JP2003276289A - Printing controller and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable displaying an early abnormality of a detachable memory for printing in a printing controller and an imaging apparatus. <P>SOLUTION: When it is judged that an external RAM is absent (S3) or the external RAM is abnormal (S9), a memory error display program is read from a ROM and carried out by a first CPU (S14). When a necessary program process is not finished (S15: NO) and it is not a sub routine process (S16: NO), the process returns to S14 to continue a main routine program. When it is the sub routine process (S16: YES), an address where the main routine program before the sub routine process exists is stored in an internal RAM (S17). Then, the sub routine process is carried out (S18). When the sub routine process is finished, the address of the main routine program is read out from the internal RAM (S19), and the process returns to S14 to continue processing the main routine program. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print control apparatus for controlling printing which is output from a computer or the like, and an image forming apparatus using this print control apparatus.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a laser printer, print data sent from a host computer via a cable is temporarily stored in a main memory. Then, the data is expanded into image data and stored again in the main memory. When print data that has been expanded into image data is sent from the host computer, the data is stored in the main memory. At the time of printing, one to several lines of image data are transmitted from the main memory to the internal memory (line buffer), and are further supplied to the print engine.

Such a main memory may be built in the device, but the capacity required for the memory is increased and the expandability is also increased. Therefore, a removable SDRAM is used.
The use of such memory is also increasing.

[0004]

When such a removable memory is used as the main memory, if the user forgets to insert the memory or the memory is not properly installed, the memory may be totally or partially damaged. In this case, when the power is turned on, an abnormality is detected in the initial check program. The printer cannot start normally due to a memory error. Regarding various errors during operation, error messages are displayed on a display device such as LCD.
Memory is also required to execute such an error display program, and normally the main memory is used. Therefore, in the case of a memory abnormality, the error cannot be displayed by the same method as that of a normal error display program, and no display is made and the result cannot be started. Even if you forget to insert a simple memory or make a slight mistake in the mounting method, the user will not know the reason why it will not start normally and will turn the power on and off many times. Was hindering me.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to make it possible to display an initial abnormality of a removable printing memory in a print control apparatus and an image forming apparatus. And

[0006]

In order to achieve the above object, a print control device according to a first aspect of the present invention comprises a computing device and an internal memory attached to the computing device, and prints received from the outside. Data is stored in a detachably mounted external memory, the print data is transferred from the external memory to the internal memory, and the print data transferred to the internal memory is supplied to a print engine to perform printing. In the print control apparatus, the external memory presence / absence determining means for determining whether or not the external memory is present at power-on, and the internal memory if the external memory presence / absence determining means determines that the external memory does not exist Display control means for controlling the display device to display that the external memory does not exist using a memory.

In the print control apparatus having this structure, if the external memory cannot be found by the initial check after the power is turned on, for example, because the external memory is not installed or is not installed correctly, the fact is notified. Display to inform the operator. This allows the operator to take measures such as confirming the mounting state of the external memory.

According to a second aspect of the present invention, a print control apparatus stores print data received from the outside in an external memory that is detachably attached, and transfers the print data from the external memory to an attached internal memory. And a second arithmetic unit that supplies the print data transferred to the internal memory to a print engine to perform printing, and whether the external memory exists. External memory presence / absence determining means for determining when the power is turned on, and when the external memory presence / absence determining means determines that the external memory does not exist, the internal memory is used to indicate to the display device that the external memory does not exist. And a display control unit for controlling the display.

In the print control apparatus having this configuration, if the external memory cannot be found in the initial check after the power is turned on, for example, because the external memory is not installed or is not installed correctly, a message to that effect is given. Display to inform the operator. This allows the operator to take measures such as confirming the mounting state of the external memory.

A print control apparatus according to a third aspect of the present invention includes an arithmetic unit and an internal memory attached to the arithmetic unit,
The print data received from the outside is stored in a detachably mounted external memory, the print data is transferred from the external memory to the internal memory, and the print data transferred to the internal memory is supplied to a print engine. A print control device for performing printing by means of an error determination means for determining whether or not the external memory operates normally at power-on, and the error determination means determines that the external memory is abnormal. Further, a display control means for controlling the display device to indicate that the external memory has an abnormality using the internal memory is provided.

In the print control device having this structure, if the external memory cannot be read or written normally in the initial check after the power is turned on, for example, because the external memory is damaged,
A display is provided to inform the operator of that fact. This allows the operator to take measures such as exchanging the external memory.

According to a fourth aspect of the present invention, a print control device stores print data received from the outside in an external memory that is detachably attached, and transfers the print data from the external memory to an attached internal memory. And a second arithmetic unit that supplies the print data transferred to the internal memory to a print engine to perform printing, and whether the external memory operates normally. An error determining means for determining whether or not the power is turned on, and when the error determining means determines that the external memory is abnormal, the internal memory is used to indicate to the display device that the external memory is abnormal. And a display control unit for controlling the display.

In the print control apparatus having this structure, when the external memory cannot be normally read / written in the initial check after the power is turned on due to the damage of the external memory or the like,
A display is provided to inform the operator of that fact. This allows the operator to take measures such as exchanging the external memory.

According to a fifth aspect of the present invention, in addition to the configuration of the print control apparatus according to the second aspect, the display device is connected to the second arithmetic device, and the first arithmetic device is The external memory presence / absence determining means and the display control means are provided.

In addition to the operation of the print control device according to the second aspect of the present invention, in the print control device having this configuration, the first arithmetic unit checks the presence or absence of the external memory, and if the external memory cannot be found, This is transmitted to the second arithmetic device, and the second
The display device connected to the computing device of No. 1 displays that the external memory does not exist. This allows the operator to take measures such as confirming the mounting state of the external memory.

According to a sixth aspect of the present invention, in addition to the configuration of the print control apparatus according to the fourth aspect, the display device is connected to the second arithmetic device, and the first arithmetic device is , And the display control means.

In addition to the operation of the print control device according to the fourth aspect, in the print control device having this structure, the first arithmetic unit checks whether or not the external memory normally operates, and if the external memory is abnormal. In some cases, this is transmitted to the second arithmetic device, and the display device connected to the second arithmetic device is caused to display that there is an abnormality in the external memory. This allows the operator to take measures such as exchanging the external memory.

A print control device according to a seventh aspect of the present invention is the fifth aspect.
Alternatively, in addition to the configuration of the print control device according to the sixth aspect, the first arithmetic device communicates with the second arithmetic device to display on the display device via the second arithmetic device. And performing control to save the data being executed in the internal memory at the time of an interrupt generated during the communication.

In addition to the operation of the print control device according to the fifth or sixth aspect, the print control device of this configuration has the function of the second arithmetic device to which the display device is connected in order to cause the display device to display an error. , Communication is performed from the first arithmetic unit that has checked the external memory. At that time, since communication is performed using the timer interrupt, the internal memory is used as a destination for saving the data being executed by the first display device at the time of the interrupt.

According to a eighth aspect of the present invention, in addition to the configuration of the print control apparatus according to the seventh aspect, the communication performed by the first arithmetic unit and the second arithmetic unit is serial communication. It is characterized by being.

In addition to the operation of the print control device according to the seventh aspect, the print control device of this configuration performs serial communication between the first arithmetic device and the second arithmetic device. The first display device uses the internal memory as a destination for saving the data being executed at the time of interruption.

In addition to the configuration of the print control device according to any one of claims 1 to 8, the print control device according to claim 9 is for displaying that there is no external memory or there is an abnormality in the external memory. It is characterized by having a non-volatile memory storing the error display program.

In the print controller of this structure, in addition to the operation of the print controller according to any one of claims 1 to 8, the display controller reads the error display program from the non-volatile memory and causes the arithmetic unit to execute the error display program. Display on the display device.

According to a tenth aspect of the present invention, in addition to the configuration of the print control apparatus according to the ninth aspect, in the internal memory, the display control means reads the error display program from a non-volatile memory and executes the error display program. It is characterized in that it is used for subroutine control when performing.

In the print control device having this structure, in addition to the operation of the print control device according to the ninth aspect, the display control means reads the error display program from the nonvolatile memory into the register of the arithmetic unit and executes it. When a subroutine is used in the display program, it is necessary to remember the address of the main routine at the time of shifting to the subroutine and return to the address after the subroutine is completed. Internal memory is used to store this address.

A print control apparatus according to an eleventh aspect of the present invention is the same as the print control apparatus according to any one of the first to tenth aspects, and whether or not the external memory exists in the nonvolatile memory. Alternatively, a memory check program for causing the arithmetic unit to perform at least one determination process of whether or not the external memory normally operates is stored, and the external memory presence / absence determination means and the error determination means execute the memory check program. It is characterized in that it is read to determine whether or not the external memory exists or whether or not the external memory operates normally.

In the print control device having this structure, in addition to the operation of the print control device according to any one of claims 1 to 10,
The external memory presence / absence determining unit or the error determining unit causes the arithmetic unit to execute the memory check program read from the nonvolatile memory.

An image forming apparatus according to a twelfth aspect includes a print engine and the print control apparatus according to any one of the first to eleventh aspects. With the image forming apparatus having this configuration, the operation of the print control apparatus according to any one of claims 1 to 11 can be achieved.

According to a thirteenth aspect of the present invention, in addition to the configuration of the image forming apparatus according to the twelfth aspect, the internal memory is a line buffer for storing print data corresponding to at least one line of an image. It is characterized by being.

According to the image forming apparatus of this structure,
In addition to the operation of the image forming apparatus described in (1), since a line buffer used at the time of printing is used as an internal memory, it is not necessary to prepare a special mechanism.

According to a fourteenth aspect of the present invention, in addition to the configuration of the image forming apparatus according to the twelfth aspect, the internal memory corresponds to at least one line of color pixels of each color used for printing. And a line buffer for storing print data to be printed.

According to the image forming apparatus having this structure,
In addition to the operation of the image forming apparatus described in (1), since a line buffer used at the time of printing is used as an internal memory, it is not necessary to prepare a special mechanism.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser printer 1 which is an embodiment of an image forming apparatus of the present invention will be described below with reference to the drawings. FIG. 1 shows a laser printer 1 according to this embodiment.
It is a block diagram which shows the outline. As shown in FIG. 1, the laser printer 1 of the present embodiment includes a video controller 2
And the engine controller 3, and prints print data of characters and images sent from the host computer 4.

The video controller 2 expands (converts) the print data received from the host computer 4 into video data (image data) and outputs it to the engine controller 3. Video controller 2 is host computer 4
The print data received from is not limited to the data before expansion,
It may have been expanded to video data. In this case, it is transferred to the engine controller 3 as it is.

The engine controller 3 controls the print engine that actually forms an image by using the photosensitive drum 5 and the laser. The second controller 6 reads the program and performs various controls, and the laser controller 7 is provided. , Various control programs for temperature control, toner amount detection control, etc., to form images by laser, photoconductor drum 5, various sensors such as belt sensor 8 and drum sensor, drive motor main motor 10, toner cartridge 11 (four color toners in this embodiment), a control panel, etc. are connected. The control panel 12 is an LCD 19 (FIG. 2), which is a display device showing an operating state and an error display.
(See) and an operation switch section for switching the operation mode and the like.

FIG. 2 is a block diagram of main parts of the video controller 2 and the engine controller 3. The video controller 2 is the laser printer IC of the present embodiment.
ASIC13 (Application Specific Integrat
ed Circuit), the first CPU 14 and the internal RAM 15 are mounted, and the external RA via the data bus from the ASIC 13.
It is connected to M16 and ROM17.

Internal RAM 15 also called video RAM
Is also called a line buffer because it stores print data expanded into video data for one line to several lines immediately before printing and transmits it to the print engine. The present embodiment is a color laser printer provided with toner of four colors, and has a line buffer for one line of each color for a total of four lines as an internal RAM 15. (Delete)

The external RAM 16 is an SDR in this embodiment.
The AM is used, the laser printer 1 is detachably mounted, the serial EEPROM is provided, and the SPD (Ser
The memory type, interface type, number of banks, memory capacity for each bank, etc. can be retrieved by ialPresence Detect). The SPD is such that information about the memory module can be read from the module itself, and a large amount of information is stored using a serial EEPROM. By reading this SPD, whether the external RAM 16 is properly installed,
It is possible to check whether the capacity is sufficient.

The ROM 17 stores various programs such as an initialization program including a memory check program and a memory error display program. The initialization program is read from a predetermined address of the ROM 17 to a register of the first CPU 14 and executed when the power is turned on. In addition to the program, the ROM 17 executes a memory error display program to display the LCD.
The error message displayed in 19 is stored. When displaying an error, the first CPU 14 reads the corresponding message from the ROM 17 and sends it to the LCD 19 via the engine controller 3 to display it.

Between the video controller 2 and the engine controller 3, each engine interface 18 is provided.
Via serial communication. In addition, between the ASIC 13 in the video controller 2 and the engine interface 18, the second 6 in the engine controller 3 is provided.
The CPU and the engine interface 18 are also connected by serial communication.

An LCD 19 which is a display device provided on the control panel 12 is connected to the engine controller 3. The LCD 19 has an LC for controlling this.
The D circuit 20 is connected, and the LCD circuit 20 receives data from the engine controller 3 and displays a message to the operator. For example, when the memory error display program is executed, when the external RAM 16 is not installed, or when it is not installed correctly, a message such as "no memory" is displayed when the external RAM 16 is damaged or cannot be read or written normally. Displays a message such as "Memory error". The engine controller 3 and the LCD circuit 20 are also connected by serial communication.

In serial communication, a timer is used to manage the communication time. FIG. 3 is an example of a time chart of communication between the video controller 2 and the engine controller 3. As shown in FIG. 3, an interrupt is generated by the timer 21, the counter of the interrupt counter 22 is started from there, and data is transmitted. When the counter value of the interrupt counter 22 becomes 10, for example (when an interrupt occurs 10 times), the next data is transmitted.

In this embodiment, all communication is configured by serial communication, but the communication method is not limited to this, and parallel communication may be used, for example. In this case as well, an interrupt process is performed for communication time management as in serial communication. Further, in the present embodiment, the display device is connected to the engine controller 3, but it may be connected to the video controller 2. Further, in the present embodiment, the video controller 2 and the engine controller 3 each have a CPU, and the LCD 19 which is a display device is connected to the engine controller 3. However, the video controller 2 and the engine controller 3 are connected to each other. It may be configured such that one CPU performs all control without distinction. In these cases as well, since communication is required between the display device and the CPU, an interrupt process is performed and data is saved to the internal RAM 15 in the same manner.

Next, the operation of the laser printer 1 having the above configuration will be described with reference to the flowchart of FIG. FIG. 4 is a flowchart showing an outline of the processing of the memory check program and the memory error display program. When the power is turned on, the initialization program is read from the designated address of the ROM 17 and executed by hardware control. Initialization program 1
First, the memory check program is ROM
The data is read out from the first CPU 17 and executed by the first CPU 14. The memory check program is a program that does not use a subroutine, unlike the memory error display program described later. That is, the first CPU 14 can execute the memory check program using only the registers of the first CPU 14, and the RA for data saving is executed.
Does not require M First, in order to determine whether or not there is a memory, the SPD is read (S1). If it is determined whether or not any SPD can be read (S2), and if the SPD cannot be read at all (S2: NO), the external RAM 16 is not mounted at all, or the mounting method is incorrect, or the like.
It is determined that there is no M16 (S3).

If any SPD can be read (S2: YE
S), go to read the memory type and interface type information in the SPD (S4). If these pieces of information cannot be read (S5: NO), it is determined that the external RAM 16 does not exist because the external RAM 16 is not mounted at all or the mounting method is incorrect (S3). If the SPD items of the memory type and the interface type can be read (S5: YES), it is determined that the external RAM 16 is present, that is, it is normally attached (S6).

If it is determined that the external RAM 16 is present, SP
The number of banks of the item D and the module capacity for each bank are read to confirm the capacity of the external RAM 16 (S7). Then, it is sequentially checked whether or not the designated data of all banks of the number of banks read in S7 can be read and written, and if there is a bank that cannot be read and written, the external RAM 16 is for some reason.
It is judged that there is something abnormal. First, data $ for all banks
Check whether you can read and write 00 (S
8) If it is not possible to read and write (S8: NO), external RA
M16 is determined to be abnormal (S9). If the data can be read / written (S8: YES), then it is confirmed whether or not the data $ FF can be read / written to all banks (S10). If the data cannot be read / written (S10: NO), the external RAM 16
Is judged to be abnormal (S9). If you can read and write (S1
0: YES), then, it is confirmed whether or not the data $ 55 can be read / written to / from all banks (S11). If the data cannot be read / written (S11: NO), the external RAM 16 is determined to be abnormal (S9). If you can read and write (S11: Y
ES), then it is confirmed whether or not the data $ AA can be read / written to / from all the banks (S12). If the data / AA cannot be read / written (S12: NO), the external RAM 16 is judged to be abnormal (S9). If the above four designated data can be read and written in all banks (S12: YES), it is determined that the external RAM 16 is operating normally (S13),
Exit the memory check program.

It is determined that the external RAM 16 does not exist (S
3) If it is determined that the external RAM 16 is abnormal (S9), the memory error display program is read from the ROM 17 and executed by the first CPU 14 (S14). Specifically, the error message stored in the ROM 17 is read out, transmitted to the LCD circuit 20, and displayed on the LCD 19. This memory error display program is a program including a subroutine in terms of ease of processing, reduction of the program capacity, and the like. After processing the subroutine, you must always return to the main routine program before the subroutine processing.
It is necessary to store a certain address of the main routine program before the subroutine processing. But outside RA
Since M16 has an error and cannot be used, the address is stored in the internal RAM 15 and the subroutine processing is performed.

In the memory error display program, it is first determined whether the necessary program processing is completed (S15),
If it has ended (S15: YES), the processing of the memory error display program is ended. If the necessary program processing is not completed (S15: NO), it is judged whether it is a subroutine processing (S16). If it is not the subroutine processing (S16: NO), the procedure returns to S14 to return to the main routine program (memory error display program). ) To continue. If it is a subroutine process (S16: YES), the address of the main routine program before the subroutine process is stored in the internal RAM 15 (S17). Then, a subroutine process is performed (S18), and when the subroutine process is completed, the address of the main routine program is read from the internal RAM 15 (S19) and the process returns to S14 to continue the process of the main routine program (memory error display program).

By the way, since the LCD 19 is connected to the engine controller 3, the memory error display is indicated by L.
A memory error message is transmitted from the video controller 2 executing the memory error display program to the engine controller 3 in order to cause the CD 19 to perform the operation. Here, since serial communication is performed between the video controller 2 and the engine controller 3, the timer 21 is used to generate an interrupt for communication time management. Figure 5
3 is a flowchart showing an outline of processing when an interrupt occurs. The interrupt process is prioritized over all other processes. When an interrupt occurs, the memory error display program is interrupted first, and necessary data is saved in the internal RAM 15 (S31). At the time of the interrupt, the first CPU 14 is exclusively used for the interrupt process, so the data being executed at that time is the first CPU.
It is necessary to save from the external RAM 16 in the normal program processing. However, since the external RAM 16 cannot be used because it has an error here, it is saved in the internal RAM 15. Then, the first CPU 14 performs an interrupt process (S32), and when the interrupt process is completed, the saved data is read from the internal RAM 15 and the memory error display program is restarted (S33).

As described above, when the memory error display program of this embodiment is used, the laser printer 1 is normally activated even when there is no external memory or the external memory is not operating normally. The result does not end, but the memory error display program displays on the LCD 19 that there is an external memory error. In response to this, the operator can take measures such as checking whether the memory is properly mounted or replacing the memory.

[0051]

As is apparent from the above description, claim 1
According to the print control device described in, when the external memory cannot be found in the initial check after the power is turned on due to the external memory not being installed or not being installed correctly, etc. Display to inform the person. This allows the operator to take measures such as confirming the mounting state of the external memory.

According to the print control device of the second aspect,
If the external memory cannot be found in the initial check after the power is turned on because the external memory is not installed or is not installed correctly, a display is displayed to inform the operator of that fact. This allows the operator to take measures such as confirming the mounting state of the external memory.

According to the print control device of the third aspect,
If the external memory cannot be read or written normally in the initial check after the power is turned on because of the damage of the external memory or the like, a display is provided to inform the operator of that fact. This allows the operator to take measures such as exchanging the external memory.

According to the print control device of the fourth aspect,
If the external memory cannot be read or written normally in the initial check after the power is turned on because of the damage of the external memory or the like, a display is provided to inform the operator of that fact. This allows the operator to take measures such as exchanging the external memory.

According to the print control device of the fifth aspect,
In addition to the effect of the print control apparatus according to claim 2, the first arithmetic unit checks the presence / absence of an external memory, and if the external memory cannot be found, the first arithmetic unit transmits it to the second arithmetic unit. The display device connected to the second arithmetic device is caused to display that the external memory does not exist. This allows the operator to take measures such as confirming the mounting state of the external memory.

According to the print control device of the sixth aspect,
In addition to the effect of the print control apparatus according to claim 4, the first arithmetic unit checks whether or not the external memory operates normally, and if the external memory has an abnormality, the first arithmetic unit performs the second arithmetic operation. This is transmitted to the device and the display device connected to the second arithmetic device is caused to display that there is an abnormality in the external memory. This allows the operator to take measures such as exchanging the external memory.

According to the print control device of the seventh aspect,
In addition to the effect of the print control device according to claim 5 or 6, in order to cause the display device to display an error, the first arithmetic unit that checks the external memory with respect to the second arithmetic device to which the display device is connected. Communicate from the computing device. In that case, since communication is performed using the timer interrupt, the internal memory can be used as a destination for saving the data being executed by the first display device at the time of the interrupt.

According to the print control device of the eighth aspect,
In addition to the effects of the print control apparatus according to claim 7, since serial communication is performed between the first arithmetic unit and the second arithmetic unit, a timer interrupt is required at the time of communication, and the first interrupt is required at the time of interruption.
The internal memory can be used as a destination for saving the data being executed by the display device.

According to the print control device of the ninth aspect,
In addition to the effects of the print control apparatus according to any one of claims 1 to 8, the display control unit can read the error display program from the nonvolatile memory, cause the arithmetic unit to execute the error display program, and display the error display program on the display apparatus.

According to the print control device of the tenth aspect, in addition to the effect of the print control device of the ninth aspect, the display control means reads the error display program from the nonvolatile memory into a register of the arithmetic unit. However, if a subroutine is used in the error display program, it is necessary to remember the address of the main routine at the time of shifting to the subroutine and return to that address after the subroutine ends. Internal memory can be used to store this address.

According to the print control device of the eleventh aspect, in addition to the effect of the print control device according to any one of the first to tenth aspects, the external memory presence / absence determining means or the error determining means is a nonvolatile memory. The memory check program can be read from and executed by the arithmetic unit.
According to the image forming apparatus of the twelfth aspect, it is possible to achieve the effects of the print control apparatus of the first aspect.

According to the image forming apparatus of the thirteenth aspect, in addition to the effect of the image forming apparatus of the twelfth aspect, a special mechanism is prepared because the line buffer used at the time of printing is used as the internal memory. No need.

According to the image forming apparatus of the fourteenth aspect, in addition to the effect of the image forming apparatus of the twelfth aspect, a special mechanism is prepared because the line buffer used at the time of printing is used as the internal memory. No need.

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of a laser printer of this embodiment.

FIG. 2 is a block diagram of main parts of a video controller and an engine controller.

FIG. 3 is an example of a time chart of communication between a video controller and an engine controller.

FIG. 4 is a flowchart showing an outline of processing of a memory check program and an error display program.

FIG. 5 is a flowchart showing an outline of processing when an interrupt occurs.

[Explanation of symbols]

1 laser printer 2 video controller 3 engine controller 4 Host computer 5 photoconductor drum 6 Second CPU 7 Laser control section 8 Belt sensor 9 Drum sensor 10 Main motor 11 toner cartridge 12 Control panel 13 ASIC 14 First CPU 15 Internal RAM 16 External RAM 17 ROM 18 engine interface 19 LCD 20 LCD circuit

Claims (14)

[Claims] 1. An arithmetic unit and an internal memory attached to the arithmetic unit, wherein print data received from the outside is stored in a detachably mounted external memory, and the print data is stored from the external memory. A print control device that transfers to the internal memory, supplies the print data transferred to the internal memory to a print engine to perform printing, and determines whether or not the external memory exists at power-on external Display control for controlling presence / absence of external memory when the external presence / absence determining unit determines that the external memory does not exist by using the internal memory. And a printing control device. 2. A first arithmetic unit for storing print data received from the outside in an external memory that is detachably mounted, and transferring the print data from the external memory to an attached internal memory, and the internal memory. A print control device comprising a second arithmetic device for supplying the transferred print data to a print engine to perform printing, wherein the presence or absence of an external memory is determined when the power is turned on. And a display control means for controlling the display device to display that the external memory does not exist by using the internal memory when the external memory presence / absence judging means determines that the external memory does not exist. A print control device comprising: 3. An arithmetic unit and an internal memory attached to the arithmetic unit, wherein print data received from the outside is stored in a detachably mounted external memory, and the print data is stored from the external memory. A print control device that transfers to the internal memory, supplies the print data transferred to the internal memory to a print engine to perform printing, and determines whether or not the external memory operates normally at power-on. And a display control for controlling to display on the display device that the external memory has an abnormality using the internal memory when the error determination means determines that the external memory has an abnormality. And a printing control device. 4. A first arithmetic unit for storing print data received from the outside in an external memory that is detachably mounted, and transferring the print data from the external memory to an attached internal memory, and the internal memory. A print control device comprising a second arithmetic device for supplying the transferred print data to a print engine to perform printing, wherein an error is determined when the power is turned on to determine whether or not the external memory operates normally. Determination means, and display control means for controlling, when the error determination means determines that there is an abnormality in the external memory, using the internal memory to display on the display device that there is an abnormality in the external memory. A print control device comprising: 5. The display device is connected to the second arithmetic device, and the first arithmetic device has the external memory presence / absence determining means and the display control means. The printing control device described in 1. 6. The display device according to claim 4, wherein the display device is connected to the second arithmetic device, and the first arithmetic device has the error determination means and the display control means. Print controller. 7. The first arithmetic unit communicates with the second arithmetic unit to display on the display unit via the second arithmetic unit, and during the communication, 7. The print control device according to claim 5, wherein the print control device is controlled so as to save the data being executed in the internal memory when an interrupt occurs. 8. The print control apparatus according to claim 7, wherein the communication performed by the first arithmetic unit and the second arithmetic unit is serial communication. 9. The nonvolatile memory according to claim 1, further comprising a non-volatile memory storing an error display program for displaying that the external memory does not exist or there is an abnormality in the external memory. Print controller. 10. The print control apparatus according to claim 9, wherein the internal memory is used for subroutine control when the display control unit reads the error display program from the nonvolatile memory and executes the error display program. . 11. A memory check program for causing the arithmetic unit to execute at least one of determination processing of whether or not the external memory exists in the nonvolatile memory and whether or not the external memory normally operates. The external memory presence / absence determining means or the error determining means reads the memory check program and determines whether the external memory exists or whether the external memory operates normally. The print control device according to claim 1, wherein the print control device is a print control device. 12. An image forming apparatus comprising a print engine and the print control apparatus according to claim 1. 13. The image forming apparatus according to claim 12, wherein the internal memory is a line buffer that stores print data corresponding to at least one line of an image. 14. The image forming apparatus according to claim 12, wherein the internal memory is a line buffer that stores print data corresponding to at least one line of color pixels of each color used for printing. apparatus.