Game clock
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A game clock consists of two adjacent clocks and buttons to stop one clock while starting the other, such that the two component clocks never run simultaneously. Game clocks are used in two-player games where the players move in turn. The purpose is to keep track of the total time each player takes for his or her own moves, and ensure that neither player overly delays the game.
Game clocks were first used extensively in tournament chess, and are often referred to as chess clocks, but their use has since been adopted for tournament Scrabble, Shogi, Go, and nearly every competitive two-player board game.
The simplest time control is "sudden death", in which players must make a predetermined number of moves in a certain amount of time or forfeit immediately. A particularly popular variant in informal play is blitz chess, in which each player is given five minutes on the clock for the entire game.
The players may take more or less time over any individual move. The opening moves in chess are often played quickly due to their familiarity, which leaves the players more time to consider more complex and unfamiliar positions later. It is not rare in slow chess games for a player to leave the table, but the clock of the absent player continues to run if it is his turn, and/or starts to run if his opponent makes a move.
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[edit] Analog game clocks
Analog clocks (as pictured to the right) are equipped with a "flag" (a Dutch invention) that falls to indicate the exact moment the player's time has expired. Analog clocks used mechanical buttons. Pressing the button on your side physically stopped the movement of your clock and released the hold on your opponents. The drawbacks of the mechanical clocks included accuracy and matching of the two clocks, and matching of the indicators (flags) of time expiration. Unfortunately, additional time can't easily be added for more complex time controls, especially those which call for an increment or delay on every move, such as some forms of byoyomi. Therefore more versatile digital clocks are becoming increasingly popular.
[edit] Early development of digital game clocks
In 1973, to address the issues with analog clocks, Bruce Cheney, a Cornell University Electrical Engineering student and chess player, created the first digital chess clock as a project for an undergraduate EE course. Typical of most inventions, it was crude compared to the products on the market 30 years later and was limited by the technology that existed at the time. For example, the display was done with red LEDs. LEDs take significant power,and, as a result, the clock had to be plugged in to a wall outlet. There were other constraints that were financially, not technology, based. LEDs were expensive and thus only one full set of digits were used. When the toggle switch was moved toward one opponent, his time was shown, along with an indicator of whose time was on display. This meant that each player's time had to be multiplexed to the display when their time was running. In 1973, LSI (Large Scale Integration) chips were not readily or cheaply available, so all the multiplexing and logic were done using chips that consisted of 4 two-input TTL nand gates !! That meant a lot nand gates and even more power. Being plugged into the wall is obviously a major drawback, but had one advantage: the timebase for the clock was driven off of a rectified version of 60 cycle AC current. Each player had a separate counter, and, in a parallel to the original mechanical architecture, one players counter was disabled while the others was running. The clock only had one mode: time ran forward. It could be reset, but not set. It did not count the number of moves. But it successfully addressed the original goals of the project (accurate & matched, timing).
[edit] Recent developments of digital clocks and current usage
Digital clocks and Internet gaming have spurred a wave of experimentation with more varied and complex time controls than the traditional standards. One particularly notable development, which has gained quite wide acceptance in chess, was proposed by former world champion Bobby Fischer, who in 1988 filed for U.S. Patent #4,884,255 (awarded in 1989) for a new type of digital chess clock. Fischer's digital clock gave each player a fixed period of time at the start of the game and then added a small amount after each move. In this way, the players would never be desperately short of time, but games could also be completed more quickly, doing away with the need for adjournments (in which a game is left incomplete to be finished at a later date). Although it was slow to catch on, as of 2004 a very large number of top class tournaments use Fischer's system, though usually in combination with the more traditional clocks (at lower levels, more traditional clocks are still employed as they are cheaper). Other aspects of Fischer's patent, such as a synthesized voice announcing how much time the players have, thus eliminating the need for them to keep looking at the clock, have not been adopted.
[edit] Delay clocks
There are two main types of delay clocks: (1) Bronstein (invented by David Bronstein) and (2) Fischer (invented by Bobby Fischer). With a delay clock, a small amount of time is added for each move. The reason is that with a sudden-death time limit, all moves must be completed in the specified time, or the player loses. With a small delay added at each move, the player always has at least that much time to make a move. The two types of delay clocks differ in how the delay is implemented.
- Bronstein delay - when it becomes a player's turn to move, the clock waits for the delay period before starting to subtract from the player's remaining time. For example, if the delay is five seconds, the clock waits for five seconds before counting down. The time is not accumulated. If the player moves within the delay period, no time is subtracted from his remaining time.
- Fischer delay - when it becomes a player's turn to move, the delay is added to the player's remaining time. For example, if the delay is five seconds and the player has ten minutes remaining on his clock, when his clock is activated, he now has ten minutes and five seconds remaining. Time can be accumulated, so if the player moves within the delay period, his remaining time actually increases.
[edit] External links
Categories: Games | Clocks | Chess
