OBDI is the computers before 1996 each manufacturer had there own connector so i have a couple of boxes with different connectors. there are exceptions around 1993 to 1998.
in 1996 the manufactures went to a standardize connector ( the obdII ) along with that they put in place the standardize generic OBDII codes P0001 to P1000 . they also manufacturer specific codes. abs,anti lock, 4x4,body, trans,ect modules
what info you get from the computer depends on the type of scanner you are using.
on are scanners if we limit the info to just a few items then the data is much faster if we have about 15 lines then it is slower.
when we go into a chev obd2 then we have about 15 items when i put in the vin# info we get 3 pages info. when i go into a foreign car obd2 i get about 5 items.
the rocket computer is not that complicated but i do get a lot of info when i put my scanner on it. i have not tried the tune ecu so i don't know what it has. hth