Thanks Paul for the Dynatron link - good stuff and very informative.
I've tried that link for the Hacker booklet download again, but have still been unable to open.
I've had an Adobe Reader message stating: 'There was an error opening this document. This file cannot be found'. I use my Adobe Reader quite a lot and so I don't think there's a problem with it.
Never mind, I'll try it again later.
Tony