@schestowitz SecureBoot is just their latest attempt at making sure no other OS can exist.
cf.
https://birdhouse.org/beos/byte/30-bootloader/
He Who Controls the Bootloader

@mmu_man @schestowitz I remember how beos installed on my PC: Spent a good 4 hours or so downloading on dialup; ran an executable that set beos to launch from a shortcut on the windows desktop. This was before Ubuntu and knoppix. Caldera Linux was probably the only other that did something similar. #Anvin (?) was still doing lilo things if I recall right. I had windows 98se running then. Was an awful experience. On an 12 GB HDD, 98se was demanding up to 4 GB space.