Simple Operating System programs starting from Bootloader in assembly to Kernel in C, and other programs like OS Calculator, Low Level Graphics etc.
Bootloader contains simple 16 bit as well as 32 bit OS bootloader assembly programs.
Kernel contains C programs for Simple HelloWorld, Keyboard I/O etc... and little bit assembly programs for low level operations.
Global_Descriptor_Table contains code that sets up GDT in both x86 NASM Assembly and in C.
Interrupt_Descriptor_Table contains code that sets up IDT in C with interrupt service routines.
GUI contains graphics related programs in C for drawing boxes, DOSBox GUI etc.
x86 Calculator contains an x86 calculator program capable to run on booting.
Graphics contains simple low level pixels drawing, as well as objects such as Lines using DDA algorithm, Rectangles etc.
VGA contains C kernel and assembly program for seeting up Video Graphics Array(VGA) and drawing some basic shapes by ploting pixels.
Tic-Tac-Toe a simple tic-tac-toe DOS game with boxes.
First read this page before you start: https://wiki.osdev.org/Beginner_Mistakes