Assembly programming tutorials online

Assembly programming may not be for the new programmer, but it can be a powerful tool to develop tight code for your utility programs. If you're interested in learning Assembly programming on FreeDOS, you might try these Assembly tutorials by Michael Chourdakis. They are listed on his Github page as Assembly Manual. His full article on The Intel Assembly Manual might be a good place to start because "it includes all the previous hardware articles (Internals, Virtualization, Multicore, DMMI) along with some new information (HIMEM.SYS, Flat mode, EMM386.EXE, Expanded Memory, DPMI information)."

The tutorials of course need a warning: This stuff still is a lot more complicated than just using a 32 bit C/C++ compiler like DJGPP and a DOS extender to keep your code in high level land while still using 4 GB of your RAM. But multi core and long mode in DOS are cool tricks! So you will want to have a look at the tutorial series nevertheless.