I have an idea for a small project. I want to build a small, low power, computer that I can program to record simple real-world events (i.e. a door opened) and send messages to either my phone or a networked server. The component doesnt have to be general purpose or re-progammable, it could just start by flashing an led or something simple. I think that building this will give me a really good idea of what are the minimal components it takes to hook something up to the internet or just power a small machine.
I know logic gates and remember vaguely finite state machines from school. I am wondering where this community would suggest I start. Thanks.