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ARM processors
Family of 32-bit microcontroller processors
ARM has changed their name several times:
What is it?
Who makes it?
Acorn RISC Machines (1985)Advanced RISC Machines (1990)ARM Holdings (1998)
Mid-high level complexity hand-held consumer electronics
What is its niche?
PDA’s (1980’s)Cell phones (1990’s)Handheld game devices (2000’s)
Example Consumer Products
Gameboy advance
Nintendo DS Apple Ipod
Apple Iphone
TASC ChessMachine
Apple Newton PDA
Processor design, not a chip
Nintendo DS
Core designChip design & fabrication
ARM licenses core designs to other companies
OEMs can customize chips
ARM provides compilers, development tools, and debugging tools for chip development and product development
ARM processor features
• Small number of transistors (~35,000)• No microcode, all instructions hard-wired (no flexibility in ISA)• 3-stage pipeline (simple fetch-decode-execute)• 4-8 KB cache memory, typically unified (data/instruction)• 32-bit ISA (not used for simple control stuff)• 18-56 MHz clock speed
ARM1 (1985) to ARM11 and Cortex lines, most having 5+ flavors
ARM7 cores
• “Thumb” instruction set – 16 bit ISA packed into 32-bit code• “Jazelle” instruction set – java code executed in hardware (instead of JVM)
ARM extensions
ARM assembly code is dense
C program code: while (i != j) { if (i > j) i -= j; else j -= i; } ARM assembly code: loop CMP Ri, Rj ; set condition "NE" if (i != j) ; "GT" if (i > j), or "LT" if (i < j) SUBGT Ri, Ri, Rj ; if "GT", i = i-j SUBLT Rj, Rj, Ri ; if "LT", j = j-I BNE loop ; if "NE", then loop
multiple pieces of work per instruction
ARM chip pricing
Core licensing – $200,000 to $10,000,000 depending
Some chip examples:Atmel AT91SAM family -- $3/unit qty 10,000 (2005)NXP LPC24xx family -- $8-14/unit qty 1 (2009)Texas Instruments MS470 family - $10-22/unit qty 1 (2009)
For further pricing, check www.digikey.com
For further information, see www.arm.com