4.3BSD/usr/src/sys/GENERIC/ubvec.s

#define	I_CLOCK	0
#define	I_CNR	4
#define	I_CNX	8
#define	I_TUR	12
#define	I_TUX	16
#define	I_MBA0	20
#define	I_MBA1	24
#define	I_MBA2	28
#define	I_MBA3	32
#define	I_UBA0	36
#define	I_UBA1	40
#define	I_UBA2	44
#define	I_UBA3	48