It has been awhile since I used it and I do not remember websites off the top of my head but the software from what I remember is backwards of autocad. The software was created by IBM if I remember correctly, you might want to give them a visit. If I remember any sites I will drop you a new post.
Amazon.com have copies of USING MICRO CADAM by T.Daniel Smyth, ISBN: 0969751001. They are not cheap at about $192 but for 1200 pages of information plus DOS version of software on disc it's good value.
I was trained on it back in 1982 and have used it on and off ever since. It's very logical, fast and easy to learn, You can leave it alone for several years and still come back to it.
CADAM was developed in 1964/5 by Lockheed and later marketed by IBM, in the early days it ran only on a large mainframe computer but is fine on a PC as MicroCadam.
Your Library may be able to find an archive copy somewhere, all my training stuff went years ago otherwise it could have been copied.
CADAM was bought out by Dassult Systemes the makers of CATIA software. It was included in the early versions of CATIA v5. I think they still support it.