Abstract:
A data reproducing apparatus according to the present invention enables a recorder to rewrite recorded contents of a memory card. A digital signal processing section (DSP) detects a compression system for compressed data recorded in the memory card. A central processing unit (CPU) detects whether or not the memory card records a decoding file corresponding to the detected compression system. When such decoding file is not detected, internal memory stores data indicating the undetected decoding file.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2001-163391, filed May 30, 2001; and No. 2001-163392, filed May 30, 2001, the entire contents of both of which are incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a portable electronic device and more particularly to a data reproducing apparatus, a data processing apparatus, and a data transfer system capable of outputting voice signals. 
   2. Description of the Related Art 
   In recent years, there is commercialized a voice recording/reproducing apparatus having a reproducing-only mode (player mode) and a recording/reproducing mode (voice memo mode or recorder mode) as operation modes. The reproducing-only mode can reproduce music data distributed from a pay database, etc. The recording/reproducing mode can record voice data on internal memory and reproduce it. 
   There is known a data reproducing apparatus which compresses and digitizes music or voice information, stores this information as data in a personal computer, and records the data on removable memory. The removable memory can be mounted on a portable electronic device for reproduction and reproducing the desired music or voice information. 
   Such data reproducing apparatus need not previously record a program for expanding compressed data on a portable electronic device. There is provided a method of reading a program for expanding compressed data into a digital signal processing section during reproduction, operating the digital signal processing section, and then reading the recorded data for reproduction. 
   However, before reproduction, the above-mentioned data reproducing apparatus requires a user to check whether or not the transferred data records a decompression program capable of reproducing desired music or voice. 
   Such apparatus is not easy to use because a user can check whether or not the removable memory contains that decompression program only during reproduction. 
   In addition, when the removable memory does not contain the decompression program as a check result, the user must transfer the decompression program from the personal computer to the data reproducing apparatus. This is another user unfriendly aspect of the apparatus. 
   BRIEF SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to provide a data reproducing apparatus, a data processing apparatus, and a data transfer system capable of reproducing music or voice information when memory is connected and such information is transferred to the memory. 
   It is another object of the present invention to provide a data reproducing apparatus which, when memory is connected, facilitates confirmation whether or not intended music or voice information can be reproduced. 
   A first object of the present invention is to provide a data reproducing apparatus comprising: 
   a recording medium whose recording contents can be rewritten by an external device; 
   a compression system detection section which detects a compression system for compressed data recorded on the recording medium; 
   a decoding file detection section which detects whether or not the recording medium records a decoding file corresponding to the detected compression system; and 
   a storage section which, when the decoding file is not detected, stores data indicating the undetected decoding file. 
   A second object of the present invention is to provide a data processing apparatus capable of sending and receiving data from a data reproducing apparatus which reproduces compressed data recorded on a recording medium by using a corresponding decoding file, the data processing apparatus comprising: 
   a detection section which detects connection of the data reproducing apparatus; 
   an information acquisition section which obtains information about a decoding file needed to reproduce the compressed data from the data reproducing apparatus in response to connection with the data reproducing apparatus; and 
   a transmission section which transmits a necessary decoding file based on the obtained information to the data reproducing apparatus. 
   A third object of the present invention is to provide a data transfer system including a data reproducing apparatus and a data processing apparatus, 
   wherein the data reproducing apparatus comprising: 
   a recording medium whose recording contents can be rewritten by an external device; 
   a compression system detection section which detects a compression system for compressed data recorded on the recording medium; 
   a decoding file detection section which detects whether or not the recording medium records a decoding file corresponding to the detected compression system; 
   a storage section which, when the decoding file is not detected, stores data indicating the undetected decoding file; 
   a connection section which connects with the external device; and 
   a first control section which provides control to record a decoding file transferred from the external device on the recording medium in response to connection with the external device and based on the data stored in the storage section, 
   and wherein the data processing apparatus capable of sending and receiving data from a data reproducing apparatus which reproduces compressed data recorded on a recording medium by using a corresponding decoding file, the data processing apparatus comprising: 
   a detection section which detects connection of the data reproducing apparatus; 
   an information acquisition section which obtains information about a decoding file needed to reproduce the compressed data from the data reproducing apparatus in response to connection with the data reproducing apparatus; 
   a transmission section which transmits a necessary decoding file based on the obtained information to the data reproducing apparatus; and 
   a second control section which controls the data reproducing apparatus so as to record a decoding file transmitted by the transmission section on the recording medium. 
   A fourth object of the present invention is to provide a data reproducing apparatus comprising: 
   a mounting section which mounts a attachable/detachable recording medium; 
   a recording medium detection section which detects installation of the recording medium; 
   a compression system detection section which detects a compression system for compressed data recorded on the recording medium when the recording medium is mounted; 
   a decoding program detection section which detects whether or not the recording medium records a decoding program corresponding to the detected compression system; and 
   a warning section which generates an alarm when the decoding program is not detected. 
   Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention. 
       FIG. 1  is a block diagram showing a configuration of a voice recording/reproducing apparatus according to a first embodiment of the present invention; 
       FIG. 2  is a block diagram illustrating how data is recorded on a memory card  46  used in the voice recording/reproducing apparatus according to the first embodiment of the present invention; 
       FIG. 3  is a flowchart which shows a main operation of the voice recording/reproducing apparatus according to the first embodiment of the present invention; 
       FIG. 4  is a flowchart which shows a process when an operation mode is set to player mode and the memory card  46  is mounted on the voice recording/reproducing apparatus body (P/S); 
       FIG. 5  is a flowchart which shows a process when an operation mode is set to player mode and the memory card  46  is not mounted on the voice recording/reproducing apparatus body; 
       FIG. 6  is a subroutine which shows a communication mode process at step S 32  of the flowchart in  FIG. 4 ; 
       FIG. 7  is a subroutine which shows a decoding file check process of the flowchart in  FIG. 6 ; 
       FIG. 8  is a flowchart which shows a main operation of a personal computer to transfer a music file to the voice recording/reproducing apparatus; 
       FIG. 9  is a subroutine which shows an event detection process at step S 102  of the flowchart in  FIG. 8 ; 
       FIG. 10  is a subroutine which shows a serial port detection process at step S 113  of the flowchart in  FIG. 9 ; 
       FIG. 11  illustrates data transfer between a recorder (voice recording/reproducing apparatus) and a personal computer (PC); 
       FIGS. 12A and 12B  provide a flowchart which shows an operation of a voice recording/reproducing apparatus according to a second embodiment of the present invention, explaining another example of a process when an operation mode is set to player mode and the memory card  46  is not mounted on the voice recording/reproducing apparatus body; and 
       FIGS. 13A and 13B  describes decoding file management specifications. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Embodiments of the present invention will be described in further detail with reference to the accompanying drawings. A voice recording/reproducing apparatus represented as an example has a capability of recording and reproducing a dictation memo and a capability of recording and reproducing a music file by communicating with a personal computer. Semiconductor memory is used as a storage medium. 
     FIG. 1  is a block diagram showing a configuration of a voice recording/reproducing apparatus according to a first embodiment of the present invention. 
   First described are parts in a voice recording system. 
   As shown in  FIG. 1 , the voice recording/reproducing apparatus comprises a microphone  12  and a line-in terminal  14 . The microphone  12  converts voice to an electric signal. The line-in terminal  14  is used as a microphone jack for inputting a voice signal from an external apparatus such as an external microphone, etc. An input switch (SW)  16  comprises terminals  16   a ,  16   b , and  16   c , and selects the microphone  12  or the line-in terminal  14  to be used. 
   According to the embodiment, a single monaural voice channel is used for input to the microphone  12  and the line-in terminal  14 . 
   A voice signal selected by the input switch  16  is input to a preamplifier  18  and is amplified there. The voice signal amplified in the preamplifier  18  is input to an input amplifier  20   a  of a stereo codec  20  which converts a voice signal to a digital signal, and vice versa. 
   The stereo codec  20  comprises an input amplifier  20   a , an A/D converter (R)  20   b , an A/D converter (L)  20   c , a digital filter  20   d , a D/A converter (R)  20   e , a D/A converter (L)  20   f , an output amplifier (R)  20   g , and an output amplifier (L)  20   h.    
   When input to the input amplifier  20   a , the voice signal is re-amplified here, and then is input to the A/D converter (R)  20   b  and the A/D converter (L)  20   c . These converters convert the analog voice signal to a digital signal. The converted digital signal is input to the digital filter  20   d.    
   The digital filter  20   d  eliminates an unnecessary quantization noise called an aliasing noise from the digital voice signal. This noise occurs when the voice signal is converted to a digital voice signal. When the quantization noise is eliminated, the digital voice signal is transferred to a digital signal processing section (hereafter abbreviated as a DSP)  42 . Under control of a CPU  40 , the DSP  42  encodes (compresses and converts) the input digital voice signal according to a specified format in units of frames to generate coded data. 
   The voice recording/reproducing apparatus uses a coding system called the Digital Speech Standard (hereafter abbreviated as a DSS). The DSS format supports two recording modes: standard mode (SP) and long mode (LP). The SP mode provides relatively high sound quality. The LP mode enables high compressibility and is suitable for long recording with slightly degraded sound quality. 
   The generated coded data is transferred to a bidirectional bus transceiver IC  44 , then to a memory card  46  as a coded data recording section. The memory card  46  is configured as card-shaped semiconductor memory such as flash memory etc. which can be attached to or detached from the voice recording/reproducing apparatus. The memory card  46  is available as Smart Media (registered trademark), for example. The voice recording/reproducing apparatus according to the present invention uses Smart Media. 
   The coded data is sequentially written to specified addresses in the memory card  46  under control of the CPU  40  via the bidirectional bus transceiver IC  44 . The coded data written in the memory card  46  is handled on a file basis. A DSS-coded data file is hereafter referred to as a DSS file. 
   The voice recording/reproducing apparatus records a voice monaurally. The memory card  46  records only coded data for a digital voice signal output from the A/D converter (R)  20   b.    
   Parts of a reproducing system will be described hereinafter according to a flow of signals for reproducing coded data recorded in the memory card  46 . 
   The coded data is sequentially transferred from the memory card  46  to the DSP  42 . The coded data transferred to the DSP  42  is decoded (decompressed and converted) to a digital voice signal in units of specified frames under control of the CPU  40 . As will be described later, the memory card  46  can record coded data other than DSS files. Accordingly, the DSP  42  determines which encoding is used for the coded data sent from the memory card  46 . The coded data is decoded according to that encoding. 
   Here, the voice recording/reproducing apparatus according to the embodiment is assumed to be capable of three decoding systems: Windows Media (registered trademark) of Microsoft (registered trademark), Motion Picture Experts Group-1 Audio Layer  3 , and DSS. The Windows Media system is hereafter abbreviated as the WMA system. Its coded data file is represented as a WMA file. The Motion Picture Experts Group-1 Audio Layer  3  is hereafter abbreviated as the MP3 system. Its coded data file is represented as an MP3 file. 
   The decoded digital voice signal is transferred to the stereo codec  20 . A digital filter  20   d  in the stereo codec  20  eliminates a quantization noise from the transferred digital voice signal. The D/A converter (R)  20   e  and the D/A converter (L)  20   f  convert the digital voice signal to an analog voice signal for right and left channels, respectively. The converted signal is amplified in the output amplifier (R)  20   g  and the output amplifier (L)  20   h  and is output from the stereo codec  20 . When the original coded data is monaural, the same signal is input to the right and left channels, and then is processed for output. 
   The stereo codec  20  outputs voice signals for the right and left channels. Interlocking output switches  24  and  26  specify output destinations of the signals. The output switch  24  comprises terminals  24   a ,  24   b , and  24   c . The output switch  26  comprises terminals  26   a ,  26   b , and  26   c.    
   As output destinations of the voice signal, there are provided headphone terminals (R)  32  and (L)  34  and a speaker  38 . The headphone terminals  32  and  34  are used to connect with an external headphone etc. (not shown) and reproduce a voice signal by using an external reproduction device. The speaker  38  is provided on the voice recording/reproducing apparatus and functions via a speaker amplifier  36 . 
   The CPU  40  connects with some circuits etc. in addition to the above-mentioned blocks. A display section  52  is connected to the CPU  40  via a display drive circuit  50 . Further, the CPU  40  connects with an operation switch group  54 , a power supply circuit  56 , internal memory  58 , the DSP  42 , the bidirectional bus transceiver IC  44 , a USB connection terminal  62  via a USB driver  60 . 
   The display section  52  comprises a two-color LED and a liquid crystal display having a backlight and displays operational states etc. of the voice recording/reproducing apparatus. The display drive circuit  50  drives the display section  52  under control of the CPU  40 . 
   The operation switch group  54 , including a recording button, a reproducing button, a fast forward button, a fast backward button, a folder/repeat button, an index/equalizer button, a menu button, a delete button and a stop button, is provided outside the voice recording/reproducing apparatus and controls various functions. The power supply circuit  56  supplies power to drive the voice recording/reproducing apparatus. The power supply circuit  56  contains power control circuits (not shown) such as a battery, a battery check circuit, a power-on reset circuit, step-up transformer circuit, a step-down transformer circuit, an external power supply connection circuit, etc. 
   The internal memory  58  comprises EEPROM, i.e., rewritable nonvolatile memory built in the apparatus. The internal memory  58  stores various settings, parameters, etc. to be recorded when no power is supplied to the CPU  20  such as a user ID, selection of the recording mode (standard or long), selection of the beep sound (ON/OFF), locations of data to be reproduced, etc. 
   The voice recording/reproducing apparatus can be connected to external devices such as a personal computer, etc. The voice recording/reproducing apparatus is capable of various processing by means of bidirectional communication with external devices connected. 
   As such processing, for example, the apparatus transfers a coded data file recorded on a hard disk in the personal computer to the memory card  46 . Adversely, the apparatus transfers a coded data file recorded in the memory card  46  to a recording medium in the personal computer. As another example, the stereo codec  20  converts a voice signal input from the microphone  12  to a digital voice signal. Coded data processed in the DSP  42  is directly recorded on a recording medium in the personal computer. 
   For communication with external devices such as the above-mentioned personal computer etc., the voice recording/reproducing apparatus according to the embodiment is configured to use an interface called the Universal Serial Bus (hereafter abbreviated as USB) for connection with external devices. The USB connection terminal  62  is an external connection terminal for connection with a USB cable. The USB connection terminal  62  is controlled by a USB driver  60  as a communication driver and is connected to the CPU  40  via an internal bus. 
   The following describes operation modes of the voice recording/reproducing apparatus. 
   The voice recording/reproducing apparatus provides two operation modes. A first mode is referred to as a recorder mode capable of recording and reproducing a voice input from the microphone or the microphone jack (line-in terminal). A second mode is referred to as a player mode only for reproducing a coded data file recorded on a recording medium, not for recording. 
   In the voice recording/reproducing apparatus according to the embodiment, the recorder mode is mainly used for a message memo, dictation, recording of a meeting, etc. The DSS encoding is used because it is suitable for high compressibility and long recording. The player mode is chiefly intended for music listening and uses the WMA and MP3 encoding capable of high-quality reproduction. 
   Referring now to  FIG. 2 , the following describes how data is recorded on the memory card  46  used for the voice recording/reproducing apparatus. 
   For a route of the memory card  46 , there are provided a coded data file  70 , a song sequence data file  72 , DSS file folders  74 ,  76 , and  78 , and a system folder  80 . 
   The coded data file  70  uses “mp3” or “wma” as a file extension, indicating an MP3 or WMA encoded music data file. An mp3 or wma file is a coded data file reproducible in the player mode. 
   The song sequence data file  72  stores table data for maintaining an order of coded data files to be reproduced in the player mode. It is possible to change the order of coded data files to be reproduced in the player mode by modifying the song sequence data file  72  under control of the CPU  40 . 
   The DSS file folders  74 ,  76 , and  78  store DSS files. In the recorder mode, there are provided three folders A, B, and C for organizing DSS files. The DSS file folders  74 ,  76 , and  78  correspond to the folders A, B, and C, respectively. 
   The DSS file folders  74 ,  76 , and  78  store DSS files  84 ,  86 , and  88 , respectively. The DSS files  84 ,  86 , and  88  are reproducible in the recorder mode. During recording, a DSS file is created in any of the DSS file folders  74 ,  76 , and  78 . The reproduction order of the DSS files  84 ,  86 , and  88  is recorded as table data in reproduction sequence data files  94 ,  96 , and  98  corresponding to the folders. 
   In consideration of the capability of the display section  52  and user-friendliness, the voice recording/reproducing apparatus according to the embodiment specifies up to  199  recordable files per folder in the recorder mode and  597  files in total. 
   The DSS file folder  74  contains a folder name data file  90  and a recovery data file  92  in addition to the above-mentioned files. The voice recording/reproducing apparatus allows the folders A, B, and C to be changed to any names displayed on the display section  52 . The folder name data file  90  records data for maintaining correspondence among the display names and the DSS file folders  74 ,  76 , and  78 . 
   The recovery data file  92  stores data for recovering data which is contained in the DSS file folders  74 ,  76 , and  78  and is destroyed for some reasons. 
   The system folder  80  stores decoding files  100  and  102  for coded data files to be reproduced in the player mode. Each of the decoding file  100  and  102  has a filename whose first three characters use an extension of the corresponding coded data file. The decoding file extension is “img”. A decoding file used in the recorder mode is stored in ROM (not shown) in the CPU  40 . 
   Referring now to flowcharts in  FIGS. 3 through 7 , the following describes operations of the voice recording/reproducing apparatus according to the embodiment. 
     FIG. 3  is a flowchart which shows a main operation of the voice recording/reproducing apparatus according to the first embodiment of the present invention. 
   An operation starts when the power is supplied to each circuit, e.g., when a battery is loaded. At step S 1 , the initialization is performed to clear the memory, set various parameters, reset the hardware, etc. At step S 2 , the current time stamp is set. 
   At step S 3 , it is determined whether the recorder mode or the player mode is enabled. Specifically, the CPU  40  detects to which mode an operation mode switch (not shown) is set. When the recorder mode is enabled, the process proceeds to step S 4 . When the player mode is enabled, the process proceeds to step S 5 . 
   At step S 4 , it is determined whether or not the memory card  46  is mounted on the apparatus. When the memory card  46  is mounted on the apparatus, the process proceeds to step S 6  to perform an R/S (recorder mode/stop) process. When the memory card  46  is not mounted on the apparatus, the process proceeds to step S 7  to perform an R/NC (recorder mode/no card) process. 
   When the player mode is enabled, it is determined at step S 5  whether or not the memory card  46  is mounted on the apparatus. When the memory card  46  is mounted on the apparatus, the process proceeds to step S 8  to perform a P/S (player mode/stop) process. When the memory card  46  is not mounted on the apparatus, the process proceeds to step S 9  to perform a P/NC (player mode/no card) process. 
   An appropriate process is performed depending on which operation mode is enabled and whether or not the memory card  46  is mounted on the voice recording/reproducing apparatus. 
     FIG. 4  is a flowchart which shows a process when the operation mode is set to the player mode and the memory card  46  is mounted on the voice recording/reproducing apparatus body (P/S). 
   At step S 11 , it is determined whether or not a recording button (not shown) is turned on. Since the player mode cannot record a voice, the process proceeds to step S 12  to issue a warning. 
   When the recording button is not turned on at step S 11 , the process proceeds to step S 13  to determine whether not a playback button is turned on. When the playback button is turned on, the process proceeds to step S 14  to reproduce the current file. 
   When the playback button is not turned on at step S 13 , the process proceeds to step S 15  to determine whether or not a fast forward button is turned on. When the fast forward button is turned on at step S 15 , the process proceeds to step S 16  to perform a forward skip operation (F.SKIP). This operation increments a data file number by one to move a file to be reproduced or edited. 
   When the fast forward button is not turned on at step S 15 , the process proceeds to step S 17  to determine whether or not the fast backward button is turned on. When the fast backward button is turned on at step S 17 , a reverse skip operation (R.SKIP) is performed. This operation decrements the data file number by one to move a file to be reproduced or edited. 
   When the fast backward button is not turned on at step S 17 , the process proceeds to step S 19  to determine whether or not a folder/repeat button (not shown) is turned on. In the player mode, the folder/repeat button functions as a repeat mode changeover button. Accordingly, when the folder/repeat button is turned on, the process proceeds to step S 20 . 
   Each time the folder/repeat button is turned on at step S 20 , the repeat mode cyclically changes to normal playback mode, single-song repeat playback mode, all-song repeat playback mode, random playback repeat mode, random playback mode, and then back to normal playback mode. 
   When the folder/repeat button is not turned on at step S 19 , the process proceeds to step S 21  to determine whether or not an index/equalizer button (not shown) is turned on. The index/equalizer button functions as an equalizer (frequency characteristics) changeover button. Each time the index/equalizer button is turned on at step S 22 , the equalizer mode cyclically changes to normal, pops, jazz, classic, user-defined, and then back to normal. 
   When the index/equalizer button is not turned on at step S 21 , the process proceeds to step S 23  to determine whether or not a menu button (not shown) is turned on. When the menu button is turned on, the process proceeds to step S 24  to perform a player menu setup process which configures various settings for the player mode. 
   When the menu button is not turned on at step S 23 , the process proceeds to step S 25  to determine whether or not a delete button (not shown) is turned on. When the erase button is turned on, the process proceeds to step S 26 . At step S 26 , a specified file is deleted from the memory card  46 . The file deletion process is applicable to files that are contained in the memory card  46  and are reproducible in the player mode. 
   When the delete button is not turned on at step S 25 , the process proceeds to step S 27  to determine whether or not a stop button is turned on. When the stop button is turned on at step S 27 , the process proceeds to step S 28  to display properties. Specifically, the display section  52  displays the encoding algorithm and the bit rate of a current file only while the stop button is turned on. When the operation stops, the display section  52  displays the playback number and the current position of the file. 
   When the stop button is not turned on at step S 27 , the process proceeds to step S 29  to determine whether or not an alarm reproduction time is reached. When it is determined that the alarm reproduction time is reached, the process proceeds to step S 30  to reproduce the alarm. 
   When it is determined at step S 29  that the alarm reproduction time is not reached, the process proceeds to step S 31 . At step S 31 , it is determined whether or not the voice recording/reproducing apparatus is connected to the personal computer (PC) as an external device via the USB cable. When it is determined that the voice recording/reproducing apparatus is connected to the personal computer, the process proceeds to step S 32  to enter a communication mode with the personal computer (to be described). 
   When it is determined at step S 31  that the voice recording/reproducing apparatus is not connected to the personal computer, the process proceeds to step S 33  to perform a switch changeover process. The process detects the state of the operation mode switch, and then proceeds to the P/NC, R/S, or R/NC process according to the detected state and whether or not the memory card  46  is mounted on the apparatus. When no change is made to the operation mode switch etc., the process returns to step S 11 . 
     FIG. 5  is a flowchart which shows a process when the operation mode is set to the player mode and the memory card  46  is not mounted on the voice recording/reproducing apparatus body. 
   At step S 41 , it is determined whether or not the menu button is turned on. When the menu button is turned on, the process proceeds to step S 42  to perform the player menu process. Since the memory card  46  is not mounted on the apparatus, however, the process disables selection of items for setting the memory card such as write protection, memory card formatting, etc. 
   When the menu button is not turned on at step S 41 , the process proceeds to step S 43  to determine whether or not the memory card  46  is mounted on the apparatus. When the memory card  46  is mounted on the apparatus at step S 43 , the process proceeds to step S 44  to determine whether or not the memory card  46  is available. 
   When it is determined at step S 44  that the memory card  46  is available, the P/S process is performed (step S 11  of the flowchart in  FIG. 4 ). When it is determined at step S 44  that the memory card  46  is unavailable because the memory card  46  is not formatted (initialized) normally, for example, the process proceeds to step S 45 . 
   At step S 45 , a user determines whether or not to format the memory card  46 . When the user selects to format the card, the process proceeds to step S 46  to format the memory card  46 , and then returns to step S 44 . When the user selects not to format the card at step S 45 , the process proceeds to step S 47 . 
   At step S 47 , the operation mode of the CPU  40  changes to power saving mode to turn off indications. At step S 48 , the CPU  40  waits until any operation button is turned on. 
   When any operation button is turned on, the process changes the operation mode of the CPU  40  to the normal mode at step S 49 , and then returns to step S 45 . When the unavailable memory card  46  is mounted on the apparatus, the card must be formatted for normal operations of recording and reproducing a voice. 
   When the mounting of the memory card  46  is not detected at step S 43 , the process proceeds to step S 50  to determine whether or not an alarm time is reached. When the alarm time is reached, there is no voice file to be reproduced because the memory card  46  is not installed on the apparatus. The process proceeds to step S 51 , displays an indication notifying that the alarm time is reached, and then just generates an alarm sound. When the alarm is sounding, turning on any operation button stops the alarm from sounding. 
   When it is determined that the alarm time is not reached at step S 50 , the process proceeds to step S 52 . It is then determined whether or not action is taken to turn on a given button such as the recording button, the playback button, the delete button, etc. whose operation is meaningless when the memory card  46  is not mounted on the apparatus. 
   When the given button is turned on at step S 52 , the process proceeds to step S 53  to generate a warning sound from the speaker  38 . When it is determined that the given button is not turned on, the process proceeds to step S 54  to perform the switch changeover process, the process returns to step S 41 . 
     FIG. 6  is a subroutine which shows a communication mode process at step S 32  of the flowchart in  FIG. 4 . 
   When the communication mode is enabled, it is determined at step S 61  whether or not the voice recording/reproducing apparatus is connected to the personal computer (PC). When the apparatus is disconnected from the personal computer, the process exits the routine and returns to the original point. Otherwise, it is determined at step S 62  whether or not a transfer command is received from the personal computer. 
   When that command is received, it is determined at step S 63  whether or not data is to be transferred. When it is determined that data is to be transferred from the personal computer, the process proceeds to step S 64  to transfer the data. 
   When it is determined at step S 63  that data is not to be transferred from the personal computer, the process proceeds to step S 65  and determines whether or not a decoding file check command is transferred. When it is determined that the decoding file check command is not transferred, the process proceeds to step S 75  for other processes, and then returns to step S 61 . When it is determined at step S 65  that the decoding file check command is transferred, the process proceeds to step S 66  to execute a decoding file check subroutine as will be described later in detail. 
   At step S 67 , a decoding file check transfer request flag (DRF) is read. The DRF=0 indicates that no decoding file is requested. The DRF=1 indicates that a decoding file for MP3 is requested. The DRF=2 indicates that a decoding file for WMA is requested. The DRF=3 indicates that the decoding file for MP3 and WMA is requested. 
   At step S 68 , it is determined whether or not the DRF is set to “0”. When the flag is set to “0”, the process returns to step S 61 . When the flag is not set to “0”, the process proceeds to step S 69  to determine whether or not the DRF is set to “1”. 
   When it is determined at step S 69  that the DRF is set to “1”, the process proceeds to step S 70  to transfer the decoding file for MP3. The process returns to step S 61 . 
   When it is determined at step S 69  that the DRF is not set to “1”, the process proceeds to step S 71  to determine whether or not the DRF is set to “2”. When it is determined that the DRF is set to “2”, the process proceeds to step S 72  to transfer the decoding file for WMA. The process returns to step S 61  thereafter. 
   When it is determined at step S 71  that the DRF is not set to “2”, the process proceeds to step S 73  to determine whether or not the DRF is set to “3”. When it is determined that the DRF is set to “3”, the process proceeds to step S 74  to transfer the decoding file for MP3 and WMA. The process returns to step S 61  thereafter. When it is determined at step S 73  that the DRF is not set to “3”, the process returns to step S 61 . 
   Referring now to  FIG. 7 , the following describes a decoding file check process of the flowchart in  FIG. 6 . 
   When entering the decoding file check routine, the process initializes the decoding file transfer request flag (DRF=0) at step S 81 . The DRF is composed of two bits. At step S 82 , the process obtains information about a specified folder in the memory card  46 . In this embodiment, the root directory is specified. 
   At step S 83 , it is determined whether or not the obtained folder contains the first music file. When the first music file is unavailable, the routine is exited. When the first music file is available, the process proceeds to step S 84  to obtain the information about that file to be inspected. 
   At step S 85 , it is determined whether or not the obtained file under inspection is an MP3 music file. 
   As a result of step S 85 , when the file under inspection is an MP3 music file, the process proceeds to step S 86 . Otherwise, the process proceeds to step S 89 . 
   At step S 86 , information about the system folder  80  is obtained. At step S 87 , it is determined whether or not the obtained folder contains an MP3 decoding file. 
   The flag FMP indicates whether or not the system folder  80  contains an MP3 decoding file. When such file exists, the flag FMP3 is set to “1”. It is possible to determine whether or not the system folder  80  contains the decoding file by checking the flag FMP3&#39;s value. 
   When no MP3 decoding file is available, the process proceeds to step S 88  to set a decoding program transfer request flag. In this case, “1” is set to the lower significant position of the DRF to request an MP3 decoding file. After this flag is set, or when the MP3 decoding file is found at step S 87 , the process proceeds to step S 93 . 
   At step S 89 , it is determined whether or not the obtained file under inspection is a WMA music file. 
   As a result of step S 89 , when the file under inspection is a WMA music file and the system folder  80  does not contain a decoding file for decoding the WMA music file, the process proceeds to step S 90 . Otherwise, the process proceeds to step S 93 . 
   At step S 90 , information about the system folder  80  is obtained. At step S 91 , it is determined whether or not the obtained folder contains an WMA decoding file. 
   The flag FWMA indicates whether or not the system folder  80  contains a WMA decoding file. When such file exists, the flag FWMA is set to “1”. It is possible to determine whether or not the system folder  80  contains the decoding file by checking the flag FWMA&#39;s value. 
   When a WMA decoding file is available, the process proceeds to step S 93 ; otherwise to S 92 . The decoding program transfer request flag is set. In this case, “1” is set to the upper significant position of the DRF to request a WMA decoding file. After this flag is set, the process proceeds to step S 93 . 
   At step S 93 , it is determined whether or not the next music file is available. When the next music file is available, the process proceeds to step S 94  to obtain the information about that file. The process then returns to step S 85 . When the next music file is unavailable at step S 93 , the process proceeds to step S 95  to transfer the current decoding file transfer request flag (DRF) to the personal computer. Thereafter, the routine is exited. 
   Referring now to flowcharts in  FIGS. 8 through 10 , the following describes operations of the personal computer which transfers a music file to the voice recording/reproducing apparatus. 
     FIG. 8  is a flowchart which shows a main operation of the personal computer. 
   At step S 101 , the screen is initialized. At step S 102 , various events are detected (to be described). When the screen is updated at step S 103 , the process returns to step S 103 , the process returns to step S 102 . 
     FIG. 9  is a subroutine which shows the event detection at step S 102  of the flowchart in  FIG. 8 . When entering the event detection subroutine, the process detects a mouse (pointing device) and processes operations at step S 111 . At step S 112 , the process detects a keyboard and processes operations. At step S 113 , a serial port is detected. 
   At step S 114 , it is determined whether or not the operation due to the event terminates. When the operation terminates, the main operation terminates. Otherwise, the routine is exited. 
     FIG. 10  is a subroutine which shows the serial port detection at step S 113  of the flowchart in  FIG. 9 . 
   When the subroutine is entered, it is determined at step S 121  whether or not a recorder (the voice recording/reproducing apparatus in this case) is connected to the personal computer. When no recorder is connected, the routine is exited. When it is determined that the recorder is connected, the process proceeds to step S 122  to detect a card. During the card detection, it is determined whether or not the memory card  46  is mounted on the recorder. Further, it is determined whether or not the memory card  46  records a music file and a decoding file for decoding the music file. 
   At step S 123 , it is determined whether or not the detected memory  46  card contains a music file and the decoding file needs to be transferred. When the decoding file need not be transferred, the routine is exited. When the decoding file needs to be transferred at step S 123 , the process proceeds to step S 124 . At step S 124 , the decoding file is downloaded. The routine is exited. 
   Referring now to  FIG. 11 , the following describes a flow of interchanging data between the recorder (voice recording/reproducing apparatus) and the personal computer for transferring a music file. 
   First, the personal computer checks a connection state whether or not the recorder is connected to the personal computer. When the recorder sends a recorder identification code to the personal computer, the event detection process is executed (see the flowchart in  FIG. 9 ). 
   Here, the personal computer confirms the serial port. When it is confirmed that the recorder is connected, the card (memory card) detection process is executed (see step S 122  of the flowchart in  FIG. 10 ). When the card is mounted on the recorder, availability of the card is sent to the personal computer. 
   The personal computer requests the recorder to transfer the decoding file check transfer request flag (DRF). In response to this, the recorder transfers the decoding file check transfer request flag to the personal computer. 
   When the flag is transferred to the personal computer, it sends a request to transfer a music file, or the MP3 code in this case, to the recorder. In response to the code transfer request, the recorder transfers the MP3 code to the personal computer. 
   The following describes a second embodiment of the present invention. 
   The second embodiment explains another example of a process when the operation mode is set to player mode and the memory card  46  is not mounted on the voice recording/reproducing apparatus. 
   The second embodiment uses the same configuration of the voice recording/reproducing apparatus as the first embodiment. A description of the configuration is omitted. 
     FIGS. 12A and 12B  provide a flowchart which shows another example of a process when the operation mode is set to player mode and the memory card  46  is not mounted on the voice recording/reproducing apparatus body. 
   Operations at steps S 131  through S 133  and steps S 135  through S 144  in this flowchart are the same as those at steps S 41  through S 43  and steps S 45  through S 54  of the flowchart in  FIG. 5 . A description the corresponding operations is omitted. 
   When it is determined at step S 134  that the memory card  46  is unusable, the process proceeds to step S 135 . A user specifies whether or not to format the memory card  46 . When it is determined at step S 134  that the memory card  46  is usable, the process proceeds to step S 145 . 
   At step S 145 , a music detection flag is initialized. The MP3 flag FMP3 and the WMA flag FWMA are each reset to “0”. At step S 146 , the process obtains information about a specified folder in the memory card  46 . According to the embodiment, the root directory is specified. 
   At step S 147 , it is determined whether or not the obtained folder contains the first music file. When the music file is unavailable, the process proceeds to the P/S process (step S 11  of the flowchart in  FIG. 4 ). When the music file is available, the process proceeds to step S 148  to obtain the file information about a first music file under inspection. 
   At step S 149 , it is determined whether or not the obtained file under inspection is an MP3 music file. Further, it is determined whether or not a specified location, i.e., the system folder  80  contains a decoding file for decoding an MP3 music file. 
   As a result, when the file under inspection is an MP3 music file and the system folder  80  does not contain a decoding file for decoding the MP3 music file, the process proceeds to step S 150 . Otherwise, the process proceeds to step S 154 . 
   At step S 150 , information about the system folder  80  is obtained. At step S 151 , it is determined whether or not the obtained folder contains an MP3 decoding file. 
   When no MP3 decoding file is available, the process proceeds to step S 152 . The display section  52  displays for a specified time (e.g., 10 seconds) that the decoding file is unavailable. An alarm sound is generated as a warning via the speaker  38 . Thereafter, the process proceeds to the P/S process (step S 11  of the flowchart in  FIG. 4 ). 
   When the MP3 decoding file is available at step S 151 , the process proceeds to step S 153  to set the flag FMP3 to “1”. This flag indicates that an MP3 decoding file is detected. The process then proceeds to step S 158 . 
   At step S 154 , it is determined whether or not the obtained file under inspection is a WMA music file. Further, it is determined whether or not a specified location, i.e., the system folder  80  contains a decoding file for decoding a WMA music file. As a result, when the file under inspection is a WMA music file and the system folder  80  does not contain a decoding file for decoding the WMA music file, the process proceeds to step S 155 . Otherwise, the process proceeds to step S 158 . 
   At step S 155 , information about the system folder  80  is obtained. At step S 156 , it is determined whether or not the obtained folder contains a WMA decoding file. 
   When no WMA decoding file is available, the process proceeds to step S 152 . The display section  52  displays for a specified time (e.g., 10 seconds) that the decoding file is unavailable. An alarm sound is generated as a warning via the speaker  38 . Thereafter, the process proceeds to the P/S process (step S 11  of the flowchart in  FIG. 4 ). 
   When the WMA decoding file is available at step S 156 , the process proceeds to step S 157  to set the flag FWMA to “1”. This flag indicates that a WMA decoding file is detected. The process then proceeds to step S 158 . 
   At step S 158 , it is determined whether or not the version stored in the CPU  40  matches the decoding file version stored in the memory card  46 . 
   Referring now to  FIGS. 13A and 13B , the following describes decoding file management specifications. 
   When there is no match in version between the CPU&#39;s firmware and the decoding file, the performance cannot be ensured. The decoding file contains header information from the first address (address  0 ) to a location less than address  60  for encrypting the DSP&#39;s decoding program. The header information contains an identification, a relevant product, version information, a creator (company), etc. 
   As shown in  FIG. 13A , for example, a decoding file  110  comprises a header  110   a  and a music decoding program  110   b . The header  110   a , as shown in  FIG. 13B , comprises a plurality of items. 
   During checking, the CPU first reads item 1. When item 1 contains “0×0000”, the CPU reads item 2. When item 2 also contains “0×0000”, the CPU reads item 3, and so on. According to the specification, the CPU need not confirm item 4 and later. 
   At step S 158 , when the version stored in the CPU  40  differs from the decoding file version stored in the memory card  46 , the process proceeds to step S 152 . When both versions match, the process proceeds to step S 159  to determine whether or not the next file is available. 
   When the next file is available, the process proceeds to step S 160  to obtain the information about that file. The process then returns to step S 149 . 
   When the next file is unavailable, the process proceeds to the P/S process (step S 11  of the flowchart in  FIG. 4 ). 
   While the first and the second embodiments have explained only two examples, i.e., the MP3 and the WMA encoding techniques, the present invention is not limited thereto. For example, it may be preferable to use the encoding such as AAC, TwinVQ, etc. 
   Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.