On Fri, 27 Oct 2017, Clem Cole wrote:

> And to simplify that ...  s/operating systems/SW/

Not to mention HW...  I know how a POTS telephone works, but a cellular? 
Only vaguely...  Ditto B/W television vs. colour.  And I stopped 
maintaining my own cars years ago; about the onpy thing I recognise under 
the bonnet these days is the engine.

-- 
Dave Horsfall DTM (VK2KFU)  "Those who don't understand security will suffer."