Diacom is great but it is state off the art from 1991 and cost $500 at the time.
If you can find a used copy it works finebut will only record 20 sec logs.However you can watch in real time and it logs the fault codes seen.
To pull codes only you can jumper the ALDL connector .
There are many programmes available , some free that let you see all the engine sensors working in real time.
Datamaster is best , lets you log 20 times before you have to buy .
See
http://www.ws6.com/tts-dm.htm for sample
you also need a cable to connect to your laptop.
http://www.aldlcable.com/