Tuesday, August 4, 2009

Introduction to ARM9

The ARM9 family was introduced in 1997. The ARM9 processor family is built around the ARM9TDMI processor and incorporates the 16-bit Thumb instruction set, which improves code density by as much as 35%. Because of its five-stage pipeline, the ARM9 processor can run at higher clock frequencies than the ARM7 family. The extra stages improve the overall performance of the processor.
The ARM9 architecture follows Harvard architecture philosophy, which separates the data and instruction buses. The memory system has been redesigned, which includes a separate Data & Instruction cache and an MMU. Which results in, this processor can be used by operating systems requiring virtual memory support.
ARM9 has two variations ARM922T & ARM920T. ARM922T is a variation on the ARM920T but with half the Data + Instruction cache size. The ARM940T includes a smaller Data + Instruction cache and an MPU. The ARM940T is designed for applications that do not require a platform operating system. Both ARM920T and ARM940T execute the architecture v4T instructions.
The next processors in the ARM9 family were based on the ARM9E-S core. This core is a synthesizable version of the ARM9 core with the E extensions.
There are two variations: ARM946E-S and ARM966E-S.
Both execute architecture v5TE instructions. They also support the optional embedded trace macrocell (ETM), which allows a developer to trace instruction and data execution in real time on the processor. This is important when debugging applications with time-critical segments.
The ARM946E-S includes TCM, cache, and an MPU. The sizes of the TCM and caches are configurable. This processor is designed for use in embedded control applications that require deterministic real-time response. In contrast, the ARM966E does not have the MPU and cache extensions but does have configurable TCMs.
The latest core in the ARM9 product line is the ARM926EJ-S synthesizable processor core, announced in 2000. It is designed for use in small portable Java-enabled devices such as 3G phones and personal digital assistants (PDAs). The ARM926EJ-S is the first ARM processor core to include the Jazelle technology, which accelerates Java bytecode execution. It features an MMU, configurable TCMs, and D +I caches with zero or nonzero wait state memories.

The ARM9 family's comprehensive feature set enables developers to implement leading-edge systems, while delivering considerable savings in chip area, time-to-market, development costs and power consumption.

ARM922 Features

  • 32-bit RISC processor with ARM® and Thumb® instruction sets

  • 5-stage integer pipeline achieves 1.1 MIPS/MHz

  • Up to 300 MIPS (Dhrystone 2.1) in a typical 0.13µm process

  • Single 32-bit AMBA bus interface

  • MMU supporting Windows CE, Symbian OS, Linux, Palm OS ( and )

  • Integrated instruction and data caches

  • Excellent debug support for SoC designers, including ETM interface

  • 8-entry write buffer — avoids stalling the processor when writes to external memory are performed

  • Portable to latest 0.18µm, 0.15µm, 0.13µm silicon processes.

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