I've been tinkering with computers and networks for most of my adult life (if I can stretch the definition of the term a little). I used this as an excuse to spend four pleasant years in DCU and have subsequently managed to find a succession of foolish employers who are willing to pay me to tinker. Life is strange.
I learnt a lot in DCU, but probably the single most consistently useful piece of knowledge I acquired came from Prof. Michael Ryan in a Computer Systems Architecture course he was teaching, and that is a detailed knowledge of workings of RS/232 serial communications (thanks Michael !). Computer and Network technology has changed beyond all recognition since I was a student in DCU, but through it all the humble asynchronous RS/232 connection has remained a mainstay, connecting PCs to modems, to router/switch console ports, to digital cameras, to terminal servers and much more besides.
This page was prompted after a frustrating afternoon on a customer site trying to cobble together a cable to link my laptop to a small (and otherwise inaccessible !) UNIX server. I hope you find it useful. I'd love to hear your comments, suggestions or feedback.