simple OS

• fasm
• QEMU emulator

fasm boot.asm boot.bin
fasm print.asm print.bin
cat boot.bin print.bin > result.bin

qemu-system-x86_64 -drive format=raw,file=result.bin -nographic

Prints a string to the screen using BIOS interrupt. The string is stored in memory at address si.

Waits for a character input from the keyboard. Once a character is received:

• If it is Backspace, calls backspace.
• If it is Enter, calls cursor_enter.
• Otherwise, the character is displayed on the screen and added to the buffer, then print_buffer is called.

Displays the first character from the buffer using int 10h.

Deletes the last entered character by moving the cursor back, overwriting it with a space, and shifting the cursor back again.

Moves the cursor to a new line by increasing dh (row number) and setting dl = 0 (beginning of the line).

Displays a welcome message and moves the cursor to a new line.