I use Corel Draw 7 to draw and Adobe's Acrobat to make those drawings into deeply zoomable PDF files. Corel 7 is an antique now, email me at firstname.lastname@example.org
I have been drawing with it for many years. Since I love car wiring and mechanical details I have sort of arrived at my own drawing style. Based on the 80 zillion posts you have done here, it is a fine compliment to receive a thumbs up from you.