Patent Publication Number: US-7596041-B2

Title: Nonvolatile memory system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of application Ser. No. 11/450,435 filed Jun. 12, 2006 (now U.S. Pat. No. 7,280,416 issued Oct. 9, 2007), which is a continuation of application Ser. No. 10/753,527 filed Jan. 9, 2004 (now U.S. Pat. No. 7,072,232 issued Jul. 4, 2006). 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a technique for improving reliability of a nonvolatile memory system and, more particularly, to a technique effectively applied to data protection in a memory system constructed by using a nonvolatile semiconductor memory. 
     As external storage media of a personal computer, a multifunctional peripheral, and the like, for example, memory systems such as a CF (Compact Flash) card, Smart media, a memory stick, and a multimedia card are widely known. 
     In a process of reading/writing data from/to such a memory system, at the time of storing data into the memory card, even in the case where a write error occurs, sound data and video data is not rewritten. By sequentially writing data which is received continuously, overflow of data is prevented. With respect to data such as FAT data, in the case where a write error occurs, a spare region is retrieved and data is rewritten (refer to, for example, Japanese Patent Application No. 2001-334243). 
     In the case where a host makes a request for reading/transferring data which is erroneous from a memory system, if the memory system has a correcting function such as an ECC (Error Correcting Code) and the erroneous data is correctable, the memory system corrects the data, rewrites the data in the memory system, and transfers the data to the host. 
     In the case where the data is not correctable or the memory system has an error detecting function such as a parity check, an error is notified to the host and the process is finished. 
     SUMMARY OF THE INVENTION 
     However, the inventor herein has found that the technique of reading/writing data from/to the memory system has the following problems. 
     For example, when an external power source voltage becomes unstable for some reason during a data reading/writing process of a host such as a personal computer, there is the possibility that erroneous reading or writing occurs. 
     In this case, the data reading/writing process can be interrupted by a resetting process of interrupting the data transferring process from the host to the memory system. However, after the resetting process is finished, even when the power source voltage is unstable, the host accepts the reading/writing process again. It causes a problem such that the erroneous reading/writing occurs. 
     In the case where an abnormal operation occurs in the host, the abnormal state of the host cannot be notified to the memory system. It causes a problem such that erroneous data is stored into the memory system by a process of rewriting erroneous data. 
     In the case where the memory system corrects data by using an ECC or the like, process time for data correction is long and wait time of the host becomes long, so that real-time performance may deteriorate. 
     At the time of transferring sound data or image data, it is necessary to transfer a large amount of data. Consequently, it may be requested to continuously transfer the data without intermission even if the data includes a small amount of erroneous data (for example, interruption of sound and noise in an image) rather than notifying an error. 
     An object of the invention is to provide a memory system in which data can be protected reliably on the basis of an emergency stop request even during a data transferring process and which realizes largely improved reliability. 
     Another object of the invention is to provide a memory system capable of determining whether error correction is performed or not in accordance with data and efficiently transferring data. 
     The above and other objects and novel features of the invention will become apparent from the description of the specification and the appended drawings. 
     An outline of representative one of inventions disclosed in the specification will be briefly described as follows.
     (1) A nonvolatile memory system including one or more semiconductor memories and an information processor, wherein when an emergency stop signal is received from the outside, the information processor stops an operation being performed and enters a no-response state in which no response is given to a process request from the outside.   

     An outline of another invention in the specification will be briefly described.
     (2) A nonvolatile memory system including one or more semiconductor memories and an information processor, wherein the information processor has a transfer mode storing unit for storing transfer function setting data for setting a transfer mode of error data, refers to the transfer function setting data in the transfer mode storing unit in a data transfer process at the time of a read/write operation and, when an error data transfer function of the transfer function setting data is set to be valid, executes a transfer process even if transfer data includes error data.   

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a data memory system according to a first embodiment of the invention. 
         FIG. 2  is a flowchart of an emergency stop request process performed during transfer of read data in the data memory system of  FIG. 1 . 
         FIG. 3  is a flowchart of process performed when an emergency stop signal is issued during transfer of write data in the data memory system of  FIG. 1 . 
         FIG. 4  is a flowchart of process performed when an emergency stop signal is issued during transfer of write data in the data memory system of  FIG. 1 . 
         FIG. 5  is a sequence chart of a power source voltage supplied to the data memory system of  FIG. 1 . 
         FIG. 6  is a block diagram showing an example of connection of a reset signal in the data memory system according to the first embodiment of the invention. 
         FIG. 7  is a sequence chart of the reset signal and the emergency stop signal in the data memory system of  FIG. 6 . 
         FIG. 8  is a block diagram showing another example of connection of the reset signal in the data memory system according to the first embodiment of the invention. 
         FIG. 9  is a diagram illustrating a signal process using the data memory system of  FIG. 8 . 
         FIG. 10  is a block diagram showing an example of a data memory system according to another embodiment of the invention. 
         FIG. 11  is a sequence chart of a power source voltage by the data memory system of  FIG. 10 . 
         FIG. 12  is a block diagram showing another example of the data memory system according to another embodiment of the invention. 
         FIG. 13  is a sequence chart showing an example of operation of the data memory system of  FIG. 12 . 
         FIG. 14  is a block diagram showing an example of the data memory system according to another embodiment of the invention. 
         FIG. 15  is a sequence chart showing an example of the operation of the data memory system of  FIG. 14 . 
         FIG. 16  is a block diagram showing another example of the data memory system according to another embodiment of the invention. 
         FIG. 17  is a sequence chart showing an example of the operation of the data memory system of  FIG. 16 . 
         FIG. 18  is a block diagram showing an example of the data memory system according to another embodiment of the invention. 
         FIG. 19  is a diagram illustrating an example of registers accessed by an information processor provided for the data memory system of  FIG. 18 . 
         FIG. 20  is a block diagram showing another example of the data memory system according to another embodiment of the invention. 
         FIG. 21  is a diagram illustrating an example of registers accessed by the information processor provided for the data memory system of  FIG. 20 . 
         FIG. 22  is a block diagram of a data memory system according to a second embodiment of the invention. 
         FIG. 23  is a flowchart of transfer of read data when an erroneous data transfer function is set to be valid in the data memory system of  FIG. 22 . 
         FIG. 24  is a flowchart of transfer of read data when the erroneous data transfer function is set to be invalid in the data memory system of  FIG. 22 . 
         FIG. 25  is a flowchart of transfer of read data when an erroneous data correcting and transferring function of transferring corrected data is set to be valid in the data memory system of  FIG. 22 . 
         FIG. 26  is a flowchart of operation performed when a read and transfer request is made from a controller provided for the data memory system of  FIG. 22 . 
         FIG. 27  is a flowchart showing another example of operation performed when a read and transfer request is made from the controller of  FIG. 22 . 
         FIG. 28  is a flowchart showing an example of changing transfer function setting data by the data memory system according to the second embodiment of the invention. 
         FIG. 29  is a flowchart showing another example of changing the transfer function setting data by the data memory system according to the second embodiment of the invention. 
         FIG. 30  is a diagram illustrating an example of a data structure when transfer function setting data is set in a semiconductor memory provided for the data memory system according to the second embodiment of the invention. 
         FIG. 31  is a diagram illustrating another example of the data structure when the transfer function setting data is set in the semiconductor memory provided for the data memory system according to the second embodiment of the invention. 
         FIG. 32  is a flowchart showing an example of switching of the setting and transferring function by the data memory system according to the second embodiment of the invention. 
         FIG. 33  is a block diagram of the data memory system which sets the transfer function setting data in the semiconductor memory according to the second embodiment of the invention. 
         FIG. 34  is a flowchart of process of setting a transfer flag at the time of transfer of write data by the data memory system of  FIG. 33 . 
         FIG. 35  is a flowchart showing a read/transfer process after the transfer mode is set in  FIG. 34 . 
         FIG. 36  is a block diagram of a data memory system according to another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the invention will be described in detail hereinbelow with reference to the drawings. 
     First Embodiment 
       FIG. 1  is a block diagram of a data memory system according to a first embodiment of the invention.  FIG. 2  is a flowchart of an emergency stop request process performed during transfer of read data in the data memory system of  FIG. 1 .  FIG. 3  is a flowchart of process performed when an emergency stop signal is issued during transfer of write data in the data memory system of  FIG. 1 .  FIG. 4  is a flowchart of process performed when an emergency stop signal is issued during transfer of write data in the data memory system of  FIG. 1 .  FIG. 5  is a sequence chart of a power source voltage supplied to the data memory system of  FIG. 1 .  FIG. 6  is a block diagram showing an example of connection of a reset signal in the data memory system according to the first embodiment of the invention.  FIG. 7  is a sequence chart of the reset signal and the emergency stop signal in the data memory system of  FIG. 6 .  FIG. 8  is a block diagram showing another example of connection of the reset signal in the data memory system according to the first embodiment of the invention.  FIG. 9  is a diagram illustrating a signal process using the data memory system of  FIG. 8 . 
     In the first embodiment, a data memory system  1  is, for example, a memory card constructed by using a flash memory or the like and is used as an external storage medium of an information processor PC as a host. The information processor PC is a personal computer, a multifunctional peripheral, or the like. 
     The data memory system (memory system)  1  is constructed by, as shown in  FIG. 1 , a controller (information processor)  2 , and M pieces of semiconductor memories  3 . Although the configuration in which M pieces of semiconductor memories  3  are provided is employed, one semiconductor memory is sufficient. 
     The controller  2  reads out a program, data, or the like stored in the semiconductor memory  3  on the basis of an operation program and performs a predetermined process or gives a data writing instruction. 
     The semiconductor memory  3  is, for example, a nonvolatile semiconductor memory such as a flash memory. The semiconductor memory  3  is not limited to a flash memory but may be a memory capable of storing data such as SRAM (Static Random Access Memory), DRAM (Dynamic RAM), MRAM (Magnetoresistive RAM), EPROM (Erasable and Programmable Read Only Memory) or the like. 
     In the embodiment of the invention, the controller and the memory are separated from each other. Alternately, an embedded semiconductor obtained by forming the controller, the memory, and peripheral parts as one component may be used. 
     The controller  2  and the semiconductor memory  3  are connected to each other via a semiconductor memory bus MB. The controller  2  is constructed by a control circuit  4 , an input/output circuit  5 , and the like. The control circuit  4  controls the input/output circuit  5 , and the input/output circuit  5  controls transmission of data between the semiconductor memory  3  and the information processor PC. 
     Further, the information processor PC and the controller  2  are connected to each other via an information processor bus PCB. The information processor bus PCB has a mechanical coupling means and may be of a contact type which is electrically connected or a non-contact type of transmitting information by an information transmission medium such as electric waves. 
     To the control circuit  4  of the controller  2 , a signal line S is connected. The signal line S also has a mechanical coupling means and may be of a contact type which is electrically connected or a non-contact type of transmitting information by an information transmission medium such as electric waves. 
     Via the signal line S, an emergency stop signal is supplied from the outside to the control circuit  4 . When the emergency stop signal is received, the controller  2  stops a data transfer process in reading/writing operation. 
     The action of the data memory system  1  in the embodiment will now be described. 
     First, a process of requesting emergency stop during transfer of read data in the data memory system  1  will be described by using the flowchart of  FIG. 2 . 
     When the information processor PC sends a request for reading and transferring data  0  to N to the controller  2  (step S 101 ), the controller  2  sends the request for reading and transferring data  0  to N ( FIG. 1 ) to the semiconductor memory  3  (step S 102 ) and notifies the information processor PC of transfer of read data (step S 103 ). 
     By the notification of transfer of read data, data in the semiconductor memory  3  is read and transferred sequentially from data  0  to the information processor PC via the controller  2  (step S 104 ). 
     For example, when an emergency stop signal for requesting emergency stop is received via the signal line S on completion of transfer of data up to data K to the information processor PC during the process of step S 104  (step S 105 ), the control circuit  4  receives the emergency stop signal, immediately stops the transfer process, and notifies the information processor PC of end of the read data transfer (step S 106 ). The end of the read data transfer is notified irrespective of whether the transfer is finished normally or abnormally. 
     Even if a request for transferring read data is sent again from the information processor PC after notifying the information processor PC of the end of the read data transfer (step S 107 ), the controller  2  does not transfer data but notifies the information processor PC of an untransferable state of read data (step S 108 ). 
     Next, a process performed when the emergency stop signal is issued during transfer of write data in the data memory system  1  will now be described by using the flowchart of  FIG. 3 . 
     When the information processor PC sends a request for transferring write data  0  to N to the controller  2  (step S 201 ), the controller  2  sends the request for transferring write data  0  to N to the semiconductor memory  3  (step S 202 ) and notifies the information processor PC of transfer of write data (step S 203 ). 
     By the notification of transfer of write data, data is sequentially transferred from the information processor PC to the semiconductor memory  3  (step S 204 ). 
     For example, when an emergency stop signal for requesting emergency stop is received via the signal line S on completion of transfer of write data up to data K during the process of step S 204  (step S 205 ), the control circuit  4  immediately stops the transfer process on reception of the emergency stop signal and notifies the information processor PC of end of the write data transfer (step S 206 ). The end of write data is notified irrespective of whether the transfer is finished normally or abnormally. 
     Even if a request for transferring write data  0  to N is sent again from the information processor PC after notifying the information processor PC of the end of transfer of write data (step S 207 ), the controller  2  notifies the information processor PC of an untransferable state of write data without transferring data (step S 208 ). 
     Another example of process performed when the emergency stop signal is issued during transfer of write data in the data memory system  1  will now be described by using the flowchart of  FIG. 4 . 
     When the information processor PC sends a request for transferring write data  0  to N to the controller  2  (step S 301 ), the controller  2  sends the request for transferring the write data  0  to N to the semiconductor memory  3  (step S 302 ) and notifies the information processor PC of transfer of the write data (step S 303 ). 
     By the notification of transfer of write data, write data is sequentially transferred from the information processor PC to the semiconductor memory  3  (step S 304 ). 
     For example, when the emergency stop signal for requesting emergency stop on completion of transfer of write data up to the data K is input via the signal line S during the process of step S 304  (step S 305 ), the control circuit  4  immediately stops the transfer process on reception of the emergency stop signal and notifies the information processor PC of a busy state (step S 306 ) so that the next command is not transmitted from the information processor PC. 
       FIG. 4  shows the process performed at the time of transfer of write data. At the time of transfer of read data, similar process is performed. 
       FIG. 5  is a diagram showing an example of a sequence of power source voltage supplied to the data memory system  1  after the emergency stop request is made by the emergency stop signal. 
       FIG. 5  shows, from top to bottom, sequence of each of the emergency stop signal, external power source voltage VCC, and a control status input to the data memory system  1 . 
     If a data transfer request is sent from the information processor PC when the data memory system  1  is in an idle state, based on the request, the data memory system  1  performs the data transfer process. When the emergency stop signal of an active state (low level) is input during the data transfer process, the data memory system  1  executes an interrupting process and enters a process unacceptable state in which any process is not accepted. 
     The process unacceptable state is canceled when the power source voltage VCC of the data memory system  1  is set to the low level (the power source voltage VCC is set to an OFF state) and the external power source voltage is set again to an ON state, thereby performing the process of resetting the data memory system  1 . 
       FIG. 6  is a block diagram showing an example of connection in the case where the information processor PC transmits a power-on-reset signal to the data memory system  1 . 
     In this case, a reset signal RS output from the information processor PC is supplied to the data memory system  1 . 
       FIG. 7  is a sequence chart showing the difference between the operation of the power-on-reset signal and that of the emergency stop signal in the data memory system  1  of  FIG. 6 . 
       FIG. 7  shows, from top to bottom, sequences of the emergency stop signal, external power source voltage VCC, and a control status input to the data memory system  1 . 
     The process performed by the emergency stop signal is similar to that of  FIG. 5 . In the case where the power-on-reset signal which is active (low level) is supplied from the information processor PC, the data memory system  1  performs the resetting process and, after that, enters an idle state to start again accepting the data transfer process or the like. 
     That is, the data memory system  1  enters the idle state after the resetting process and accepts the data transfer process of the information processor PC. After the emergency stop process performed by the emergency stop signal, however, the data memory system  1  does not accept the data transfer process. 
     Consequently, by performing the emergency stop process by the emergency stop signal in the case where the external power source voltage level becomes unstable during the data transfer process or the like, data in the data memory system  1  can be protected. 
     The emergency stop signal input to the data memory system  1  may be output from the information processor PC as shown in  FIG. 8 . In this case, the emergency stop signal output from the information processor PC is supplied to the data memory system  1  via the signal line S 1 . 
     As described above, the configuration in which the emergency stop signal is output from the information processor PC is effective, for example, when the information processor PC has multiple tasks (tasks A and B) as shown in  FIG. 9 . 
     If necessity of protecting data in the data memory system  1  arises when the task A occupies the data memory system  1 , the task B can output the emergency stop signal to the data memory system  1  via an I/O (Input/Output) port which is different from the information processor bus PCB. 
       FIG. 10  is a block diagram showing another example of a data memory system  1   a.    
     In this case, the data memory system  1   a  has a configuration obtained by adding a power supply stabilizing IC (power source voltage unit)  6  and voltage monitoring ICs  7  and  8  to the data memory system  1  of  FIG. 1 . 
     The power supply stabilizing IC  6  generates an internal power supply voltage VDD from the external power supply voltage VCC supplied from the outside and supplies the internal power supply voltage VDD to each of the controller  2 , semiconductor memory  3 , and voltage monitoring IC (first voltage monitoring unit)  7  via an internal power supply line NS. 
     The voltage monitoring IC  7  monitors the voltage level of the internal power supply voltage VDD generated by the power supply stabilizing IC  6  and, if an abnormal state occurs, outputs the power-on-reset signal to the control circuit  4 . To the voltage monitoring IC (second voltage monitoring unit)  8 , the external power supply voltage VCC is supplied. In the case where an abnormal state occurs in the external power supply voltage VCC, the emergency stop signal is output to the control circuit  4 . 
     The operation in the data memory system  1   a  will be described by using the sequence chart of  FIG. 11 . 
       FIG. 11  shows, from top to bottom, sequences of the external power supply voltage VCC, internal power supply voltage VDD, the power-on-reset signal output from the voltage monitoring IC  7 , the emergency stop signal output from the voltage monitoring IC  8 , and a control status supplied to the data memory system  1   a.    
     In the diagram, the external power supply voltage VCC drops from a normal voltage level (VCC level) to the GND (reference potential) level and, again recovers to the VCC level. 
     First, when the external power supply voltage VCC drops to a certain voltage level during the data transfer process of the data memory system  1   a , the voltage monitoring IC  8  detects the drop in the external power source voltage VCC and outputs the emergency stop signal to the control circuit  4 . 
     On receipt of the emergency stop signal, the data memory system  1   a  executes an interrupting process and enters a process unacceptable state in which any process is not accepted. 
     After that, when the voltage level of the external power supply voltage VCC drops, the internal power supply voltage VDD also decreases. The voltage monitoring IC  7  detects the voltage drop and outputs the power-on-reset signal to the control circuit  4 . Subsequently, the external power supply voltage VCC becomes the GND level. 
     When the voltage level of the external power supply voltage VCC increases again, accordingly, the voltage level of the internal power source voltage VDD also increases. When the internal power supply voltage VDD becomes a certain voltage level or higher, the voltage monitoring IC  7  resets the power-on-reset signal (to the high level) and the process of resetting the data memory system  1   a  is performed. 
     When the external power supply voltage VCC becomes a certain voltage level or higher during the resetting process, the voltage monitoring IC  8  sets the emergency stop signal to an inactive state (high level). 
     Since the emergency stop signal is ignored during the resetting process, when the resetting process is finished after the power is turned on, the data memory system  1   a  enters an idle state. 
       FIG. 12  is a block diagram showing a data memory system  1   b  which is similar to the data memory system  1   a  except that a capacitor (power supplying unit)  9  of a large capacity is provided in place of the power supply stabilizing IC  6 ( FIG. 10 ). 
     In this case, the capacitor  9  is connected between the ground and the internal power supply line NS. Via the internal power supply line NS, the internal power supply voltage VDD (which is equal to the external power source voltage VCC) is supplied to the controller  2 , semiconductor memory  3 , and voltage monitoring IC  7 . To the voltage monitoring IC  8 , the external powers supply voltage VCC is directly supplied without using the internal power source line NS. In place of the capacitor  9 , a battery or the like may be connected to the internal power source line NS. 
       FIG. 13  is a sequence chart showing an example of operation in the data memory system  1   b.    
       FIG. 13  shows, from top to bottom, sequences of the external power supply voltage VCC, internal power supply voltage VDD supplied via the internal power supply line NS, the power-on-reset signal output from the voltage monitoring IC  7 , the emergency stop signal to be output from the voltage monitoring IC  8 , and a control status supplied to the data memory system  1   b.    
     When the external power supply voltage VCC drops to a certain voltage level during the data transfer process of the data memory system  1   b , the voltage monitoring IC  8  outputs the emergency stop signal to the control circuit  4 . On receipt of the emergency stop signal, the data memory system  1   b  executes an interrupting process and enters the process unacceptable state. 
     Since the capacitor  9  is connected to the internal power supply line NS, the internal power supply voltage VDD supplied via the internal power supply line NS drops slowly more than the external power supply voltage VCC. 
     The voltage monitoring IC  7  detects the voltage drop in the internal power supply voltage VDD and outputs the power-on-reset signal to the control circuit  4 . When the external power supply voltage VCC increases from the GND level and becomes equal to or higher than a certain voltage level, the voltage monitoring IC  8  sets the emergency stop signal to an inactive state (high level). 
     After that, when the internal power source voltage VDD becomes a certain level or higher, the voltage monitoring IC  7  resets the power-on-reset signal (to the high level), the process of resetting the data memory system  1   b  is performed, and the data memory system  1   b  enters an idle state. 
       FIG. 14  is a block diagram of a data memory system  1   c  having another configuration. 
     The data memory system  1   c  is different from the data memory system  1   b  ( FIG. 12 ) with respect to the point that a power supply switching IC (power supply switching unit)  10  for outputting an emergency stop signal is newly provided in place of the voltage monitoring IC  8 . 
     The power supply switching IC  10  monitors the voltage level of the external power supply voltage VCC. When the voltage level becomes equal to or lower than a certain voltage level, the power supply switching IC switches the supply source of the internal power supply voltage VDD via the internal power supply line NS to the capacitor  9  and outputs the emergency stop signal to the control circuit  4 . In this case as well, the capacitor  9  is not limited to a capacitor of large capacity but may be a battery or the like. 
       FIG. 15  is a sequence chart showing an example of operation of the data memory system  1   c.    
       FIG. 15  shows, from top to bottom, sequences of the external power supply voltage VCC, internal power supply voltage VDD supplied via the internal power supply line NS, the power-on-reset signal output from the voltage monitoring IC  7 , the emergency stop signal output from the power supply switching IC  10 , and a control status supplied to the data memory system  1   c.    
     When the external power supply voltage VCC drops during the data transfer process of the data memory system  1   c , the power supply switching IC  10  switches the power supply source from the external power source voltage VCC to the capacitor  9 . Consequently, the data memory system  1   c  can reduce influence of the external power supply voltage VCC. 
     The power supply switching IC  10  outputs the emergency stop signal to the control circuit  4 , and the voltage monitoring IC  7  outputs the power-on-reset signal to the control circuit  4 . The controller  2  executes the interrupting process on receipt of the emergency stop signal and enters the process unacceptable state. 
     After that, when the voltage level of the external power source voltage VCC becomes a certain level or higher, the voltage supply switching IC  10  resets the power-on-reset signal (to the high level) and the voltage monitoring IC  7  sets the emergency stop signal to an inactive state (high level). 
     By the above, the process of resetting the data memory system  1   a  is performed and the data memory system  1   c  enters an idle state. 
       FIG. 16  is a block diagram of a data memory system  1   d  as an example of the case of using the same signal as the emergency stop signal and an external reset signal. 
     The data memory system  1   d  has a configuration obtained by newly adding an AND circuit  11  to the configuration of the data memory system  1  ( FIG. 1 ). 
     The emergency stop signal is input to one of input terminals of the AND circuit  11  and the external reset signal which is output from the information processor PC is input to the other input terminal. An output signal of the AND circuit  11  becomes an internal reset signal and is connected so as to be supplied to the control circuit  4  of the controller  2 . 
     The operation in the data memory system  1   d  will be described with reference to the sequence chart of  FIG. 17 . 
       FIG. 17  shows, from top to bottom, sequences of the external reset signal which is output from the information processor PC, the emergency stop signal, the external reset signal which is output from the AND circuit  11 , and a control status. 
     When the external reset signal (low level) is output during the data transfer process of the data memory system  1   d , an output of the AND circuit  11  becomes the low level. The internal reset signal becomes active and the process of resetting the data memory system  1   d  is performed. 
     After the resetting process, if the emergency stop signal (low level) is output again during the data transfer process, an output of the AND circuit  11  becomes the low level, so that the internal reset signal becomes active and the process of resetting the data memory system  1   d  is performed. 
     As described above, by using the emergency stop signal also as the external reset signal, an I/O pin or the like for inputting the emergency stop signal to the controller  2  becomes unnecessary. The cost can be suppressed and the function can be simplified, so that designing of the controller  2  can be facilitated. 
       FIG. 18  is a block diagram of a data memory system  1   e  as an example of the case of sending the emergency stop request via the information processor bus PCB. 
     In the data memory system  1   e , the controller  2  is provided with an emergency stop request register (register)  12 . The emergency stop request register  12  can be directly accessed by the information processor PC. Consequently, by setting data in the emergency stop request register  12 , the emergency stop request can be made.  FIG. 19  is a diagram illustrating an example of registers which are provided for the controller  2  and can be accessed by the information processor PC. 
     By using the emergency stop request register  12 , without performing a resetting process or the like at the time of resetting the data memory system  1   e  from the process unacceptable state to the idle state, the data memory system  1   e  can be freely reset. 
     Alternately, as shown in  FIG. 20 , the emergency stop request can be set by using a part of a process requesting register (register)  12   a  for requesting reading/writing of data without newly providing the controller  2  with the emergency stop request register  12 . The process request register  12   a  is, as shown in  FIG. 21 , one of existing registers which can be accessed by the information processor PC. 
     According to the first embodiment, transfer of erroneous data, rewriting of data to erroneous data, and the like can be prevented even during the data transfer process, so that reliability of the data memory system can be improved. 
     In the first embodiment, the case where the read/write data transfer process is being performed has been described. In any of the other cases such as a case where a request for process which does not accompany data transfer is made, in an idle state, during a resetting process, and in a sleep state, the emergency stop request can be accepted. 
     Second Embodiment 
       FIG. 22  is a block diagram of a data memory system according to a second embodiment of the invention.  FIG. 23  is a flowchart of transfer of read data when an erroneous data transfer function is set to be valid in the data memory system of  FIG. 22 .  FIG. 24  is a flowchart of transfer of read data when the erroneous data transfer function is set to be invalid in the data memory system of  FIG. 22 .  FIG. 25  is a flowchart of transfer of read data when an erroneous data correcting and transferring function of transferring corrected data is set to be valid in the data memory system of  FIG. 22 .  FIG. 26  is a flowchart of operation performed when a read and transfer request is made from a controller provided for the data memory system of  FIG. 22 .  FIG. 27  is a flowchart showing another example of operation performed when a read and transfer request is made from the controller of  FIG. 22 .  FIG. 28  is a flowchart showing an example of changing transfer function setting data by the data memory system according to the second embodiment of the invention.  FIG. 29  is a flowchart showing another example of changing the transfer function setting data by the data memory system according to the second embodiment of the invention.  FIG. 30  is a diagram illustrating an example of a data structure when transfer function setting data is set in a semiconductor memory provided for the data memory system according to the second embodiment of the invention.  FIG. 31  is a diagram illustrating another example of the data structure when the transfer function setting data is set in the semiconductor memory provided for the data memory system according to the second embodiment of the invention.  FIG. 32  is a flowchart showing an example of switching of the setting and transferring function by the data memory system according to the second embodiment of the invention.  FIG. 33  is a block diagram of the data memory system which sets the transfer function setting data in the semiconductor memory according to the second embodiment of the invention.  FIG. 34  is a flowchart of process of setting a transfer flag at the time of transfer of write data by the data memory system of  FIG. 33 .  FIG. 35  is a flowchart showing a read/transfer process after the transfer mode is set in  FIG. 34 . 
     In the second embodiment, a data memory system (memory system)  13  is a memory card constructed by using, for example, a flash memory and is used as an external storage medium of the information processor PC as a host. The information processor PC is, for example, a personal computer, a multifunctional peripheral, or the like. 
     The data memory system  13  is, as shown in  FIG. 22 , constructed by a controller (information processor)  14  and a semiconductor memory  15 . Although one semiconductor memory  15  is used here, a plurality of semiconductor memories may be provided. 
     The controller  14  reads a program, data, and the like stored in the semiconductor memory  15  on the basis of an operation program and an instruction of the information processor PC and performs a predetermined process, an instruction for writing data, and the like. 
     The semiconductor memory  15  is, for example, a nonvolatile semiconductor memory such as a flash memory. In a manner similar to the first embodiment, the semiconductor memory  15  is not limited to a flash memory but may be a memory capable of storing data such as SRAM (Static Random Access Memory), DRAM (Dynamic RAM), MRAM (Magnetoresistive RAM), EPROM (Erasable and Programmable Read Only Memory) or the like. 
     In the embodiment of the invention, the controller and the memory are separated from each other. Alternately, an embedded semiconductor obtained by forming the controller, the memory, and peripheral parts as one component may be used. 
     In the semiconductor memory  15 , a data storage area and a data area for error detection are provided in correspondence with addresses (physical addresses)  0  to n. The data storage area is an area in which the user data ( 0 ) to (n) is stored. The data area for error detection is an area for storing ECCs in the user data ( 0 ) to (n). 
     The controller  14  and the semiconductor memory  15  are connected to each other via a semiconductor memory bus MB 1 . The information processor PC and the controller  14  are connected to each other via the information processor bus PCB. 
     The information processor bus PCB has a mechanical coupling means and may be of a contact type which is electrically connected or a non-contact type of transmitting information by an information transmission medium such as electric waves. 
     The controller  14  is constructed by a control circuit  16 , an input/output circuit  17 , a memory  18  for referring to transfer mode switching (transfer mode storing unit), and an error data detecting and correcting circuit (error data detecting and correcting unit)  19 . 
     The control circuit  16  controls the input/output circuit  17 , memory  18  for referring to transfer mode switching, and error data detecting and correcting circuit  19 . The input/output circuit  17  has a data buffer  17   a  and controls transfer of data to/from the semiconductor memory  3  and the information processor PC. 
     The memory  18  for referring to transfer mode switching stores transfer function setting data for setting whether error data is to be transferred or not. The memory  18  for referring to transfer mode switching may be nonvolatile or volatile. The memory  18  may be a register constructed by using a random gate. 
     The error data detecting and correcting circuit  19  detects an error in transfer data by using an ECC or the like. An error may be detected not only by an ECC but also by a simple detecting function such as a CRC (Cyclic Redundancy Check) or a parity check. 
     The action of the data memory system  14  in the embodiment will now be described. 
     A process of transferring read data in a state where the error data transfer function is set to be valid in the memory  18  for referring to transfer mode switching will now be described by using the flowchart of  FIG. 23 . It is assumed here that user data (k−1) stored in an address k−1 in the semiconductor memory  13  is erroneous. 
     First, when the information processor PC sends a request for reading user data (k−1) to the controller  14  (step S 401 ), the controller  14  sends the request for reading the user data (k−1) in the address k−1 to the semiconductor memory  15  (step S 402 ) and notifies the information processor PC of transfer of read data (step S 403 ). 
     By the notification of transfer of read data, the user data (k−1) in the semiconductor memory  15  is read and transferred to the information processor PC via the controller  14  (step S 404 ). In this case, the error data transfer function is valid, so that all of the user data (k−1) including the error data is transferred. 
     When the transfer of the user data (k−1) is finished, the controller  14  notifies the information processor PC of the end of transfer of the read data (step S 405 ). The end of transfer of read data is notified irrespective of whether the transfer is finished normally or abnormally. 
     The read data transfer process when the memory  18  for referring to transfer mode switching sets the error data transfer function to be invalid will be described by using the flowchart of  FIG. 24 . It is also assumed here that user data (k−1) stored in the address k−1 in the semiconductor memory  13  includes error data. 
     When the information processor PC sends a request for reading and transferring the user data (k−1) to the controller  14  (step S 501 ), the controller  14  sends the request for reading and transferring the user data (k−1) in the address k−1 to the semiconductor memory  15  (step S 502 ) and, after that, the user data (k−1) in the semiconductor memory  15  is read by the controller  14  (step S 503 ). By the error data detecting and correcting circuit  19 , an error data check is made. 
     When the error data detecting and correcting circuit  19  detects error data in the user data (k−1), the controller  14  notifies the information processor PC of the end due to the error (step S 504 ). 
     A read data transfer process performed in a state where the memory  18  for referring to transfer mode switching sets the error data transfer function for correcting error data and transferring the corrected data to be valid will now be described by using the flowchart of  FIG. 25 . It is also assumed here that error data is included in the user data (k−1) stored in the address k−1 in the semiconductor memory  13 . 
     When a request for reading user data (k−1) is sent from the information processor PC to the controller  14  (step S 601 ), the controller  14  requests the semiconductor memory  15  to read and transfer the user data (k−1) in the address k−1 (step S 602 ). 
     After that, the controller  14  reads the user data (k−1) in the semiconductor memory  15  (step S 603 ) and the error data detecting and correcting circuit  19  checks the user data (k−1). 
     If error data is detected in the user data (k−1), the error data detecting and correcting circuit  19  corrects the error data, requests a transfer of write data to the semiconductor memory  15  (step S 604 ), and rewrites the data with the corrected user data (k−1) (step S 605 ). 
     The corrected user data (k−1) in  FIG. 25  is written again into the address k−1. It is also possible to provide a spare area in the semiconductor memory and another semiconductor memory and replace the user data (k−1). 
     Subsequently, the controller  14  notifies the information processor PC of transfer of read data (step S 606 ), and the corrected user data (k−1) is transferred (step S 607 ). 
     After completion of the transfer of the user data (k−1), the controller  14  notifies the information processor PC of the end of transfer of the read data (step S 608 ). In this case as well, the end of transfer of read data is notified irrespective of whether the transfer is finished normally or abnormally. 
     The operation of the controller  14  when the read and transfer request is made will now be described by using the flowchart of  FIG. 26 . 
     First, when a read and transfer request is sent from the information processor PC, the control circuit  16  refers to the transfer function setting data of the memory  18  for referring to transfer mode switching and determines whether even error data is transferred or not (step S 701 ). 
     In the case of transferring even error data, data read from the semiconductor memory  15  is transferred as it is to the information processor PC (step S 702 ). 
     In the case where error data is not transferred, data read from the semiconductor memory  15  is transferred to the error data detecting and correcting circuit  19  (step S 703 ) and whether error data is included or not is checked (step S 704 ). 
     In the case where error data is detected and is correctable (step S 705 ), the error data detecting and correcting circuit  19  corrects the data and transfers the corrected data to the information processor PC (step S 707 ). 
     If error data cannot be corrected (step S 705 ), an untransferable state is notified to the information processor PC (step S 706 ). 
     In this case, if the transfer function setting data is set to the function of transferring even error data, data is transferred without making an error data check, so that high-speed transfer process can be realized. 
     Another example of operation of the controller  14  when the read and transfer request is made will now be described by using the flowchart of  FIG. 27 . 
     First, when a read and transfer request is sent from the information processor PC, data is read from the semiconductor memory  15  and transferred to the error data detecting and correcting circuit  19  (step S 801 ) and whether error data is included or not is checked (step S 802 ). 
     If no error data is included, the read data is transferred to the information processor PC (step S 803 ). If error data is included, when the data is correctable (step S 804 ), the error data detecting and correcting circuit  19  corrects the data and transfers the corrected data to the information processor PC (step S 805 ). 
     When the error data is not correctable (step S 804 ), the control circuit  16  refers to the transfer function setting data in the memory  18  for referring to transfer mode switching and determines whether even error data is transferred or not (step S 806 ). 
     In the case of transferring data even if the data includes error data, the data read from the semiconductor memory  15  is transferred as it is to the information processor PC (step S 807 ). In the case where error data is not transferred, the controller  14  notifies the information processor PC of an untransferable state (step S 808 ). 
     In this case, even when the transfer function setting data is set to the function of transferring even error data, transfer of error data is limited to the case where the data is uncorrectable, so that the reliability of data can be improved. 
     The case of changing the transfer function setting data in the memory  18  for referring to transfer mode switching by the information processor PC will now be described by using the flowchart of  FIG. 28 . 
     The case of changing a setting of transferring no error data to a setting of transferring error data at the time of data transfer will now be described. 
     For example, when a request for reading and transferring user data (k−1) is sent from the information processor PC (step S 901 ), the controller  14  requests the semiconductor memory  15  to read and transfer the user data (k−1) (step S 902 ). 
     Subsequently, data in the semiconductor memory  15  is read and transferred to the controller  14  (step S 903 ). 
     Since the transferred user data (k−1) includes error data, the controller  14  notifies the information processor PC of end due to an error (step S 904 ). 
     When the notification of end due to an error is transferred, the information processor PC requests the controller  14  to perform a mode switching process for changing the transfer function setting data (step S 905 ). The controller  14  receives the mode switching process request, changes the transfer function setting data in the memory  18  for referring to transfer mode switching, and notifies the information processor PC of completion of change in the transfer function setting data (step S 906 ). 
     Subsequently, the information processor PC makes the request of reading and transferring the user data (k−1) again (S 907 ). The controller  14  sends the request of reading and transferring the user data (k−1) to the semiconductor memory  15  (step S 908 ) and transfers the notification of transfer of read data to the information processor PC (step S 909 ). 
     The data in the semiconductor memory  15  is read and transferred to the information processor PC via the controller  14  (step S 910 ). After completion of transfer of all of the read data, the controller  14  notifies the information processor PC of end of transfer of the read data (step S 911 ). 
     The transfer function setting data can be set not necessarily in the memory  18  for referring to transfer mode switching but can be set in, for example, the semiconductor memory  15 . 
     Change in the transfer function setting data by the information processor PC in this case will now be described by using the flowchart of  FIG. 29 . 
     When a request for reading and transferring the user data (k−1) is sent from the information processor PC (step S 1001 ), the controller  14  sends the request for reading and transferring the user data (k−1) to the semiconductor memory  15  (step S 1002 ). 
     After that, data in the semiconductor memory  15  is read and transferred to the controller  14  (step S 1003 ). Since the transferred user data (k−1) includes error data, the controller  14  notifies the information processor PC of end due to an error (step S 1004 ). 
     By the notification of end due to an error, the information processor PC requests the controller  14  to perform a mode switching process of changing the transfer function setting data (step S 1005 ). On reception of the mode switching process request, the controller  14  changes the transfer function setting data of the semiconductor memory  15  (step S 1006 ) and notifies the information processor PC of completion of change in the transfer function setting data (step S 1007 ). 
     The information processor PC sends the request for reading and transferring the user data (k−1) again (step S 1008 ), and the controller  14  sends the request for reading and transferring the user data (k−1) to the semiconductor memory  15  (step S 1009 ) and transfers the notification of transfer of read data to the information processor PC (step S 1010 ). 
     The data in the semiconductor memory  15  is read and transferred to the information processor PC via the controller  14  (step S 1011 ). When transfer of all of read data is finished, the controller  14  notifies the information processor PC of end of transfer of the read data (step S 1012 ). 
     In the embodiment, a rewrite flag stored in the semiconductor memory is not checked every reading and transfer operation for the reason that a transfer flag is stored in the controller. Thus, the invention can be realized without deteriorating the performance of the reading and transferring operation from the information processor PC. A rewrite flag stored in the semiconductor memory is checked by the controller during the resetting process requested by the information processor PC during resetting after turn-on of the power. This method of storing the flag in the semiconductor memory can easily address a request from a customer at the time of shipping from a manufacturer. The information processor PC compatible with the customer does not have to be aware of switching of a mode. 
       FIG. 30  is a diagram illustrating a data structure in the case where the transfer function setting data in which the error data transfer function is invalid is set in the semiconductor memory  15 .  FIG. 31  is a diagram illustrating a data structure in the case where the transfer function setting data in which the error data transfer function is valid is set in the semiconductor memory  15 . 
     As shown in  FIGS. 30 and 31 , the data storage area corresponding to the address “n” in the semiconductor memory  15  serves as an area for setting the transfer function setting data. When the transfer invalid flag is set in the area, the error data transfer function is made invalid. When the transfer valid flag is set, the error data transfer function is made valid. 
     The transfer function setting data is set in at least one of the semiconductor memories and may be used for a function setting of the whole memory system of the invention. Further, the transfer function setting data may be set in each semiconductor memory. By setting the data in each semiconductor memory, for example, by storing data for file management requiring relatively high data reliability and data such as image and sound data requiring relative high data transfer speed into different semiconductor memories, a memory system having high usability can be realized. 
       FIG. 32  is a flowchart of a process of switching the setting and transfer function by changing a command code at the time of a read and transfer request. 
     When the information processor PC makes a request for reading and transferring (k−1) address data while inhibiting error data by using a command code (step S 1101 ), the controller  14  sends a request for reading and transferring the user data (k−1) to the semiconductor memory  15  (step S 1102 ), and data read from the semiconductor memory  15  is transferred to the controller  14  (step S 1103 ). 
     Since the transferred user data (k−1) includes error data, the controller  14  notifies the information processor PC of end due to an error (step S 1104 ). 
     Subsequently, when the information processor PC sends a request for reading and transferring user data (k−1) while permitting error data by using a command code (step S 1105 ), the controller  14  sends a request for reading and transferring the user data (k−1) to the semiconductor memory  15  (step S 1106 ) and transfers notification of transfer of read data to the information processor PC (step S 1107 ). 
     After that, data in the semiconductor memory  15  is read and transferred to the information processor PC via the controller  14  (step S 1108 ). When transfer of all of read data is finished, the controller  14  notifies the information processor PC of end of the read data transfer (step S 1109 ). 
       FIG. 33  is a diagram illustrating an example of the configuration of the semiconductor memory  15  in which the transfer function setting data can be set in each of user data ( 0 ) to (n−1). 
     In this case, the semiconductor memory  15  has not only a data storage area and a data area for data detection but also an area for storing a transfer flag for setting whether user data is transferred or not even if the user data is error data. 
     By setting an error data untransferable flag or an error data transferable flag in the transfer flag storing area, the memory for referring to transfer mode switching can be made unnecessary. Since whether error data is transferable or untransferable can be selectively set to each user data, reliability of the data storage can be improved. 
     A process of setting a transfer flag in the semiconductor memory  15  at the time of transfer of write data will now be described by using the flowchart of  FIG. 34 . It is assumed here that user data (k−1) is set to the error data transferable state, and user data (k) is set to the error data untransferable state. 
     The information processor PC sends a request for transferring user write data (k−1) while inhibiting error data by using a command code (step S 1201 ), the controller  14  sends the request for transferring the user write data (k−1) to the semiconductor memory  15  (step S 1202 ), and write data is transferred to the semiconductor memory  15  via the controller  14  (step S 1203 ). 
     The controller  14  sets the transfer flag which inhibits transfer of error data in the semiconductor memory  15  (step S 1204 ) and stores the detected user data (k−1) into the data area for error detection in the semiconductor memory  15  (step S 1205 ). 
     Subsequently, the controller  14  notifies the semiconductor memory  15  of normal end of write transfer (step S 1206 ) and notifies the information processor PC of end of the write transfer (step S 1207 ). 
     When the information processor PC makes the request of transferring user write data (k) while permitting error data by using a command code (step S 1208 ), the controller  14  sends a request for transferring the user write data (k) to the semiconductor memory  15  (step S 1209 ), and the write data is transferred to the semiconductor memory  15  via the controller  14  (step S 1210 ). 
     The controller  14  sets the error data transferable flag in the semiconductor memory  15  (step S 1211 ) and stores detected user data (k) into the data area for error detection in the semiconductor memory  15  (step S 1212 ). 
     Subsequently, the controller  14  notifies the semiconductor memory  15  of normal end of the transfer of write data (step S 1213 ) and transfers a write data transfer end notification to the information processor PC (step S 1214 ). 
       FIG. 35  is a flowchart showing a read and transfer process after the transfer mode is set in  FIG. 34 . 
     When the information processor PC makes a request for reading and transferring user data (k−1) (step S 1301 ), the controller  14  sends the request for transferring the user write data (k−1) to the semiconductor memory  15  (step S 1302 ). In response to the request, the read data is transferred to the controller  14  (step S 1303 ). 
     Since the user data (k−1) includes error data, the controller  14  transfers an error end notification to the information processor PC (step S 1304 ). 
     When the information processor PC sends again the request for reading and transferring the user data (k) (step S 1305 ), the controller  14  sends the request for reading and transferring the user data (k) to the semiconductor memory  15  (step S 1306 ) and sends the read and transfer request to the information processor PC (step S 1307 ). 
     Although the user data k also includes error data, read data is transferred from the semiconductor memory  15  to the information processor PC via the controller  14  (step S 1308 ). After all of read data is transferred, the controller  14  transfers a notification of end of the read and transfer to the information processor PC (step S 1309 ). 
     In the second embodiment, user data can be transferred even it includes error data without interruption, so that unnecessary wait time can be eliminated. 
     Since data is transferred without interruption, a buffer of a large capacity becomes unnecessary for the information processor PC. Thus, reduction in the cost of the information processor PC can be realized. 
     Further, in the second embodiment, the case of setting the error data transfer function by the information processor PC has been described. For example, as shown in  FIG. 36 , a transfer mode switching signal may be supplied from the outside other than the information processor PC to the control circuit  16  in the controller  14 . 
     In the second embodiment, obviously, the error uncorrectable state is not limited to a state where an error cannot be corrected in reality but includes a case where an error cannot be corrected within predetermined time. 
     For example, by providing a register or the like in which error correction time can be set and designating the error correction time for each kind of data, each of data of which transfer time is more important than accuracy and data whose accuracy is more important can be transferred at proper speed. 
     In the second embodiment, in the case where error correction is impossible, data read from the memory array is supplied to the host without being subjected to error correction. In this case, it is obvious that, for example, all of data “0” or all of data “1” can be supplied to the host. 
     Effects obtained by representative ones of the inventions disclosed in the specification will be briefly described as follows.
     (1) Even when an abnormal state occurs in the host, the power supply voltage, or the like during the data transfer process, transfer of error data, rewriting of data to error data, and the like can be prevented by the emergency stop requesting process, so that reliability of the data memory system can be improved.   (2) Since user data including error data can be also transferred without interruption, useless wait time can be reduced and reliability of the memory system can be further improved.   (3) Further, by the above effects (1) and (2), the performance and reliability of an electronic system constructed by using the memory system or the like can be largely improved.