Emax

I booted the pc in dos , but I can't get the emxp program to open. How do I open the emxp program from dos ?

You don't.

As the name implies, emXP is for Windows XP. You install Omniflop, the Omniflop drivers, and then simply run EMXP by double-clicking on it. It's styled like a DOS program, but it's a true Windows program.

EMX, however, is a similarly named program that DOES run under DOS. In my opinion, EMX is more difficult to get to work reliably. Refer to the recently posted Emax OS floppy creation primer post for more details.