init

Makefile

@@ -0,0 +1,6 @@
+all:
+	as -o boot.o boot.s
+	ld -o boot.bin --oformat binary -e init boot.o
+
+run:
+	qemu-system-x86_64 boot.bin

boot.s

@@ -0,0 +1,10 @@
+.code16 # tell the assembler that we're using 16 bit mode
+.global init # makes our label "init" available to the outside
+
+init: # this is the beginning of our binary later.
+  jmp init # jump to "init"
+
+.fill 510-(.-init), 1, 0 # add zeroes to make it 510 bytes long
+# . is current position - start position
+.word 0xaa55 # magic bytes that tell BIOS that this is bootable
+# x86 is little endian - so bytes are swapped in memory!