Putting together a home alarm system

Hi All,

I've pondered the idea of creating a home alarm system. Actually, the
purpose I need it for is not to detect intrusion, but rather find out when a
particular door opens and closes and do something when that happens (perhaps
store it in a DB, send an email, who knows). I thought the easiest way would
be to get a reed and put it on the door, and then hook it up to a Linux box
(hopefully allowing for more reeds if I want to hook them up in future). In
theory it sounds OK, but given my lack of electronics knowledge I'm not sure
where to begin (whether to hook it up to the serial or parallel port, etc).
Unfortunately we didn't get to play with serial ports at Uni. I've heard the
parallel port is the easiest to work with, but I'm still a little lost as to
where to begin.

Apart from my need for this system, I'm more interested in the knowledge
I'll gain from it so if anyone has done this sort of thing and can recommend
a good path to follow (keeping in mind I'm a total newbie at electronics),
I'd really appreciate it (URLs on the subject would be great!).

Thanks in advance!
- Gonzalo

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