AutoCAD

I used CAD a lot in the eighties - At school I did technical drawing but my first computer-based design was with PAFEC as an undergraduate (running on a Prime 500 mainframe with a Bosch graphics terminal) and then when I went to the Beeb I used AutoCAD v.9 under DOS - a text monitor for commands and a Hercules-driven graphics monitor (monochrome 640x480) for the diagram. It also had a Summagraphics tablet that needed degaussing on a daily basis! After I left the Beeb there didn't seem to be ever enough time to keep diagrams up to date or even transform the wiring schedules into a drawing and so I pretty much lost my CAD skills. Having been at Root6 for over three years now (and doing increasingly large projects) I have to turn in diagrams and so a couple of years ago I did a little refresher at BBC Wood Norton.
AutoCAD has been around for nearly a quarter of a century and is a mature piece of software in the very best ways. It runs on modest hardware (generally it's needs are less than the OS!) and it uses that now obsolete file-size measurement, the kilobyte. Even big diagrams with many layers fit on an old floppy and you can scroll and scrub around the drawing very quickly - Avid, Microsoft et al. could learn a thing from these guys. You can still drive it through the command line as if it were one of those early DOS releases but it is so comfortable to use with the mouse. My only beef is that if you do lots of zooming and scrolling then a wheeled-mouse is essential. Aside from that I actually look forward to a day of diagramming with it.