Add mechanism for additional files on floppy

Makefile

@@ -2,6 +2,9 @@ FD_CYLINDERS = 40
 FD_HEADS = 2
 FD_SECTORS = 9
 
+PROGRAMS = $(patsubst %.asm,%.com,$(wildcard programs/*.asm))
+DISTFILES = kernel.com $(PROGRAMS)
+
 QEMU_ARCH = $(shell uname -m)
 QEMU = qemu-system-$(QEMU_ARCH)
 
@@ -31,14 +34,16 @@ debug.rom: debug/*.asm lib/*.inc
 floppy.bs: boot/fatvbr.asm
 	nasm -s -DCMDLINE='"KERNEL.COM"' -o $@ $<
 
-fdimage.img: floppy.bs kernel.com
+programs/%.com: programs/%.asm
+	nasm -s -I lib -o $@ $<
+
+fdimage.img: floppy.bs $(DISTFILES)
 	dd if=/dev/zero bs=512 count=$$(( $(FD_CYLINDERS) * $(FD_HEADS) * $(FD_SECTORS) )) of=$@
 	mformat -i $@ -t $(FD_CYLINDERS) -h $(FD_HEADS) -n $(FD_SECTORS) -B floppy.bs ::
-	mcopy -i $@ kernel.com ::kernel.com
-	mattrib -i $@ +s ::kernel.com
+	mcopy -i $@ $(DISTFILES) ::
 
 clean:
-	rm -f *.com *.bin *.rom *.img *.log *.bs *.lst
+	rm -f *.com *.bin *.rom *.img *.log *.bs *.lst programs/*.com
 
 qemu-floppy: fdimage.img $(DEBUGROM)
 	$(QEMU) $(QEMU_ARGS) -boot c -fda fdimage.img

programs/hello.asm

@@ -0,0 +1,17 @@
+org 0x0100
+
+main:
+  mov si, hello
+.loop:
+  lodsb
+  test al, al
+  jz .ret
+  mov dl, al
+  mov ah, 0x02
+  int 0x21
+  jmp .loop
+.ret:
+  ret
+
+hello:
+  db "Hello!", 0