resident segment para public 'code' public b_chain assume cs:resident b_max equ 20 db buf_head dup (?) b_chain: rept b_max buf <$+((size buf)+buf_head)> db buf_head dup (?) endm if card12 b_num dw 16 else b_num dw 16 endif resident ends init segment para public 'data' public lastbuff lastbuff dw ? init ends