initial commit

.gitignore

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+boot.bin
+dittoOS.img

Makefile

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+prog: bin image
+
+image:
+	dd status=noxfer conv=notrunc if=boot.bin of=dittoOS.img
+
+bin:
+	nasm -f bin -o boot.bin boot.asm

boot.asm

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+	BITS 16
+
+start:
+	mov ax, 07C0h		; Set up 4K stack space after this bootloader
+	add ax, 288		; (4096 + 512) / 16 bytes per paragraph
+	mov ss, ax
+	mov sp, 4096
+
+	mov ax, 07C0h		; Set data segment to where we're loaded
+	mov ds, ax
+
+
+	mov si, text_string	; Put string position into SI
+	call print_string	; Call our string-printing routine
+
+	jmp $			; Jump here - infinite loop!
+
+
+	text_string db 'This is my cool new OS!', 0
+
+
+print_string:			; Routine: output string in SI to screen
+	mov ah, 0Eh		; int 10h 'print char' function
+
+.repeat:
+	lodsb			; Get character from string
+	cmp al, 0
+	je .done		; If char is zero, end of string
+	int 10h			; Otherwise, print it
+	jmp .repeat
+
+.done:
+	ret
+
+
+	times 510-($-$$) db 0	; Pad remainder of boot sector with 0s
+	dw 0xAA55		; The standard PC boot signature

run.sh

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+qemu-system-x86_64 -fda dittoOS.flp