Explain the difference between x86 protected mode and real mode in simple terms.
In simple terms, x86 protected mode and real mode refer to two different operating modes of the x86 architecture used in many personal computers.

Real mode is the original mode of operation for x86-compatible processors. In real mode, the processor operates in 16-bit mode and has limited memory access, meaning that only the first 1 MB of memory can be accessed. This mode is commonly used for booting an operating system and running legacy software designed for earlier computers.

Protected mode, on the other hand, provides more advanced memory protection, larger memory access, and support for 32-bit mode. This mode allows multiple programs to run simultaneously and provides better security, as it prevents programs from interfering with each other or accessing sensitive areas of memory. Most modern operating systems run in protected mode.

In summary, real mode is a simpler, older operating mode with limited memory access, while protected mode is a more advanced mode that provides better memory protection and support for advanced features.
Let's say that the processor just started and is currently in real mode. Can you give me a short overview of all the steps that I need to follow to prepare for protected mode and then switch to it?
Sure! Here's a brief overview of the steps to prepare for and switch to protected mode:

1. Load the GDT (Global Descriptor Table) with segments for code, data, stack, etc. and set GDTR register to the address of the GDT.

2. Load the IDT (Interrupt Descriptor Table) with interrupt and exception handlers and set IDTR register to the address of the IDT.

3. Set up a stack for the protected mode using a data segment in the GDT.

4. Enable the A20 line to access more than 1 MB of memory.

5. Set up Page Tables to map virtual addresses to physical addresses.

6. Set up control registers CR0, CR3 and CR4 to enable paging and other protected mode features.

7. Set up the protection level in the task register (TR) by loading a segment selector for a TSS (Task State Segment) into it.

8. Finally, execute a far jump or far call to switch to protected mode by loading a code segment selector into the CS register.

Note: It's important to note that the steps listed above are just a high-level overview, and in practice, there are many subtleties and optimizations that you need to take into account. Additionally, make sure that you have a solid understanding of the underlying concepts before attempting to implement the switch to protected mode.