Why Does the BIOS INT 0x19 Load Bootloader at "0x7C00"?
bootloader, operating-system
Solution
Maybe because the MBR is loaded into the memory (by the BIOS) into the 0x7c00 address then int 0x19 searches for the MBR sector signature 0xAA55 on sector 0x7c00
about 0xAA55:
Not a checksum, but more of a signature. It does provide some simple evidence that some MBR is present.
0xAA55 is also an alternating bit pattern: 1010101001010101
It's often used to help determine if you are on a little-endian or big-endian system, because it will read as either AA55 or 55AA. I suspect that is part of why it is put on the end of the MBR.
about 0x7c00:
Check this website out (this might help u in finding the answer): https://www.glamenv-septzen.net/en/view/6
Problem
As we know the BIOS Interrupt (INT) 0x19 which searches for a boot signature (0xAA55). Loads and executes our bootloader at 0x7C00 if it found. My Question : Why 0x7C00? What is the reason ? How to evaluate it through some methods?