in fact the probability is much lower. In the 1980s in the U.K., machines embodying microprocessors became common. These used a number of features to ensure the payout was controlled within the limits of the gambling legislation. As a coin was inserted into the machine, it could go either directly into the cashbox for the benefit of the owner or into a channel that formed the payout reservoir, with the microprocessor monitoring the number of coins in this channel. The drums themselves were driven by stepper motors, controlled by the processor and with proximity sensors monitoring the position of the drums. A "look-up table" within the software allows the processor to know what symbols were being displayed on the drums to the gambler. This allowed the system to control the level of payout by stopping the drums at positions it had determined. If the payout channel had filled up, the payout became more generous; if nearly empty, the payout became less so (thus giving good control of the odds). Video slot machines Video slot machines do not use mechanical reels, but use graphical reels on a computerized display. As there are no mechanical constraints on the design of video slot machines, games often use at least five reels, and may also use non-standard layouts. This greatly expands the number of possibilities: a machine can have 50 or more symbols on a reel, giving odds as high as 300 million to 1 against – enough for even the largest jackpot. As there are so many combinations possible with five reels, manufacturers do not need to weight the payout symbols (although some may still do so). Instead, higher paying symbols will typically appear only once or twice on each reel, while more common symbols earning a more frequent payout will appear many times. Video slot machines usually make more extensive use of multimedia, and can feature more elaborate minigames as bonuses. Modern cabinets typically use flat-panel displays, but cabinets using larger curved screens (which can provide a more immersive experience for the player) are not uncommon. Video slot machines typically encourage the player to play multiple "lines": rather than simply taking the middle of the three symbols displayed on each reel, a line could go from top left to the bottom right or any other pattern specified by the manufacturer. As each symbol is equally likely, there is no difficulty for the