Abstract:
One data processor ( 101 ) is provided with an interface means ( 119 ) for realizing connection with the other data processor ( 100 ), this interface means is provided with a function for connecting the other data processor as a bus master to an internal bus ( 108 ) of one data processor, and the relevant other data processor is capable of operating in direct peripheral functions memory mapped to the internal bus from an external side via said interface means. Accordingly, the data processor can utilize the peripheral functions of the other data processor without intermission of the program being executed. In short, one data processor can use in common the peripheral resources of the other data processor.

Description:
BACKGROND OF THE INVENTION  
         [0001]    The present invention relates to a technical field of a data transfer system of bus connecting data processors and a data transfer system in the system formed of a plurality of data processors and a plurality of system buses. For example, the present invention relates to the technique which may be applied effectively to the technique in which a data processor uses in common the built-in circuits of the other data processors and to the technique in which a data processor makes access to the external buses of the other data processors. Moreover, the present invention relates to the technique of boot control in which operation program of data processor is initially stored in the memory.  
           [0002]    With complication of system, the number of data processors and components mounted on the system is increasing. For example, in the mobile phone system, a baseband data processor for controlling communication has controlled software (application and key control or the like) and hardware (components of RF circuit, LCD and memory or the like). However, with diversification of functions, it is now difficult that the baseband processor performs all processes. In the PC system of the prior art, this problem has been solved by improving operation frequency of data processor but in the battery-driven type mobile terminal in these years cannot simply improve performance with higher frequency because the operation life of battery must be expanded.  
           [0003]    It is also considered to use a method to vary the frequency with the processes executed by the data processor, but realization of the practical use is difficult because actual realization is very difficult in the system. Moreover, the data processor which can realize high speed operation tends to become large in the chip area and it is also difficult to reduce a current value during the standby state.  
           [0004]    In order to solve this problem, applications which cannot be processed with the data processors of the prior art have been processed with the co-processor or with the other data processor. Accordingly, since it is possible to operate only the data processors suitable for particular processes when such particular processes are required, the system can be formed easily and finally power consumption of the system as a whole can also be realized.  
           [0005]    When a plurality of data processors such as data processor and co-processor or the like are mounted to one system, a common bus is frequently used for connection of the data processors. However, when a data processor which cannot use in common the bus is used and when full-performance cannot be exhibited through common use of bus because memory access performance is insufficient, it is required to conduct the data transfer by comprising a certain interface to one data processor and then connecting this interface to the bus of the other processor. As this interface, there is a host port interface supported, for example, by the DSP (TMS320C54x) of TI. In actual, data transfer is performed between data processors by utilizing the RAM built in the data processor and the interruption function. However, software must be executed to use the data transferred.  
           [0006]    Not only the system but also the function itself of data processor are highly sophisticated. When a plurality of data processors are mounted to the system, it is not required for a plurality of data processors to support the duplicated same function by efficiently using the functions mounted to the data processors, such as memory interface, USB (universal serial bus), memory card, serial interface for SDRAM (Synchronous DRAM) or the like. When data processors are connected with an interface not depending on the common bus, the data transferred must be processed with software under the condition that the functions supported by respective data processors are used. For example, when a certain data processor desires to make access to a memory by utilizing a memory interface of another data processor, it has been required that the data to be accessed with the above interface is once transferred to another data processor, a program of the other data processor is thereafter executed as the interruption process, thereby the other data processor to execute such program makes access to a memory, and the other data processor issues, after such access, an interruption to one data processor for the data transfer to one data processor via the interface.  
           [0007]    As another problem resulting from complicated system structure, reduction of mounting area may be listed. Particularly, at a mobile information terminal, it is required to reduce the number of components used in the system in order to reduce the mounting area from the viewpoint of reduction in power consumption and cost. However, when the system is improved to have multiple functions, the number of components also increases to realize such functions. Particularly, when a plurality of data processors are comprised as described above, this problem becomes more serious.  
           [0008]    In the case where a plurality of data processors are mounted on the system as described in regard to the technology of the prior art and such data processors cannot be connected with a common bus, it is required to comprise an interface for mutually connecting the data processors. The host interface such as DSP of TI performs handshake to realize data transfer by utilizing the RAM built in the data processor and the interruption function. In this method, since it is required to execute the interruption process program for every data transfer, the performance may be deteriorated because the execution of the program being operated is interrupted. Particularly, there rises a problem when it is required to use only external interface supported by the data processor.  
           [0009]    Moreover, the inventors of the present invention have discussed the technology to initially store an operation program of data processor to a memory. For example, in a microprocessor where an electrically reprogrammable flash memory is formed on a chip to store the operation program of CPU, an initial program for such flash memory is generally written, for example, using, in its fabrication stage, a write device such as EPROM writer. However, such write operation is complicated and moreover takes a longer time because such write operation is accompanied by a verify process and a rewrite process. Therefore this write operation is also considered as a cause of rise of fabrication cost of data processor.  
         OBJECT AND SUMMARY OF THE INVENTION  
         [0010]    It is therefore an object of the present invention to realize that a data processor realizes a data transfer interface for data transfer in addition to a memory interface in a data processing system which is complicated for multiple functions. Moreover, the present invention has another object to effectively use the internal function of the relevant data processor or external circuits of the relevant data processor from the other data processor or device connected to such interface. Moreover, the present invention is intended to finally realize low power consumption through improvement of system performance and realization of low cost.  
           [0011]    The other object of the present invention is to provide a data processing system and moreover a data processor which can easily realize the process to initially write the program to be executed by the data processor to a nonvolatile memory.  
           [0012]    The abovementioned and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.  
           [0013]    The typical inventions disclosed in this specification will be briefly described below.  
           [0014]    [1] According to a first aspect of the present invention, an internal bus access of data processor is allowed to the other data processors.  
           [0015]    According to this first aspect of the present invention, a data processor ( 100 ) is provided with an interface means ( 119 ) to enable connection with another data processor ( 101 ) and this interface means is provided with a function to connect the other data processor as a bus master to the internal bus of one data processor to support the function to operate in direct the peripheral function memory-mapped to the internal bus with the relevant other data processors from an external side via the interface means. Thereby, the data processor is capable of utilizing the peripheral functions of the other data processor without interruption of programs being executed. When the first data processor makes access, for example, to the particular memory using the memory interface of the second data processor, the first data processor is capable of making access and then using the peripheral memory and the other peripheral circuits via the interface means of the second data processor. In short, one data processor can use in common the peripheral resources of the other data processors. In other words, the first data processor can use in direct the other interface function comprised in the second data process. Thereby, high performance of the system can be realized.  
           [0016]    The invention according to above aspect will be described in further detail. The data processing system according to the first aspect includes the first data processor ( 100 ) and the second data processor ( 101 ). The second data processor comprises the interface means ( 119 ) which makes the first data processor obtain the right to use the internal bus of the second data processor. The interface means makes the first data processor having obtained the right use the internal bus to access to an input/output circuit connected to the internal bus.  
           [0017]    The input/output circuit is formed of single circuit or of a plurality of circuits selected, for example, from a SDRAM interface circuit connected to SDRAM, LCD interface circuit connected to a liquid crystal display device, memory card interface circuit connected to a memory card, serial interface circuit, nonvolatile memory, electrically reprogrammable nonvolatile memory and general purpose input/output port circuit.  
           [0018]    The interface means may include a buffer RAM ( 107 ) which exclusively responds to realize operation to the access from the second data processor and the access from the first data processor.  
           [0019]    [2] According to a second aspect of the present invention, the other data processor is allowed to make access to the inherent external bus of one data processor via the relevant one data processor.  
           [0020]    The present invention according to this second aspect is provided with a means ( 114 ) which enables interface, within the second data processor, between the first data processor ( 100 ) and the external device ( 104 ) of the relevant second data processor while the second processor ( 101 ) is in the waiting condition (power supply is off or standby state). Accordingly, the first data processor is capable of controlling the device connected to the second data processor without use of an external circuit during the waiting condition of the relevant second data processor. In short, even when the second data processor is in the waiting condition, the first data processor is capable of controlling the external circuit connected to the relevant second data processor by bypassing the internal circuits of second data processor. Thereby, the number of components forming the data processing system can be reduced and reduction in cost can also be realized.  
           [0021]    The invention based on the above aspect will be described in further detail. The data processing system according to the second aspect includes the first data processor ( 100 ), a first bus ( 103 ) connected to the first data processor, the second data processor ( 101 ) connected to the first bus and a second bus ( 105 ) connected to the second data processor. The second data processor includes a first external interface circuit ( 119 ) which is connected to the first bus in one terminal and to the internal bus in the other terminal, a second external interface ( 113 ) which is connected to the second bus in one terminal and to the internal bus in the other terminal, and a switch circuit ( 114 ) for connecting one terminal of the first interface circuit to the second bus in place of one terminal of the second external interface circuit while the second data processor is in the waiting condition.  
           [0022]    In the waiting condition of the second data processor, supply of clock signal, for example, to a clock synchronization circuit included in the second data processor is suspended. Moreover, a power supply control circuit ( 116   b ) is also included in the second data processor to separate the operation power supply of the switch circuit from the operation power supply of the other circuits and to suspend supply of the operation power supply to a part or the entire part of the above-described and the other circuits in response to the waiting condition of the second data processor. Thereby, the power consumption may be reduced in the waiting condition of the second data processor.  
           [0023]    The second external interface circuit includes an LCD interface circuit which can be connected, for example, to a liquid crystal display controller. In this case, the second bus is connected with the liquid crystal display controller. Accordingly, the first data processor is capable of controlling the liquid crystal display controller via the switch circuit.  
           [0024]    [3] According to a third aspect, operation control for initially writing an operation program to be executed with a data processor after the reset operation is cancelled to an on-chip nonvolatile memory and nonvolatile memory on the local bus may be realized via the relevant data processor.  
           [0025]    The data processing system of the present invention according to this third aspect includes the first data processor ( 100 ) and the second data processor ( 101 ). The second data processor includes a nonvolatile memory ( 107 ) which is controlled to write the data with the first data processor in a first operation mode after the reset operation is cancelled, a CPU ( 109 ) which considers the nonvolatile memory as the object of instruction fetch after the write operation in the first operation mode, and an electrically reprogrammable nonvolatile memory ( 502 ) which is considered as the object of instruction fetch by the CPU in the second operation mode after the reset operation is cancelled. The first data processor designates the first operation mode to the second data processor and then stores, to the nonvolatile memory, a write control program for the nonvolatile memory and allows the CPU to fetch the instruction. Accordingly, the second data processor is capable of executing the write control program written to the nonvolatile memory and then initially writing the operation program of the first data processor to the on-chip nonvolatile memory depending on such execution. It is enough for execution of this operation program that the second operation mode is designated after the reset operation is cancelled.  
           [0026]    The electrically reprogrammable nonvolatile memory is never limited to the on-chip memory of the first data processor. This memory may be an electrically reprogrammable nonvolatile memory ( 501 ) connected to the local bus of the first data processor.  
           [0027]    According to the invention of the third aspect, operation control to initially write the operation program to be executed by the data processor after the reset operation is cancelled to the on-chip nonvolatile memory and the nonvolatile memory on the local bus can be realized via the relevant data processor. In short, it is no longer required to execute the process to write the program to the on-chip program memory or the like in the fabrication process of data processor.  
           [0028]    [4] According to a fourth aspect of the present invention, attention is paid to the data processor to be applied to the data processing system based on the first to third aspects described above.  
           [0029]    A data processor includes the CPU ( 109 ), the internal bus connected to the CPU, a peripheral circuit ( 116 ) connected to the internal bus, the first external interface circuit ( 119 ) connected to a first external terminal in one terminal thereof and to the internal bus in the other terminal, and the second external interface circuit ( 113 ) connected to a second external terminal in one terminal thereof and to the internal bus in the other terminal thereof. The first external interface circuit obtains the right to use the internal bus in response to an external access request and enables access to the peripheral circuit connected to the internal bus. Accordingly, a data processor is capable of making the other data processors use the on-chip peripheral circuits connected to the internal bus.  
           [0030]    Moreover, the switch circuit ( 114 ) for connecting the first external terminal to the second external terminal in place of the second external interface circuit during the waiting condition of the CPU may also be included. The other data processors are allowed via the relevant one data processor to make access to the inherent external bus of one data processor. For example, when an LCD controller is connected to the local bus of a data processor, the other data processor can realize the time display control function for the LCD via the LCD control on the local bus via the system bus when the relevant data processor is in the waiting condition.  
           [0031]    According to the third aspect of the present invention that a boot program of data processor is initially written, a data processor further includes a nonvolatile memory which is externally written via the first external interface circuit in the first operation mode after the reset operation is cancelled and a program memory such as an electrically reprogrammable nonvolatile memory. The CPU can fetch an instruction from the nonvolatile memory after the write operation in the first operation mode and then execute such instruction and moreover the CPU can fetch the instruction from the program memory in the second operation mode after the reset operation is cancelled and then execute this instruction. The boot program of data processor can be initially written to the nonvolatile program memory by writing a write control program for the program memory to the nonvolatile memory in the second operation mode and then executing the written write control program in the second operation mode.  
           [0032]    A data processor can be configured with single chip by forming, to one semiconductor substrate, the CPU, internal bus, first external interface circuit, second external interface circuit, switch circuit, nonvolatile memory and program memory. Moreover, it is also possible to form a multi-chip module by forming, on the first semiconductor substrate, the CPU, internal bus, first external interface circuit, second external interface circuit, switch circuit and nonvolatile memory, forming the program memory ( 501 ) on the second semiconductor substrate, and mounting both first and second semiconductor substrates, for example, on a high density mounting substrate to form a sealed package.  
           [0033]    [5] According to a fifth aspect of the present invention, a data processor to be applied to the data processing system based on the first aspect is investigated from the other aspect.  
           [0034]    A data processor includes a first terminal connected to a first bus, a second terminal connected to a second bus, a first internal circuit and a second internal circuit which can selectively take a first condition or a second condition, a first signal route connected to the second terminal from the first terminal via the first internal circuit and second internal circuit and a second signal route connected to the second terminal from the first terminal via the second internal circuit. The second internal circuit selects a desired signal route from the first signal route or second signal route depending on the condition of the first internal circuit.  
           [0035]    The first condition is, for example, the operating condition to be executed by the first internal circuit, while the second condition is, for example, the waiting condition in which execution of instructions is suspended. The second internal circuit selects the first route in the operating condition and also selects the second route in the waiting condition.  
           [0036]    Moreover, a power supply control circuit is also provided to control supply of a first power source to the first internal circuit and supply of a second power source to the second internal circuit. In this case, the power supply control circuit stops, when the second signal route is selected for the second internal circuit, supply of the first power source to the entire part or a part of the first internal circuit. In short, in the waiting condition, supply of useless operation power source to the circuit which is not requested to operate is stopped.  
           [0037]    The first internal circuit, second internal circuit and power supply control circuit may be formed on one semiconductor substrate. Moreover, it is also possible that the first internal circuit and power supply control circuit are formed on the first substrate, the second internal circuit is formed on the second semiconductor substrate, and the first and second semiconductor substrates are sealed in one package. Thereby, a data processor can be formed as a multi-chip module or the like.  
           [0038]    When the first internal circuit includes a clock control circuit ( 116   a ) to supply a clock signal for synchronous operation to the first internal circuit, it is recommended that the clock control circuit stops supply of the clock signal to the first internal circuit when the second signal route is selected by the second internal circuit. In the waiting condition, it is more desirable to stop the supply of clock signal to the circuit which is not required to operate in order to prevent useless power consumption.  
           [0039]    As the desirable profile, the power supply control circuit for controlling supply of the first power source to the first internal circuit and supply of the second power source to the second internal circuit stops the supply of power source to the entire part or a part of the first internal circuit when supply of the clock signal to the first internal circuit is stopped.  
           [0040]    The first internal circuit, second internal circuit, clock control circuit and the power supply control circuit may be formed on one semiconductor substrate. Moreover, the first internal circuit, clock control circuit and power supply control circuit are formed on the first semiconductor substrate, the second internal circuit is formed on the second semiconductor substrate, and the first semiconductor substrate and the second semiconductor substrate may be sealed in one package to form a multi-chip module of the data processor.  
           [0041]    [6] According to a sixth aspect of the present invention, the information processing system based on the first aspect will be discussed from a different aspect.  
           [0042]    An information processing system comprises a first bus, a second bus and a data processor connected to the first bus and the second bus. The data processor has a first operation profile and a second operation profile. In the first operation profile, the data processor processes the information supplied from the first bus to supply the predetermined information to the second bus. In the second operation profile, the data processor supplies in direct the information supplied from the first bus to the second bus.  
           [0043]    Moreover, according to the other aspect of the present invention, a mobile phone system comprises first to third semiconductor integrated circuits, a first bus for connecting the first semiconductor integrated circuit and the second semiconductor integrated circuit and a second bus for connecting the second semiconductor integrated circuit and the third semiconductor integrated circuit. The second semiconductor integrated circuit includes a first operation profile and a second operation profile. In the first operation profile, the second semiconductor integrated circuit performs the predetermined process based on the information supplied from the first semiconductor integrated circuit and supplies the result of process to the third semiconductor integrated circuit. In the second operation profile, the second semiconductor integrated circuit supplies in direct the information supplied from the first semiconductor integrated circuit to the third semiconductor integrated circuit.  
           [0044]    In the mobile phone system described above, the first semiconductor integrated circuit may supply a control signal which controls the second semiconductor integrated circuit to be shifted to any one of the first and second operation profiles. Such control signal may be given as a command.  
           [0045]    In the mobile phone system, the first semiconductor integrated circuit is provided, for example, for process of baseband, while the third semiconductor integrated circuit is provided for display control. The predetermined processes are performed, for example, for at least the video signals.  
           [0046]    A storage device may be connected to the second bus. For example, the storage device may store the processing program which specifies the processes to be executed in the second semiconductor integrated circuit. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0047]    [0047]FIG. 1 is a block diagram illustrating an example of the data processing system of the present invention.  
         [0048]    [0048]FIG. 2 is a block diagram illustrating in detail a bypass region in the second data processor of FIG. 1.  
         [0049]    [0049]FIG. 3 is a block diagram illustrating an example in the case where a data processor is formed of a multi-chip module.  
         [0050]    [0050]FIG. 4 is a block diagram illustrating a practical example of a first external interface circuit provided in the second data processor of FIG. 2.  
         [0051]    [0051]FIG. 5 is a block diagram of another practical example of the first external interface circuit provided in the second data processor.  
         [0052]    [0052]FIG. 6 is a diagram for describing the initial write operation of a boot program of the data processor in the data processing system of the present invention.  
         [0053]    [0053]FIG. 7 is a timing charge of boot operation in the data processing system of FIG. 6.  
         [0054]    [0054]FIG. 8 is another timing chart of boot operation in the data processing system of FIG. 6.  
         [0055]    [0055]FIG. 9 is a timing chart for updating a boot program or adding/updating applications executed by the second data processor in the condition that the boot program is stored in the program memory.  
         [0056]    [0056]FIG. 10 is a cross-sectional view of a multi-chip module which forms the data processor of FIG. 3. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0057]    [0057]FIG. 1 illustrates an example of the data processing system of the present invention. This system is composed of a first data processor  100  connected to a first external bus  103  and a second data processor  101  connected to a second external bus  105 . The first external bus  103  is connected with a plurality of external devices  102  such as RAM, ROM and flash memory (FLASH). The second external bus  105  is connected with external devices  104  such as RAM, ROM, FLASH, and liquid crystal display (LCD) controller. The second data processor  101  is connected to the first external bus  103  via a first external interface circuit  119  as a device on the first external bus  103 .  
         [0058]    The second data processor  101  includes an internal high-speed bus  108  and an internal low-speed bus  115 . The internal high-speed bus  108  is connected with a CPU  109 , a cache memory  110 , a digital signal processing processor (DSP)  111 , a bridge circuit  112  as a bus bridge circuit between the internal high-speed bus  108  and internal low-speed bus  115 , a first external interface circuit  119 , a second external interface circuit  113  and a RAM  107 . The internal low-speed bus  115  is connected with a serial interface circuit (SCI), a USB (Universal Serial Bus), a timer, a memory card interface circuit (MCIF), a general purpose input/output port (IOP) such as IO port, a clock pulse generator (CPG) and a peripheral circuit  116  such as flash memory. In FIG. 1, the clock pulse generator (CPG) is given the reference numeral  116   a  and the general purpose Input/output port (IOP) is given the reference numeral  116   b.    
         [0059]    The data processing system is configured, although not particularly restricted, as a mobile phone system. In this case, the first data processor  100  performs the baseband process. The second data processor  101  controls video display for the external device  104  such as liquid crystal display controller and performs signal processes such as compression and expansion of signal. Controls such as display of time via the liquid crystal display controller are performed, although not particularly restricted, by the first data processor  100  via the second data processor  101 .  
         [0060]    The first external interface circuit  119  makes the first data processor  100  obtain the right for use of the internal bus of the second data processor, for example, the high-speed bus  108  and also makes the first data processor  100  having obtained the right for use of the internal bus  108  access to the input/output circuit connected to the internal bus  108 . The input/output circuit means a resister or the like of DSP  111 . In short, the first data processor  100  is allowed to operate as a bus master of the internal high-speed bus  108 . Such operation as the bus master is controlled by the internal bus control unit  106 .  
         [0061]    Moreover, the first external interface circuit  119  controls operation of the RAM as a common memory or a common buffer of the CPU  109  and first data processor  100 . Namely, this first external interface circuit  119  operates the RAM  107  exclusively in response to the access request to the RAM  107  from the CPU and to the access request to the RAM  107  from the first data processor  100 . With the common buffer function to this RAM  107 , the data transfer can be realized between the first data processor  100  and the second data processor  101 . For this data transfer, the handshake control, for example, may be employed using an interruption signal  117 . In more practical, when data is stored to the RAM  107  from the first data processor  100 , the interruption signal  117  of the CPU  109  is given and the CPU  109  fetches the data of RAM  107  with the interruption process responding to such interruption. In the inverse occasion, the external interface circuit  119  issues an interruption request to the first data processor  100 .  
         [0062]    The second external interface circuit  113  has the interface specification to realize the interface for the external devices connected to the external bus  105 . For example, when it is assumed that the FLASH and liquid crystal display (LCD) controller are connected as the external devices  104 , the second external interface circuit  113  has the interface function as the flash memory interface circuit and LCD interface circuit.  
         [0063]    In the structure of FIG. 1, a region  118  is provided with a switch circuit  114  for connecting the external bus  103  in the first external interface circuit to the external bus  105 , in place of the connecting end to the external bus  105  in the second external interface circuit  113  while the second data processor  101  is in the waiting condition. Namely, the switch circuit  114  selects the connection profile to connect the first external bus  103  to the second external bus  105  in place of the second external interface circuit  113  while the second data processor  101  is in the waiting condition. Accordingly, the first data processor  100  is capable of making access to a device on the second external bus  105  via a switching control unit  114 . For example, the first data processor  100  is capable of controlling the liquid crystal display controller as the external device  104  on the external bus  105  via the switch circuit  114 . Here, the circuit in the region  118  of FIG. 1 operates when the second data processor  101  is in the waiting condition.  
         [0064]    In the waiting condition of the second data processor  101 , supply of the clock signal to the CPU  109 , DSP  111 , serial interface circuit and clock synchronization circuit such as timer included in the relevant second data processor  101  is stopped. For example, when the CPU  109  sets a waiting condition enable bit to a waiting condition register of the clock pulse generator  116   a , this clock pulse generator  116   a  stops the output operation of the clock signal CLK or the oscillating operation to stop the supply of clock signal.  
         [0065]    In FIG. 1, the reference numeral  120  designates a power supply circuit. In the second data processor  101 , the operation power source vdd 1  of the switch circuit  114  and the operation power source vdd 2  of the other circuits can be isolated from each other. For example, an external power supply terminal and a power supply wiring of the operation power source vdd 1  and an external power supply terminal and a power supply wiring of the operation power source vdd 2  may be isolated physically. The power supply circuit  120  supplies the operation power sources vdd 1  and vdd 2  to the corresponding power supply terminals. The general purpose input/output port  116   b  is used as a power supply control circuit for the power supply circuit  120 . The general purpose input/output port  116   b  stops supply of the operation power source vdd 2  to the entire part or a part of the other circuits during the period where the second data processor  101  shifts to the waiting condition. The operation power source vdd 1  is always supplied to the switch circuit  114  when the second data processor  101  can operate. When the second data processor  101  goes out of the waiting condition through the interruption, the operation power source is supplied to an interruption control circuit. The power supply control circuit  116   b  sets the power supply control register of the power supply circuit  120  to the power source supply stop instructing condition during transition to the waiting condition. Accordingly, supply of the operation power source vdd 2  is stopped. Here, it is enough that the reset operation to the power source supply instructing condition for the power supply control register is performed during the recovery process to the operating condition from the waiting condition.  
         [0066]    [0066]FIG. 2 illustrates an example of detailed circuits in the region  118  of the second data processor  101  of FIG. 1. Moreover, in this example, the first external interface circuit  119  is connected as a bus master of the internal low-speed bus  115  with a signal line  200 . As the signal line  200  of FIG. 2 illustrates, the internal bus where the first external interface circuit  119  operates as a bus master is not limited to the high-speed bus  108  and may be the low-speed bus.  
         [0067]    In the data processor  1 , a circuit formed in the region  118  is called a second circuit, while a circuit such as the CPU  109  formed in the other region is called a first circuit. The region  118  includes a first external terminal  210 , a first bus  211  for connecting the first external terminal and the first circuit, a second bus  212  for connecting the first circuit and the second circuit, a third bus  213  for connecting the first external terminal and the second internal circuit, a second external terminal  215 , a fourth bus  216  for connecting the second external terminal and the second circuit, a selector  217  for selecting any one of the second bus  212  and third bus  213  for connection to the fourth bus, a bus driver  218 , and a fifth bus  219 . The selector  217  selects the connection profile to connect the first bus  211  to the fourth bus  216  during the period of transition to the waiting condition. When attention is paid to the condition of CPU  109 , execution of instruction by the first circuit is controlled (first condition) in the waiting condition, while instruction is executed by the first circuit (second condition) in the operating condition. In the waiting condition, the second data processor  101  can connect, in direct, the first external bus  103  to the second external bus  105 . In this example, data of the first external bus  103  is transferred, without any condition, to the second external bus  105  in the waiting condition of the second data processor  101 , but it is also possible to connect the first external bus  103  and second external bus  105  by way of input/output buffer (not illustrated). Accordingly, input/output to the second external bus  105  from the first external bus  103  can be controlled.  
         [0068]    In FIG. 1 and FIG. 2, the second data processor  101  is formed as the so-called single chip data processor formed on one semiconductor substrate.  
         [0069]    [0069]FIG. 3 illustrates an example where a second data processor  300  is configured by a multi-chip module. The second data processor  300  is composed of the first external interface circuit  119 , a chip  301  having the function of the switch circuit  114  and a chip  302  having the other functions. The chip  302  has a connecting unit  303  to the internal high-speed bus  108  as the first external interface circuit  119  and the chip  301  connected to the connecting unit  303  can be operated as the bus master of the internal high-speed bus  108 . The first external bus  103  can be connected to the second external bus  105  by operating only the chip  301  in the waiting condition of the second data processor  300 .  
         [0070]    [0070]FIG. 4 illustrates a practical example of the first external interface  119  of the second data processor  101 . The first external interface circuit  119  is composed of an external bus access control unit  401 , a bus conversion mediating unit  402 , an internal bus access control unit  403 , a RAM access control unit  404  and a reset/interruption control unit  405 .  
         [0071]    The access information from the first external bus  103  is inputted to the external bus access control unit  401  and is then transferred to the bus conversion mediating unit  402  through synchronization of the input information. The bus conversion mediating unit judges whether the relevant access is made to the RAM  107  or to the internal bus  108 . When this access is issued to the internal bus  108 , an access request is outputted to the internal bus access control unit  403  to drive the bus access operation depending on the bus access specification of the internal bus  108 . In short, the address signal, bus access control signal and data are supplied to the bus  108  conforming to the bus access specification of the internal bus  108  and moreover the data is received from the bus  108 . When the access request is issued to the RAM  107 , a memory access request is sent to the RAM access control unit  404  to drive the access operation conforming to the access specification of the RAM  107 . In short, the address signal, memory control signal and data are supplied to the RAM  107  conforming to the memory access specification, and moreover the data is received from the RAM  107 .  
         [0072]    Issuance of interruption/reset instruction to the CPU  109  and interruption instruction from the CPU  109  are processed in the reset/interruption control unit  405  and the external bus access control unit  401  issues the corresponding request to the device on the first external bus  103 . Moreover, the request from the device on the first external bus  103  and operation request from the RAM access control unit  404  are given, by the external bus access control unit  401 , to the reset/interruption control unit  405  as the corresponding interruption request.  
         [0073]    [0073]FIG. 5 illustrates another practical example of the first external interface  119  of the second data processor  101 . In this figure, a practical example to realize interface for the bus  103 , interface for the bus  115  and interface for the RAM  107  is illustrated. The first external interface circuit  119  includes a control circuit  410 , an index register IDX and an address flag FG. The control circuit  410  includes a register comprising a built-in control circuit such as an address register ADR, a data register DAT, a command register CMD, an access control register ACS and a status register STS. The address flag FG designates selection of the index register IDX when the logical value “1” is set and designates selection of the register comprising the built-in control circuit when the logical value “0” is set. Which register should be selected among the registers comprising a built-in control circuit when the logical value “0” is set is determined with the value of the index register IDX. The index register IDX and address flag FG are accessed via the first external bus  103 . The bus  103  is composed of a data bus  103 D, an address bus  103 A and a control bus  103 C. The register comprising a built-in control circuit is selected depending on the value of index register IDX, the address information, data information, bus access control information and command information are loaded to the corresponding register via the data bus  103 D, and access to the RAM  107  and access to the bus  115  are driven depending on the command information loaded. For the access, in this case, a setting value of the register is used and the access timing is determined with the access control information. The data written to the RAM  107  via the external bus  103  can be accessed from the CPU  109  via the internal bus  108 . The bus  108  is composed of a data bus  108 D, an address bus  108 A and a control bus  108 C. The bus  115  is composed of a data bus  115 D, an address bus  115 A and a control bus  115 C.  
         [0074]    [0074]FIG. 6 illustrates an example of initial write of a boot program of the data process in the date processing system of the present invention. In the example of FIG. 6, a memory  502  is allocated in the internal bus  115  of the CPU  109  and moreover a memory  501  is also allocated in the second external bus  105 . In this example, although not particularly restricted, the memories  501 ,  502  are used as the user program storage regions. In this case, the boot program executed immediately after the second data processor  101  is reset is usually stored in the memory  501  or  502 . In FIG. 6, the internal memory  502  is connected to the internal low-speed bus  115  but may also be connected to the internal high-speed bus  108 . The internal memory  502  of the second data processor is an electrically reprogrammable nonvolatile memory such as a flash memory and may be formed on one semiconductor substrate together with the CPU  109  or the like or may be formed on different semiconductor substrate and also may be sealed in one package. When it is formed on the different semiconductor substrate and is then sealed in one package, it may be connected, within the package, to the second external bus  105  in place of connection to the internal buses  108 ,  115  of the second data processor  101 . Here, the electrically reprogrammable nonvolatile memories  501  and  502  are used as the program memory.  
         [0075]    The initial write of program to the electrically reprogrammable nonvolatile memories  501 ,  502  has been performed using a write device such as an EPROM writer in the fabrication process of semiconductor integrated circuit such as a data processor  101 . The example of FIG. 6 is based on the assumption that a boot program is not initially written in the nonvolatile memories  501 ,  502  in the initial stage where the data processor  101  is mounted on the data processing system. The data processing system of FIG. 6 enables initial write operation of the boot program from such initial stage. In short, the system for booting the second data processor  101  from the RAM  107  is comprised within the second data processor  101 . Namely, the boot program of the second data processor  101  is written to the RAM  107  from the first data processor  100  via the first external bus  103  to control the second data process  101  to execute the program of the RAM  107  after such write operation. For this purpose, switching is required to drive the second data processor  101  with execution of the program of RAM  107  or with execution of the program of the memory  501  or  502 . This switching operation is performed using level of a boot mode signal (BT)  503  when a reset signal (RES)  504  instructs the reset operation. For example, when the boot mode signal  503  is in the high level during the period where the reset signal  504  is in the low level, the switching is driven by execution of program of RAM  107 , while when the boot mode signal  503  is in the low level, the switching is driven by execution of program of the memories  501 ,  502 .  
         [0076]    A structure for initial write operation of the boot program will be described in detail. In the second data processor  101 , the RAM  107  is set to the write-ready condition by the first data processor  100  in the first operation mode after the reset operation is cancelled by the reset signal  504 . In the first operation mode, the boot mode signal  503  is set to the high level, for example, during the reset period where the reset signal  504  is set in the low level and thereby the reset signal  504  is negated to the high level to cancel the reset operation. In this case, the CPU  109  is controlled in the instruction fetch. In short, supply of start vector to the CPU  109  is controlled. As described above, in this case, the access to RAM  107  is extended to the first external interface circuit  106  by the first data processor  100 . When write operation to the RAM  107  by the data processor  100  is completed, the start vector for designating the leading address of the RAM  107  is supplied to the CPU  109  with the command given to the first external interface circuit  119  from the data processor  100  or in response to change of the boot mode signal  503  to the low level from the high level. Accordingly, the CPU  109  executes the program stored in the RAM  107 . Here, since attention is paid to the initial write operation of a user program, it is enough when the program stored in the RAM  107  is at least the write control program of the user program. The user program itself may be transferred previously to the RAM  107  together with the program described above. Otherwise, it is also possible to initially write the user program to the memory  502  by reading this program from the serial interface circuit  116  or the like through execution of the write control program transferred to the RAM  107 .  
         [0077]    In the second operation mode after the reset operation is cancelled, the memory  501  or  502  is considered as the object of instruction fetch with the CPU  109 . In the second operation mode, the boot mode signal  503  is set to the low level and the reset signal  504  is negated to the high level during the period where the reset signal  504 , for example, is set to the low level, and thereby the reset operation is cancelled. Accordingly, the CPU  109  executes the user program initially stored in the memory  501  or  502  via the first operation mode.  
         [0078]    The operation for storing the program for write control as the boot program to the RAM  107  from the first data processor  100  will be described.  
         [0079]    First, prior to the booting the second data processor  101 , the boot program inputted from the external storage such as memory  505  or memory card  506  connected to the first data processor  100  or from the serial interface (not illustrated) is written by the first data processor  100  to the RAM  107  of the second data processor  101 .  
         [0080]    The boot program transferred to the RAM  107  may include up to the application but a short boot program may be used when it includes the following processes. For example, the programs to be written to the memory  501  or  502  are stored to the program on the RAM  107  through the transfer of programs via the first external interface circuit  119  from the first data processor  100 . Otherwise, the programs to be written by transferring a program to the memories  501 ,  502  are stored using the serial, USB terminals or memory card of the peripheral device  116  of the second data processor.  
         [0081]    From above description, when the memories  501 ,  502  for boot of the second data processor  101  are flash memories, the system for initializing the flash memory has been required intrinsically in the post-process of the system assembling, but since the flash memory can be initialized in the mode for booting from the RAM  107 , mass-production cost of the data processor  101  can be reduced.  
         [0082]    [0082]FIG. 7 illustrates an example of timing chart of the boot operation in the data processing system of FIG. 6.  
         [0083]    The first data processor  100  supplies a boot mode signal  503  and a reset signal  504  to control the drive of the second data processor  101 .  
         [0084]    When the first data processor sets the boot mode signal  503  to the high level to cancel the reset (the reset signal shifts to the high level from the low level) and thereby the second data processor is driven in the mode of boot from the RAM  107 . Accordingly, the boot program is transferred to the RAM  107  via the first external bus  103 . The CPU  109  of the second data processor detects that the boot mode signal is in the high level and the boot program is fetched from the RAM  107  via the first external interface circuit  119 . The CPU  109  is controlled to perform the instruction fetch during transfer of boot program and is therefore set in the waiting condition because the boot program is not supplied thereto. Upon completion of the transfer of boot program, the first data processor  100  transfers the transfer completion command to the first external interface circuit  119  and when the first external interface circuit  119  instructs fetch of the boot program to the CPU  109 , the second data processor  101  is driven with the program of RAM  107 . The CPU  109  executes the boot program in the RAM  107  and performs the write process of boot program to the memories  501 ,  502  via the internal high-speed bus  108 . When the write process of the boot program to the memories  502 ,  502  is completed, the second data processor  101  is reset again (reset signal (RES)  504  is shifted to the low level from the high level) and this reset is cancelled under the condition that the boot mode signal (BT)  503  is set to the low level to drive the second data processor  101 . Accordingly, the CPU  109  fetches the boot program from the memories  501 ,  502  to execute this program and thereby the data processing operation of the second data processor is driven.  
         [0085]    The example of FIG. 7 illustrates the operation timing to supply the boot program to the memories  501 ,  502  from the memory  505  or memory card  506  connected to the first data processor  100  via the first external bus  103 .  
         [0086]    [0086]FIG. 8 illustrates an example of the other timing chart of the boot operation in the data processing system of FIG. 6. The timing illustrated in FIG. 8 assumes that the boot program stored in the memories  501 ,  502  is supplied via the serial and USB terminals  116  or the like of the second data processor  101 . The others are same as that of FIG. 7.  
         [0087]    [0087]FIG. 9 illustrates an example of the timing chart when the boot program is updated or the application executed by the second data processor  101  is added/updated under the condition that the boot program is stored in the memory  501  or  502 .  
         [0088]    When the first data processor  100  sets the boot mode signal  503  to the low level to cancel the reset, the second data processor  101  starts the drive by fetching the boot program from the memories  501 ,  502 . The memories  501 ,  502  previously store the transfer program for update of the boot program or addition/update of the application executed by the processor 2 and the transfer program is driven with drive instruction or the like from the first data processor  100 . For example, the application for addition is received through radio communication via an antenna connected, for example, to the first data processor  100 , the first data processor  100  transfers the received application for addition to the RAM  107  via the external bus  103 . The second data processor  101  fetches the application for addition stored in the RAM  107  to the internal bus  108  via the first external interface circuit  119  and then transfers this application to the memory  501  or  502  for the write operation.  
         [0089]    [0089]FIG. 10 illustrates an example of the cross-sectional view of a multi-chip module forming the data processor  300  of FIG. 3. On one plane of the high density mounting board  510 , many bump electrodes  511  connected to the mounting surface of a printed circuit board formed of a glass epoxy substrate are allocated, while on the other plane, many micro-bump electrodes  512  and pad electrodes  513  connected to the bump electrodes  511  are allocated. At a part of the micro-bump electrodes  512 , a bonding pad of the semiconductor chip  302  is mounted on the face-down basis. The other semiconductor chip  301  is stacked for allocation on the semiconductor chip  302  and the bonding pad of this semiconductor chip  301  is connected to the corresponding pad electrode  513  with a bonding wire  515 . The entire part of the bonding wire  515  and semiconductor chips  301 ,  302  are molded with resin  516 .  
         [0090]    The present invention has been described on the basis of the preferred embodiment thereof but the present invention is never limited thereto and allows various changes and modifications within the scope of the claims thereof.  
         [0091]    For example, the peripheral circuits and the other circuit modules comprised in the data processor are not limited to those described with reference to FIG. 1 and may be changed as required. The internal bus of the data processor may not be sorted as the high-speed bus and low-speed bus. In addition, the operation supply systems for the first circuit and second circuit are not always separated from the external power source terminals and stop of supply of the power source may be controlled with a switch circuit. In addition, when the data processor is formed as the multi-chip module, kind of the semiconductor integrated circuit to be loaded is not limited only to that described above and three chips in total such as a semiconductor chip like the flash memory  502 , a processor core chip such as the other CPU  109  and an interface chip like the semiconductor chip  301  may be mounted. A plurality of flash memory chips may also be mounted to the multi-chip module.  
         [0092]    As described above, the present invention may be widely applied to the data processing system which is intended to dispersion of processing loads using a plurality of data processors such as the mobile phone system, display control system, printer system and the other mobile information terminals and to the data processor which utilizes such data processing system.