Patent Publication Number: US-9406198-B2

Title: Jackpot controller and a method of providing a jackpot for a gaming machine

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/843,945, filed Jul. 27, 2010, which claims priority to Australian Application No. 2009903515, filed Jul. 27, 2009. The above-identified applications are hereby incorporated herein by reference in their entirety. 
    
    
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     [Not Applicable] 
     MICROFICHE/COPYRIGHT REFERENCE 
     [Not Applicable] 
     BACKGROUND OF THE INVENTION 
     The present invention generally relates to gaming machines and methods of gaming. A particular embodiment of the present invention relates to gaming machines and methods of gaming that award jackpot prizes. 
     Gaming venue operators continuously look for new variations and types of games in order to attract both new and return customers to their venues. In response to this need, suppliers of gaming devices and systems have attempted to provide the sought after variety, while still developing games that comply with the relevant regulations in the jurisdiction of the gaming venue operator. Suppliers of gaming devices therefore are faced with restrictions on the types of games and gaming machines that are allowable, both in terms of the prevailing regulations and in terms of providing a return on investment to the gaming venue operators. 
     One method that has been used with gaming machines is to offer a jackpot prize. A jackpot prize may be funded through gaming activity on the gaming machine, for example by taking a percentage of all wagers placed on the gaming machine. The jackpot prize is awarded on the occurrence of a jackpot prize winning event. Various methods of contribution to a jackpot prize and determination of when the jackpot prize is to be awarded have been developed. 
     A problem with jackpot prizes is finding an appropriate method of determining how to award the jackpot prize. A compromise typically needs to be reached between awarding large jackpot prizes infrequently and awarding smaller jackpot prizes relatively frequently. Selecting the right combination of prize size and frequency of award may present a difficult choice. A choice is required from a range of jackpot values, probabilities and returns in order to achieve desired jackpot sizes and frequencies. Any particular choice may be a compromise between the diverse requirements of different players. 
     BRIEF SUMMARY OF THE INVENTION 
     According to one aspect of the invention, there is provided a method for facilitating an award of a prize on a gaming device, the method comprising the steps of: 
     obtaining a turnover value for at least one gaming device over a period of time; 
     calculating a probability value based on the turnover value; and 
     using the probability value to determine whether the prize is to be awarded. 
     According to another aspect of the invention, there is provided a method of awarding a jackpot, the method including setting a trigger event dependent on a required frequency of award of a jackpot, determining the value of at least two jackpots, and when the trigger event occurs selecting one of the jackpots to award, wherein the probability distribution between the jackpots is variable and determined dependent on a measure of turnover over a previous period. 
     According to another aspect of the invention, there is provided a gaming machine or system including a jackpot controller programmed to perform the method of the preceding paragraph and/or embodiments of the method described herein. There is also provided instructions stored in electronic storage to program a jackpot controller to perform the method. 
     According to another aspect of the invention, there is provided a gaming device comprising an electronic processor and a data storage device comprising data, the electronic processor and the data storage device being arranged such that the electronic processor can process the data whereby processing of the data causes the electronic processor to carry out a method for facilitating an award of a prize, the method comprising the steps of: 
     obtaining a turnover value for at least one gaming machine over a period of time; 
     calculating a probability value based on the turnover value; and 
     using the probability value to determine whether the prize is to be awarded. 
     According to a further aspect of the invention, there is provided a gaming machine or system operable to award at least a first and a second jackpot amount wherein: 
     the first jackpot amount is larger than the second jackpot amount, 
     the gaming machine or system is configurable between at least a first and a second configuration, 
     in the first configuration there is a first probability of award of the first jackpot amount and a second probability of award of the second jackpot, wherein the first probability is larger than the second probability, 
     in the second configuration there is a first probability of award of the first jackpot amount and a second probability of award of the second jackpot, wherein the first probability is smaller than the second probability, 
     wherein the number of jackpot awards in a period for the first and the second each configurations is different and the probabilities and number of awards are constrained to result in a substantially equal amount for the product of number of awards per period and the average jackpot per award. 
     Further aspects of the present invention will be apparent from the following description, given by way of example and with reference to the accompanying drawings. Also, various embodiments of the aspects described in the preceding paragraphs will be apparent from the appended claims, the following description and/or the accompanying drawings. 
     As used herein, except where the context requires otherwise, the term “comprise” and variations of the term, such as “comprising”, “comprises” and “comprised”, are not intended to exclude further additives, components, integers or steps. 
    
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1 : shows diagrammatically, a view of a gaming console. 
         FIG. 2 : shows a block diagram of gaming machine. 
         FIG. 3 : shows a block diagram of components of the memory of the gaming machine represented in  FIG. 2 . 
         FIG. 4 : shows diagrammatically, a network gaming system. 
         FIG. 5 : shows a flow diagram of a method performed in accordance with an embodiment of the present invention. 
         FIG. 6 : shows an example screen display of two possible jackpot values. 
         FIG. 7 : shows a flow diagram of a method performed in accordance with another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In  FIG. 1  of the accompanying drawings, one example of a gaming console that is suitable to implement the present invention is generally referenced by arrow  114 . 
     The gaming console  114  includes two displays  106 A,  106 B on one or both of which is displayed representations of a game that can be played by a player and a bank of buttons  107 A and/or a touch screen  1078  to enable a player to play the game. The displays  106  may be video display units, such as a cathode ray tube screen device, a liquid crystal display, plasma screen, any other suitable video display unit, or the visible portion of an electromechanical device. The display  106 B may display artwork, including for example, pay tables and details of bonus awards and other information or images relating to the game. In alternative gaming consoles the display  106 B may be omitted, optionally replaced by a static display. 
     A credit input including a coin input  110 A and/or bill collector  1108  allows a player to provide credit for wagering and a coin output  111  is provided for cash payouts from the gaming console  114 . A card and/or ticket reader  108  and a printer  109  may be provided to provide player tracking, cashless game play or other gaming and non-gaming related functions. 
       FIG. 2  shows a block diagram of a gaming machine, generally referenced by arrow  100 , suitable for implementing the present invention. The gaming machine  100  may include the gaming console  114  shown in  FIG. 1  and accordingly like reference numerals have been used to describe like components in  FIGS. 1 and 2 . 
     The gaming machine  100  includes a game controller  101 , which in the illustrated example includes a computational device  102 , which may be a microprocessor, microcontroller, programmable logic device or other suitable device. Instructions and data to control operation of the computational device  102  are stored in a memory  103 , which is in data communication with, or forms part of, the computational device  102 . Typically, the gaming machine  100  will include both volatile and non-volatile memory and more than one of each type of memory, with such memories being collectively represented by the memory  103 . The instructions to cause the game controller  101  to implement the present invention will be stored in the memory  103 . 
     The game controller  101  may include hardware credit meters  104  for the purposes of regulatory compliance and also include an input/output (I/O) interface  105  for communicating with the peripheral devices of the gaming machine  100 . The input/output interface  105  and/or the peripheral devices may be intelligent devices with their own memory for instructions and data. 
     In the example shown in  FIG. 2 , the peripheral devices that communicate with the controller are the displays  106 , bank of buttons/touch screen  107 , the card and/or ticket reader  108 , the printer  109 , a bill acceptor and/or coin input  110  and a coin output  111 . Additional devices may be included as part of the gaming machine  100 , or devices omitted as required for the specific implementation. 
     The bank of buttons  107 A and/or touch screen  107 B together with one or both of the displays  106  may provide a user interface  115  through which the gaming machine  100  and player communicate. If a card/ticket reader  108  is provided, this may also form part of the user interface  115 . 
     In addition, the gaming machine  100  may include a communications interface, for example a network card  112 . The network card  112 , may for example, send status information, accounting information or other information to a central controller, server or database and receive data or commands from the central controller, server or database. The network card  112  may also enable communication with a central player account, allowing cashless gaming. One or more of the peripheral devices, for example the card/ticket reader  108  may be able to communicate directly with the network card  112 . The network card  112  and the I/O interface  105  may be suitably implemented as a single machine communications interface. 
     The game controller  101  may also include a random number generator  113 , which generates a series of random numbers that are used by the computational device  102  to determine the outcomes of games played on the gaming machine  100 . 
     The game controller  101  may have distributed hardware and software components that communicate with each other directly or through a network or other communication channel. The game controller  101  may also be located in part or in its entirety remote from the user interface  115 . Also, the computational device  102  may comprise a plurality of devices, which may be local or remote from each other. 
       FIG. 3  shows an exemplary block diagram of the main components of the memory  103 . The RAM  103 A typically temporarily holds instructions and data related to the execution of game programs and communication functions performed by the computational controller  102 . The EPROM  103 B may be a boot ROM device and/or may contain system and game related code. The mass storage device  103 C may be used to store game programs, the integrity of which may be verified and/or authenticated by the computational controller  102  using protected code from the EPROM  103 B or elsewhere. 
       FIG. 4  shows a gaming system  200  in the form of a network of devices. The gaming system  200  includes a network infrastructure  201 , which for example may be in the form of an Ethernet network. Alternatively, a wireless network and/or direct communication channels, or a different type of network may be used to link the gaming machines to a server, each other and/or other devices. Gaming consoles  114 , shown arranged in three banks  203  of two gaming consoles  114  in  FIG. 4 , are connected to the network infrastructure  201 . The gaming consoles  114  may form part or all of a gaming machine  100 . Single gaming consoles  114  and banks  203  containing three or more gaming devices  202  may also be connected to the network infrastructure  201 , which may also include bank controllers, hubs, routers, bridges to other networks and other devices (not shown). 
     One or more displays  204  may also be connected to the network  201 . The displays  204  may, for example, be associated with a bank  203  of gaming consoles  114 . The displays  204  may be used to display representations associated with game play on the gaming devices  202 , and/or used to display other representations, for example promotional or informational material. 
     Servers may also be connected to the network  201 . For example, a game server  205  may generate game outcomes for games played on one or more of the gaming consoles  114 , a database management server  206  may manage the storage of game programs and associated data in a database  206 A so that they are available for downloading to, or access by, game controllers  101 , and a jackpot server  207  may control one or more jackpots for the gaming system  200 . 
     Further servers may be provided to assist in the administration of the gaming system  200 , including for example a gaming floor management server  208 , and a licensing server  209  to monitor the use of licenses to particular games. An administrator terminal  210  is provided to allow an administrator to manage the network  201  and the devices connected to the network. The different servers depicted can be distinct physical servers or logically distinct server processes running on a single physical server. 
     It will be appreciated that controllers other than servers may be used for any of the servers shown in  FIG. 4 . The servers may be programmed by instructions stored on suitable media, for example a compact disc, or communicated to the server through an appropriate communication channel. 
     The gaming system  200  may communicate with other gaming systems, other local networks, for example a corporate network and/or a wide area network such as the Internet through a firewall  211 . 
       FIG. 5  shows a process flow diagram of a method performed in accordance with an embodiment of the present invention. The method may be performed by the gaming system  200 , in which the gaming consoles  114  each include game controllers  101  to form gaming machines  100  and the following description assumes this implementation. However, those skilled in the relevant arts will appreciate that the method will also be able to be implemented by other gaming systems. The method may also be performed for a standalone gaming system of a group of linked gaming machines linked through dedicated communications channels. 
       FIG. 5  shows a combination of a method to establish a gaming machine or system with jackpot prizes and a method to operate the gaming machine or system once it has been established. The method of operating the gaming machine or system may be implemented in isolation of the steps to establish the gaming machine system, after the gaming machine or system has been established. Although the steps shown in  FIG. 5  are in a particular order, it will be appreciated that some variations may be made to the order without affecting the effect of the method. 
     For the purposes of explanation, it is assumed that the jackpot awarding method is controlled predominantly by the jackpot server  207 . However, some or all of the functions described herein as performed by the jackpot server  207  may be performed by another device in the gaming system  200  or by a functionally equivalent device in a different gaming system. 
     One type of jackpot award method that may be utilised in the method shown in  FIG. 5  is to provide a feature game. In this context, a feature game means that an event (a ‘trigger event’) on a gaming machine leads to one of two or more possible outcomes according to a selection method involving a random aspect to it. There may or may not be images, sounds and/or other player interaction to represent the selection method. If images are provided, for example on a display  106  of a gaming console  114 , then these images may be controlled by the jackpot server  207  or by the game controller  101 , which may either determine the result of the feature game itself or receive notice of the result from the jackpot server  207 . Where the game controller  101  determines the result of the feature game itself, then it may receive the probability distribution for the jackpots (see herein below) from the jackpot server  207 . 
     For this type of jackpot award method, a jackpot award trigger event can result in any one of a plurality of jackpots being awarded. For example, if the jackpots are a $100 mini jackpot and a $100,000 major jackpot, for an expected average turnover of $10,990 between jackpot trigger events, each trigger event may provide a 99% chance of winning the $100 jackpot and a 1% chance of winning the $100,000 jackpot. If there was an average turnover of $10,990 per day, then there would be one jackpot award per day. Absent the method described herein below in relation to  FIG. 5 , the higher the turnover, the higher the frequency of jackpot awards and the lower the turnover the lower the frequency of jackpot awards. 
     The gaming console  114  that caused the trigger event may be awarded the jackpot. Alternatively, when the triggering event occurs, a random determination may be made from the gaming consoles  114  that are currently being played as to which one wins the jackpot. Again, absent the method described below, the frequency of jackpot awards is directly related to the rate of turnover. 
     Steps  1  to  5  show a method to establish a jackpot for a gaming system. This may involve configuring the jackpot server  207 , which includes a program executable within the server that implements the method shown in  FIG. 5 . 
     In step  1 , the gaming venue operator or designer of the gaming system selects the return to player that the jackpots are to provide. For example, the gaming venue operator or designer of the gaming system may select a return to player of 10%, in which case on average, for every $1000 of turnover, then $100 is caused to be awarded by the jackpot server  207 . 
     In steps  2  and  3 , the number, value and frequency of the jackpots is selected. The number of jackpots, value of the jackpots and frequency of the jackpots may all be fixed, or subject to some operational constraints set by a gaming venue operator using a user interface to the jackpot server  207 , for example the administrator terminal  210 . 
     The minimum number of jackpots is two. The frequency of the jackpots could vary widely, for example from one every ½ hour, one every day through to one every month. The value of the jackpots would normally be constrained by the return to player selected in step  1  and the number and frequency of the jackpots selected in steps  2  and  3 . 
     For example, if two jackpots, a mini and a major jackpot were selected and the frequency was selected to be an award of one of the two jackpots on a daily basis, then the value of the jackpots may be constrained to satisfy the conditions: 
     1) Mini jackpot approximately equal to or less than 10% of the minimum turnover in a day; and 
     2) Major jackpot approximately equal to or greater than 10% of the maximum turnover in a day. 
     The minimum turnover and maximum turnover in a day may be established using historical information if available, or by experience. If more than two jackpots are selected, then the highest and lowest values may be constrained to satisfy these conditions and there may be substantially no constraints on the value of the other jackpots. 
     In one embodiment, the jackpot server  207  may dynamically set the values of the jackpots. For example, the highest jackpot could be set at 10% of the highest turnover in a single day over the last month and the lowest jackpot could be set at 10% of the lowest turnover in a single day over the last month. This resetting of the values may occur immediately following the award of one of the jackpots. 
     Typically, the jackpot server  207  will control, either directly or indirectly, one or more displays, for example the display  204 , and/or the display  106 B to display the jackpots that are available and their respective values. An example display is shown in  FIG. 6 , which shows an example of the selection of two fixed jackpots, a Mini Jackpot of $100 and a Major Jackpot of $100,000. 
     If a variable jackpot is selected, the seed value and increment rate of the variable jackpot may be selected to provide a required expected average award size. For example, the jackpots may both be variable, but controlled to award on average $100 and $100,000 respectively. 
     In step  4 , the gaming consoles  114  that are to participate in the jackpot are selected. The selected gaming consoles  114  may be all of the gaming consoles  114  in a single bank  203 , all of the gaming consoles in a group of banks  203 , all of the gaming consoles  114  in the gaming system  200 , or all of the gaming consoles  114  across a plurality of gaming systems. Alternatively, one gaming console  114  may be selected, which may be a standalone gaming machine  100 . In another alternative, where each gaming console  114  is individually addressed, any grouping of gaming consoles  114  may be made eligible to win the jackpots. 
     Following steps  1  to  4 , game play of the gaming consoles  114  selected in step  4  is permitted. In step  5 , the jackpot server  207  receives signals indicating the turnover on each of the gaming consoles  114  and accumulates this. The accumulated total turnover since the last jackpot award is maintained. In addition, the total turnover since commencement or the last reset of the jackpot system may be maintained. The second counter may be used to track the contribution of the gaming consoles  114  to the jackpots in comparison to the award of the jackpots. 
     In step  6  the method involves monitoring for a trigger event for the feature game that awards one of the jackpots. This monitoring may be, but is not necessarily, performed by the jackpot server  207 . The monitoring may instead by performed by the gaming machines  100 . If the trigger event has not occurred, the method returns to step  5 . If the trigger event has occurred, the method proceeds to step  7 . 
     In one embodiment, the trigger event is a time-based event. The gaming venue operator has entered the required frequency that a jackpot award should be awarded in step  3 . An example is the previously mentioned award of, on average a single jackpot per day. The jackpot controller could then randomly determine a time from a range of selections between 0 and 48 hours, with equal weight. When that time arrives, the next gaming machine to cause an increase in the accumulated turnover monitored in step  5  may be deemed the winner of one of the two jackpots. 
     In another embodiment, the trigger value for the turnover may be dynamic. To form a dynamic trigger value, use may be made of a type of trigger event that is described in Australian patent number 754689, the entire contents of which are incorporated herein by reference. This type of trigger event involves determining a required turnover between awards on a gaming console  114  and then determining a probability of winning the feature game based on that turnover. While AU 754689 describes determining the turnover on an individual console basis, alternative embodiments that may be used in the method of  FIG. 5  determine turnover for group of gaming consoles  114 , which may be all of the gaming consoles  114  that are eligible for the same jackpots. If the turnover is monitored for individual consoles, then when a console triggers the feature game, then that same console may win the jackpot that is selected to be awarded. If the turnover is determined for a group of consoles, the console that wins the award may be the gaming console  114  that next causes an increase in the turnover monitored in step  5 . 
     The jackpot controller may determine the turnover over a previous period of play, for example over the last 10 minutes and if the feature game was to be awarded once a day, calculate the total daily turnover if that rate was continued throughout the day. For example, if the turnover was $200 in the previous 10 minutes, then the forecast daily turnover is $28800. Each unit wager, for example $1, that is currently being played would then have a  1  in 28800 chance of triggering the feature game that awards one of the jackpots. If the turnover decreased to $100 over the next ten minutes, then each $1 turnover would result in a 1 in 14400 chance of triggering the feature game. 
     In step  7 , the jackpot server  207  determines the probability distribution for the jackpots. This method allows a gaming venue operator to control the frequency with which jackpots are awarded, despite variations in turnover. For example, the gaming venue operator may require one jackpot to be awarded per day. In  FIG. 5 , step  7  is conducted between the occurrence of a trigger event and the award of one of the jackpots. Alternatively, the probability distribution may be updated daily, or more or less frequently and maintained at a fixed level between updates, in which case step  7  would involve determining the more recently set probability distribution. 
     The probability distribution between the jackpots is varied dependent on the turnover since the previous jackpot, which has been recorded in step  5 . Continuing with the example of two jackpots of $100,000 and $100 with a 10% return to player, then for any amount of turnover from the previous jackpot award of between $1,000 and $1,000,000, an appropriate probability distribution exists. 
     If the conditional probability of awarding the $100,000 jackpot is A, then the conditional probability of awarding the $100 jackpot given that some jackpot is to be awarded is 1-A. A value for A can be found by solving equation 1:
 
$100,000A+$100(1− A )=0.1 t    equation 1
 
     where t is the turnover since the last jackpot winning event. 
     If the turnover t was $10,990, then the solution to equation 1 is A=0.01. If the turnover t was $500,500, then the solution is A=0.50. If the turnover was $750,250, then the solution is A=0.75. Therefore, as the turnover increases, the probability of awarding the $100,000 jackpot increases and the probability of awarding the $100 jackpot decreases. 
     In step  8  the jackpot server  207  determines which jackpot to award, using the conditional probability calculated in step A. For example, if the conditional probability was calculated to two decimal places, then the jackpot server  207  may determine a random number within the range 0 to 99, awarding the minor jackpot if the selected number is greater than or equal to A multiplied by 100, and awarding the major jackpot otherwise. The appropriate jackpot is then awarded, typically through a gaming console  114 , although alternatively a gaming console  114  may lock up so that the player knows to await a manual pay by an attendant. The determination of which gaming console  114  awards the jackpot was previously described herein in relation to the trigger events that may be used. 
     In step  9  the jackpot that is awarded is recorded. As previously mentioned the awards may be tracked against the accumulated turnover. In step  10  the accumulation of turnover is restarted, for use in determining the probability distribution for the next feature game that awards one of the jackpots. 
     Variations may be made to the method described herein. One variation may be that the feature game may occur more often than the required frequency of award of one of the jackpots. This may be required to provide increased entertainment when there is an entertaining presentation of the feature game. In this variation, there will be a chance that no jackpot is awarded from the feature game. The player of the relevant gaming console  114  may receive no award, or a small consolation award. 
     For example, if the gaming venue operator selected a prize to be awarded once every day, but wanted a feature game to occur 10 times day, then the feature game may be awarded on average once every 2.4 hours. Determination of the outcome of the feature game may then first determine on a 1 in 10 chance that one of the jackpots is to be awarded and only proceed to steps  7 ,  8 ,  9  and  10  if it is determined that one of the jackpots is to be awarded. Therefore, in this embodiment the trigger event for awarding one of the jackpots is a two-stage method, the first stage being the trigger event for the feature game and the second stage being the determination that one of the jackpots is to be awarded from the feature game. 
     The method described in relation to  FIG. 5  allows control over the frequency of the award of a jackpot. Sometimes gaming venue operators may place a higher importance on the size of the award to be made. 
     To achieve this, the jackpot server  207  may include a different method for the award of the jackpots. Keeping with the example of a minor jackpot of $100 and a major jackpot of $100,000, then there may be two configuration options: 
     Large and infrequent: the probability of award of the major jackpot is 0.999 
     the probability of award of the minor jackpot is 0.001 
     the number of awards per period is 1 
     the average jackpot per award is $99,900.10 
     Small and frequent: probability of award of the major jackpot is 0.000999 
     probability of award of the minor jackpot is 0.999001 
     the number of awards per period is 500 
     the average jackpot per award is $199.80 (to the nearest cent) 
     More than two configuration options may be provided if required, with each configuration constrained to have the same amount for the product of number of awards per period and the average jackpot per award. In addition, one or more of the configuration options may have three or more jackpot amounts. 
     If a 10% return to player is required, then the period referred to is the period required to obtain a turnover of $1,000,000. Therefore, in one embodiment, for the small and frequent configuration, each $1 turnover may result in a 1/2000chance of triggering the feature game and for the large and infrequent configuration, each $1 turnover may result in a 1/1000000chance of triggering the feature game. Giving each game play a chance to win the jackpot allows the gaming venue operator to change between configurations at any time. 
       FIG. 7  shows a flow diagram representing an alternative method of implementing a jackpot award. The method may be implemented using the apparatus described herein with reference to  FIGS. 1 to 4  or other suitable gaming apparatus. 
     Steps  21  to  24  are equivalent to steps  1  to  4  described in relation to  FIG. 5  and therefore are not described further. In the method shown in  FIG. 7 , the determination of the probability distribution between the jackpots is made periodically, for example, once per day, once per week, or twice per day. Shorter or longer probability distribution periods may be used, for example 10 minutes or 1 month, depending on the requirements for the particular implementation. 
     When the jackpot is initialised, in step  26 , an operator enters a turnover for the previous period. The operator may use their own records for this, or may enter an amount that is largely arbitrary. As described below, after this first value is entered, the turnover value used in subsequent determinations of the probability distribution is dependent on the actual turnover of the gaming machines participating in the jackpot. 
     In step  26 , the probability distribution is determined in the same way as described herein in relation to step  7  of  FIG. 5 . This probability distribution is stored, for example in a central jackpot controller and/or in the individual gaming machines. Once determined, this probability distribution is fixed until the end of the current distribution period. 
     As the gaming machines are played, the messages indicating gaming machine turnover are received and accumulated in a counter (step  28 ), which is reset at the commencing of each distribution period (step  27 ). If a gaming machine wins a jackpot, (steps  29  and  30 ) then the jackpot that is awarded is determined in the same manner as was described in relation to the method represented by  FIG. 5 , except using the probability distribution set in step  26 . The jackpot winning event is then recorded (step  31 ). 
     Whether or not a jackpot is won, the method includes determining whether the current probability distribution period has expired (step  32 ). If not, then the method returns to step  28  and the turnover for the current probability distribution continues to be accumulated. If the current distribution period has expired, then the value of the accumulated turnover is used as the value of t in equation 1 above to determine a new probability distribution for the next probability distribution period. The current turnover counter is reset to zero (step  27 ), to allow the method to be repeated when the next probability distribution period expires. 
     As the method described in relation to  FIG. 7  involves a fixed probability distribution for a period, the determination of the jackpot which is won may be readily made by the individual gaming machine, without input from any central controller that may maintain the current turnover across all the gaming machines participating in the jackpot. 
     While the foregoing description has been provided by way of example of the preferred embodiments of the present invention as presently contemplated, which utilise gaming machines of the type found in casinos, those skilled in the relevant arts will appreciate that the present invention also may have application to internet gaming and/or have application to gaming over a telecommunications network, where handsets are used to display game outcomes and receive player inputs. 
     Where in the foregoing description reference has been made to integers having known equivalents, then those equivalents are hereby incorporated herein as if individually set forth. 
     Those skilled in the relevant arts will appreciate that modifications and additions to the embodiments of the present invention may be made without departing from the scope of the present invention. 
     It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.