Binary clock
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Image:Thinkgeek binary clock.jpg
A binary clock is a clock which displays traditional sexagesimal time in a binary format. More precisely it shows each decimal digit of sexadecimal time as a binary value. Most binary clocks are digital, although analog varieties exist.
As of 2005, the most common binary clock is sold by ThinkGeek, and uses six columns of LEDs to represent zeros and ones. Each column represents a single decimal digit, a format known as binary-coded decimal (BCD). The bottom row in each column represents 1 (or 20), with each row above representing higher powers of two, up to 23 (or 8). To read each individual digit in the time, the user adds the values that each illuminated LED represents, then reads these from left to right. The first two columns represent the hour, the next two represent the minute, and the last two represent the second. Since zero digits are not illuminated, this clock is not usable in the dark.
To read a BCD clock add the values of each column of LEDs to get six decimal digits. This gives two decimal digits each for hours, minutes, and seconds.
A more complete binary clock format would use just three binary numbers to give the time (one number each for hours, minutes, and seconds) rather than six numbers for the decimal digits of the time units as BCD binary clocks do:
Hours Minutes Seconds
------- ------- -------
32 | 1 1
16 | 0 0 1
8 | 1 0 0
4 | 0 1 0
2 | 1 0 0
1 | 0 1 1
============================
decimal: 10 : 37 : 49
The above display uses three binary number columns, one for each of the units (hours, minutes, seconds) of the conventional time system.
Powers of two can also be used for the ratios between units in a time system (in place of the conventional ratios of 24 and 60); this is done in the hexadecimal time system.it:Orologio binario