You car might have OBD1 and OBD2, depending on the automaker.
Like the 1994 Nissan Maxima have both in, but 1994 Mitsubishi Galant on have one.
The federal government required all automake put the same OBD2 system in every car starting in 1994.
To find out if you have OBD2 IT IS right under the dash on the driverside of the vehicle directly below the steering column.(required by law)
OBD1 is on the passenger side somewhere,
Thanks