DOS was basically bare-metal programming with a few hardware and software calls thrown in. With 50 cent ARM processors these days having the power of an 80's mainframe Bare-metal on $5 dev-board is still my preferred way to go for simple projects that boot instantly and never need updates. I'm currently listening to music on a DOS MP3 player on a throwaway industrial x86 motherboard I built into an amplifier case 23 years ago.