UNIX and Time
While reading The Overspill this morning I came across the following post:
TL;DR The iPhone countdown timer doesn’t strictly display the correct time but adds 500ms, or half a second, to the remaining time. It does this to make the reading of time more intuitive for humans. The alarm at the end of the countdown is not affected by this 500ms inaccuracy.
There’s a core design feature in UNIX called a “command line interface.” In this system, you type instructions, you hit “return,” and the instructions are carried out.* A unifying design principle of UNIX is that a program can’t tell if a person hit return or a program did so. Since real people are slower than simulated people at operating keyboards, the importance of precise timing is suppressed by this particular idea. As a result, UNIX is based on discrete events that don’t have to happen at a precise moment in time. The human organism, meanwhile, is based on continuous sensory, cognitive, and motor processes that have to be synchronized precisely in time..
The arguments in favor of UNIX focused on how computers would get literally millions of times faster in the coming decades. The thinking was that the speed increase would overwhelm the timing problems I was worried about. Indeed, today’s computers are millions of times faster, and UNIX has become an ambient part of life. There are some reasonably expressive tools that have UNIX in them, so the speed increase has sufficed to compensate for UNIX’s problems in some cases. But not all.
I have an iPhone in my pocket, and sure enough, the thing has what is essentially UNIX in it. An unnerving element of this gadget is that it is haunted by a weird set of unpredictable user interface delays. One’s mind waits for the response to the press of a virtual button, but it doesn’t come for a while. An odd tension builds during that moment, and easy intuition is replaced by nervousness. It is the ghost of UNIX, still refusing to accommodate the rhythms of my body and my mind, after all these years.
Note, he states he’s not just picking on the iPhone or UNIX, Windows is guilty as well.