During this period Intel became the dominant supplier of microprocessors for PCs, and was known for aggressive and sometimes illegal tactics in defense of its market position, particularly against Advanced Micro Devices , as well as a struggle with Microsoft for control over the direction of the PC industry. The 2013 rankings of the world's 100 most valuable brands published by Millward Brown Optimor showed the company's brand value at number 61. Intel has also begun research into electrical transmission and generation.