Monday, August 3, 2009

ARM History

"ARM stands for Advanced RISC Machine."
The first ARM processor was introduced in the year of 1985. Since then, the evolution continued in ARM processor implementation.


  • Cores: ARM6, ARM7, ARM9, ARM10, ARM11
  • Extensions: Thumb, El Segundo, Jazelle etc.
  • IP-blocks: UART, GPIO, memory controllers, etc

ARM architecture

  • 32-bit RISC-processor
  • 32-bit integer registers
  • Pipelined
  • Cached
  • Von Neuman-type bus structure (ARM7), Harvard (ARM9)
  • 8 / 16 / 32 -bit data types
  • 7 modes of operation (usr, fiq, irq, svc, abt, sys, und)
  • Simple structure
  • speed to power consumption ratio

ARM Thumb

  • T (Thumb)-extension shrinks the ARM instruction set to 16-bit word length -> 35-40% saving in amount of memory compared to 32-bit instruction set
  • Extension enables simpler and significantly cheaper realization of processor system. Instructions take only half of memory than with 32-bit instruction set without significant decrease in performance or increase in code size.
  • Extension is made to instruction decoder at the processor pipeline.
  • Registers are preserved as 32-bit but only half of them are

ARM as a standard component

  • Even tough ARM is mostly used as a processor core in SoC and other ASICs have some manufacturers brought ARM-based standard products to market
  • Examples of manufacturers: Atmel, Cirrus Logic, Hyundai, Intel, Oki, Samsung, Sharp …
  • Most of the products are based on 7TDMI-core, some to 720T- and 920T-cores
  • ARM + FPGA: Altera and Triscend
  • In addition, there are a number of ASSP (Application Specific Standard Product) -chips available for example to communication applications (Philips VWS22100 = ARM7 based GSM baseband chip).

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