard Socket 7 motherboards, and it will support the full Intel MMX instruction set. The processors will be manufactured at the Oregon and California wafer fabrication plants run by Centaur's parent company, Integrated Device Technology (IDT)
Centaur's approach is to keep it simple. Its processor uses a relatively uncomplicated design that runs at high internal clock speeds, uses large, on-chip caches, and eschews such sixth-generation concepts as superscalar execution, out-of-order instruction execution, reorder buffers and nonblocking caches. There are no fractional clock multipliers that could result in a 233MHz clock speed, for example, rather than a 240MHz speed.
To strip down to the basics in an x86 processor, the company is drawing largely on the experience of Henry-who is a former IBM fellow and former senior vice president and chief technology officer at Dell-in RISC processor design. The IDT-C6 is optimized for the most basic x86 instructions (load, store, branch, register-to-register) that comprise 90 percent of code anyway: There is a five-stage pipeline execution core. Instructions are issued one at a time in program order, and executed and retired in order. Cache misses stall the pipeline until data is available to complete the instruction. This is very basic design, but Centaur compensates with high internal clock frequency, large on-chip caches, TLBs-and lots of fine-tuning.
The result is a smaller (88mm2, using a 0.35micron process), lower-power chip that produces higher yields on a typical silicon wafer, which means lower cost.
Henry is quite candid about the fact that there are some operations for which the C6 will be slower-perhaps substantially slower-than its competitors from Intel, AMD and Cyrix. But the trade-offs, he believes, are worth it to achieve impressive performance for the vast majority of applications at very low cost. Henry envisions 200MHz P55C-level performance in systems costing less than $1,000.
Intel has traditionally kept its margins high by manufacturing its ever-more-complex chips in very expensive FABs, whose cost alone provided a barrier to entry. AMD met the challenge head-on, with state-of-the-art plants in California, Texas and Germany. Cyrix chose to pursue the role of "FABless" chip maker, contracting with IBM and SGS Thomson to produce its designs. Now, IDT will be manufacturing a low-cost chip in wafer FAB plants converted from memory production. If the company succeeds, it will lower the barriers to entry in the microprocessor
business, which will result in more competition, lower prices-and lower margins, not just for Intel, but for AMD and Cyrix as well.
Yes, things are starting to get interesting ...
Copyright r 1997 CMP Media Inc. |
