The ARM processor used in current devices are in most cases, chip ARM7, ARM9 and ARM11. The ARM11 chips are the current stars, used in devices like the Nokia N95, the HTC TyTN II and the iPhone, while the ARM9 are common in older appliances such as the Nokia E61 and E62 and various models from Sony Ericsson, Siemens and other manufacturers .

The ARM11 chips offer a slightly higher performance per cycle (1.2 DMIPS per MHz, against 1.1 DMIPS per MHz of ARM9), but the big difference (in terms of performance) between the two families is the number of pipeline stages, used processing instructions. The ARM9 chips use a pipeline of 5 stages, while the ARM11 pipeline using one of 8 stages.

Similar to what we have to micro-processor PC, the use of more stages of pipeline allows each stage run a smaller volume of processing per cycle (ie that each run a smaller percentage of the work), which allows the processor operate at a higher frequency. A simple analogy would compare with a production line, imagining that each pipeline stage corresponds to a worker. If the work is divided among a greater number of workers, each will run a smaller number of steps and line can run faster, resulting in a greater production.

This explains why the ARM9 processor-based chips are restricted to around 200 to 250 MHz (and are therefore used in older appliances, or cheaper), while the newer chips, based on ARM11 processors reach frequencies from 400 to 600 MHz

The ARM7 chip, in turn, are very simple processors, which were originally used in devices of the 1990s, as the Psion 5 and the Apple Newton, but that recently re-emerged as auxiliary chips, used as part of the 3G transmitter. Being very simple, they perform this task in a very efficient, consuming less power than other chips (more complex) need to run the same workload.

From 2009 we have the migration to chip based on ARM Cortex A8, which uses a more complex architecture, but in contrast, offers a considerably higher performance per clock (up to 2 DMIPS per MHz) and is capable of operating at up 1.0 GHz, while maintaining an acceptable energy consumption. It is used, for example, in TI OMAP3430, a chip that can be used in devices of the next generation. 

The DMIPS "is a measure of performance based on Dhrystone, a benchmark widely used to measure processor performance in operations of integers. Originally, the measure was the standard "MIPS (million instructions per second), the problem is that the gross volume of instructions is not a direct indicator of the performance between processors of different architectures, since processors with more complex sets of instructions can perform more work with the same volume of instructions, which processor with simple combinations.

Arose, then the idea of using the Dhrystone benchmark as a standard, comparing the number of loops per second that each processor is capable of running on a VAX 11/780 computer (a computer in the 1970s, with estimated processing power of at 1 MIPS). The VAX 11/780 was able to run the Dhrystone loop of 1.757 times per second, which led to "DMIPS" which, although not an accurate indicator is a measure of performance closer to reality than the MIPS.

An interesting question about the ARM chips is that they are not produced by a single company (as in the case of the Intel processors), but licensed and produced by different manufacturers. The ARM Ltd. (www.arm.com), which is responsible for the development of chips and holder of rights in the architecture, the processors can not produce, is limited to license the projects at affordable prices for other manufacturers who may choose various types of leave, including options to modify the chips and add additional components. This is the case of manufacturers such as Qualcomm, Texas Instruments and Samsung, to develop their own solutions, including various modifications and auxiliary controller.