The startup process is as follows
1. Add some points first, enter the BIOS
2. Bios reads the content (512 bytes) of the first sector of the boot device into 0x7C00.
3. Execute boot/bootsect.s of 0x7c00, the program reads itself to 0x90000, and reads boot/setup.s to 0x90200 and system to 0x10000.
The code that reads itself to 0x90000 is as follows:
From the second sector, read setup.s to 0x90200 through interrupt 0x13.
Display'Loading system...' on the screen via interrupt 0x10
Read system to 0x10000 through interrupt 0x13, the main code is as follows:
