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.

ARM

• 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).