Fix the implementation to be supported by GCC compiler
Adapt the os loader to be compiler with GCC and NASM
Change the Makefile to generate the OS loader as a flat binary
Port the OS loader to GCC and add minor fixes in the CD-ROM bootloader
Port the kernel to compile with GCC
Modify the function names for kernel timer API
Minor improvements in the OS loader
Modify intenal macros and add minor improvements in the kernel