I started developing software in the days before the Internet. It was indeed very different. My choices about what to remember and how I remember things have changed significantly since the ubiquitous availability of searchable information. I no longer have tomes of K&R, processor manuals, Inside Macintosh or Java books on my desk. The only technical book which happens to be on my desk at the moment is "Anti-patterns".

I have been "weeding" my paper books, especially technical books over the last couple of years and gotten rid of an entire bookshelf of books. I still have an entire bookshelf with Knuth TAoCP, math books, type theory, graphics, graph theory, control theory, physics and some nostalgic books like my original Motorola 68000 processor guide, Rodney Zaks Z80 book, "Adventure game programming in BASIC", Commodore 64 Innerspace Compendium, etc.

When a puppy chewed up my copy of "Linux in a Nutshell" I was tempted to buy the new edition but decided to try it online for a month with O'Reilly Safari through work and have not bothered to replace the paper copy for more than 2 years.

I would categorize the main change in style of memory as a shift from focus on remembering details and facts, which I can look up, to using memory for decision trees, processes and methodologies which either can't be looked up or are significantly personally customized. I consciously "outsource" the simpler and to me, less valuable, aspects of memory. Some of this is handled automatically by the IDE I use and the rest is done with mostly Google searches.