Casio F-91W: Difference between revisions
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==Specifications== |
==Specifications== |
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The F91W has a 1/100 second [[stopwatch]] with a count up to 59:59.99 (almost one hour) in hundredths of a second. After one hour the stopwatch still counts until stopped; however, the display changes to hours:minutes:seconds. Thus the stopwatch could be started at a certain time marking midnight, effectively displaying a secondary time zone clock in stopwatch mode until stopped. Measuring modes of net and split time ( 1st and 2nd place, or lap ) are included. There are the options of an hourly time beep and a single daily alarm. It has an automatic calendar, although auto-adjustment for [[leap year]]s is not supported, as the watch does not record the year.<ref name="casiofeatures" /> The watch uses a green [[Light-emitting diode|LED]] backlight to illuminate the display. The watch is reported to be as accurate as ±30 seconds per month<ref name="casiofeatures" /> (6 minutes per year) by the manufacturer; some units produced could be more accurate timekeepers still. |
The F91W has a 1/100 second [[stopwatch]] with a count up to 59:59.99 (almost one hour) in hundredths of a second. After one hour the stopwatch still counts until stopped; however, the display changes to hours:minutes:seconds. Thus the stopwatch could be started at a certain time marking midnight, effectively displaying a secondary time zone 24 hour clock in stopwatch mode until stopped. Measuring modes of net and split time ( 1st and 2nd place, or lap ) are included. There are the options of an hourly time beep and a single daily alarm. It has an automatic calendar, although auto-adjustment for [[leap year]]s is not supported, as the watch does not record the year.<ref name="casiofeatures" /> The watch uses a green [[Light-emitting diode|LED]] backlight to illuminate the display. The watch is reported to be as accurate as ±30 seconds per month<ref name="casiofeatures" /> (6 minutes per year) by the manufacturer; some units produced could be more accurate timekeepers still. |
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The watch is powered by a single [[CR2016]] 3 Volt lithium button cell, which Casio claims will last at least seven years, assuming 20 seconds of alarm and one second of light usage per day. However, practice shows that owners seldom use its light and alarm, so it is not uncommon that the battery would last significantly longer. The watch case measures 37.5 × 33.5 × 8.5 mm and weighs 21 g. The manufacturer's module number for this model (stamped on the stainless steel rear of the watch case) is 593. |
The watch is powered by a single [[CR2016]] 3 Volt lithium button cell, which Casio claims will last at least seven years, assuming 20 seconds of alarm and one second of light usage per day. However, practice shows that owners seldom use its light and alarm, so it is not uncommon that the battery would last significantly longer. The watch case measures 37.5 × 33.5 × 8.5 mm and weighs 21 g. The manufacturer's module number for this model (stamped on the stainless steel rear of the watch case) is 593. |
Revision as of 13:04, 24 April 2016
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Type | Quartz |
---|---|
Display | Digital |
Introduced | 1991[1] |
The Casio F91W is a quartz digital watch, manufactured by the Japanese company Casio Computer Co., Ltd. It was introduced in 1991 and is still in production and demand.[1] It is popular for its simplicity, longevity and unpretentious, clean design. The watch is available in several variants. Casio does not release sales figures for the model, but admits it continues to sell "very well".[1]
Specifications
The F91W has a 1/100 second stopwatch with a count up to 59:59.99 (almost one hour) in hundredths of a second. After one hour the stopwatch still counts until stopped; however, the display changes to hours:minutes:seconds. Thus the stopwatch could be started at a certain time marking midnight, effectively displaying a secondary time zone 24 hour clock in stopwatch mode until stopped. Measuring modes of net and split time ( 1st and 2nd place, or lap ) are included. There are the options of an hourly time beep and a single daily alarm. It has an automatic calendar, although auto-adjustment for leap years is not supported, as the watch does not record the year.[2] The watch uses a green LED backlight to illuminate the display. The watch is reported to be as accurate as ±30 seconds per month[2] (6 minutes per year) by the manufacturer; some units produced could be more accurate timekeepers still.
The watch is powered by a single CR2016 3 Volt lithium button cell, which Casio claims will last at least seven years, assuming 20 seconds of alarm and one second of light usage per day. However, practice shows that owners seldom use its light and alarm, so it is not uncommon that the battery would last significantly longer. The watch case measures 37.5 × 33.5 × 8.5 mm and weighs 21 g. The manufacturer's module number for this model (stamped on the stainless steel rear of the watch case) is 593.
Water resistance
The watch has a reliable rubber seal between its steel back and case; however, does not have any seals for its buttons. Since they fit tight enough, surface tension prevents the water from getting inside, but only to a certain point when the pressure will prevail. Therefore, the watch front is marked WATER RESIST.,[2] but Casio reports different values for different variants of the watch. The black version (F91W-1XY)[3] is "30 Meter / 3 Bar", the ISO standard meaning of which is: "Suitable for everyday use. Splash/rain resistant. NOT suitable for showering, bathing, swimming, snorkeling, water related work and fishing.", but the colored versions (e.g. F-91WC-2AEF) are "DIN 8310 / ISO 2281- resistant to minor splashing". Even though the black version may resist rare, short and shallow submersions, the watch should never be used in such conditions on a regular basis.
Operation
![](http://upload.wikimedia.org/wikipedia/commons/thumb/6/66/Casio_f91w_digital_watch.png/220px-Casio_f91w_digital_watch.png)
The watch is controlled by three side-mounted pushbuttons. The upper left button turns on the backlight, cancels the alarm, resets the stopwatch or marks the split (lap) time, and is used for selecting settings. The lower left button cycles the modes of the watch: time display, alarm, stopwatch, and time/date adjustment. The button on the right is the function button: when used it starts and stops the stopwatch, changes the settings currently being adjusted, or switches between the 12- and 24-hour modes, depending on what mode the watch is currently in. In time mode, pressing this button for three seconds will make the display read "CASIo" if the watch has genuine parts or ones produced under legit license. Pressing all three buttons at the same time will fill all the cells on the LCD until any button is pressed again.[4]
The time or date is adjusted by pressing the lower left button three times to bring the watch to time adjustment mode. The top left button is used to cycle through seconds, hours, minutes, month, date, day, and normal mode. The right button is used to adjust the flashing value displayed. Unlike all the other values, the seconds can only be zeroed. Should this happen before :30 seconds, the watch will zero in at the beginning of the current minute. After :30 seconds it will start the next minute as displayed. When the adjustments are finished, the bottom left button can be pressed once to return the watch to normal mode.
The watch display shows the day of the week, day of the month, hour, minute, seconds, and the signs PM or 24H (24-hour clock), the alarm signal status, and the hourly signal status (double beep on the hour).
In stopwatch mode, minutes, seconds and hundredths of a second are shown until an hour is reached; then hours, minutes and seconds are displayed.
Claimed use in terrorism
![](http://upload.wikimedia.org/wikipedia/commons/thumb/c/ca/Al_Qaida_watch_timer_on_perf_board_84071_-abc.jpg/220px-Al_Qaida_watch_timer_on_perf_board_84071_-abc.jpg)
According to secret documents issued to interrogators at Guantánamo Bay, obtained[5] and released by The Guardian, "the Casio F-91W digital watch was declared to be 'the sign of al-Qaeda' and a contributing factor to continued detention of prisoners by the analysts stationed at Guantánamo Bay. Briefing documents used to train staff in assessing the threat level of new detainees advise that possession of the F91W – available online for as little as £4 – suggests the wearer has been trained in bomb making by al-Qaeda in Afghanistan."[6] United States Military intelligence officials have identified the F91W as a watch that terrorists use when constructing time bombs.[7][8][9][10][11]
This association was highlighted in the Denbeaux study, and may have been used in some cases at the Guantanamo Bay detention camp.[12] An article published in the Washington Post in 1996 reported that Abdul Hakim Murad, Wali Khan Amin Shah, and Ramzi Ahmed Yousef had developed techniques to use commonly available Casio digital watches to detonate time bombs.[13]
Variants
![](http://upload.wikimedia.org/wikipedia/commons/thumb/b/b5/Casio_F-105.jpg/220px-Casio_F-105.jpg)
There are many variants of the F91W that have the same specifications and operational features, including the Casio F105W, which uses an electroluminescent backlight instead of an LED to illuminate the display, the Casio A158W, A159W, A168W, LA680, and B640, with stainless steel bands, and the W59 and F94W.
References
- ^ a b c Denise Winterman (April 26, 2011). "Casio F-91W: The strangely ubiquitous watch". BBC News magazine. Retrieved April 27, 2011.
- ^ a b c "F91W-1 Classic Timepiece". Casio. Retrieved April 27, 2011.
- ^ "F-91W-1XY". Casio. Retrieved May 22, 2013.
- ^ "Manual" (PDF). Casio. Retrieved November 26, 2014.
- ^ http://www.theguardian.com/world/interactive/2011/apr/25/guantanamo-files-interrogators-al-qaida-taliban#the-sign-of-al-qaida
- ^ James Ball (April 25, 2011). "Guantánamo Bay files: Casio wristwatch 'the sign of al-Qaida'". The Guardian. London.
- ^ "USA v. al Qahtani" (PDF). US Department of Defense. November 7, 2005. Retrieved February 27, 2007.
- ^ "Combatant status review board for Mohammed Ahmad Said el Edah". The New York Times. October 6, 2004.
- ^ "Why Am I in Cuba?". Mother Jones. July 12, 2006.
- ^ "Guantanamo Captives Jailed Because Of Digital Watches". WCVB. March 10, 2006.
- ^ "Summary of Evidence memo (.pdf) prepared for Sabri Mohammed Ebrahim Al Qurashi's Combatant Status Review Tribunal – page 216" (PDF). October 13, 2004.
- ^ "Empty Evidence". National Journal. February 3, 2006.
- ^ R. Jeffrey Smith (July 21, 1996). "New Devices May Foil Airline Security". Washington Post. pp. A01. Retrieved March 14, 2008.
External links
Media related to Casio F91W at Wikimedia Commons
Media related to IED timers that use a Casio f91w at Wikimedia Commons
- F91W-1 product page, Casio website