JP4191066B2 - Gaming machine, fraud prevention method and program for gaming machine - Google Patents

Description

  The present invention relates to a gaming machine such as a slot machine, a fraud prevention method for the gaming machine, and a program.

  A gaming machine such as a slot machine or a pachinko machine has a built-in microcomputer (CPU), and controls lottery, winning, payout, and production by a program. This type of gaming machine receives an operation from the player, performs an internal lottery and a prize determination according to the lottery result, and controls a game medium payout control according to the prize, and receives a command from the main board. And a sub-board for notifying the result of the internal lottery and performing various effects.

  In many games, the display itself such as a liquid crystal display device, a speaker, or a display lamp is used to notify a player of a prize or the like, or a specific small role is played between certain games during a so-called assist time (AT). Tell the user with some action. (Assist time (AT): Even if a specific small role is established, the player will not be refunded if the reels are not aligned. After the big bonus ends (or at the time of establishment) to ensure payout by the small role) Alternatively, a lottery of assist time is drawn at any other opportunity, and if this is won, the player is instructed to perform an operation to establish a specific small role for a certain game with some action)

  As with the AT, there is a gaming machine in which the weight of the winning rate is controlled by software on the sub-board side. The sub-board side has a function to adjust the protruding balls. Specifically, as described above, an instruction for obtaining a ball is displayed on the liquid crystal display device so that the player can easily obtain the ball if the player operates according to the instruction. This instruction is not always issued, but is issued in a specific case.

  In this way, the main board and the sub board realize the lottery, winning, payout, and production control by the program. The program for each board performs important control related to the game.

  There are some who try to get the ball out illegally by using the AT function. A ROM whose program has been tampered with in an advantageous manner is illegally attached to the main board or sub board.

  By the way, gaming machines such as slot machines and pachinko machines are regulated by law, and therefore the program for each board needs to be subject to prior verification and approval by the relevant organizations, and can be altered without permission. Not. The program mounted on each board, specifically, the content of the ROM is determined at the time of application to the related organizations, and the content of the ROM of the same type of gaming machine is always required to be the same. The ROM is protected by a structure that cannot be removed from the substrate by caulking or the like so that it is not altered arbitrarily in a hall or the like.

  However, there are cases where the ROM is exchanged using unauthorized means and the contents of the program are changed. The damage caused by such fraudulent acts is squeezing up the hall management and becoming a social problem. In order to prevent such fraud, measures are taken such as sealing the substrate or making the structure so that it cannot be easily removed. However, fraud still continues. For this reason, it has become necessary to detect an illegal ROM when it is installed, together with measures for preventing illegal ROM replacement structurally or physically.

  An object of the present invention is to solve such a problem, and provides a gaming machine, a gaming machine fraud prevention method, and a program that can determine whether a program (specifically, the contents of a ROM) has been tampered with. The purpose is to do.

The present invention includes a main board that performs internal lottery and winning determination in response to a player's operation, and controls payout of game media in accordance with winning, and at least a CPU and a program ROM, and receives commands from the main board. In a gaming machine comprising a sub-board that produces an effect and a display control board that receives a command from the sub-board and displays a predetermined image on a display,
Return address for adding the return address of the program stored when the CPU of the sub-board receives an interrupt for command transmission to the display control board while executing the processing to the command to be sent to the display control board An additional part;
A command transmitter for transmitting the command and the return address to the display control board;
A use address range storage unit for storing in advance the address of the use range of the program;
A determination unit that determines whether the program ROM of the sub-board has been tampered with by comparing the return address added to the command with the contents of the use address range storage unit;

The present invention includes at least a CPU and a program ROM, performs an internal lottery and winning determination in response to a player's operation, and controls a game medium payout control according to winning, and receives a command from the main substrate. In a gaming machine equipped with a sub-board for performing production,
A return address adding unit for adding a return address of a program stored when the CPU of the main board receives an interrupt for transmitting a command to the sub board while executing processing to a command to be sent to the sub board When,
A command transmission unit for transmitting the command and the return address to the sub-board;
A use address range storage unit for storing in advance the address of the use range of the program;
And a determination unit that determines whether the program ROM of the main board has been tampered with by comparing the return address added to the command with the contents of the use address range storage unit.

The present invention includes a main board that performs internal lottery and winning determination in response to a player's operation, and controls payout of game media in accordance with winning, and at least a CPU and a program ROM, and receives commands from the main board. In a gaming machine comprising a sub-board that produces an effect and a display control board that receives a command from the sub-board and displays a predetermined image on a display,
Return address for adding the return address of the program stored when the CPU of the sub-board receives an interrupt for command transmission to the display control board while executing the processing to the command to be sent to the display control board An additional part;
A command transmitter for transmitting the command and the return address to the display control board;
An unused address range storage unit that stores in advance an address of an unused range of the program;
A determination unit that determines whether the program ROM of the sub-board has been tampered with by comparing the return address added to the command with the contents of the unused address range storage unit;

The present invention includes at least a CPU and a program ROM, performs an internal lottery and winning determination in response to a player's operation, and controls a game medium payout control according to winning, and receives a command from the main substrate. In a gaming machine equipped with a sub-board for performing production,
A return address adding unit for adding a return address of a program stored when the CPU of the main board receives an interrupt for transmitting a command to the sub board while executing processing to a command to be sent to the sub board When,
A command transmission unit for transmitting the command and the return address to the sub-board;
An unused address range storage unit that stores in advance an address of an unused range of the program;
A determination unit that determines whether the program ROM of the main board has been tampered with by comparing the return address added to the command with the contents of the unused address range storage unit;

  Furthermore, an error processing unit may be provided that performs error notification when the determination unit determines that the program ROM has been tampered with or stops execution of processing according to the command.

  According to the present invention, it is possible to determine whether or not a program has been tampered with. When tampered, an error can be displayed on the display unit, and the game can not be continued.

Embodiment 1 of the Invention
A gaming machine according to Embodiment 1 of the present invention will be described with reference to the drawings.
FIG. 1 is a front view of a gaming machine (slot machine).
A player who wants to enjoy a game with the slot machine 10 first borrows a medal as a game medium from a medal lending machine (not shown) or the like, and inserts a medal directly into the medal insertion slot 100 of the medal insertion device. The medal slot 100 is provided at a substantially central position in front of the slot machine 10.

  The slot machine 10 has a square box-shaped housing 11. A square window-like display window 12 facing the player side is formed at the center and upper part of the casing 11. A symbol display window 13 through which the symbols 61 of the three rotary reels 40 can be seen is formed at the center of the display window 12 at the center. The bet switch 16 is a switch located below the rotary reel 40 and reduces the number of stored medals to replace medal insertion. The settlement switch 17 is a switch located obliquely below the rotating reel, and pays out the stored inserted medal. The start switch 30 is a lever positioned obliquely below the rotary reel 40 and starts driving the reel unit 60 on condition that a game medal is inserted or the bet switch 16 is inserted. The stop switch 50 is for stopping the driving of the reel unit 60. The reel unit 60 is composed of three rotating reels 40. Each rotary reel 40 includes a rotary drum made of synthetic resin and a tape-like reel tape 42 attached around the rotary drum. A plurality of (for example, 21) symbols 61 are displayed on the outer peripheral surface of the reel tape 42. Reference numeral 62 denotes a liquid crystal display unit for performing various effects.

  Inside the slot machine 10, although not shown, a control device for controlling the entire operation of the slot machine 10 is incorporated. Although not shown, the control device is configured around a CPU and includes a ROM, a RAM, an I / O, and the like. Then, the CPU operates by reading a program stored in the ROM, and controls the rotation and stop of the rotary reel 40 based on the operation of the start switch 30 and the stop switch 50, and also controls the display of lamps, speakers, and the like.

  As described above, the start switch 30 is a lever that is positioned obliquely below the rotary reel 40. The start switch 30 is subject to the insertion of a game medal or the bet switch 16, or from the previous game at the time of “Replay”. This is for starting the driving of the reel unit 60 on condition that the predetermined time elapses.

  The stop switch 50 is for stopping the driving of the reel unit 60 as described above. Specifically, the stop switch 50 includes three switches corresponding to each rotary reel 40, and one stop switch 50 is disposed below each rotary reel 40. The operation of the stop switch 50 corresponding to the rotating reel 40 is set to stop the rotation of the corresponding rotating reel 40.

  When the start switch 30 is operated on the condition that the medal is inserted or the bet switch 16 is inserted, or on the condition that a predetermined time has elapsed from the previous game at the time of “replay”, the reel unit 60 is driven, and the three units The rotating reel 40 starts to rotate. Thereafter, when one of the stop switches 50 is operated, the rotation of the corresponding rotary reel 40 is stopped. When all three stop switches 50 are operated, the rotation of the three rotary reels 40 is stopped. At this time, when a preset symbol 61 stops on the effective pay line of the display window 12, a predetermined number of medals are paid out through a hopper unit (not shown). In addition, you may credit instead of paying out medals.

  When the above-described control device controls the rotation and stop of the rotary reel 40 based on the operation of the start switch 30 and the stop switch 50, a prize is awarded for determining whether or not to win based on a predetermined lottery probability. Includes lottery means. A winning flag is established when the lottery result by the winning lottery means is a winning, and a winning is achieved on the condition that the combination of the stopped symbols of the rotating reel 40 matches a predetermined winning symbol while the winning flag is established. It is determined so that the player is given a medal or a special game.

  FIG. 2 is a block diagram showing an electrical schematic structure of the slot machine 10. In this figure, the display about the power supply system is omitted. The slot machine 10 includes a main substrate 1 and a sub-substrate 2 that operates in response to commands from the main substrate 1 as main processing devices.

  The main board 1 is for performing an internal lottery in response to a player's operation, and processing such as reel rotation / stop and medal payout. The main board 1 includes a CPU that performs a control operation according to a preset program, and ROM and RAM that are storage means.

  The sub-board 2 is for receiving a command signal from the main board 1 and notifying the result of the internal lottery and performing various effects. The sub-board 2 includes a CPU that performs a control operation according to a preset program, and a ROM and a RAM that are storage means.

  The sub-board 2 receives a command from the main board 1 and performs processing such as rendering according to the command. The flow of commands is only one from the main board 1 to the sub board 2, and conversely, no command or the like is issued from the sub board 2 to the main board 1.

  2a is a return address adding unit for adding a return address of a program to be stacked when a timer interrupt is applied to the CPU of the sub board 2 to a command to the liquid crystal control board 200, and 2b is a command and a return added thereto. It is a command transmission unit that transmits an address to the liquid crystal control board 200.

  Connected to the main board 1 are a start switch 30, a stop switch 50, a reel drive unit 70, a reel position detection circuit 71, a hopper drive unit 80, and a medal detection unit 82 for counting the number of medals paid out from the hopper 81. ing. A peripheral substrate (local substrate) such as a control substrate 200, a speaker substrate 201, and an LED substrate 202 of the liquid crystal display device 62 is connected to the sub substrate 2. Hereinafter, these peripheral substrates / devices except for the start switch 30 and the stop switch 50 will be described.

  The reel driving unit 70 is a circuit that drives a stepping motor (not shown) that rotationally drives the three reels 40. Each stepping motor is subjected to 1-2 phase excitation by the reel drive circuit 70 and rotates once when a drive signal having a predetermined number of pulses is supplied.

  The reel position detection circuit 71 is provided in the vicinity of the reel 40, receives an output pulse signal from a photo sensor (not shown) for detecting the rotation position of the reel 40, detects the rotation position of each of the three reels 40, and detects the detection signal. Is output. A photo sensor (not shown) detects a shielding plate provided on each reel 40 and generates a reset pulse every time each reel 40 rotates once. This reset pulse is given to the CPU of the main board 1 via the reel position detection circuit 71. In the RAM of the main board 1, a count value corresponding to the rotation position within one rotation range is stored for each reel 40, and when the CPU receives the reset pulse, the count value formed in the RAM is stored. Clear to "0". By this clearing process, the deviation generated between the movement display of each symbol and the rotation of each stepping motor is eliminated every rotation.

  The hopper driving unit 80 is a circuit that drives a motor of the hopper 81 that stores medals and pays out the designated number of medals.

  The medal detection unit 82 is for counting the number of medals paid out from the hopper 81. When the medal count value actually paid out received from the medal detection unit 82 reaches the predetermined payout number data, the CPU of the main board 1 stops the driving by the hopper driving unit 80 and ends the medal payout. . The hopper drive circuit 80 and the medal detection unit 82 pay out a predetermined number of medals to the player based on the game result.

  The liquid crystal control board 200 is a circuit for driving the liquid crystal display unit 62. Reference numeral 200a denotes a use address range storage unit which stores in advance a range of addresses used in the program of the sub-board 2, and 200b denotes a sub-address by comparing the return address received from the sub-board 2 with the contents of the use address range storage unit 200a. A ROM tampering determination unit 200c that determines whether the ROM of the substrate 2 has been tampered with, and 200c is an error processing unit that receives an output from the ROM tampering determination unit 200b and performs error processing.

The speaker board 201 is a circuit for driving a loudspeaker (not shown).
The LED substrate 202 is a circuit for driving a display lamp and a back lamp (not shown).

  The liquid crystal display device 62, a speaker and a display lamp (not shown), etc. constitute an effect display device. This effect display device is for notifying a player of a prize or the like, or for teaching a user a specific small role during a certain game with some action during a so-called assist time (AT).

  Prior to the description of the apparatus / method according to the first embodiment of the present invention, ROM alteration and timer interrupt processing will be described.

  The alteration of the ROM is to mount a ROM that stores a program that has been altered so as to cause a fraudulent person to execute a process that is advantageous to a ROM that stores a legitimate program. Tampering with a program is not done entirely by changing the legitimate program, but by changing the processing of a specific part, often by adding several instructions. For example, a part of the instructions is rewritten with a jump instruction to an illegal program, and an illegal processing program added to the jump destination is added. This means that an illegal program is written to an address where no program is originally written, so the size of the illegal program is larger than that of the original program.

  This will be described with reference to FIG. FIG. 4A shows the concept of the usage status of the address of a regular program. The example in the figure shows a case where a program for performing three processes A to C is stored in the ROM. The programs of process A to process C are stored at addresses from the first address AS to the last address CE. Addresses from ES (= CE + 1) to EE (last address of the memory) are free areas. An empty area may exist between the processes A to C. FIG. 4B shows the state of the used address of the altered program. The process C is altered to the process C ′, and the last address of the process C ′ is changed to C′E. The free space is reduced by this increase (= C′E−CE). The increased address is never used in a legitimate program, and if the CPU reads and executes the program at the increased address, the program is an illegal program that has been altered. Can be determined. In the first embodiment of the present invention, the CPU reads out and executes the address read from the address saved at the time of the timer interruption, and this is an incremented address that is not originally used (the illegal program here is written). When there is, it is determined that the program has been tampered with.

  An interrupt is an interruption of the execution of one program by hardware means so that it can be resumed later, and another program is executed. There is a timer for interrupting at predetermined intervals as hardware for interrupting. In the hardware interrupt, a hardware such as a timer sends a signal to the CPU, interrupts the process being executed, and forcibly executes a process designated in advance. In order to return to the original process after executing the interrupt process, the address of the program currently being executed is saved in a stack provided in the RAM. In general, hardware interrupts occur (asynchronously) regardless of the program being executed. Therefore, it cannot be predicted which address will be saved in the stack, and the probability of being stacked is the same for all addresses in the program. In gaming machines, command transmission interruptions from the sub-board to the liquid crystal control board occur frequently, so that the address of the stack can take all the addresses of the program in a sufficiently long time. If the program has been tampered with, the address of the stack will always become an unused address. The processing of FIG. 3 is performed under such a premise.

  FIG. 3 shows an outline of processing of the gaming machine according to Embodiment 1 of the present invention. FIG. 3 shows only the processing part for detecting the alteration of the program. In FIG. 3, S1, S3, S11, S12, and S16 are processes similar to the conventional interrupt process, and S2, S13 to S15 indicate characteristic processes according to the first embodiment of the present invention. S <b> 1 to S <b> 3 are processing of the sub-substrate 2, and S <b> 11 to S <b> 16 are processing of the liquid crystal control substrate 200.

  In general, the CPU temporarily interrupts the processing that has been performed so far to execute the interrupt processing, and then continues the original processing. Therefore, in order to return to the original processing, there is a mechanism for holding a history of which part the program was executing. Specifically, when the CPU is interrupted by a timer (not shown), the CPU saves the address of the program currently being executed in a stack provided in the RAM. Then, the interrupt process of FIG. 3 is executed.

S1: A command to be transmitted to the liquid crystal control board is acquired. Commands are frequently transmitted from the sub board to the liquid crystal control board as animation management. Command transmission to the liquid crystal control board by the CPU of the sub board is performed at a certain interval, and is performed by timer interrupt processing.

S2: The address saved at the start of interrupt processing (hereinafter referred to as “return address”) is read from the stack, and “return address” is added to the command acquired in S1. The “return address” is used to return to the original process after completing the interrupt process, and is not transmitted to the outside.

S3: A command and a “return address” added thereto are transmitted from the sub board to the liquid crystal control board.

S11: When the command and “return address” are received by the liquid crystal control board, these data are acquired from the received port and stored in the buffer.

S12: It is determined whether a series of commands has been received. If received (YES), the process of S13 is performed.

S13: The “return address” added to the command is confirmed. “Return address” means the address of the program executed by the CPU of the sub-board.

S14: It is determined whether the “return address” is normal. Specifically, the determination is performed by comparing the contents of the used address range storage unit 200a with the “return address”. For example, it is assumed that used address ranges AS to CE as shown in FIG. 4A are stored in the used address range storage unit 200a. If the “return address” is in the range of AS to CE, it is determined to be normal, and if the “return address” is not in that range, for example, between CE to C′E in FIG. To do. Instead of storing the used address ranges AS to CE in the used address range storage unit 200a, unused address ranges ES to EE may be stored. In this case, when an unused address is detected, it is determined that the address is not normal.

S15: When the “return address” is not normal, error processing is performed. For example, an error is displayed on the liquid crystal display device or error information is transmitted to the outside. Alternatively, the effect of the liquid crystal display device simply by command may be stopped. Providing information (assist) that is advantageous to the player through the production, but the fraudster alters the ROM in order to receive the assist illegally. Actors cannot enjoy the benefits and the meaning of tampering is lost.

S16: When the “return address” is normal, processing according to the command is performed.

  The above is the description of the first embodiment of the present invention. Conventionally, there has been no countermeasure against falsification of the contents of the ROM of the sub-board. According to the first embodiment of the present invention, the liquid crystal control CPU checks whether the history is correct by adding the processing history (which address program is being executed) of the sub-board CPU to the transmission command. In the case of fraud, an error is displayed on the liquid crystal display, and the game cannot be continued due to fraud. In order to avoid the check according to the first embodiment of the present invention, it is necessary to falsify the ROM of the liquid crystal control board, which makes it difficult to perform fraud. Therefore, according to Embodiment 1 of the present invention, it is possible to expect an effect of reducing fraud due to ROM alteration of the sub-board.

  In the first embodiment of the present invention, in order to check the processing history of the CPU on the sub-board, the return address of the interrupt processing is added and transmitted at the time of command transmission. Since it is common for unauthorized programs to tamper with other than interrupt processing, data for determining whether or not a predetermined interrupt processing return address has been registered in advance in the liquid crystal control ROM is not within that range. When the command is received, the liquid crystal control CPU executes an error display process.

  Timer interrupt processing is used in the sub-board. Timer interrupt processing always operates during CPU operation at a certain interval, and since it is not synchronized with the non-interrupt unit, it is impossible to predict where the interrupt will occur when executing the non-interrupt unit. Suitable for checking.

  The first embodiment of the present invention can be easily realized by, for example, partial modification of a program, has a feature that processing time is short and a load is not imposed on the CPU.

Embodiment 2 of the Invention
In the first embodiment of the invention, it is determined whether or not ROM alteration has been performed using the return address of interrupt processing, that is, whether or not an address that is not used in a regular program is used. In the second embodiment of the invention, the address of the instruction read by the CPU is directly acquired by hardware, and this is compared with the contents of the used address range storage unit 200a.

  FIG. 5 shows a block diagram of a gaming machine according to the second embodiment of the present invention. In FIG. 5, the same or equivalent parts as in FIG.

  The address monitoring unit 20 monitors the address bus of the sub-board 2 and acquires an address at the timing (fetch cycle) at which the CPU reads an instruction. Some CPUs output a specific signal when the CPU reads a program. In the case of such a CPU, if the address bus data is acquired at the timing of the specific signal, the address of the instruction read by the CPU, that is, the address of the program can be acquired. Alternatively, the address of the instruction read by the CPU may be acquired by tracing the operation of the CPU.

  The ROM falsification determining unit 200b determines whether the program address acquired in this way has been falsified. If it is determined that the program has been falsified, the error processing unit 200c performs error processing.

  According to the second embodiment of the present invention, whether or not the ROM has been tampered with is determined. If it is illegal, an error is displayed on the liquid crystal display device, and if the ROM is tampered with, the game cannot be continued.

  The second embodiment of the present invention can be realized by adding relatively simple hardware, has a feature that the processing time is short, and the CPU is not burdened.

  In the above description, the alteration of the ROM of the sub board is detected by the liquid crystal control board. However, the alteration of the ROM of the main board may be detected by the sub board using the same technique.

  In the above description, the use address range storage unit 200a, the ROM tampering determination unit 200b, and the error processing unit 200c are provided in the liquid crystal control board 200, but the present invention is not limited to this. The used address range storage unit 200a, the ROM alteration determination unit 200b, and the error processing unit 200c may be provided on an independent substrate or may be provided on another substrate.

  The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.

  Further, in the present specification, the term “unit” does not necessarily mean a physical means, but includes a case where the function of each unit is realized by software. Furthermore, the function of one part may be realized by two or more physical means, or the function of two or more parts may be realized by one physical means.

It is a front view of a gaming machine (slot machine). 1 is a block diagram of a gaming machine according to a first embodiment of the invention. It is a process flowchart regarding ROM alteration determination of the gaming machine according to the first embodiment of the invention. It is explanatory drawing of the operation principle of Embodiment 1 of invention. It is a block diagram of the gaming machine according to the second embodiment of the invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main board | substrate 2 Sub board | substrate 2a Return address addition part 2b Command transmission part 10 Slot machine 11 Case 12 Display window 13 Symbol display window 16 Bet switch 17 Checkout switch 20 Address monitoring part 30 Start switch 31 Connector 32 Processing / display part 33 Connector 40 Reel 42 Reel Tape 50 Stop Switch 60 Reel Unit 61 Symbol 62 Liquid Crystal Display Unit 70 Reel Drive Unit 71 Reel Position Detection Circuit 80 Hopper Drive Unit 81 Hopper 82 Medal Detection Unit 100 Medal Insert Port 200 Liquid Crystal Control Board (Display Control Board)
200a Usage address range storage unit 200b ROM alteration determination unit 200c Error processing unit 201 Speaker board 202 LED board 304 Medal payout slot 311 Medal receiving part (lower plate)

Claims (5)

In response to the player's operation, it performs internal lottery and winning determination, and includes a main board that controls the payout of game media in accordance with winning, and at least a CPU and a program ROM, and receives a command from the main board to produce an effect. In a gaming machine comprising a sub board and a display control board for receiving a command from the sub board and displaying a predetermined image on a display device,
Return address for adding the return address of the program stored when the CPU of the sub-board receives an interrupt for command transmission to the display control board while executing the processing to the command to be sent to the display control board An additional part;
A command transmitter for transmitting the command and the return address to the display control board;
A use address range storage unit for storing in advance the address of the use range of the program;
A game machine comprising: a determination unit that determines whether the program ROM of the sub-board has been tampered with by comparing the return address added to the command with the contents of the use address range storage unit. It includes at least a CPU and a program ROM, and performs an internal lottery and winning determination in response to a player's operation, and performs an effect in response to a command from the main board that controls payout of game media in accordance with winning. In a gaming machine comprising a sub-board,
A return address adding unit for adding a return address of a program stored when the CPU of the main board receives an interrupt for transmitting a command to the sub board while executing processing to a command to be sent to the sub board When,
A command transmission unit for transmitting the command and the return address to the sub-board;
A use address range storage unit for storing in advance the address of the use range of the program;
A gaming machine comprising: a determination unit that determines whether the program ROM of the main board has been tampered with by comparing the return address added to the command with the contents of the use address range storage unit. In response to the player's operation, it performs internal lottery and winning determination, and includes a main board that controls the payout of game media in accordance with winning, and at least a CPU and a program ROM. In a gaming machine comprising a sub board and a display control board for receiving a command from the sub board and displaying a predetermined image on a display device,
  Return address for adding the return address of the program stored when the CPU of the sub-board receives an interrupt for command transmission to the display control board while executing the processing to the command to be sent to the display control board An additional part;
  A command transmitter for transmitting the command and the return address to the display control board;
  An unused address range storage unit that stores in advance an address of an unused range of the program;
  A game machine comprising: a determination unit that determines whether the program ROM of the sub-board has been tampered with by comparing the return address added to the command with the contents of the unused address range storage unit. It includes at least a CPU and a program ROM, and performs an internal lottery and winning determination in response to a player's operation, and performs an effect by receiving a command from the main substrate and controlling the payout of game media in accordance with winning. In a gaming machine comprising a sub-board,
  A return address adding unit for adding a return address of a program stored when the CPU of the main board receives an interrupt for transmitting a command to the sub board while executing processing to a command to be sent to the sub board When,
  A command transmission unit for transmitting the command and the return address to the sub-board;
  An unused address range storage unit that stores in advance an address of an unused range of the program;
  A game machine comprising: a determination unit that determines whether the program ROM of the main board has been tampered with by comparing the return address added to the command with the contents of the unused address range storage unit.   An error processing unit that performs error notification or stops execution of processing according to a command when the determination unit determines that the program ROM has been tampered with, is provided. 4. A gaming machine according to any one of the above.

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