A PC Chip for the Masses

Centaur's new WinChip C6 delivers application performance that approaches that of a 200-MHz Pentium with MMX at an appealing price.

Dave Andrews

Centaur's WinChip C6 processor isn't the fastest x86 processor we've tested, but its performance approaches that of a 200-MHz Pentium with multimedia extensions (MMX), and at an attractive price. Centaur, a subsidiary of static RAM (SRAM) and RISC processor manufacturer Integrated Device Technology, has created a CPU that's small (just 88 square millimeters compared to 141 square mm for the Pentium MMX) and streamlined (for more information, see "Keeping It Simple," October BYTE).

Although benchmark tests indicate that the performance of a 200-MHz WinChip C6 is below that of a 200-MHz MMX Pentium, the chip is priced attract ively at $135 for the 200-MHz version, compared to the $252 (in quantities of 1000) that a 200-MHz Pentium with MMX technology cost at press time. The Win Chip C6 targets PCs costing $1000 or less. The 180-MHz WinChip C6 costs just $90. Centaur plans to release 225- and 240-MHz versions of the CPU in this quarter.

BYTE tested a 200-MHz WinChip-based PC using the BYTEmark CPU/FPU and Photoshop application benchmarks. As Centaur engineers predicted, the chip didn't perform very well compared to a 200-MHz Pentium processor in the BYTEmark CPU/FPU tests, which are CPU-intensive, synthetic tests. According to Centaur officials, the WinChip C6 would do better in Windows application tests than in BYTEmarks compared to a Pentium. Our Photoshop tests confirm Centaur's assertions.

BYTE tested the 200-MHz Pentium and WinChip C6 CPUs in the same reference system running Windows NT 4.0. As we do when running Photoshop tests on other systems, we configured the system with 64 MB of RAM to minimize hard drive activity and measured performance only in terms of the processing time required to complete each operation to deemphasize video card performance. We ran the tests at 1024- by 768-pixel resolution and 256 colors on the Pentium/WinChip C6 system, because that was the maximum color depth the system supported at that resolution. We also include the scores of an AST 300-MHz Pentium II-based system tested at the same color depth and pixel resolution.

In Photoshop operations that make use of MMX, such as the default unsharp mask and Gaussian blur (but not the RGB to CMYK mode change), the WinChip C6 beat a non-MMX Pentium 200. And in two operations that are not MMX-intensive -- arbitrary rotate and the custom unsharp mask -- the non-MMX Pentium 200 edged the WinChip C6. (Intel says the performance benefit accrued from MMX optimization in the unsharp mask test starts diminishing when the radius setting is at 4 or more pixels, and in the custom unsharp mask ope ration, our setting is 10 pixels. For more information on the Photoshop tests, see the Bits article "MMX in Fits and Starts" in the February 1997 BYTE or http://www.whidbey.com/gallery/photoshop/ .

All this suggests that Centaur's support for MMX will make the WinChip C6 a better processor for some MMX-optimized operations than a plain Pentium. But Intel is rapidly phasing out non-MMX chips, and in MMX-optimized operations, the Pentium with MMX beats the WinChip C6.

Centaur officials say they will improve the WinChip C6's MMX performance as well as its rather dismal floating-point performance in the future. Adobe officials say the Photoshop tests that BYTE runs are predominantly integer-based. The arbitrary rotate test does use floating-point slightly during the setup, but this doesn't account for a significant amount of time. Nevertheless, the WinChip C6's poor BYTEmark FPU score indicates that it is not a great chip for running FPU-intensive applications such as CAD.

With speed increases and other enhancements, the WinChip C6's performance will continue to improve. Even at its current performance, it's worth checking out if you're in the market for an inexpensive PC. Power users who need maximum performance will need to look elsewhere.

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WinChip C6 vs. Pentium

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Centaur: Decent Integer, Poor FPU

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