Paul Graham’s latest essay mentions his style of work: isolated from non-physical interruptions. All the communications paths to him require intentional interruption. You can call him on the phone or walk into his office, but he won’t interrupt his work for e-mail. It strikes me that Knuth describes a similar mode for different reasons:
I currently use Ubuntu Linux, on a standalone laptop—it has no Internet connection. I occasionally carry flash memory drives between this machine and the Macs that I use for network surfing and graphics; but I trust my family jewels only to Linux. Incidentally, with Linux I much prefer the keyboard focus that I can get with classic FVWM to the GNOME and KDE environments that other people seem to like better. To each their own.
I’ve certainly found it helps my own work to have no browser open, no biff running, no chat room or running IM conversations. My door’s open and my phones are on the desk, but I have open just those papers or windows relevant to the task at hand. I read e-mail a few times each day, when I’ll already be switching contexts. I see around me that much work is lost by conformance to the default many-windows approach of modern office automation systems, or by insistence that upper-management e-mail is answered within minutes of receipt.