about operating mode dear sir or madam i am so sorry to bother you but i've seen your post on processor register the original text is copied to bellow ia e early concept of em t coded name yamhill the register were extending from bit to bit unlike x this design do not come with additional general purpose register r r and lack of bit mmu and address mode support bit address mode with pae for maximum compatibility with legacy application early prescott tejas and timna were the only implement of this isa and later is replaced by em t that is so interesting and amazing besides i wonder the information on operating mode is the original ia e mode a sub mode of protected mode or a new mode like it in amd does the original bit protected os need to be changed from the scratch or just provides extension support for those new introduced bit instructions that is most amazing thing for me i am sorry to bother you i was just a computer science student when i knew it and i am merely a computer hobbyist right now thank you with my best wishes