First commit

.gitignore

@@ -0,0 +1,2 @@
+*.bin
+*.img

Makefile

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+.SUFFIXES:
+.SUFFIXES: .bin .asm
+
+all: bootsector.bin
+
+.asm.bin:
+	nasm -fbin -o $@ $<
+
+clean:
+	rm -f *.bin *.img
+
+run: bootsector.bin
+	qemu-system-i386 -fda $<
+
+.PHONY: all clean run

bootsector.asm

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+cpu 8086
+org 0x7c00
+
+jmp short _code
+nop
+
+; 1440K floppy
+; BPB
+oemidentifier     db "nor86   "
+byterpersector    dw 512
+sectorspercluster db 1
+reservedsectors   dw 1
+fats              db 2
+rootdirentries    dw 224
+totalsectors      dw 2880
+mediadescription  db 0xf0
+sectorsperfat     dw 9
+sectorspertrack   dw 18
+heads             dw 2
+hiddensectors     dd 0
+totalsectorslarge dd 0
+
+; EBPB
+drivenumber       db 0 ; useless
+reserved          db 0 ; winnt flags
+signature         db 0x29 ; mkdosfs uses this, dunno how 0x28 differs
+serial            dd 0
+volumelabel       db "nor86 boot "
+fstype            db "FAT12   "
+
+_code:
+	jmp 0:_start
+
+_start:
+	mov ax, 0x0e40
+	int 0x10
+
+hang:
+	hlt
+	jmp hang
+
+times 510-($-$$) db 0
+db 0x55, 0xaa