0.11 Way (iii): System module

Now load the third batch of code--system module, still using int 0x13 interrupt.
This batch of code is much more than before, so it takes a little time, so the word "Loading system ..." appears. However, the main function of the operating system is not executed at this time, so it is implemented using a compilation.
The system module is loaded into the memory of the 0x10000 back 120KB space. This way the entire operating system's code is loaded into memory, and finally, the root device number is determined again.

What is a root device?
Root file system device (root device):
0.11 uses the Minix operating system to manage the file system, requires the system must exist a root file system, the other file system hangs on it, rather than the same status. A well-formatted floppy disk can be a root filesystem device.

The first thing the Setup program does is use the BIOS Interrupt service program to extract the machine system data needed for the kernel to run from the device. And then put the data in the 0x90000 ~ 0X901FD location, visible already covered the original Bootsect code, bootsect only 2 B is not covered, it can be seen that the operating system of memory usage is very rigorous-the use of unused memory, and almost suitable, Only 2 bytes is difference.

Finally, summarize the entire loading process.

Power on--bios--bootsect (int 0x19)--setup (int 0x13)--system (int 0x13)

0.11 Way (iii): System module