Casio F91W
Encyclopedia
The Casio F-91W is a quartz
digital watch
, manufactured by the Japanese firm Casio Computer Co., Ltd.
. It was introduced in 1991. This watch is widely available throughout the world. Prices vary, normally in the $7.50–$15 US$ or £7.50-£9 GBP
range. Casio does not release sales figures for the watch, but says the watch continues to be a "huge seller".
with a capacity of up to 59'59.99" and measuring modes of net time, split time, and 1st and 2nd place times. 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. The watch is claimed to be accurate to ±30 seconds per month.
The watch is powered by a single CR2016 lithium button cell, which Casio claims will last approximately seven years (assuming 20 seconds of alarm and one second of light usage per day). The watch case measures 37.5 × 33.5 × 9.5 mm and weighs 20 g. The manufacturer's module number for this model (stamped on the stainless steel rear of the watch case) is 593. The watch front is marked WATER RESIST.. The instructions state that water resistance is limited to splashes, rain, etc., so the watch should not be worn while swimming.
The watch is controlled by three side push-buttons. The upper left button turns on the backlight, cancels the alarm, and is used for selecting settings. The lower left button cycles the modes of the watch: → Alarm → Stopwatch → Time adjustment and back to the normal time display. The button on the right is the function button: when used after pressing the lower left mode button it starts and stops the stopwatch, or changes the settings currently being adjusted; but when pressed alone switches between the 12 and 24 hour modes.
The time or date is adjusted by pressing the lower left button three times to bring the watch to time adjustment mode. This causes the seconds to flash on the display. The top left button is pressed to cycle through seconds, hours, minutes, month, date, day, and normal mode. The right button is then pressed to adjust the flashing value displayed. When the adjustments are finished, the bottom left button is pressed repeatedly until the watch returns to normal mode.
The watch's display shows the day of the week, day of the month, hour, minute, seconds, and the signs for PM (or 24-hour clock
), alarm signal, and hourly signal (double beep on the hour).
In stopwatch mode, minutes, seconds and hundredths of a second are shown.
, "the Casio F-91W digital watch was declared to be 'the sign of al-Qaida' 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 F-91W – available online for as little as £4 – suggests the wearer has been trained in bomb making by al-Qaida in Afghanistan." United States Military intelligence
officials have identified the F91W as a watch that terrorists use when constructing time bombs.
This association was highlighted in the Denbeaux study, and may have been used in some cases at the Guantanamo Bay detention camp. 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.
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
digital watch
Watch
A watch is a small timepiece, typically worn either on the wrist or attached on a chain and carried in a pocket, with wristwatches being the most common type of watch used today. They evolved in the 17th century from spring powered clocks, which appeared in the 15th century. The first watches were...
, manufactured by the Japanese firm Casio Computer Co., Ltd.
Casio
is a multinational electronic devices manufacturing company founded in 1946, with its headquarters in Shibuya, Tokyo, Japan. Casio is best known for its electronic products, such as calculators, audio equipment, PDAs, cameras, musical instruments, and watches...
. It was introduced in 1991. This watch is widely available throughout the world. Prices vary, normally in the $7.50–$15 US$ or £7.50-£9 GBP
Pound sterling
The pound sterling , commonly called the pound, is the official currency of the United Kingdom, its Crown Dependencies and the British Overseas Territories of South Georgia and the South Sandwich Islands, British Antarctic Territory and Tristan da Cunha. It is subdivided into 100 pence...
range. Casio does not release sales figures for the watch, but says the watch continues to be a "huge seller".
Specifications
The F-91W has a 1/100 second stopwatchStopwatch
A stopwatch is a handheld timepiece designed to measure the amount of time elapsed from a particular time when activated to when the piece is deactivated. A large digital version of a stopwatch designed for viewing at a distance, as in a sports stadium, is called a stopclock.The timing functions...
with a capacity of up to 59'59.99" and measuring modes of net time, split time, and 1st and 2nd place times. 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
Leap year
A leap year is a year containing one extra day in order to keep the calendar year synchronized with the astronomical or seasonal year...
s is not supported as the watch does not record the year. The watch is claimed to be accurate to ±30 seconds per month.
The watch is powered by a single CR2016 lithium button cell, which Casio claims will last approximately seven years (assuming 20 seconds of alarm and one second of light usage per day). The watch case measures 37.5 × 33.5 × 9.5 mm and weighs 20 g. The manufacturer's module number for this model (stamped on the stainless steel rear of the watch case) is 593. The watch front is marked WATER RESIST.. The instructions state that water resistance is limited to splashes, rain, etc., so the watch should not be worn while swimming.
Operation
The time or date is adjusted by pressing the lower left button three times to bring the watch to time adjustment mode. This causes the seconds to flash on the display. The top left button is pressed to cycle through seconds, hours, minutes, month, date, day, and normal mode. The right button is then pressed to adjust the flashing value displayed. When the adjustments are finished, the bottom left button is pressed repeatedly until the watch returns to normal mode.
The watch's display shows the day of the week, day of the month, hour, minute, seconds, and the signs for PM (or 24-hour clock
24-hour clock
The 24-hour clock is a convention of time keeping in which the day runs from midnight to midnight and is divided into 24 hours, indicated by the hours passed since midnight, from 0 to 23. This system is the most commonly used time notation in the world today...
), alarm signal, and hourly signal (double beep on the hour).
In stopwatch mode, minutes, seconds and hundredths of a second are shown.
Claimed use in terrorism
According to The GuardianThe Guardian
The Guardian, formerly known as The Manchester Guardian , is a British national daily newspaper in the Berliner format...
, "the Casio F-91W digital watch was declared to be 'the sign of al-Qaida' 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 F-91W – available online for as little as £4 – suggests the wearer has been trained in bomb making by al-Qaida in Afghanistan." United States Military intelligence
Military intelligence
Military intelligence is a military discipline that exploits a number of information collection and analysis approaches to provide guidance and direction to commanders in support of their decisions....
officials have identified the F91W as a watch that terrorists use when constructing time bombs.
This association was highlighted in the Denbeaux study, and may have been used in some cases at the Guantanamo Bay detention camp. An article published in the Washington Post in 1996 reported that Abdul Hakim Murad, Wali Khan Amin Shah
Wali Khan Amin Shah
Wali Khan Amin Shah was a man who had a role in the foiled Bojinka plot. He was convicted of terrorism, and has been imprisoned on these charges since 1995....
, and Ramzi Ahmed Yousef had developed techniques to use commonly available Casio digital watches to detonate time bombs.
External links
- F91W-1 product page, Casio website