Do I have ABS

ok I'm wondering if my car has ABS... i know this may seem to be a strange Q. but here goes.

ABS light doesn't light up.
80Amp ABS fuse in place
ABS sensors in place on all four wheels....
brakes lock up... well when i brake too hard.

the car's a '90 JDM GT and i thought perhaps they fitted the sensors to the vehicle and just didn't include the ABS computer unless it was selected as an option on the vehicle. If this is the case so i just get an ABS computer? or if it wasn't meant to have ABS would the car not have been fitted with the sensors?

I'm confused!

I think it was an option, but I'm not sure.

It Was Definately An Option And The Wirings There But I Dunno Bout The Abs Computer