ARM.SoC.Architecture

8 the arm9tdmi processor core arm9tdmi applications

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Unformatted text preview: ture v4T instructions supported by the ARM9TDMI, the ARM9E-S supports the full ARM architecture version v5TE (see Section 5.23 on page 147), including the signal processing instruction set extensions described in Section 8.9 on page 239. The ARM9E-S is 30% larger than the ARM9TDMI on the same process. It occupies 2.7 mm2 on a 0.25 um CMOS process. 9.4 ARM10TDMI The ARM10TDMI is the current high-end ARM processor core and is still under development at the time of writing. Just as the ARM9TDMI delivers approximately twice the performance of the ARM7TDMI on the same process, the ARM10TDMI is positioned to operate at twice the performance of the ARM9TDMI. It is intended to deliver 400 dhrystone 2.1 MIPS at 300 MHz on 0.25 urn CMOS technology. In order to achieve this level of performance, starting from the ARM9TDMI, two approaches have been combined (again, see the discussion in Section 4.2 on page 78): 1. The maximum clock rate has been increased. 2. The CPI (average number of Clocks Per Instruction) has been reduced. Since the ARM9TDMI pipeline is already fairly optimal, how can these improvements be achieved without resorting to a very complex organization, such as superscalar execution, which would compromise the low power and small core size that are the hallmarks of an ARM core? Increased clock rate The maximum clock rate that an ARM core can support is determined by the slowest logic path in any of the pipeline stages. 264 ARM Processor Cores The 5-stage ARM9TDMI is already well balanced (see Figure 9.7 on page 261); four of the five stages are heavily loaded. The pipeline could be extended to spread the logic over many more stages, but the benefits of such a 'super-pipelined' organization tend to be offset by the worsened CPI that results from the increased pipeline dependencies unless very complex mechanisms are employed to minimize these effects. Instead, the ARM10TDMI approach is to retain a very similar pipeline to the ARM9TDMI but to support a higher clock rate by optimizin...
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