make bootable

boot.s

@@ -0,0 +1,41 @@
+; assemble this and concatenate sp2.com with it to make it bootable!
+
+[org 0x7C00]
+[bits 16]
+
+NUMSEG equ (1993/512)+1 ; filesize is 1993 bytes
+
+mov ax, 0x100
+mov ss, ax
+mov ds, ax
+mov es, ax
+mov gs, ax
+mov fs, ax
+mov bp, 0xF000
+mov sp, bp
+
+mov bx, 0x100
+mov al, NUMSEG
+inc ah
+mov cl, ah
+xor ch, ch
+xor dh, dh
+int 13h
+
+xor cx, cx
+mov ds, cx
+mov word [ds:0x21*4], int21
+mov word [ds:0x21*4+2], 0
+
+inc ch
+mov ds, cx
+push 0x100
+push 0x100
+retf
+
+int21:
+hlt
+
+times 510 - ($-$$) db 0
+
+dw 0xAA55