Slow film BUT....

Then microprocessor then determines the proper aperture f-stop.

If you use your brain instead of relying on a microprocessor, you'll see that exposure compensation has exactly the same effect as altering the ISO, whether it's a separate control or not.

 

It really doesn't matter whether it's a set of markings on an ASA/ISO dial, a dumb backlight button or a separate dial, the effect is just to alter the exposure away from what's metered for the set ISO.

 

Your brain is more flexible than a microprocessor program, since it can decide whether any compensation is done by changing the aperture, the shutter speed, or both.

Using 200 ISO film, if you have the camera set to aperture priority, the program may select 1/500 sec at a designated f/11. If you want to increase exposure by one stop you can go manual and set to 1/250 sec @f/11. Or, you can change the ISO setting to 100 ISO and the camera will set automatically in aperture priority to 1/250 sec at f/11.