I have been going through assembly tutorials to understand how computers function at low level. I learned most of the standard x86/64 CPU instructions, but also still did not get all the answers, mostly relating to accessing the I/O and other hardware. So I have perhaps a somewhat silly question
- Starting from scratch (PC without any operating system), is it possible to program any computer program only by giving the processor the assembly instructions? In specific then, the CPU controls the computation and the operating system can be coded only using the instructions.
And if so then
- How does one access the sound cards/GPUs/monitors or other hardware through these instructions? The Int command is all I could find, but this does not seem to be enough to even draw something on the screen.