Patent Publication Number: US-2009239644-A1

Title: Slot Machine Executing Free Game and Control Method Thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of priority based on U.S. Provisional Patent Application No. 61/038,972 filed on Mar. 24, 2008. The contents of this application are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a slot machine executing free games and a control method thereof. 
     2. Discussion of the Background 
     In conventional slot machines, when a player inserts game media such as medals, coins or bills into an insertion slot of the slot machine and presses a spin button, then a plurality of symbols are scroll-displayed to a display portion provided on the front surface of a casing and, thereafter, the respective symbols are automatically stopped, as disclosed in U.S. Pat. Nos. 6,960,133, 6,012,983 and 6,093,102. In this case, when scroll-display of respective symbols starts by an input from the spin button, symbols are selected using random numbers, and the selected symbols are stop-displayed to the display portion. Then, when a combination of the stop-displayed symbols along a winning line is a predetermined winning combination (prize), an award is paid out. 
     In such a conventional slot machine, in general, odds are preliminary determined for each type of prizes. In the present description, odds show a relation between the type of the prize and an amount of game media to be paid out in the case of establishment of the prize. For example, in many slot machines, a number of a coin to be paid out based on the establishment of a prize in the case that the prize is established when a single coin is BET (number of payouts per single coin) is determined for each type of the prizes. 
     Further, conventionally, there are some slot machines executing free games when a predetermined condition (for example, rearrangements of specific symbols in a slot machine game) is established. The free game is a game which allows a player to play without consuming game media. For example, Australian Patent Publication No. 1972901 discloses a slot machine in which a free game is executed as a secondary game when a predetermined condition (predetermined rearrangements of symbols) is established in a basic game. 
     In addition, among slot machines, there are some slot machines executing bonus games when a predetermined condition is established in a game. The bonus game is a game which is relatively advantageous to a player. One example of the bonus games is a game in which coins paid out upon establishment of a prize is determined based on relatively large odds. 
     Further, among the slot machines executing free games, there are some slot machines executing bonus games when a predetermined condition is established during a free game period. Such a slot machine is generally configured not to restart a free game even when a bonus game ends in the case where a bonus game is generated before completion of the free game. As thus described, since generation of the bonus game in the free game ends a state which allows a player to play without a BET of a game medium, some player are not eager for generation of the bonus game (establishment of the predetermined condition) in the free game. Further, establishment of the predetermined condition in the free game may causes a problem of making such players feel frustrated. 
     Moreover, slot machines executing free games are generally configured to avoid establishment of the above-mentioned predetermined condition (a trigger condition for generating free games) Therefore, although this allows a player to play games with a expectation for establishment of the predetermined condition until generation of the free game, it is impossible to make the player have such a expectation once the free game is generated. Accordingly, there have been cases where a player is unlikely to have interests in the free game. This has caused a problem of making the player soon bored of a game. 
     In light of the aforementioned problem, the present invention has been devised, and an object of the present invention is to provide a slot machine which allows a player to enjoy playing games very much, and a control method of the slot machine. 
     The contents of U.S. Pat. No. 6,960,133, U.S. Pat. No. 6,012,983, U.S. Pat. No. 6,093,102 and Australian Patent Publication No. 1972901 are incorporated herein by reference in their entirety. 
     SUMMARY OF THE INVENTION 
     The present invention provides a slot machine having the following configuration. 
     That is, the slot machine comprises a symbol display capable of variably displaying a plurality of symbols. Further the slot machine comprises a memory capable of storing data concerning games. Furthermore, the abovementioned slot machine comprises a controller programmed to execute the following processing of: (A) executing a normal game in which the plurality of symbols are variably displayed and then stop-displayed to the symbol display after a BET of a game medium and a payout amount is determined according to the stop-displayed symbols or a combination thereof; (B) executing a free game which is conducted without a BET of a game medium as triggered by establishment of a predetermined condition in the normal game executed in the processing (A); (C) storing state data indicating a state of the free game and executing a bonus game which is relatively advantageous to a player when a specific condition is established in the free game before completing execution of the processing (B); and (D) executing the free game based on the state data stored in the memory after executing the processing (C) instead of executing the processing (B). 
     According to the above-mentioned slot machine, the free game is executed as triggered by establishment of the predetermined condition in the normal game. When the predetermined condition is established before completing execution of the free game (in the free game), the bonus game is executed. At this time, the state data indicating a state of the free game is stored in the memory. Then, the free game is executed after completion of the bonus game based on the state data. 
     Namely, when the predetermined condition is established in the free game, the free games are interrupted and the bonus games are generated. Then, the free games are restarted after completion of the bonus games. Thereby, it is possible to prevent a player from having such a fear that generation of the bonus games ends a state which allows the player to play games without a BET of a game medium. As a result, even in the free game, it is possible to make the player have an expectation for generation of the bonus games without hesitation, and fully enjoy the free games. 
     Further, the slot machine of the present invention preferably has the following configuration. 
     That is, the free games include a unit free game repeatedly executed plural times. Further, the processing (C) is processing of storing number data indicating a number of unit free games identified based on a number of unit free games executed before establishment of a specific condition in the specific memory and executing the bonus game when the specific condition is established in the free game before completing execution of processing (B). Furthermore, the processing (D) is processing of executing the unit free games a number of times identified based on the number data stored in the memory after executing the processing (C) instead of executing the processing (B). 
     According to the above-mentioned slot machine, the free games include a unit free game repeatedly executed plural times. When the predetermined condition is established before completion of all of a predetermined number of unit free games to be executed, the bonus games are generated and then the unit free games restarts after completion of the bonus games. The number of free games to be executed after completion of the bonus game is determined based on the number of the unit free games executed before generation of the bonus games. 
     Thereby, the player is allowed to play the game remained unexecuted at the time of generation of the bonus games after completion of the bonus games, and to enjoy absolute benefits of the free game. Namely, when the bonus games are generated in the free game, the player is allowed to enjoy benefits of the bonus game without suffering from something unprofitable. Therefore, it is possible to provide the player with a great satisfaction. 
     Further, the slot machine of the present invention preferably has the following configuration. 
     That is, the slot machine comprises a symbol display capable of variably displaying a plurality of symbols. Further, the slot machine comprises a controller programmed to execute the following processing of: (A) executing a normal game in which the plurality of symbols are variably displayed and then stop-displayed to the symbol display after a BET of a game medium and a payout amount is determined according to the stop-displayed symbols or a combination thereof; (B) executing unit free games which are conducted without a BET of a game medium a number of times determined based on a predetermined method as triggered by establishment of a predetermined condition in the normal game executed in the processing (A); and (C) executing the unit free games a number of times determined again after executing the processing (B) when a predetermined condition is established in the unit free game before completing execution of the processing (B). 
     According to the slot machine, the unit free games are executed the number of times determined based on the predetermined method, as triggered by establishment of the predetermined condition in the normal game. When the predetermined condition is established before completing execution of the predetermined number of free games, the unit free games are executed the number of times determined again after completing execution of the predetermined number of unit free games. Namely, when the predetermined condition is established in the free game, the remaining number of the unit free games increases. As a result, even in the free games, it is possible to make the player have an expectation for generation of the free games, and fully enjoy the free games. 
     Further, the slot machine of the present invention preferably has the following configuration. 
     That is, the slot machine comprises a symbol display capable of variably displaying a plurality of symbols. Further, the slot machine comprises a controller programmed to execute the following processing of: (A) executing a normal game in which the plurality of symbols are variably displayed and then stop-displayed to the symbol display after a BET of a game medium and a payout amount is determined according to the stop-displayed symbols or a combination thereof; (B) executing unit free games which are conducted without a BET of a game medium a number of times determined based on a predetermined method as triggered by establishment of a predetermined condition in the normal game executed in the processing (A); and (C) executing the unit free games a number of times determined again when a predetermined condition is established in a last unit free game out of the unit free games executed in the processing (B). 
     Further, according to the above-mentioned slot machine, the unit free games are executed the number of times determined based on the predetermined method as triggered by establishment of the predetermined condition in the normal game. When the predetermined condition is established in the last unit free game, the unit free games are executed the number of times determined again. Namely, the unit free games can be successively executed even after execution of the initially predetermined number of unit free games. Accordingly, it is possible to make the player continuously have an expectation for a possibility that the free games may not end even after execution of the initially predetermined number of the unit free games. Therefore, it is possible to make the player have an expectation for generation of the free games in the last unit free game, and thereby make the player fully enjoy the free games. 
     Further, the slot machine of the present invention preferably has the following configuration. 
     That is, the processing (B) includes the following processing of: (B-1) determining a number of the unit free games as triggered by establishment of the predetermined condition in the normal game executed in the processing (A); and (B-2) executing the unit free games the number of times determined in the processing (B-1). Further, the processing (B-2) includes processing of establishing the predetermined condition in the last unit free game when the number of the unit free games determined in the processing (B-1) is less than a predetermined number. 
     According to the above-mentioned slot machine, the unit free games are executed the number of times determined based on the predetermined method as triggered by establishment of the predetermined condition in the normal game. When the number is less than the predetermined number, the predetermined condition is established without failure in the last unit free game. Accompanying this, the unit free games are executed the number of times determined again. 
     In the last unit free game, the player is generally supposed to feel sad in a sort of way because of the last game which allows the player to play without a BET of a game medium. According to the above-mentioned slot machine, since the unit free games are further offered at the time when the player has such a feeling, it is possible to make the player feel unpredictable and give the player an impression that the player has got significantly large benefits. This allows the player to feel further interested in the games. 
     Further, according to the control method of a slot machine of the present invention preferably has the following configuration. 
     That is, the control method of a slot machine comprises the following steps of: (A) executing a normal game in which a plurality of symbols are variably displayed and then stop-displayed to a symbol display after a BET of a game medium and a payout amount is determined according to the stop-displayed symbols or a combination thereof; (B) executing a free game which is conducted without a BET of a game medium as triggered by establishment of a predetermined condition in the normal game executed in the processing (A); (C) storing state data indicating a state of the free game and executing a bonus game which is relatively advantageous to a player when a specific condition is established in the free game before completing execution of the processing (B); and (D) executing the free game based on the state data stored in the memory after executing the processing (C) instead of executing the processing (B). 
     According to the above-mentioned control method of a slot machine, the free game is executed as triggered by establishment of the predetermined condition in the normal game. When the predetermined condition is established before completing execution of the free game (in the free game), the bonus game is executed. At this time, the state data indicating a state of the free game is stored in the memory. Then, the free game is executed after completion of the bonus game based on the state data. 
     Namely, when the predetermined condition is established in the free game, the free games are interrupted and the bonus games are generated. Then, the free games are restarted after completion of the bonus games. Thereby, it is possible to prevent a player from having such a fear that generation of the bonus games ends a state which allows the player to play games without a BET of a game medium. As a result, even in the free game, it is possible to make the player have an expectation for generation of the bonus games without hesitation, and fully enjoy the free games. 
     Further, the present invention provides a control method of a slot machine, the control method having a following configuration. 
     That is, the control method of a slot machine of the present invention comprises the following steps of: (A) executing a normal game in which a plurality of symbols are variably displayed and then stop-displayed after a BET of a game medium and a payout amount is determined according to the stop-displayed symbols or a combination thereof; (B) executing unit free games which are conducted without a BET of a game medium a number of times determined based on a predetermined method as triggered by establishment of a predetermined condition in the normal game executed in the processing (A); and (C) executing the unit free games a number of times determined again after executing the processing (B) when a predetermined condition is established in the unit free game before completing execution of the processing (B). 
     As thus described, according to the above-mentioned control method of a slot machine, the unit free games are executed the number of times determined based on the predetermined method, as triggered by establishment of the predetermined condition in the normal game. When the predetermined condition is established before completing execution of the predetermined number of free games, the unit free games are executed the number of times determined again after completing execution of the predetermined number of unit free games. Namely, when the predetermined condition is established in the free game, the remaining number of the unit free games increases. As a result, even in the free games, it is possible to make the player have an expectation for generation of the free games, and fully enjoy the free games. 
     Further, the present invention provides a control method of a slot machine, the control method having a following configuration. 
     That is, the control method of a slot machine of the present invention comprises the following steps of: (A) executing a normal game in which a plurality of symbols are variably displayed and then stop-displayed to a symbol display after a BET of a game medium and a payout amount is determined according to the stop-displayed symbols or a combination thereof; (B) executing unit free games which are conducted without a BET of a game medium a number of times determined based on a predetermined method as triggered by establishment of a predetermined condition in the normal game executed in the processing (A); and (C) executing the unit free games a number of times determined again when a predetermined condition is established in a last unit free game out of the unit free games executed in the processing (B). 
     As thus described, according to the above-mentioned control method of a slot machine, the unit free games are executed the number of times determined based on the predetermined method as triggered by establishment of the predetermined condition in the normal game. When the predetermined condition is established in the last unit free game, the unit free games are executed the number of times determined again. Namely, the unit free games can be successively executed even after execution of the initially predetermined number of unit free games. Accordingly, it is possible to make the player continuously have an expectation for a possibility that the free games may not end even after execution of the initially predetermined number of the unit free games. Therefore, it is possible to make the player have an expectation for generation of the free games in the last unit free game, and thereby make the player fully enjoy the free games. 
    
    
     
       BRIEF DESCRIPTIONS OF DRAWINGS 
         FIG. 1A  is a view illustrating an exemplary image to be displayed to a lower image display panel. 
         FIG. 1B  is another view illustrating an exemplary image to be displayed to a lower image display panel. 
         FIG. 1C  is another view illustrating an exemplary image to be displayed to a lower image display panel. 
         FIG. 1D  is another view illustrating an exemplary image to be displayed to a lower image display panel. 
         FIG. 1E  is another view illustrating an exemplary image to be displayed to a lower image display panel. 
         FIG. 1F  is another view illustrating an exemplary image to be displayed to a lower image display panel. 
         FIG. 1G  is another view illustrating an exemplary image to be displayed to a lower image display panel. 
         FIG. 2  is a perspective view illustrating the external appearance of a slot machine. 
         FIG. 3  is a block diagram illustrating an internal configuration of the slot machine illustrated in  FIG. 2 . 
         FIG. 4  is a flowchart illustrating main processing executed in the slot machine  10 . 
         FIG. 5  is a flowchart illustrating a subroutine of slot machine game execution processing. 
         FIG. 6  is a view illustrating a corresponding relationship between a rearranged symbol and a payout amount. 
         FIG. 7A  is a flowchart illustrating a subroutine of free game execution processing. 
         FIG. 7B  is a flowchart illustrating a subroutine of free game execution processing. 
         FIG. 8  is a flowchart illustrating a procedure of activation processing. 
         FIG. 9  is a view illustrating peripheral device initialization processing. 
         FIG. 10  is a flowchart illustrating a subroutine of activation processing executed by a central controller. 
         FIG. 11  is a perspective view illustrating an external appearance of a slot machine according to another embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     A general description of the present embodiment will be given by using  FIG. 1A  to  FIG. 1G . 
       FIGS. 1A to 1G  are views each illustrating an exemplary image to be displayed to a lower image display panel. 
     In a slot machine  10  (see  FIG. 2 ) according to the present embodiment, a free-game-trigger symbol  100  (see  FIG. 1A ) may be rearranged in a symbol matrix SM. The symbol matrix SM is displayed to a lower image display panel  16  provided in the slot machine  10 . The lower image display panel  16  (see  FIG. 2 ) corresponds to the symbol display of the present invention. 
     In the present embodiment, when three or more free-game-trigger symbols  100  are rearranged in the symbol matrix SM, a free game is played. In a free game period, a slot machine game is played even a game medium is not BET. 
       FIG. 1A  shows an example of a state that three free-game-trigger symbols  100  are rearranged. As triggered by this, a text image  120  for notifying the player of “Free game trigger established!” is displayed. A rearrangement of three or more free-game-trigger symbols  100  is referred to as “a free game trigger is established” in the present description. 
     Further, in the present embodiment, card images  110 A to  110 C showing three down cards are displayed as shown in  FIG. 1B  as triggered by establishment of the free game trigger. Moreover, a character image  121  indicating that a player is allowed to select one card is displayed. The player can select one card by touching a portion on a touch panel corresponding to a card image of a card which the player wants to select. 
     When one card is selected, the card images  110 A to  110 C are changed in such a manner as to show up cards. Each card image has a number of 5, 10 or 20 displayed thereon. An example shown in  FIG. 1C  illustrates a state in which the player has selected the card of the card image  110 B. 
     In the slot machine of the present embodiment, the number of free games is determined based on the number displayed on the card having been selected by the player. In the example shown in  FIG. 1C , a character image  122  indicating generation of 10 free games is displayed based on the number “10” displayed on the card image  110 B selected by the player. 
     During the free games, the number of remaining free games is displayed in a number-of-free-game display section  102  in a lower image display panel  16 . An example shown in  FIG. 1D  illustrates that the number of remaining free games is 6. 
     Further, in  FIG. 1D , three or more bonus-game-trigger symbols are rearranged in a symbol matrix SM, bonus games are conducted. During a period of the bonus game, slot machine games are conducted based on the relatively large odds (special odds). The odds are determined for each type of and number of the normal symbols, and indicate the number of coin-outs upon a BET of one coin (see  FIGS. 6A and 6B ). Odds used in games in a period other than the bonus game period are referred to normal odds. 
     Here, rearrangements of three or more bonus-game trigger symbols  101  are also referred to “establishment of the bonus trigger” in the present description. 
     As thus described,  FIG. 1D  illustrated a state of the establishment of the bonus game trigger in the free game in which the remaining number of free games is 6. 
       FIG. 1E  illustrates an example displayed to the lower image display panel  16  upon completion of the bonus game. In  FIG. 1E , a character image  124  indicating “End of bonus game” and “Restart of free game” is displayed. Further, a number-of-free-game display section  102  shows a state that the remaining number of free games is 6. 
     The slot machine  10  of the present embodiment is configured to restart the free games after completion of the bonus games when the bonus games are generated during the free games. The number of free games to be executed after the restart is the number of free games remained unexecuted. 
       FIG. 1F  illustrates a state of establishment of the free game trigger in the free game in which the remaining number of free games is 1, that is, the last free game. 
     As described using  FIG. 1B , the card images indicating three down cards are displayed, and the player are allowed to select one card. 
       FIG. 1G  is a view illustrating images displayed in the lower image display panel  16  after selection of one card by the player. Each of the card images  110 A to  110 C has a number of 5, 10 or 20 displayed thereon. This example illustrates a state in which the player has selected the card of the card image  110 C. In addition, a character image  126  indicating “10 more free games service!!” is displayed. 
     As described using  FIG. 1C , 10 free games are generated in the examples shown in  FIGS. 1C to 1G . 
     The slot machine  10  according to the present embodiment is configured to establish the free game trigger in the last free game when the number of the free games determined based on the number displayed on the card selected by the player is less than 20. Moreover, the free games are executed a number of times obtained by subtraction of the number from 20 after completion of the last free game. Namely, 20 free games are finally executed. 
     There has been described the outline of the present embodiment. 
     Hereinafter, the first embodiment will be described in more detail. 
       FIG. 2  is a perspective view illustrating the external appearance of the slot machine. 
     In the slot machine  10 , a coin, a bill, or electronic valuable information corresponding thereto is used as a game medium. However, in the present invention, a game medium is not particularly limited. Examples of the game medium may include a medal, a token, electronic money, or a ticket. It should be noted that the ticket is not particularly limited, and examples thereof include a ticket with a bar code, which will be described later. 
     Here, the slot machine  10  is a stand-alone type slot machine that is not connected to a network, but the present invention can also be applied to a slot machine connected to a network. 
     The slot machine  10  includes: a cabinet  11 ; a top box  12  placed on the upper side of the cabinet  11 ; and a main door  13  provided at the front face of the cabinet  11 . The lower image display panel  16  is provided in front of the main door  13 . The lower image display panel  16  includes a liquid crystal display panel and the symbol matrix SM (see  FIG. 1A ) is displayed thereto. In the lower image display panel  16 , there are provided a number-of-credits display section  31  and a number of payouts display section  32  (not shown). 
     The number-of-credits display section  31  displays an image indicating the number of credited coins. The number-of-payouts display section  32  displays an image indicating the number of coins to be paid out as the payout. 
     Further, a touch panel  69 , which is not shown in the figure, is provided on the front face of the lower image display panel  16 , and the player can input various kinds of commands by operating the touch panel  69 . 
     Below the lower image display panel  16 , there are provided a control panel  20  comprised of a plurality of buttons  23  to  27  with each of which a command according to the game progress is inputted by the player, a coin receiving slot  21  through which a coin is accepted into the cabinet  11 , and a bill validator  22 . 
     The control panel  20  is provided with a start button  23 , a change button  24 , a CASHOUT button  25 , a 1-BET button  26 , and a maximum BET button  27 . The start button  23  is used for inputting a command to start a game. The change button  24  is used for making a request of staff at a recreation facility for exchange. The CASHOUT button  25  is used for inputting a command to pay out credited coins to a coin tray  18 . 
     The 1-BET button  26  is used for inputting a command to BET one coin on a game out of credited coins. The maximum BET button  27  is used for inputting a command to BET the maximum number (50 coins in the present embodiment) of coins that can be bet on a single game out of credited coins. 
     The bill validator  22  not only discriminates a regular bill from a false bill, but also accepts the regular bill into the cabinet  11 . It should be noted that the bill validator  22  may be configured so as to be capable of reading a later-described ticket  39  with a barcode. At the lower front face of the main door  13 , namely below the control panel  20 , there is provided a belly glass  34  on which a character or the like of the slot machine  10  is drawn. 
     At the front face of the top box  12 , an upper image display panel  33  is provided. The upper image display panel  33  is provided with a liquid crystal panel to display, for example, an image representing an introduction of the contents of a game or a description of a rule of the game. 
     Further, the top box  12  is provided with a speaker  29 . Below the upper image display panel  33 , there are provided a ticket printer  35 , a card reader  36 , a data display  37 , and a keypad  38 . The ticket printer  35  prints on a ticket a barcode as coded data of the number of credits, date and time, an identification number of the slot machine  10 , and the like, and outputs the ticket as a ticket  39  with a barcode. The player can make another slot machine read the ticket  39  with a barcode to play a game thereon, or can exchange the ticket  39  with a barcode with bills or the like at a predetermined place in the recreation facility (for example, a cashier in a casino). 
     The card reader  36  reads data from a smart card and writes data into the smart card. The smart card is a card owned by the player, and for example, data for identifying a player and data on a history of games played by the player are stored therein. Data corresponding to a coin, a bill, or a credit may be stored in the smart card. Further, in place of the smart card, a magnetic stripe card may be adopted. The data display  37  is comprised of a fluorescent display or the like, and displays, for example, data read by the card reader  36  or data inputted by the player through the keypad  38 . The keypad  38  is used for inputting a command and data concerning the issue of a ticket and the like. 
       FIG. 3  is a block diagram showing an internal configuration of the slot machine shown in  FIG. 2 . 
     A gaming board  50  includes a CPU (Central Processing Unit)  51 , a ROM  55 , and a boot ROM  52  which are interconnected to one another via an internal bus, a card slot  53 S corresponding to a memory card  53 , and an IC socket  54 S corresponding to a GAL (Generic Array Logic)  54 . 
     The memory card  53  is formed from a nonvolatile memory such as CompactFlash (registered trademark) and stores game programs and game system programs. The game programs include a symbol selection program. The aforementioned symbol selection program is a program for determining the symbols to be rearranged in the symbol matrix SM. The aforementioned symbol selection program includes symbol weighing data in association with a plurality of types of payout ratios (for example, 80%, 84%, 88%). The symbol weighing data is data indicating the correspondence between the respective symbols, and one or more random numbers which fall in a predetermined numerical range (0 to 255). The payout ratios are determined based on payout-ratio setting data outputted from the GAL  54  and, based on the symbol weighing data associated with the payout ratios, the symbols to be rearranged in the symbol matrix are determined. 
     Here, as the symbol to be rearranged in the symbol matrix SM, there are eight types of the symbols including “RIBBON”, “HEART”, “STAR”, “MOON”, “SUN”, “JEWEL”, “CROWN” and “SMILE”. Further, all the symbols are constituted by so-called scatter symbols. 
     Further, the game program includes normal odds data (See  FIG. 6A ) indicating normal odds and special odds data (See  FIG. 6B ) indicating special odds. 
     Further, the card slot  53 S is configured so as to allow the memory card  53  to be inserted thereinto or ejected therefrom, and is connected to a mother board  40  via an IDE bus. Thus, the memory card  53  can be ejected from the card slot  53 S, and then another game program is written onto the memory card  53 , and the memory card  53  can be inserted into the card slot  53 S, to change the type and contents of a game to be played on the slot machine  10 . The game program includes a program associated with the progress of a game. The game program also includes image data and sound data to be outputted during the game. The image data includes image data indicating a symbol matrix. 
     The GAL  54  is a type of PLD having a fixed OR array structure. The GAL  54  includes plural input ports and plural output ports and, when predetermined data is inputted to an input port, the GAL  54  outputs data corresponding to the aforementioned data from an output port. The data outputted from this output port is the aforementioned payout-ratio setting data. 
     Further, the IC socket  54 S is configured to allow the GAL  54  to be attached thereto and detached therefrom and is connected to the mother board  40  through a PCI bus. Accordingly, the GAL  54  can be replaced with another GAL  54  to change the payout-ratio setting data. 
     A CPU  51 , a ROM  55  and a boot ROM  52  interconnected to one another via an internal bus are connected to the mother board  40  by PCI bus. The PCI bus supplies power to the gaming board  50  from the mother board  40 , as well as transmitting a signal between the mother board  40  and the gaming board  50 . The ROM  55  stores country identification information and an authentication program. The boot ROM  52  stores an auxiliary authentication program and a program (boot code) to be used by the CPU  51  for activating the auxiliary authentication program, and the like. 
     The authentication program is a program (falsification check program) for authenticating a game program and a game system program. The authentication program is written along a procedure (authentication procedure) for checking and proving that a game program and a game system program to be subject to authentication loading processing have not been falsified, namely authenticating the game program and the game system program. The auxiliary authentication program is a program for authenticating the above-mentioned authentication program. The auxiliary authentication program is written along a procedure (authentication procedure) for proving that an authentication program to be subject to the authentication processing has not been falsified, namely, authenticating the authentication program. 
     The mother board  40  is constructed with a general-purpose mother board commercially available (a printed circuit board on which basic parts of a personal computer are mounted) and includes a main CPU  41 , ROM (Read Only Memory)  42  and RAM (Random Access Memory)  43 . The mother board  40  is the controller of the present invention. 
     ROM  42  is constituted of a memory device such as a flash memory and stores thereon a program such as BIOS (Basic Input/Output System) executed by the main CPU  41  and permanent data. When BIOS is executed by the main CPU  41 , not only is initialization processing for predetermined peripheral devices conducted, but a capture processing for the game program and game system program stored on the memory card  53  is also started via the gaming board  50 . In the present invention, contents of ROM  42  may be rewritable or not rewritable. 
     RAM  43  stores data and a program used at the time of operation of the main CPU  41 , and various flags. RAM  43  can also store the authentication program read through the gaming board  50 , the game program, and the game system program. RAM  43  further stores data on the number of credits, the number of coin-ins or coin-outs for one game, and the like. 
     Further, in the RAM  43 , a number-of-free-game storage area and a number-of-bonus-game storage area are provided. The number-of-free-game storage area stores data indicating the remaining number of the free game. The number-of-bonus-game storage area stores data indicating the remaining number of the bonus game. 
     To the mother board  40 , a body PCB (Printed Circuit Board)  60  and a door PCB  80 , which will be described later, are connected through respective USBs. Further, the mother board  40  is connected with a power supply unit  45 . When the power is supplied from the power unit  45  to the mother board  40 , the main CPU  41  of the mother board  40  is activated and the power is supplied to the gaming board  50  through the PCI bus so that the CPU  51  is activated. 
     The body PCB  60  and the door PCB  80  are connected with equipment and devices that generate input signals to be inputted to the main CPU  41 , and equipment and devices operations of which are controlled by control signals outputted from the main CPU  41 . The main CPU  41  executes a game program stored in the RAM  43  based on an input signal inputted to the main CPU  41 , thereby executes the predetermined arithmetic processing and stores a result thereof in the RAM  43 , or transmits a control signal to each of the equipment and devices as processing for controlling each of the equipment and devices. 
     To the body PCB  60 , there are connected a lamp  30 , a hopper  66 , a coin detecting portion  67 , a graphic board  68 , a speaker  29 , a touch panel  69 , a bill validator  22 , a ticket printer  35 , a card reader  36 , a key switch  38 S, and a data display  37 . The lamp  30  lights up in a predetermined pattern based on a control signal outputted from the main CPU  41 . 
     The hopper  66  is installed inside the cabinet  11  and pays out a predetermined number of coins from the coin payout exit  19  to the coin tray  18 , based on a control signal outputted from the main CPU  41 . The coin detecting portion  67  is provided inside the coin payout exit  19 , and outputs an input signal to the main CPU  41  when detecting a payout of a predetermined number of coins from the coin payout exit  19 . 
     The graphic board  68  controls, based on a control signal outputted from the main CPU  41 , an image display to the upper image display panel  33  and the lower image display panel  16 . The number of credits stored in RAM  43  is displayed to the number-of-credits display section  31  (not shown) of the lower image display panel  16 . The number of coins-out is displayed to the number-of-payouts display section  32  (not shown) of the lower image display panel  16 . The graphic board  68  is equipped with VDP (Video Display Processor) which generates image data based on a control signal outputted from the main CPU  41  and a video RAM which temporarily stores image data generated by VDP, and of the like equipments. It should be noted that image data used in generating image data with VDP is contained in a game program read from the memory card  53  and stored in RAM  43 . 
     The bill validator  22  not only discriminates a regular bill from a false bill, but also accepts the regular bill into the cabinet  11 . When accepting a regular bill, the bill validator  22  outputs an input signal to the main CPU  41 , based on the face amount of the bill. The main CPU  41  stores, in the RAM  43 , the number of credits according to the face amount of the bill transmitted with the input signal. 
     The ticket printer  35  prints on a ticket, based on a control signal outputted from the main CPU  41 , a barcode formed by encoding data such as the number of credits, date and time, an identification number of the slot machine  10 , and of the like data stored in the RAM  43 , and outputs the ticket as a ticket  39  with a barcode. 
     The card reader  36  reads data from a smart card and transmits the data to the main CPU  41  or writes data into the smart card based on a control signal from the main CPU  41 . The key switch  38 S is provided on the keypad  38 , and outputs a predetermined input signal to the main CPU  41  when the keypad  38  is operated by the player. The data display  37  displays, based on a control signal outputted from the main CPU  41 , data read by the card reader  36  or data inputted by the player through the keypad  38 . 
     To the door PCB  80 , there are connected a control panel  20 , a reverter  21 S, a coin counter  21 C, and a cold cathode tube  81 . The control panel  20  is provided with a start switch  23 S corresponding to the start button  23 , a change switch  24 S corresponding to the change button  24 , a CASHOUT switch  25 S corresponding to the CASHOUT button  25 , a 1-BET switch  26 S corresponding to the 1-BET button  26 , and a maximum BET switch  27 S corresponding to the maximum BET button  27 . Each of the switches  23 S to  27 S outputs an input signal to the main CPU  41  when each of the buttons  23  to  27  corresponding thereto is operated by the player. 
     The coin counter  21 C is provided inside the coin receiving slot  21  and discriminates a regular coin from a false coin inserted into the coin receiving slot  21  by the player. Coins other than regular coins are discharged from the coin payout exit  19 . When the coin counter  21 C detects a regular coin, the coin counter  21 C outputs an input signal to the main CPU  41 . 
     The reverter  21 S operates based on a control signal outputted from the main CPU  41 , and distributes a coin identified by the coin counter  21 C as a regular coin into a cash box (not shown) or the hopper  66 , which are disposed in the slot machine  10 . Specifically, when the hopper  66  is filled with coins, a regular coin is distributed into the cash box by the reverter  21 S. On the other hand, when the hopper  66  is not filled with coins, the regular coin is distributed into the hopper  66 . The cold cathode tube  81  functions as a backlight installed on the rear face side of the lower image display panel  16  and the upper image display panel  33 , and lights up based on a control signal to be outputted from the main CPU  41 . 
     Next, processing executed in the slot machine  10  will be described. 
       FIG. 4  is a flowchart illustrating main processing executed in the slot machine  10  according to a first embodiment. First, in the slot machine  10 , activation processing is executed (step S 101 ). The activation processing will be specifically described later by using  FIG. 8  to  FIG. 10 . 
     After the activation processing, the main CPU  41  executes processing of addition of the number of credits stored in the RAM  43  as an interrupt processing, on receiving a detection signal outputted from the coin counter  21 C when the coin inserted into the coin receiving slot  21  is detected by the coin counter  21 . 
     After the processing of step S 101 , the main CPU  41  executes slot machine game execution processing (step S 102 ). The slot machine game execution processing will be specifically described later by using  FIG. 5 . 
     Hereinafter, slot machine game execution processing executed in the slot machine  10  will be described. 
     The main CPU  41  reads a game program and executes the game program to progress a slot machine game. 
       FIG. 5  is a flowchart illustrating a subroutine of slot machine game execution processing. 
       FIG. 6  is a view illustrating a corresponding relationship between a rearranged symbol and a payout amount. 
     First, the main CPU  41  determines whether or not a coin has been BET (step S 11 ). In the processing, the main CPU  41  determines whether or not to have received an input signal outputted from the 1-BET switch  26 S when the 1-BET button  26  is operated or an input signal outputted from the maximum BET switch  27 S when the maximum BET button  27  is operated. When determining that a coin has not been BET, the main CPU  41  returns the processing to step S 11 . 
     On the other hand, when determining that a coin has been BET in step S 11 , the main CPU  41  executes processing for making a subtraction from the number of credits stored in the RAM  43 , according to the number of BET coins (step S 12 ). It should be noted that, when the number of BET coins is larger than the number of credits stored in the RAM  43 , the main CPU  41  does not execute the processing for making a subtraction from the number of credits stored in the RAM  43 , and returns the processing to step S 11 . When the number of BET coins exceeds an upper limit of the number of coins that can be BET on a single game (50 coins in the present embodiment), the main CPU  41  does not execute the processing for making a subtraction from the number of credits stored in the RAM  43 , and the processing is proceeded to step S 13 . 
     Next, the main CPU  41  determines whether or not the start button  23  has been turned on (step S 13 ). In the processing, the main CPU  41  determines whether or not to have received an input signal outputted from the start switch  23 S when the start button  23  is pressed. 
     When determining that the start button  23  has not been turned ON, the main CPU  41  returns the processing to step S 11 . It should be noted that, when the start button  23  is not turned ON (for example, when a command to end the game is inputted without pressing the start button  23 ), the main CPU  41  cancels a result of the subtraction obtained in step S 12 . 
     On the other hand, when determining in step S 13  that the start button  23  has been turned ON, the main CPU  41  executes symbol rearrangement processing (step S 14 ). 
     In the processing, at first, the main CPU  41  starts scroll-display of the symbols in the symbol matrix SM. Then, the main CPU  41  executes the above-mentioned symbol selection program, determines symbols to be rearranged, and rearranges the symbols in the symbol matrix SM. 
     Next, the main CPU  41  determines whether or not a prize is established (step S 15 ). Here, the establishment of the prize refers to the rearrangement of three or more normal symbols of at least one type, out of “RIBBON”, “HEART”, “STAR”, “MOON”, “SUN”, “JEWEL”, “CROWN”, and “SMILE”, in the symbol matrix SM (see  FIG. 6 ). In the processing, the main CPU  41  counts the number of the symbol for each type, with regard to the rearranged symbols in step S 14 . Then, the main CPU  41  determines whether or not the counted number is equal to or more than three. 
     When determining that the prize has been established, the main CPU  41  executes processing according to payout of the coin (step S 16 ). In the processing, the main CPU  41  determines the amount of payout based on the number of rearranged symbols with reference to the normal odds data (see  FIG. 6A ) stored in the RAM  43 . 
     In the case of accumulating the coin, the main CPU  41  executes processing for adding an amount of credits corresponding to the determined amount of payout. On the other hand, in the case of paying out coins, the main CPU  41  transmits a control signal to the hopper  66  in order to pay out the coin in amount corresponding to the determined amount of payout. 
     When determining that the prize has not been established in step S 15  or after executing the processing of step S 16 , the main CPU  41  determines whether or not the free game trigger is established (step S 17 ). In the processing, the main CPU  41  determines whether or not three or more free-game-trigger symbols are rearranged. 
     When determining that the free game trigger is established, the main CPU  41  displays cards images  110 A to  110 C (see  FIG. 1B ) showing three down cards in the lower image display region  16  (step S 18 ). 
     Subsequently, the main CPU  41  accepts an input indicative of selection of one card (step S 19 ). At this time, the player can select any one card by touching a portion on the touch panel  69  corresponding to the card image of the card. 
     Next, the main CPU  41  determines whether or not the input indicative of selection of one card has been inputted (step S 20 ). In the processing, the main CPU  41  determines whether or not a signal transmitted when the player touches a portion on the touch panel  69  corresponding to the card image. 
     When determining that the input indicative of selection of one card has not been inputted, the main CPU  41  determines whether or not a predetermined time has passed (step S 21 ) since the display of the card images  110 A to  110 C starts in step S 18 . When determining that the predetermined time has not passed, the main CPU  41  returns the processing to step S 19 . On the other hand, when determining the predetermined time has passed, the main CPU  41  ends the present subroutine. 
     On the other hand, when determining that the input indicative of selection of one card has been inputted in step S 20 , the main CPU  41  changes the card images  110 A to  110 C in such a manner as to show the up cards (step S 22 ). At this time, as shown in  FIG. 1C , the main CPU  41  displays the card selected by the player in a different manner from those of other cards. 
     In the processing, the main CPU  41  determines three numbers out of numerals  1  to  20  using random numbers and displays one of the determined three numbers on the respective card images. Namely, on the present embodiment, a number is assigned to each card after the player has selected one card. However, in the present invention, a number may be assigned to each card before selection of one card by the player. 
     Thereafter, the main CPU  41  execute free game execution processing (step S 23 ), and ends the present subroutine. The free game execution processing will be described later in detail using  FIG. 7 . 
     When determining that the free game trigger is not established in step S 17 , the main CPU  41  determines whether or not the bonus game trigger is established or not (step S 24 ). In the processing, the main CPU  41  determines whether or not three or more bonus game trigger symbols are rearranged. 
     When determining that the bonus trigger is established, the main CPU  41  executes bonus game execution processing. 
     In the processing, first, the main CPU  41  sets the remaining number of bonus games to the predetermined number M in the number-of-bonus-game storage area in RAM  43 . 
     Then, the main CPU  41  executes the processing substantially same as the processing of step S 11  to step S 16  in  FIG. 5 . However, in the payout processing, the number of coins-out is determined with reference not to the normal odds data but to special odds data. 
     The main CPU  41  subtracts one from the remaining number of the bonus games in the number-of-bonus-game storage area in the RAM  43  each time of execution of one game. 
     Then, the processing substantially same as the processing of step S 11  to step S 16  is repeatedly executed until the remaining number of bonus games becomes zero. 
     When determining that the bonus game trigger is not established in step S 24  or after executing the processing of step S 25 , the main CPU  41  ends the present subroutine. 
       FIGS. 7A and 7B  are flowcharts illustrating a subroutine of free game execution processing. 
     First, the main CPU  41  sets the number of remaining free games to T=C in the number-of-free-game storage area in the RAM  43  (step S 30 ). 
     Next, the main CPU  41  determines whether or not the start button  23  has been turned on (step S 31 ). When determining that the start button  23  has not been turned on, the main CPU  41  returns the processing to step S 31 . 
     On the other hand, when determining that the start button  23  has been turned on, the main CPU  41  determines whether or not the remaining number of free games T is one (step S 32 ). 
     When determining that T is one, the main CPU  41  determines whether or not T is one at the first time in the free games (step S 33 ). In the processing, the main CPU  41  determines whether or not T is one at the first time after the last execution of the processing of step S 30 . 
     When determining that T is not zero in step S 32  or T is one but not at the first time, the main CPU  41  executes the symbol rearrangement processing similar to the processing of step S 14  in  FIG. 5  (step S 34 ). 
     Here, although not shown, when determining that T is one at the first time in step S 33 , the main CPU  41  determines whether or not a number C displayed on the card selected by the player is 20. When determining C is 20, the main CPU  41  shifts the processing to step S 34 . On the other hand, when determining that C is not 20, the main CPU  41  shifts the processing to step S 35 . 
     In step S 35 , the main CPU  41  rearranges the symbols to establish the free game trigger. In the processing, the main CPU  41  determines the number of free-game-trigger symbols to be rearranged out of three or more. Then, the main CPU  41  executes the symbol selection program to determine other symbols to be rearranged, and displays the determined symbols in the symbol matrix SM. 
     Subsequently, the main CPU  41  executes the processing of step S 36  to step S 39 . Since the processing is substantially same as the processing of step S 18  to step S 21  in  FIG. 5 , the descriptions thereof are omitted here. 
     When determining that the input indicative of selection of one card has been inputted in step S 38 , the main CPU  41  changes the card images  110 A to  110 C so as to show the up cards (see  FIG. 1C ) (step S 40 ). In the processing, the main CPU  41  displays a number obtained by subtraction of the number C displayed on the card selected by the player in step S 20  in  FIG. 5  from 20 (20−C) on the card selected by the player in step S 38 . Further, the main CPU  41  determines two numbers out of 1 to 20 using random numbers, and displays one of two numbers on the respective remaining two cards. 
     Next, the main CPU  41  sets the remaining number of free games to T=T+(20−C) in the number-of-free-game storage area in the RAM  43  (step S 41 ). 
     When determining that a predetermined time has passed, or after executing the processing of step S 34  or step S 41 , the main CPU  41  execute processing of step S 42  to step S 43 . Here, since the processing is substantially same as the processing of step S 15  to step S 16  in  FIG. 5 , the descriptions thereof are omitted here. 
     When determining that the prize is not established in the step S 42  or after executing the processing of step S 43 , the main CPU  41  executes processing of step S 44  to step S 45 . Here, since the processing is substantially same as the processing of step S 24  to step S 25  in  FIG. 5 , the descriptions thereof are omitted here. 
     When determining that the bonus game trigger is not established in step S 44 , or after executing the processing of step S 45 , the main CPU  41  sets the remaining number T of the free game to T=T−1 in the number-of-free-game storage area in the RAM  43  (step S 46 ). 
     Next, the main CPU  41  determines whether or not T is zero (step S 47 ). 
     When determining that T is not zero, the main CPU  41  returns the processing to step S 31 . On the other hand, when determining that T is zero, the main CPU  41  ends the present subroutine. 
     Subsequently, there will be described activation processing (see step S 101  in  FIG. 4 ) by using  FIG. 8  to  FIG. 10 . 
       FIG. 8  is a flowchart illustrating a procedure of activation processing. This activation processing is the processing conducted by the mother board  40  and the gaming board  50 . It should be noted that the memory card  53  is inserted into the card slot  53 S in the gaming board  50 , and the GAL  54  is mounted onto the IC socket  54 S. 
     First, when a power switch is turned on (power is turned on) in the power supply unit  45 , the mother board  40  and the gaming board  50  are activated (steps S 1 - 1 , S 2 - 1 ). In activation of the mother board  40  and the gaming board  50 , individual processing is respectively executed in parallel. Namely, in the gaming board  50 , the CPU  51  reads the auxiliary authentication program stored in the boot ROM  52 , and conducts auxiliary authentication according to the read auxiliary authentication program, to previously check and prove that the authentication program is not falsified before loading the program to the mother board  40  (step S 2 - 2 ). Meanwhile, in the mother board  40 , the main CPU  41  executes the BIOS stored in the ROM  42 , and expands compressed data which is incorporated in the BIOS into the RAM  43  (step S 1 - 2 ). The main CPU  41  then executes the BIOS expanded into the RAM  43  to diagnose and initialize a variety of peripheral devices (step S 1 - 3 ). The processing of step S 1 - 3  will be specifically described later with reference to  FIG. 12 . 
     Since the ROM  55  of the gaming board  50  is connected to the main CPU  41  via the PCI bus, the main CPU  41  reads the authentication program stored in the ROM  55 , and stores the read authentication program into the RAM  43  (step S 1 - 4 ). At this time, according to the standard BIOS function of BIOS, the main CPU  41  takes a checksum by ADDSUM system (normal checking system) and stores the authentication program into the RAM  43 , while conducting processing for confirming whether or not the storage is certainly conducted. 
     Next, after confirming what is connected to the IDE bus, the main CPU  41  accesses, via the IDE bus, the memory card  53  inserted in the card slot  53 S, to read a game program or a game system program from the memory card  53 . In this case, the main CPU  41  reads data constituting the game program and the game system program by 4 bytes. Subsequently, the main CPU  41  conducts authentication to check and prove that the read game program and game system program have not been falsified, following the authentication program stored in the RAM  43  (step S 1 - 5 ). When this authentication processing is normally completed, the main CPU  41  writes and stores the game program and the game system program, which have been the authentication targets (which have been authenticated), into the RAM  43  (step S 1 - 6 ). Next, the main CPU  41  accesses, via the PCI bus, the GAL  54  mounted on the IC socket  54 S, reads payout ratio setting data from the GAL  54 , and writes and stores the data into the RAM  43  (step S 1 - 7 ). Subsequently, the main CPU  41  conducts processing for reading country identification information stored in the ROM  55  of the gaming board  50  via the PCI bus, and writes and stores the read country identification information into the RAM  43  (step S 1 - 8 ). 
     After conducting the above-mentioned processing, the main CPU  41  sequentially reads and executes the game program and the game system program, thereby execute insurance setting processing and game execution processing. 
       FIG. 9  is a chart illustrating a procedure of peripheral-device initialization processing. 
     First, the main CPU  41  diagnoses and initializes a reel-related device (step S 3 - 1 ). In this processing, the main CPU  41  sequentially transmits request signals to the index detecting circuit  65 , the position-change detecting circuit  71 , and the motor driving circuit  62 . Then, the main CPU  41  determines whether or not to have received predetermined response signals and conducts clearance of a predetermined storage area, and the like. 
     Next, the main CPU  41  diagnoses and initializes a display (step S 3 - 2 ). In this processing, the main CPU  41  transmits the request signal to the graphic board  68 . Then, the main CPU  41  determines whether or not to have received a predetermined response signal and conducts clearance of a predetermined storage area, and the like. 
     Next, the main CPU  41  diagnoses and initializes various types of input devices (step S 3 - 3 ). In this processing, the main CPU  41  transmits request signals to the input devices such as the spin switch  23 S, the change switch  24 S, the CASHOUT switch  25 S, the 1-BET switch  26 S, the maximum BET switch  27 S, and the touch panel  11 , and then determines whether or not to have received predetermined response signals. 
     Subsequently, the main CPU  41  diagnoses and initializes other peripheral devices connected to the main CPU  41  (step S 3 - 4 ). Then the present subroutine is terminated. 
     In the present embodiment, there has been described the case where the slot machine  10  is a stand-alone type slot machine. However, in the present invention, a plurality of slot machines may be connected to a central controller via a network and controlled by the central controller. 
       FIG. 10  is a chart illustrating a procedure of activation processing executed by the central controller. 
     First, when the power switch is turned on (the power is turned on) in the power unit, a mother board is activated (step S 4 - 1 ). 
     In the mother board, a CPU executes a BIOS stored in a ROM so as to expand compressed data incorporated in the BIOS into a RAM (step S 4 - 2 ). Then, the CPU executes the BIOS expanded into the RAM, and then, diagnoses and initializes various types of peripheral devices such as a display (step S 4 - 3 ). 
     Next, the CPU executes initialization processing of each slot machine. In this processing, the CPU establishes a network connection between the central controller and each slot machine, and diagnoses if the network functions properly. 
     After the above-described processing, the CPU controls proceeding of the game executed in a plurality of the slot machines by reading and executing a game control program. 
     According to the slot machine  10  of the present embodiment, the free games include a unit free game repeatedly executed plural times. When the predetermined condition is established before completion of all of a predetermined number C of unit free games to be executed, the bonus games are generated and then the unit free games restarts after completion of the bonus games. The number of unit free games to be executed after completion of the bonus games is obtained by subtraction of the number of unit free games executed before generation of the bonus games from the predetermined number C of the unit free games to be executed. 
     Thereby, the player is allowed to play the unit free game remained unexecuted at the time of generation of the bonus games after completion of the bonus games, and to enjoy absolute benefits of the free game. Namely, when the bonus games are generated in the free game, the player is allowed to enjoy benefits of the bonus game without suffering from something unprofitable. Therefore, it is possible to provide the player with a great satisfaction. 
     According to the slot machine  10  of the present embodiment, the number of unit free games is determined based on the selection of a card by the player as triggered by establishment of the free game trigger in the normal game. When the number is less than the predetermined number (20), the free game trigger is established without failure in the last unit free game. Accompanying this, the unit free games are executed predetermined number of times determined again. 
     In the last unit free game, the player is generally supposed to feel sad in a sort of way because of the last game which allows the player to play without a BET of a game medium. According to the slot machine  10  of the present embodiment, since the unit free games are further offered at the time when the player has such a feeling, it is possible to make the player feel unpredictable and give the player an impression that the player has got significantly large benefits. This allows the player to feel further interested in the games. 
     In the embodiments described above, there have been described the cases where symbols are rearranged in the symbol matrix SM of the lower image display panel  16  (the slot machine  10  is a so-called a video slot machine). However, the slot machine according to the present invention may be configured to stop-display symbols using so-called mechanical reels. 
       FIG. 11  is a perspective view illustrating the general appearance of a slot machine according to another embodiment. 
     In the following description, the components corresponding to those of the slot machine  10  will be designated by the same reference numerals. 
     Further, the slot machine  310  has substantially the same external appearance, the same circuit structure and the like as those of the slot machine  10  and also executes substantially the same flowcharts as those executed by the slot machine  10 , except that it employs mechanical reels, and, therefore, only the mechanical reels will be described herein. 
     As illustrated in  FIG. 11 , five reels  314  ( 314 A,  314 B,  314 C,  314 D and  314 E) are rotatably provided within a cabinet  11 . On the outer peripheral surfaces of the reels  314 A,  314 B,  314 C,  314 D and  314 E, there are drawn symbol sequences constituted by symbols such as “RIBBON”, “HEART”, “STAR”, “MOON”, “SUN”, “JEWEL”, “CROWN”, and “SMILE”, and the odds-change symbol. 
     At the center portion of the lower image display panel  16 , there is provided a display area  328  for displaying the symbols. Within the display area  328 , there are formed five display windows  315  ( 315 A,  315 B,  315 C,  315 D and  315 E) visible through their back surfaces. Further, the symbols drawn on the outer peripheral surfaces of the reels  314 A,  314 B,  314 C,  314 D and  314 E are displayed on a three-by-three basis, through the display windows  315 A,  315 B,  315 C,  315 D and  315 E. 
     Although the present invention has been described with reference to embodiments thereof, these embodiments merely illustrate concrete examples, not restrict the present invention. The concrete structures of respective means and the like can be designed and changed as required. Furthermore, there have been merely described most preferable effects of the present invention, as the effects of the present invention, in the embodiments of the present invention. The effects of the present invention are not limited to those described in the embodiments of the present invention. 
     Further, in the aforementioned detailed description, characteristic portions have been mainly described, for ease of understanding the present invention. The present invention is not limited to the embodiments described in the aforementioned detailed description, but can be also applied to other embodiments over a wider range of applications. Further, the terms and phrases used in the present specification have been used for clearly describing the present invention, not for limiting the interpretation of the present invention. Further, those skilled in the art will easily conceive other structures, systems, methods and the like which are included in the concept of the present invention, from the concept of the present invention described in the present specification. Accordingly, the description of the claims is intended to include equivalent structures that fall within the technical scope of the invention. Further, the abstract aims at enabling engineers and the like who belong to the present technical field but are not familiar with the patent office and public institutions, the patent, law terms and technical terms to immediately understand the technical content and the essence of the present application through brief studies. Accordingly, the abstract is not intended to restrict the scope of the invention which should be evaluated from the description of the claims. It is desirable that literatures and the like which have been already disclosed are sufficiently studied and understood, in order to sufficiently understand the objects of the present invention and the specific effects of the present invention. 
     In the aforementioned detailed description, there have been described processing to be executed by computers. The aforementioned description and expressions have been described for the sake of enabling those skilled in the art to understand the present invention most effectively. In the present specification, each step for deriving a single result should be understood to be self-consistent processing. Further, each step includes transmission, reception, recording and the like of electric or magnetic signals. Although, in the processing at each step, such signals have been expressed as bits, values, symbols, characters, terms, numerical characters and the like, it should be noticed that they have been merely used for convenience of description. Further, although the processing at each step was described using expressions common to human behaviors in some cases, the processing described in the present specification are to be executed by various types of devices, in principle. Further, other structures required for conducting each step will be apparent from the aforementioned description.