ARM visited Federal University of Itajuba last September 18th. They stayed only one day where two employees – one application engineer and other design engineer – talked about some topics such as: basics of ARM processors, the ARM Instruction Set Architecture, system design, pipelines, and an overview of the development tools.
Prof. Dr. Otavio Carpinteiro and I lunched with them. In this time I could ask some questions, for example, why JTAG unit is so expensive? Bill answered that the JTAG from a specific vendor isn’t really necessary. I can use a home made JTAG. The high price comes from electronic circuits to speed up communication.
I’d like to emphasize some points on presentation:
- 16-bit Thumb Instruction Set: one great achievement on battle to low power consumptions. Running 16 bits instructions on a 32-bit processor.
- Jazelle Cores: running Java bytecode (all ARM processors with J on his name uses this feature)
- Barrel Shifter: to improve multiplication of some constants (constants 2^n +- 1 will be able to be executed in a single cycle guaranteed, some constants can use the barrel shifter and be executed in 2 or 3 cycles).
- AMBA (Advanced Microcontroller Bus Architecture)
In order to foment another points of view, I recommend and Embeeded.com article called Ten lies about microprocessors where the author comments issues like power consumption and the rising of Java chips.
The ARM business model is another interesting issue. They did not produce silicon but ARM license its IP (intellectual property) to a direct customer (ARM Partner) that produces it. More information here.
ARM processors runs on a lot of bleeding edge devices such as mobile phones and MIDs (Mobile Internet Devices). One curiosity: on presentation Joe Bungo guess that iphone runs eleven ARM-based processor (bluetooth, wi-fi, etc)🙂
You can download the presentation here.