well, you will need a compiler in the language of you choice, capable of compiling freestanding code
an assembler (if your using C/C++ then you prob have one with your compiler, but you could also use a separate one if you are more compfortable with it)
documentation (extremely important) (see below)
a place to ask questions:
here (
http://www.osdev.org)
MT (
http://www.mega-tokyo.com/forum/)
these are some of my most important resources:
## ---- ----- ------ Intel Manuals
this one will soon become your best friend (download all 4 and read them (several times)-- esp vol 3, and at least become familier with vol 2(A and B) if your new to asm, vol 1 will give you a good overview from an app-developers standpoint
you can also order these in hard-copies (they are free, including shipping) but they are currently unavailible (the printed version is currently being revised -- should be availible again toward the end of the month (iirc))
## ---- ----- RBIL
lots of good information about the BIOS, CMOS, ports, and I/O space for 'standard' parts
OSRC
lots of technical information about almost everything
Geezer
info and source from the most well respected OSdever in the biz -- he doesnt post to forums much, but hes always right -- if you are serious about OSdeving, you will quote him or recommend his source eventually
OS faq
answers a lot of questions -- very helpful
OSdev is a very big and very complex field, so general questions dont usually get good (if any) answers, it is all about research -- be very good at research, and read every post and question you can
the first question you will need to ask yourself (do
not ask anyone else, as it
will start a flame-war) is whether to use your own boot-loader, or use grub
this is a question only you can answer, but most people have a very strong opinion (which is why i wont start a war by giving my opinion) on both sides -- its really is a very personal question, but most people think there is only correct answer
hope i have been some help to you, please respond if you have any more specific questions