As you ca see on the picture above, the writing on the dial is a mix of English and French. On the French made ref. 844 (http://classicheuers.blogspot.com/2009/01/heuer-844-french-made-diver.html) all text is in French: 200 METRES / Professionel. On this Swiss Made watch the print on the dial says: 200 METRES / Professional. The depth rate is still French, but professional is now in English..
The movement on these early diver is ESA 536.121. This is a quite fragile movement, and it's very common to see non working examples of these diver for sale on Ebay. The can often be picked up very cheap. But be avare, it's very difficult to find parts for this movement. Even a used replacement can be very difficult to find.
It made it as "covergirl" in this 1981 Heuer catalogue....