This may seem like a silly question folks from someone who has been using Canon FD cameras for thirty five years, but this is the first camera I have owned with this facility , yes I have the CanonT90 instruction book, it tells you that if the film cassete isn't DX coded you set the film speed manually, but there no indication in the instructions how to up or down rate a DX coded film, do you let the camera set the ISO, then you change it to the speed you want, or do you adjust the exposure compensation ?
I would appreciate your advice.

My best guess is to just over ride the ISO setting that the DX code sets. At least that is how I do it on my Pentax.

My best guess is to just over ride the ISO setting that the DX code sets. At least that is how I do it on my Pentax.
I hope that's the case I know that was the case with the super A and Programme A etc. but I know the T90 is a different ball game as far as the electronics are concerned, I thought about covering the DX code with some black insulating tape might work, I recall when DX first came out a firm in the UK was advertising some stick on DX codes for re- rating the film speed speed , but must be over twenty years ago, I think I'll try what you suggest marsbars, the worst it can cost me is a film that was a freebie anyway.

You don't need to cover it or whatever, you can just overide it by using the ISO keys.

You don't need to cover it or whatever, you can just overide it by using the ISO keys.
Thanks everyone, I feel a bit embarrassed to have asked the question, since I worked in a camera shop at the time they were made, and sold many of them, that was about 1986 , they were only made for about a year as far as I recall ( I didn't like them them at the time, but most 35 mm SLR s are like that now) I bought a mint one recently as an addition to my FD gear because of its metering capability's mainly, and I couldn't remember if the ISO override would do it, it only mentions setting it with none-coded cassettes in the instruction book