Casio CA-53W

The Casio CA-53W is a digital calculator watch manufactured by the Japanese electronics company Casio and was introduced in 1988 as a successor to the CA-50. It became famous for its appearance in the American science fiction films Back to the Future Part II (1989) and Back to the Future Part III (1990) and later for appearing in the American TV series Breaking Bad (2008–2013).

Design
The case of the watch measures 43.2 by 34.4 by 8.2 millimetres and the watch has a weight of 24 grams. The case has a lug-to-lug width of 42 millimetres and a thickness of 8 millimeters (including the raised area of the case back). The case of the watch is made from resin, with a plastic watch crystal, and a stainless steel case back with the model and module number stamped on it which is secured with four screws. The inner lug width (where the strap attaches) is 20 millimeters, and the strap is made of polyurethane. The strap can be swapped or replaced.

Features
The CA-53W features an 8-digit calculator with basic operators, a 24-hour $1/100$ second stopwatch which can measure up to 23:59.99. The stop watch can also record split times and 1st and 2nd place times. Other features include a daily alarm, a full auto calendar up to the year 2099, an hourly signal and a dual time mode. The watch is claimed to be accurate to ±15 seconds per month and is powered by a CR2016 3-volt lithium button cell. The watch has basic water-resistance which for Casio Digital watches means splash-proof (washing hands or rain). The display of the watch lacks internal illumination.

Operation
The watch is controlled by a keypad and two side mounted pushers. It has a 4x4 grid calculator keypad with rubber keys consisting of number keys from 0 to 9 along with a decimal place key in the first three columns and the operator keys in the last column. The key pad is marked with secondary functions and is also used for operating other functions of the watch such as operating the stopwatch, turning the alarm on and off and switching from anti-meridian (am) to post-meridian (pm) in time setting mode. On the right side of the watch, there are two small stainless steel pushers with one recessed pusher used to adjust the settings while the other used to switch between the modes of the watch. The time is set by pressing the adjust pusher once and entering the values for the hours, minutes and seconds by using the keypad. Unlike any other value, the seconds can only be zeroed by pressing the "0" key on the keypad. Should this happen before 30 seconds, the watch will zero in at the beginning of the current minute. After 30 seconds it will advance the minutes by one minute. After adjustment of the time, the watch automatically goes to the date setting which can be cancelled by pressing the adjust pusher. Like the time, the date is also set by inputting values via the keypad. The button operation tones of the watch can be switched on and off by pressing the adjust pusher in the calculator mode.

The display of the watch shows hours, minutes, seconds and day of the week. The date can be viewed by pressing the division (÷) key on the keypad while in the main time mode. The date is shown in YY/MM/DD format. An "AM" sign on the display indicates morning hours and "PM" sign on the display indicates afternoon hours. The "AM" and "PM" indicators disappear when the watch is in 24-hour time keeping mode which is switched on by pressing the addition (+) key in the time setting mode. The alarm is indicated by vertical bars on the top left on the screen while the hourly signal is denoted by a bell icon adjacent to the alarm icon. The display also shows operators selected by the user in calculator mode when performing calculations.

In the stopwatch screen, the minutes, seconds and one-hundredths of a second are shown. The watch displays the elapsed hours when the key marked with the secondary function "ST-hour" on the keypad is pressed while in the stopwatch mode. Another feature of the stopwatch is the interval beep in which the watch beeps after every ten minutes elapsed in the stopwatch mode. However, this feature works in the stopwatch mode only.

In the timekeeping mode, holding down the adjustment button and simultaneously pressing the mode button twice will enter the LCD test mode. All of the LCD cells will be filled. Pressing the mode button again will fill only some of the cells, and pressing the mode button one more time will display the module number.

Variants
Since its introduction, the CA-53W was only available in a single variation, CA-53W-1, with a black case and strap sporting a digital display consisting of dark characters against a light background. This version has changed only slightly over time.

In early 2020, Casio introduced five new variants with the model name CA-53WF, each sporting a different color case and strap. These all feature an inverted LCD, showing light characters on a dark background.

In popular culture
A common misconception about the CA-53W is that the watch was worn by Marty McFly in Back to the Future (portrayed by Michael J. Fox), who in reality wore the Casio CA-50. He actually wore the CA-53W in the two sequels Back to the Future Part II and Back to the Future Part III.

The watch was also seen throughout the American TV series Breaking Bad, in which it is worn by the main protagonist, Walter White (portrayed by Bryan Cranston).