Comments on: 9 minutes with the clock gods http://blog.amber.org/2006/05/24/9-minutes-with-the-clock-gods/ Thoughts of a minor lunatic Fri, 29 Aug 2008 22:37:43 +0000 http://wordpress.org/?v=2.6.1 By: Tim http://blog.amber.org/2006/05/24/9-minutes-with-the-clock-gods/#comment-7599 Tim Thu, 25 May 2006 14:51:58 +0000 http://blog.amber.org/2006/05/24/9-minutes-with-the-clock-gods/#comment-7599 I've always thought it's because 9 minutes is the longest snooze that's possible with a single-digit compare: take the current time in minutes, subtract one from the least-significant digit, and set off the alarm when the least-significant digit in the current time in minutes equals the saved snooze digit. Cecil addresses this, and, unsurprisingly, gets it wrong: "On a digital clock, nine is the greatest interval obtainable by advancing some sort of "snooze counter" on the ones column. But why mess with the ones column? Why not put the snooze counter on the tens column and advance that by one?" The reason this doesn't work is because if you had your alarm set for 6:45 and pushed snooze, then incremented the tens digit and compared, the alarm would go off in 5 minutes, not 10, when the time reached 6:50. To get it to do 10 full minutes, you need to store and compare the last two digits of the time, which was a non-trivial extra cost when LED clocks were first invented. I’ve always thought it’s because 9 minutes is the longest snooze that’s possible with a single-digit compare: take the current time in minutes, subtract one from the least-significant digit, and set off the alarm when the least-significant digit in the current time in minutes equals the saved snooze digit.

Cecil addresses this, and, unsurprisingly, gets it wrong: “On a digital clock, nine is the greatest interval obtainable by advancing some sort of “snooze counter” on the ones column. But why mess with the ones column? Why not put the snooze counter on the tens column and advance that by one?”

The reason this doesn’t work is because if you had your alarm set for 6:45 and pushed snooze, then incremented the tens digit and compared, the alarm would go off in 5 minutes, not 10, when the time reached 6:50. To get it to do 10 full minutes, you need to store and compare the last two digits of the time, which was a non-trivial extra cost when LED clocks were first invented.

]]> By: petrilli http://blog.amber.org/2006/05/24/9-minutes-with-the-clock-gods/#comment-7597 petrilli Thu, 25 May 2006 14:43:07 +0000 http://blog.amber.org/2006/05/24/9-minutes-with-the-clock-gods/#comment-7597 Perhaps it is a conspiracy to confuse? I just found it odd that it wasn't just straight up 10 minutes. That seems "logical." Perhaps it is a conspiracy to confuse? I just found it odd that it wasn’t just straight up 10 minutes. That seems “logical.”

]]> By: Neil Greenwood http://blog.amber.org/2006/05/24/9-minutes-with-the-clock-gods/#comment-7596 Neil Greenwood Thu, 25 May 2006 14:38:27 +0000 http://blog.amber.org/2006/05/24/9-minutes-with-the-clock-gods/#comment-7596 So why does my phone snooze for 11 minutes then? :-) So why does my phone snooze for 11 minutes then? :-)

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