Nowadays we rarely program in Assembly, particularly in modern processors. Since ILP (intruction level parallelism) is now very common in general purpose processors, compilers became better than humans in selecting instructions to execute them out of order, resulting in faster executables than programming in Assembly. Therefore, although low level programming using other machine resources that are accessible in high level languages is still quite useful in modern processors, low level programming involving machine intructions became practically obsolete.
Old processors or microcontrollers are rare exceptions where Assembly can still be and it's still used. This repository deals mostly with these exceptional cases.
One interesting case is the famous Intel 8051 microcontroller that's still used nowadays. I had been in contact with this microcontroller when I was a professional embedded 8085 Assembly programmer in 1985/86. I mostly used 8085 and a little bit of 8031/8048 microcontrollers.
I didn't program an actual 8051, but I became quite interested in it and we had a Databook for it in the company I worked for. That's where I realized how good it was. I was invited by another company to work with the 8051, since it became like a passion to me. But I had to decline the offer because I was accepted for a Masters' program in my university.
This is why I have a section dedicated to 8051 microcontroller in this repository.