Here’s a hypothetical example. The time control is 40/90 SD/30; d/5. The clock furnished by player A cannot be set for two time controls, and player B does not furnish a clock. Player A sets his clock for G/90 d/5, intending to adjust the time after Black’s 40th move, and informs player B of this situation. Player B says, “Hey, I have a better idea. Just set the clock for G/120 d/5, with the understanding that our times for the first 40 moves expire when the clock shows 30 minutes remaining.” Player A agrees, and the game proceeds.
Later, around move 37, with both clock faces showing 31 minutes, the players suddenly realize that this particular clock is not showing running seconds (mm:ss), and will not do so until it gets below 20 minutes (or perhaps 10 minutes). The clocks are displaying h:mm, which in this case is 0:31. Now, after the display drops from 0:31 to 0:30, neither player will know how much time he has left to complete moves 38 through 40. Could be anywhere from 1 second to 59 seconds. In a complicated position with many pieces hanging and many forks threatened, the players are forced to guess how much time they have. Not nice.
If an experienced TD had heard the players’ conversation at the start of the game, he/she might have foreseen the problem and vetoed player B’s “better” idea.
In the hypothetical, as soon as the clock shows 0:30, the player has already overstepped the time limit. The key point is that the player actually has no more time than is shown on the clock, but may have a fraction of a second less. The clock has to work this way; when the clock shows 0:00, the player must have no time remaining.
As an experiment, set a clock for G/5 d/0 blitz and start the clock. Pay careful attention, and you’ll see that the clock only shows 4:59 one full second after starting the clock. So, even though the clock shows 5:00 for one full second, the player actually has somewhere between 4 minutes 59 seconds and five minutes left.
It depends on the clock. On many clocks, if the clock shows 0:30 the player can have anywhere from 0:30:00 to 0:30:59 remaining. That’s why, if a player fails to appear at a CCA tournament with a 40/120, SD/30, d10 time control and the opponent’s clock doesn’t show the number of seconds, I tell the opponent to wait until the clock shows 59 minutes remaining before claiming the forfeit.
As for “The clock has to work this way; when the clock shows 0:00, the player must have no time remaining”, many clocks switch from showing hours and minutes to showing minutes and seconds at some point.
Not true. Try it on the DGT. The display drops from 0:31 to 0:30 at the moment the actual time drops from 31:00 to 30:59.
The confusing phenomenon here is that all clocks, when displaying h:mm, round the displayed time down to the next full minute, but when displaying m:ss (or h:mm:ss), round the displayed time up to the next full second.
And, as you said, the clock must work that way.
Correct, but that’s because at 0:00 the clock is displaying m:ss rather than h:mm. (Or, on some clocks, 0:00:00, which is h:mm:ss).
Just to add another monkey wrench, a clock that shows tenths of seconds (m:ss.t or h:mm:ss.t, like the Chronos in one of its blitz modes) rounds hours, minutes, and seconds downward, but tenths of a second upward – which, again, is the only reasonable option the clock has.
Apparently, the operating principle is that the smallest displayed time unit is always rounded up, while the others are always rounded down.
Ah, I do see my mistake clearly now. Not one of my finer moments … Well, that just adds another reason for me to dislike the “three and a half” digit displays.
exactly, mr parker! if either player objected to the pieces, they should’ve said something before the game even started. if no objections, i would have to assume neither player had a problem with it.
cheers, …scot…
Actually, though, I now think my explanation wasn’t completely accurate, either.
If time remaining is, say, 30:17, but the clock is showing only h:mm, it still rounds the minutes down (not up) and shows 0:30, even though minutes is the smallest displayed time unit.
So I guess it would more accurate to say that the clock always rounds up to the nearest second, but then, if the clock is in a mode that displays only h:mm, it then truncates the result, in effect rounding the already-rounded result down to the nearest minute.
Of course, none of this changes the lack of wisdom in using a 30-minute time mark to simulate a time forfeit at the end of the first control. In fact, during the 60 seconds that the display shows 0:30 (h:mm), for the first 59 seconds there has not been a time forfeit, but during the final second there has been.
So, the way clocks round up to the next second is to actually start the countdown 0.999 seconds too high, then round down (to seconds, tenths of seconds, or whatever) for display purposes.
I guess it all works out the same way. Rounding down is easier than rounding up, because all you have to do is truncate.
I edited my post to show the URL. I always assumed that it would be programmed to start at 24 and display 24 as long as the time was 23+epsilon, etc. so that 0 meant violation. I’m not sure I see any good reason to do everything rounded up by just shy of a second, but maybe with timing devices from the 1950’s or whenever they implemented the shot clock it was easier to do that way.
Bill does what I would do. Same thing for an analog clock set with a different T/c from 6:00. I think there is no correct answer, just TD preference to avoid future problems.
Regards, Ernie
