OSDev.org

1. Can I load a new LDT when I am in protected mode? For example would it work if I load one and after entering protected mode decides to change it and reload it?
2. How is the start and end (in CHS) of a partition stored in a partition table?
3. How do I measure the speed of the CPU?
4. Do anyone know which port(s) to use when switching the screen (in VGA and SVGA)?
5. Is there anyone who knows the ports, set of commands and parameter structure that SCSI use? The same for ATAPI?

LDTs, GDTs, IDTs, etc. can all be reloaded in protected mode IFF you're at CPL 0. ?I wouldn't want to give you inaccurate information for the rest of your questions but may I suggest:

http://www.nondot.org/sabre/os/articles. ?It is a VERY good starting place for many of your questions.