Remove rom and serial boot methods from qemu testing

Makefile

@@ -29,7 +29,7 @@ debug.rom: debug/*.asm lib/*.inc
 	nasm -s -o $@ -I lib -I debug debug/main.asm && scripts/fix-rom.sh $@
 
 floppy.bs: boot/fatvbr.asm
-	nasm -s -o $@ $<
+	nasm -s -DCMDLINE='"KERNEL.COM"' -o $@ $<
 
 fdimage.img: floppy.bs kernel.com
 	dd if=/dev/zero bs=512 count=$$(( $(FD_CYLINDERS) * $(FD_HEADS) * $(FD_SECTORS) )) of=$@
@@ -40,11 +40,5 @@ fdimage.img: floppy.bs kernel.com
 clean:
 	rm -f *.com *.bin *.rom *.img *.log *.bs *.lst
 
-qemu-rom: kernel.rom $(DEBUGROM)
-	$(QEMU) $(QEMU_ARGS) -option-rom kernel.rom
-
 qemu-floppy: fdimage.img $(DEBUGROM)
 	$(QEMU) $(QEMU_ARGS) -boot c -fda fdimage.img
-
-qemu-serial: boot/serial.bin $(DEBUGROM)
-	$(QEMU) $(QEMU_ARGS) -hda boot/serial.bin

kernel/main.asm

@@ -42,7 +42,13 @@ init:
   push cs
   call isr_dos_main
 
-  int3
+  mov cx, WORD [0x80]
+  xor ch, ch
+  mov si, 0x81
+.loop:
+  lodsb
+  call putc
+  loop .loop
 
   cli
 .halt: