Resources for understanding hard drive
Here is a list of resources related to Hard Drive design and functionality:
1- Disk Drive Terms and Concepts http://www.c-jump.com/CIS24/Slides/DiskDrives/
2- Disk Partitions and Drive Lettering http://www.c-jump.com/CIS24/Slides/Partitions/index.html
3- The Boot Process and Operating Systems http://www.c-jump.com/CIS24/Slides/Booting/index.html
4- The FAT File System http://www.c-jump.com/CIS24/Slides/FAT/index.html
5-File Storage Hardware and Disk Organization https://www.ntfs.com/hard-disk-basics.htm
6- Very useful page about MBR, OS Booting https://thestarman.pcministry.com/