For flash based systems such as the AlphaPC64, EB164 and the EB66+, there are a number of possible boot options and these are changed using the bootopt command. This has one argument, a decimal number which is the type of the image to be booted the next time the system is power cycled or reset:
Boot the Evaluation Board Debug Monitor, Boot the Windows NT ARC firmware.
In order to tell the boot code to boot the Milo firmware from flash then you need a boot option that means boot the N'th image. For this, you need to 128 plus N, so if Milo is the third image, you would use the command:
MILO> bootopt 131
Note: Be very careful with this command. A good rule is never to set bootopt to 0 (the Evaluation Board Debug Monitor), but instead use the system's jumpers to achieve the same thing.