Trademarks must be registered before they are under legal actions. Of
course there is countries where registration of trademarks is
impossible. In global aspect you post application to WIPO (World
Intellectual Property Organisation) and you have to have application in
process in country of company origin, or preferably an existing trademark.
Logo itself isn't a trademark, (it may present a trademarked product)
logo is always under copyright law.
Definitely not, and copyright is something that comes always along with
produced material, pictures, books, texts, articles, music, software
etc. Depending on country copyright usually lasts life time of author
and 70 years _after_ that.
Another thing is copyright that doesn't really concern material, more
like performance, photographs, movies, signal broadcasts and such. There
is shorter period for copyright (50 years from performace/publication
day). Databases and (big, combined) lists are also protected, but only
for 15 years.
Yes, this is very true. Until someone claims his/her rights to Oric logo
you can use it. Well, actually you shouldn't use it, but since no-one is
after his/her rights you can break the laws.. =) In some cases long
term ignorance can be seen as giving up rights.
Now what comes to Atari I was very surprised to see that at least two
newest Deer Hunter games for PC contains very big Atari logo in intro..
=) I think it's first thing that comes up when starting game in question...