Last month Tensilica announced a new line of licensable processor cores called the Diamond Standard family. The new family is based on Tensilica’s Xtensa family of licensable cores, but there is an important difference between the two families: The Xtensa cores can be customized by licensees, but the Diamond cores cannot be customized. Hence, the Diamond cores are essentially fixed, pre-configured versions of the Xtensa architecture.
The Diamond family includes six family members:
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The 108Mini, a RISC microcontroller with a minimal feature set. Unlike the other Diamond cores, the 108Mini does not provide a MAC unit or hardware support for zero-overhead looping.
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The 212GP, a general-purpose RISC microprocessor.
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The 232L, a RISC microprocessor with a memory management unit (MMU) that enables the core to run Linux.
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The 330HiFi, a 24-bit audio processor based on the Xtensa HiFi 2 Audio Engine.
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The 570T, a 3-issue very long instruction word (VLIW) processor.
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The 545CK, a 3-issue VLIW processor featuring single-instruction, multiple-data (SIMD) capabilities. This core can perform up to eight multiply accumulate operations per cycle.
All of the cores operate at clock speeds near 250 MHz, but there are large architectural differences between the cores. As a result, the cores span a wide range of performance points. For example, the high-end 545CK achieves a BDTIsimMark2000™ score of 3820 at 230 MHz, making it the fastest licensable core BDTI has benchmarked to date.
In contrast, the 108Mini—which BDTI has not analyzed—will likely be about as fast as an ARM9. If so, the 108Mini will be roughly ten times slower than the 545CK on signal-processing tasks. The cores also vary widely in terms of die area: The cores range in size from 0.45 mm² to 2.84 mm². (These area figures do not include any memory. All performance data in this article assumes fabrication using the TSMC CL013G process and ARM Artisan SAGE-X library. See /Services/Benchmarks for more info and benchmark scores.)
The wide range of performance and features found in the Diamond family cores means that they will have many competitors, including most of the cores offered by ARM and MIPS, as well as most of the DSP cores on the market. For example, the 108Mini will compete mainly with low-end ARM cores such as the ARM7 and ARM9. The 545CK, in contrast, will compete mainly with high-end DSPs such as the CEVA-X1620 and the StarCore SC2400.
The introduction of the Diamond family represents a major shift in Tensilica’s strategy. Until now, configurability has been Tensilica’s main selling point. From a technical perspective, this focus on configurability makes sense: In some applications—particularly signal-processing applications—a modest amount of customization can provide a huge boost in a processor’s performance.
The Diamond cores clearly won’t have the performance advantages of a configurable core. Hence, the success of the Diamond cores will be largely determined by factors other than performance. For example, potential licensees are likely to focus on the quality of the tools and the availability of third-party software. Unfortunately for Tensilica, its competitors—ARM, MIPS, and DSP core vendors—often have advantages in these areas.
Nonetheless, the Diamond cores are an important addition to Tensilica’s offerings, because they will give Tensilica access to a wider range of chip designers. Designing a customized processor core can add significant risk and time to the chip-development process. This is particularly true if the chip designers aren’t experts in processor architecture. As a result, many chip designers are wary of configurable cores. These designers are likely to be more comfortable with the fixed Diamond cores.
Tensilica is also attempting to expand its reach by offering the Diamond cores through a variety of ASIC design firms. This option will be most interesting to companies that want to create custom chips but don’t want to do the full chip design themselves. Such companies typically limit their design work to creating a high-level description of the chip.They then work with an ASIC design firm, which handles the detailed design. By partnering with ASIC design houses, Tensilica is making the Diamond cores available to companies that outsource their chip design work.
In some ways, the Diamond cores make Tensilica’s lineup look more like that of competitor ARC. ARC also offers a family of configurable cores, and, like Tensilica, ARC offers a variety of pre-configured cores. However, there is an important difference in ARC’s approach: The pre-configured ARC cores retain their configurability, enabling licensees to add instructions and make other modifications.
Overall the Diamond cores appear to be solid offerings, but they will face tough competition. For the cores to succeed, Tensilica will need to expand the tools, off-the-shelf software, and other development infrastructure supporting these cores.
The Diamond Standard family of processors is available now. Pricing starts at $75,000 for a single-use license with a royalty of 5 cents per core.
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