When I think of vintage computers I think of computers old enough that they have no concept of virtual memory. In particular, the Atari ST, the Amiga and the Acorn Archimedes - on all of those platforms the user interface wasn't merely another task running among dozens, it was the most important thing the computer was doing - and while it's hard to describe, the feeling of immediacy is noticeable (even if the task your mouse click set in motion takes minutes or hours to complete - the widget will give you instant visual feedback when you click it) and its absence on more modern machines is also noticeable. (If a modern machine's thrashing the hard disk - especially on spinning rust - it can take seconds for the same feedback to happen, even if the machine itself is thousands of times faster.)

Yesterday's topic about the memory footprint of desktop environments touched on this - the fact that if a memory-hungry process triggers a swapstorm it can take minutes to regain control of a Linux desktop.

I call that sense of immediacy the feeling of "having the computer's full attention" - and ensuring that nothing required for interactivity gets paged out is the only robust way I can see of creating that feeling - but instead we use the somewhat crude, brute-force approach of throwing more RAM at the computer until the swap-outs stop happening!

QnX.

http://toastytech.com/guis/qnxdemo.html