TECHNICAL FIELD 0001 The present invention relates to information processing apparatuses. In particular, the present invention relates to an information processing apparatus in which an access can be properly acquired on a network formed by an institute of electrical and electronic engineers (IEEE) 1394 high-speed serial bus.

BACKGROUND ART 0002 Networks using the serial bus protocol (SBP) 2 are becoming widespread. SBP2 is a kind of communication protocol standard and is regarded as most suitable for connection based on the standard of the IEEE 1394 high-speed serial bus (hereinafter, referred to as IEEE 1394). 0003 FIG. 1 shows an example of the configuration of a known network system using IEEE 1394. 0004 A personal computer 1-1 includes a hard disk drive (HDD) 2 connected to an IEEE 1394 connector 3. In FIG. 1, the HDD 2 and the IEEE 1394 connector 3 are shown outside the personal computer 1-1 for clarity. 0005 The personal computer 1-1 and a personal computer 1-2 are connected by an IEEE 1394 cable 4. (Hereinafter, the personal computers 1-1 and 1-2 are referred to as a personal computer 1 when it is not necessary to distinguish one computer from the other. The same applies to other parts.) 0006 The personal computer 1-1 can transmit an operation command to the HDD 2 via the IEEE 1394 connector 3. Also, the personal computer 1-2 can transmit an operation command to the HDD 2 via the IEEE 1394 cable 4 and the IEEE 1394 connector 3. The HDD 2 operates in response to a command transmitted from the personal computer 1 (for example, stores predetermined data). 0007 In the SBP2 standard, a device which can transmit an operation command, such as the personal computer 1-1 or the personal computer 1-2, is called the initiator. A device which operates in response to a command transmitted from the initiator, such as the HDD 2, is called the target. 0008 A target can be accessed by only one initiator, and thus one target cannot be shared by a plurality of initiators. Accordingly, only the initiator which first requests access to the target can access the target. That is, the initiator which first requests access monopolizes access to the target. Hereinafter, the condition in which the initiator that first requests access to the target monopolizes access is called a race condition. 0009 According to the race condition, in the example shown in FIG. 1, when the personal computer 1-2 first requests access, the personal computer 1-2 monopolizes access to the HDD 2. That is, at this time, the personal computer 1-1 cannot access the HDD 2, even though the personal computer 1-1 includes the HDD 2. 0010 It has been proposed that access be set in order of connection via IEEE 1394. However, in this case, the setting of access will change when the connection order is changed, and thus this method is not a fundamental solution for overcoming the above-described problems. 0011 Also, it has been proposed that access be set for only the initiator which requests access by using a proper password generated by a password function provided in the SBP2 standard. However, if a plurality of initiators know the password, access to the target is monopolized by the initiator which accesses the target first. Therefore, this method is not a fundamental solution for overcoming the above-described problems.

DISCLOSURE OF INVENTION 0012 The present invention has been made in view of these circumstances so that a proper initiator can acquire access to a target on a SBP2 network. 0013 An information processing apparatus of the present invention comprises storage means for storing authentication information of the control device for which control is allowed; obtaining means for obtaining the authentication information of the control device which requests control via the bus; comparing means for comparing the authentication information stored in the storage means and the authentication information obtained by the obtaining means; and allowing means for allowing the control device which requests control to perform control based on the comparison result obtained from the comparing means. 0014 The storage means can store the authentication information of one of the control devices in advance. 0015 When the storage means does not store authentication information, the storage means stores the authentication information of the control device that first requests control from among the plurality of control devices. 0016 The information processing apparatus further comprises setting means for setting a mode. When a first mode is set by the setting means and when the storage means does not store authentication information, the storage means stores the authentication information of the control device that first requests control from among the plurality of control devices. 0017 When a second mode is set by the setting means and when control is requested for the first time, the allowing means deletes the authentication information stored in the storage means and allows the control device which requests control to perform control. 0018 An information processing method of the present invention comprises a storing step for storing authentication information of the control device for which control is allowed; an obtaining step for obtaining the authentication information of the control device which requests control via the bus; a comparing step for comparing the authentication information stored in the storing step and the authentication information obtained in the obtaining step; and an allowing step for allowing the control device which requests control to perform control based on the comparison result obtained in the comparing step. 0019 A program in a recording medium of the present invention comprises a storing step for storing authentication information of the control device for which control is allowed; an obtaining step for obtaining the authentication information of the control device which requests control via the bus; a comparing step for comparing the authentication information stored in the storing step and the authentication information obtained in the obtaining step; and an allowing step for allowing the control device which requests control to perform control based on the comparison result obtained in the comparing step. 0020 A program of the present invention allows a computer to execute processes comprising a storing step for storing authentication information of the control device for which control is allowed; an obtaining step for obtaining the authentication information of the control device which requests control via the bus; a comparing step for comparing the authentication information stored in the storing step and the authentication information obtained in the obtaining step; and an allowing step for allowing the control device which requests control to perform control based on the comparison result obtained in the comparing step. 0021 The authentication information of the control device for which control is allowed is stored, the authentication information of the control device which requests control is obtained via the bus, the stored authentication information is compared to the obtained authentication information, and the control device which requests control is allowed to perform control.

BRIEF DESCRIPTION OF THE DRAWINGS 0022 FIG. 1 shows an example of the configuration of a known network system. 0023 FIG. 2 shows an example of the configuration according to a first embodiment of a network system using the present invention. 0024 FIG. 3 shows an example of the appearance of the personal computer 1-1 shown in FIG. 2. 0025 FIG. 4 is another view showing the appearance of the personal computer 1-1 shown in FIG. 2. 0026 FIG. 5 is another view showing the appearance of the personal computer 1-1 shown in FIG. 2. 0027 FIG. 6 is another view showing the appearance of the personal computer 1-1 shown in FIG. 2. 0028 FIG. 7 is a block diagram showing an example of the inner configuration of the personal computer 1-1 shown in FIG. 2. 0029 FIG. 8 is a block diagram showing an example of the configuration of an HDD 11 shown in FIG. 2. 0030 FIG. 9 shows an example of the configuration of a network in which the personal computer 1 and the HDD 11 are connected in series. 0031 FIG. 10 is a flowchart illustrating processes performed to acquire access. 0032 FIG. 11 shows the format of LoginORB. 0033 FIG. 12 shows the format of login_response. 0034 FIG. 13 shows the format of Status_block. 0035 FIG. 14 shows an example of the configuration according to a second embodiment of the network system using the present invention. 0036 FIG. 15 is a block diagram showing an example of the configuration of the HDD 301 shown in FIG. 14. 0037 FIG. 16 is a flowchart illustrating other processes performed to acquire access.

BEST MODE FOR CARRYING OUT THE INVENTION 0038 FIG. 2 shows an example of the configuration according to a first embodiment of a network system using the present invention. The network system includes an HDD 11 instead of the HDD 2 shown in FIG. 1. The other parts are the same as in FIG. 1 and a corresponding description will be omitted. 0039 When the HDD 11 receives a request for access from a personal computer 1, the HDD 11 compares the global unique identifier (GUID) of the personal computer 1, which has requested access, with the GUID stored in the HDD 11, and gives the personal computer 1 access if both of the GUIDs match. That is, access is not granted when the two GUIDs do not match. 0040 In this case, the HDD 11 stores the GUID of the personal computer 1-1. Thus, even when the personal computer 1-2 requests access from the HDD 11 earlier than the personal computer 1-1, access to the HDD 11 is not given to the personal computer 1-2. 0041 The GUID is universal authentication information for identifying types, manufacturers, model numbers, serial numbers, and so on of all devices connected to the IEEE 1394. That is, predetermined GUIDs are allocated to the personal computers 1-1 and 1-2 and the HDD 11. 0042 Next, the configuration of the personal computer 1-1 will be described with reference to FIGS. 3 to 6. The personal computer 1-1 basically includes a main body 22 and a display unit 23, which can be opened and closed with respect to the main body 22. FIG. 3 is a perspective view showing a state where the display unit 23 is opened with respect to the main body 22. FIG. 4 is a plan view of the main body 22, and FIG. 5 is an enlarged view showing the vicinity of a jog dial 24, which will be described later, provided in the main body 22. Also, FIG. 6 is a side view showing the side of the jog dial 24 of the main body 22. 0043 On the upper side of the main body 22, a keyboard 25 which can be operated for inputting various characters and symbols, a touch pad 26 functioning as a pointing device which can be operated for moving a pointer (mouse cursor), and a power switch 28 are provided. Alternatively, a stick-type pointing device can be provided instead of the touch pad 26. 0044 Also, the jog dial 24 and an IEEE 1394 port 101-1 are provided on a side surface. An IEEE 1394 port 101-2 (FIG. 7) is provided inside the personal computer 1-1 for connecting an internal device. The IEEE 1394 port 101-2 and an IEEE 1394 terminal 201-1 (FIG. 8) of the HDD 11 are connected and an IEEE 1394 connector 3 is provided inside the personal computer 1-1. 0045 Further, a liquid crystal display (LCD) 27 for displaying images is provided on the front surface of the display unit 23. A power lamp PL, a battery lamp BL, and as required, a message lamp and other lamps including LEDs are provided on the upper right side of the display unit 23. Further, a microphone 66 is provided on the upper side of the display unit 23. The power lamp PL, the battery lamp BL, and so on can be provided on the lower side of the display unit 23. 0046 The jog dial 24 is placed between keys of the keyboard 25 on the main body 22 such that the jog dial 24 is substantially flush with the keys. The jog dial 24 performs predetermined processing according to a rotational operation indicated by an arrow a and a push operation indicated by an arrow b shown in FIG. 5. 0047 The jog dial 24 may be placed on the left side of the main body 22. Further, the jog dial 24 may be placed on the left side or right side of the display unit 23 provided with the LCD 27 or may be placed longitudinally between the G-key and the H-key on the keyboard 25. Alternatively, the jog dial 24 may be placed at the center of the front surface of the main body 22 so that the jog dial can be operated by a thumb while operating the touch pad 26 by a forefinger. Also, the jog dial 24 may be placed transversely along the upper end or the lower end of the touch pad 26 or may be placed longitudinally between a right button and a left button of the touch pad 26. Further, the positioning of the jog dial 24 is not limited to the vertical direction or the horizontal direction, and the jog dial 24 may be placed along a slanting direction at a predetermined angle so as to be easily operated with each finger. In addition, the jog dial 24 may be placed at a position on a side surface of a mouse functioning as a pointing device so as to be operated with a thumb. 0048 FIG. 7 shows the electrical configuration of the personal computer 1-1. 0049 A central processing unit (CPU) 51 includes, for example, a Pentium processor made by Intel Corporation, and is connected to a host bus 52. A bridge 53 is connected to the host bus 52, and the bridge 53 is also connected to an accelerated graphics port (AGP) 50 and a PCI bus 56. The bridge 53 includes, for example, a 400BX made by Intel Corporation, and controls the vicinity of the CPU 51 and a RAM 54. Further, the bridge 53 is connected to a video controller 57 via the AGP 50. The bridge 53 and a bridge 58 form a so-called chip set. 0050 The bridge 53 is also connected to the RAM 54 and a cache memory 55. The cache memory 55 caches data used by the CPU 51. Although not shown in the figure, a primary cache memory is provided inside the CPU 51. 0051 The RAM 54 includes, for example, a dynamic random access memory (DRAM), and stores a program executed by the CPU 51 and data which is required for the operation of the CPU 51. 0052 The video controller 57 is connected to a PCI bus 56 and the bridge 53 via the AGP 50, and controls the display on the LCD 27 based on data supplied via the PCI bus 56 or the AGP 50. 0053 A sound controller 64 is connected to the PCI bus 56. The sound controller 64 receives input sound from the microphone 66 and supplies a sound signal to a speaker 65. Also, a modem 75 and a PC card slot interface 111 are connected to the PCI bus 56. 0054 The modem 75 can be connected to a communication network 80 such as the Internet, a mail server 78, and so on via a public telephone line 76 and an Internet service provider 77. Also, when an optional function is added, transmission/reception of data is performed with an external device by loading an interface card 112 in a slot 29 connected to the PC card slot interface 111. For example, a drive 113 can be connected to the interface card 112 so that transmission/reception of data is performed with a magnetic disk 121, an optical disk 122, a magnetooptical disk 123, and a semiconductor memory 124 which are inserted into the drive 113. 0055 Further, the bridge 58 is connected to the PCI bus 56. The bridge 58 includes, for example, a PIIX4E made by Intel Corporation, and controls various input/output. That is, the bridge 58 includes an integrated drive electronics (IDE) controller/configuration register 59, a timer circuit 60, an IDE interface 61, and a universal serial bus (USB) interface 68, and controls devices connected to a USB port 107 and devices connected via an industry standard architecture/extended input output (ISA/EIO) bus 63 and an I/O interface 69. 0056 The IDE controller/configuration register 59 includes two IDE controllers: a so-called primary IDE controller and a secondary IDE controller, as well as a configuration register. 0057 The primary IDE controller and the secondary IDE controller can be connected to an external device via an IDE bus (not shown). 0058 The I/O interface 69 is connected to the ISA/EIO bus 63. The I/O interface 69, a ROM 70, a RAM 71, and a CPU 72 are connected together. 0059 An IEEE 1394 interface (I/F) program 70A, an LED control program 70B, a touch pad-input monitoring program 70C, a key-input monitoring program 70D, a wake-up program 70E, and a jog-dial state monitoring program 70F are stored in the ROM 70 in advance. 0060 The IEEE 1394 I/F program 70A is a program for performing input/output of IEEE 1394-compliant data transmitted/received via the IEEE 1394 port 101. For example, the IEEE 1394 I/F program 70A performs processing for acquiring access to the HDD 11 connected to the IEEE 1394 port 101-2. The process for acquiring access will be described later. 0061 The LED control program 70B is a program for controlling the illumination of lamps including the power lamp PL, the battery lamp BL, and a message lamp and other lamps including LEDs provided as required. 0062 The touch pad-input monitoring program 70C is a program for monitoring input performed by a user by using the touch pad 26. The key-input monitoring program 70D is a program for monitoring input performed by a user by using the keyboard 25 and other key switches. 0063 The wake-up program 70E checks whether a predetermined time has arrived based on current-time data supplied from the timer circuit 60 in the bridge 58, and when that predetermined time has arrived, the wake-up program 70E manages the power of each chip in order to start a predetermined process (or a program). 0064 The jog-dial state monitoring program 70F is a program for constantly monitoring the rotation and pushing of the rotary encoder portion of the jog dial 24. 0065 A basic input/output system (BIOS) 70G is written in the ROM 70. The BIOS refers to a basic input/output system and is a software program for controlling input/output of data between an operating system (OS) or an application program and peripheral devices (for example, the display, the keyboard, and the HDD). 0066 Further, the GUID of the personal computer 1-1 is stored in the ROM 70, and is read as required. Incidentally, a configuration ROM or a dedicated memory may be provided so as to store the GUID. 0067 The RAM 71 includes registers 71A to 71F: registers for LED control, touch pad-input status, key-input status, and the set time; an I/O register for jog-dial status monitoring; and an IEEE 1394 I/F register. For example, when the jog dial 24 is pressed, the LED control register controls the illumination of a message lamp for indicating an e-mail instant startup state. The key-input status register stores an operation key flag when the jog dial 24 is pressed. The set time register can set a certain time arbitrarily. 0068 In addition, the jog dial 24, the keyboard 25, and the touch pad 26 are connected to the I/O interface 69 via a connector (not shown). When a user operates the jog dial 24, the touch pad 26, or the keyboard 25, a signal corresponding to the operation of the jog dial 24, the keyboard 25, or the touch pad 26 is output to the ISA/EIO bus 63. 0069 The I/O interface 69 transmits/receives data to/from the outside via the IEEE 1394 ports 101-1 and 101-2. 0070 The power lamp PL, the battery lamp BL, the message lamp, a power control circuit 73, and other lamps including LEDs are connected to the I/O interface 69. The power control circuit 73 is connected to a built-in battery 74 or an AC power supply, supplies the required power to each block, and controls charging of the built-in battery 74 and secondary batteries in the peripheral devices. 0071 The CPU 72 monitors the power switch 28, which is operated to turn the power on/off, via the I/O interface 69. 0072 The CPU 72 can always execute the IEEE 1394 I/F program 70A to the BIOS 70G with an inner power supply even when the power switch 28 is off. That is, the IEEE 1394 I/F program 70A to the BIOS 70G operate constantly even when one of windows is not open on the LCD 27 of the display unit 23. Accordingly, the CPU 72 constantly executes the jog-dial state monitoring program 70F even when the power switch 28 is off and when the OS is not activated by the CPU 51. Also, the CPU 72 has a programmable power key (PPK) function even if a dedicated key is not provided in the personal computer 1-1. Thus, the user can startup any software or script file simply by pressing the jog dial 24 even in a power-saving state or a power-off state. 0073 The configuration of the personal computer 1-2 is basically the same as that of the personal computer 1-1 and a detailed description will thus be omitted. However, the GUID of the personal computer 1-2 is stored in the personal computer 1-2. 0074 Next, the configuration of the HDD 11 will be described with reference to FIG. 8. 0075 An IEEE 1394 interface 202-1 is connected to the personal computer 1-1 via the IEEE 1394 terminal 201-1 and the IEEE 1394 connector 3 and functions as an interface thereof. 0076 The HDD 11 further includes an IEEE 1394 terminal 201-2. As shown in FIG. 9, when a network including an HDD 11P is established, the IEEE 1394 terminal 201-2 is connected to an IEEE 1394 terminal 201-1P of the HDD 11P via an IEEE 1394 connector 3P1. An IEEE 1394 terminal 201-2P of the HDD 11P is connected to the personal computer 1-2 via an IEEE 1394 connector 3P2. The number of IEEE 1394 terminals 201 of the HDD 11 can be freely set in accordance with the number of devices to be connected. 0077 Referring back to FIG. 8, a GUID storage unit 204 stores the GUID of the personal computer 1-1. A CPU 203 executes a predetermined program stored in a ROM 205 by using the GUID stored in the GUID storage unit 204. A memory 206 stores data required when the CPU 203 executes processing. A data storage unit 207 stores various data processed by the personal computer 1-1 and reads the stored data as required. 0078 The GUID storage unit 204 and the data storage unit 207 are connected to the CPU 203 via a bus 208. 0079 Next, the operation of the network system shown in FIG. 2 will be described with reference to a flowchart in FIG. 10. First, a case where the personal computer 1-1 requests access from the HDD 11 will be described. 0080 In step S1, the CPU 72 of the personal computer 1-1 starts the IEEE 1394 I/F program 70A, issues a command (a command for requesting access) called login request (LoginORB: login operation request block), and outputs the command to the HDD 11 via the IEEE 1394 connector 3. 0081 The LoginORB is a kind of operation request block (ORB), which is a command defined by SBP2. The ORB is issued by an initiator and is output to a target. The target performs a predetermined process based on the ORB, and after that, the target writes predetermined information regarding the process on the received ORB and returns the ORB to the initiator. 0082 FIG. 11 shows the format of the LoginORB. In the figure, each column indicates a bit of data, and each row has 32 bits. Also, in the figure, the leftmost bit in the top row is the most significant bit and the rightmost bit in the bottom row is the least significant bit (this is the same in FIGS. 12 and 13). When a row is not divided by a partition, the data region is variable. 0083 password stores password data registered in a device which wants to acquire access. password_length stores the length of data stored in the password. The password is optional. In this example, the password is not used, and thus they are omitted. 0084 When access is granted, data indicating that fact is stored in login_response of the LoginORB, and data indicating the length of data stored in the login_response is stored in login_response_length. In this case, data is written in the login_response and the login_response_length by the HDD 11. The login_response will be described in detail later with reference to FIG. 12. 0085 In n (notify), rq_fmt (request format), and function in the row under the login_response, data for specifying the type of ORB is stored. In this case, data indicating the LoginORB is stored therein. 0086 In x (exclusive), data indicating whether the requested LoginORB is for a plurality of initiators or for only the initiator requesting access is stored. reserved is provided for adding more commands in the future. reconnect stores data of the time required for reconnection. 0087 Data for specifying the destination device of LoginORB is stored in lun (logical unit number). In this case, data for specifying the HDD 11 is stored. 0088 When the command has been executed by the HDD 11, a status block (FIG. 13), which will be described later, is written in status FIFO. 0089 Referring back to FIG. 10, in step S11, the CPU 203 of the HDD 11 receives a Login request (LoginORB) transmitted from the personal computer 1-1 via the IEEE 1394 connector 3 and the IEEE 1394 interface 202-1, and allows the memory 206 to store the LoginORB. 0090 In step S12, the CPU 203 requests GUID from the personal computer 1-1 via the IEEE 1394 interface 202-1 and the IEEE 1394 connector 3. 0091 In step S2, the CPU 72 of the personal computer 1-1 receives the request for the GUID from the HDD 11. Then, in step S3, the CPU 72 reads the GUID of the personal computer 1-1 stored in the ROM 70 and transmits the GUID to the HDD 11 via the IEEE 1394 connector 3. 0092 In step S13, the CPU 203 of the HDD 11 receives the GUID of the personal computer 1-1 transmitted from the personal computer 1-1 via the IEEE 1394 interface 202-1. Then, in step S14, the CPU 203 reads the GUID stored in the GUID storage unit 204. 0093 Next, in step S15, the CPU 203 determines whether or not the GUID received in step S13 and the GUID read in step S14 match. When the GUIDs match, the process proceeds to step S16. In this example, the GUID storage unit 204 stores the GUID of the personal computer 1-1 Thus, it is determined that the GUIDs match in step S15, and the process proceeds to step S16. 0094 In step S16, the CPU 203 reads the LoginORB, which has been stored in the memory 206 in step S11, writes login_response and status_FIFO including data indicating granting of access in the LoginORB, so as to generate a LoginORB to be returned to the personal computer 1-1. 0095 Now, the details of the login_response shown in FIG. 11 will be described with reference to FIG. 12. 0096 Data indicating the data length of login_response is stored in length at the top of login_response. Data for identifying an initiator to which access is granted is stored in login_ID. In command_block_agent, data of the address of a register (control and state register (CSR)) for performing various operations is stored. reserved is provided for adding more commands in the future, as in the above-described LoginORB. 0097 reconnect_hold stores data of the time required for the target to ensure resources for the operation performed by the initiator to which access is granted. 0098 Next, status_block written in status_FIFO shown in FIG. 11 will be described with reference to FIG. 13. 0099 Data for identifying the type of ORB is stored in src. That is, in this case, data for indicating LoginORB is stored therein. Data for identifying the type of response is stored in resp. Data indicating whether or not the current target can receive a command is stored in d. 0100 In len, data indicating the number of pieces of information of an effective status_block stored in the status_FIFO is stored. Additional data corresponding to information stored in resp is stored in sbp_status. ORB_offset_hi, ORB_offset_lo, and r are used for specifying various address spaces. In command set-dependent, various data for each command is stored. 0101 Referring back to FIG. 10, in step S17, the CPU 203 of the HDD 11 outputs the LoginORB generated in step S16 to the personal computer 1-1 via the IEEE 1394 interface 202-1 and the IEEE 1394 connector 3. 0102 Accordingly, in step S4, the CPU 72 of the personal computer 1-1 receives the LoginORB input by the HDD 11 via the IEEE 1394 connector 3. 0103 Next, in step S5, the CPU 72 determines whether or not the received LoginORB includes login_response. If it is determined that login_response is included, the process proceeds to step S6, where the CPU 72 recognizes that access to the HDD 11 has been acquired. In this case, the Login ORB includes login_response, and thus the process proceeds to step S6, where it is recognized that access to the HDD 11 has been acquired. 0104 In this way, the personal computer 1-1, which includes the HDD 11, can acquire access to the HDD 11. 0105 Next, processes performed when the personal computer 1-2 requests access from the HDD 11 will be described with reference to the flowchart in FIG. 10. 0106 Herein, the processes in steps S1 to S4 and steps S11 to S14 are the same as in the case where the personal computer 1-1 requests access to the HDD 11, and thus the corresponding description will be omitted. 0107 In step S15, the CPU 203 of the HDD 11 determines that the GUID received in step S13 (the GUID of the personal computer 1-2) and the GUID read from the GUID storage unit 204 (GUID of the personal computer 1-1) do not match, and the process proceeds to step S18. 0108 In step S18, the CPU 203 reads the LoginORB stored in the memory 206 in step S11 and generates a LoginORB which does not include login_response, that is, a LoginORB in which only a status block is written in Status_FIFO of the LoginORB. Then, in step S17, the LoginORB is output to the personal computer 1-2 via the IEEE 1394 interface 202-1 and the IEEE 1394 connector 3. 0109 Accordingly, in step S4, the personal computer 1-2 receives the LoginORB input from the HDD 11 via the IEEE 1394 connector 3 and the IEEE 1394 cable 4. 0110 Next, in step S5, the personal computer 1-2 determines that the received LoginORB does not include login_response. Then, in step S7, the personal computer 1-2 recognizes that it has failed to acquire access to the HDD 11. 0111 As described above, the personal computer 1-2 cannot acquire access to the HDD 11. That is, even if the personal computer 1-2 requests access from the HDD 11 earlier than the personal computer 1-1, access to the HDD 11 is not granted to the personal computer 1-2. 0112 FIG. 14 is an example of the configuration according to a second embodiment of a network system using the present invention. 0113 This system includes an HDD 301 instead of the HDD 11 shown in FIG. 2. The other parts are the same as in FIG. 2, and thus the corresponding description will be omitted. 0114 The HDD 301 includes a switch 311, which is set to a storage mode or a general mode by user's operation. 0115 FIG. 15 shows an example of the configuration of the HDD 301. The HDD 301 further includes a detecting unit 321 in addition to the elements of the HDD 11 shown in FIG. 8. 0116 The detecting unit 321 detects that the switch 311 is set to the storage mode or the general mode and notifies the detection result to the CPU 203. 0117 In this case, a predetermined GUID is stored in the GUID storage unit 204 in a process described later. Thus, GUID is not stored when the HDD 301 is shipped. Also, the GUID storage unit 204 stores a predetermined password. 0118 Next, the operation of the network system shown in FIG. 14 will be described with reference to the flowchart in FIG. 16. First, a case where the HDD 301 is requested access for the first time is described. Herein, the personal computer 1-1 requests access. The switch 311 of the HDD 301 is set to the storage mode. 0119 In step S21, the personal computer 1-1 starts the IEEE 1394 I/F program 70A, issues LoginORB (FIG. 11) including a password, and outputs the LoginORB to the HDD 301 via the IEEE 1394 connector 3. The password included in the LoginORB is set, for example, by a user in advance. 0120 Next, in step S31, the CPU 203 of the HDD 301 receives the Login request (LoginORB) input by the personal computer 1-1 via the IEEE 1394 connector 3 and the IEEE 1394 interface 202-1, and allows the memory 206 to store the LoginORB. 0121 In step S32, the CPU 203 determines whether or not the password included in the received LoginORB and the password stored in the GUID storage unit 204 match. When it is determined that the passwords match, the process proceeds to step S33. 0122 In step S33, the CPU 203 determines that the switch 311 is set to the storage mode or the general mode via the detecting unit 321. When the switch 311 is set to the storage mode, the process proceeds to step S34. In this case, the switch mode is set to the storage mode, and thus the process proceeds to step S34. 0123 In step S34, the CPU 203 requests a GUID from the personal computer 1-1 via the IEEE 1394 interface 202-1 and the IEEE 1394 connector 3. 0124 The CPU 72 of the personal computer 1-1 determines whether or not the GUID is requested from the HDD 301 in step S22. When it is determined that the GUID is requested, the process proceeds to step S23. 0125 In step S23, the CPU 72 reads the GUID of the personal computer 1-1 stored in the ROM 70 and transmits the GUID to the HDD 301 via the IEEE 1394 connector 3. 0126 The CPU 203 of the HDD 301 receives the GUID of the personal computer 1-1 via the IEEE 1394 interface 202-1 in step S35. 0127 Next, in step S36, the CPU 203 determines whether or not a GUID is stored in the GUID storage unit 204. If it is determined that a GUID is not stored, the process proceeds to step S37. In this case, a GUID is not stored in the GUID storage unit 204, and thus the process proceeds to step S37. 0128 In step S37, the CPU 203 allows the GUID storage unit 204 to store the GUID received in step S35. 0129 Next, in step S38, the CPU 203 reads the LoginORB stored in the memory 206 in step S31, writes login_response and status_FIFO including data indicating granting of access in the LoginORB so as to generate a LoginORB to be returned to the personal computer 101. Then, in step S39, the CPU 203 outputs the LoginORB to the personal computer 1-1 via the IEEE 1394 interface 202-1 and the IEEE 1394 connector 3. 0130 Accordingly, in step S24, the CPU 72 of the personal computer 1-1 receives the LoginORB input by the HDD 301 via the IEEE 1394 connector 3. Then, in step S25, the CPU 72 determines whether or not the received LoginORB includes login_response. 0131 In this case, the received LoginORB includes the login_response, and thus the process proceeds to step S26, where the CPU 72 recognizes that it has acquired access to the HDD 301. 0132 In step S32, if it is determined that the passwords do not match, the process proceeds to step S42, where the CPU 203 of the HDD 301 generates a LoginORB which does not include login_response. Then, in step S39, the CPU 203 transmits the LoginORB to the personal computer 1-1. That is, the personal computer 1-1 cannot acquire access to the HDD 301. At this time, in the personal computer 1-1, the process of step S23 is skipped. 0133 Next, as described above, processes performed when the personal computer 1-1 accesses the HDD 301 again after the personal computer 1-1 has acquired access to the HDD 301 will be described with reference to the flowchart in FIG. 16. The switch 311 is set to the storage mode also in this example. 0134 Herein, the same processes as in the above are performed in steps S21 to S26, steps S31 to S35, and steps S38, S39, and S42, and thus the corresponding description will be omitted. 0135 In step S36, the CPU 203 of the HDD 301 determines that the GUID (GUID of the personal computer 1-1) is stored in the GUID storage unit 204, and reads the GUID in step S40. 0136 Next, in step S41, the CPU 203 determines whether or not the GUID received in step S35 and the GUID read from the GUID storage unit 204 in step S40 match. When it is determined that the GUIDs match, the process proceeds to step S38. In this case, the GUID of the personal computer 1-1 is received in step S35 and the GUID of the personal computer 1-1 is read from the GUID storage unit 204 in step S40. Therefore, the process proceeds to step S38. 0137 That is, in this case, the HDD 301 generates a LoginORB including login_response and the LoginORB is transmitted to the personal computer 1-1. Thus, the personal computer 1-1 can acquire access to the HDD 301 again. 0138 Next, processes performed when the personal computer 1-2 requests access from the HDD 301 will be described with reference to the flowchart shown in FIG. 16. Herein, the personal computer 1-1 has already acquired access to the HDD 301 by the above-described processes. The switch 311 is set to the storage mode. 0139 In step S21, the personal computer 1-2 starts the IEEE 1394 I/F program, issues a LoginORB including a password, and outputs the LoginORB to the HDD 301 via the IEEE 1394 cable 4 and the IEEE 1394 connector 3. The password included in the LoginORB is set by a user in advance. 0140 Next, in step S31, the HDD 301 receives the Login request (LoginORB) input via the IEEE 1394 connector 3 and the IEEE 1394 interface 202-1, and allows the memory 206 to store the LoginORB. 0141 In step S32, the HDD 301 determines whether or not the password included in the received LoginORB and the password stored in the memory 206 match. If it is determined that the passwords match, the process proceeds to step S33. 0142 In step S33, the HDD 301 determines that the switch 311 is set to the storage mode. Then, in step S34, the HDD 301 requests a GUID from the personal computer 1-2 via the IEEE 1394 interface 202-1 and the IEEE 1394 connector 3. 0143 In step S22, the personal computer 1-2 determines whether or not the GUID is requested by the HDD 301, and when it is determined that the GUID is requested, the process proceeds to step S23. 0144 In step S23, the personal computer 1-2 reads the stored GUID of the personal computer 1-2 and transmits the GUID to the HDD 301 via the IEEE 1394 cable 4 and the IEEE 1394 connector 3. 0145 In step S35, the HDD 301 receives the GUID of the personal computer 1-2 via the IEEE 1394 interface 202-1 and allows the memory 206 to store the GUID. 0146 Next, in step S36, the HDD 301 determines that the GUID (GUID of the personal computer 1-1) is stored in the GUID storage unit 204, and reads the GUID in step S40. 0147 Then, in step S41, the HDD 301 determines that the GUID received in step S35 (GUID of the personal computer 1-2) and the GUID read from the GUID storage unit 204 in step S40 (GUID of the personal computer 1-1) do not match, and the process proceeds to step S42. 0148 That is, the HDD 301 generates a LoginORB which does not include login_response and the LoginORB is transmitted to the personal computer 1-2. Therefore, access to the HDD 301 is not granted to the personal computer 1-2. 0149 Next, the operation of the network system shown in FIG. 14 in case where the switch 311 is set to the general mode will be described with reference to the flowchart shown in FIG. 16. 0150 In step S21, the personal computer 1 (personal computer 1-1 or 1-2) starts the IEEE 1394 I/F program, issues a LoginORB including a password, and outputs the LoginORB to the HDD 301. 0151 Then, in step S31, the HDD 301 receives a Login request (LoginORB) output from the personal computer 1 and allows the memory 206 to store the LoginORB. 0152 In step S32, the HDD 301 determines whether or not the password included in the received LoginORB and the password stored in the GUID storage unit 204 match. If it is determined that the passwords match, the process proceeds to step S33. 0153 In step S33, the HDD 301 determines that the switch 311 is set to the general mode and the process proceeds to step S43. 0154 In step S43, the HDD 301 determines whether or not it is the first time to receive the LoginORB. If the HDD 301 determines that it is the first time to receive the LoginORB, the process proceeds to step S44. 0155 In step S44, if a GUID is stored in the GUID storage unit 204, the HDD 301 deletes the GUID, and the process proceeds to step S38. That is, in this case, a LoginORB including login_response is generated and is transmitted to the personal computer 1. Thus, access to the HDD 301 is granted to the personal computer 1. 0156 On the other hand, in step S43, if it is determined that it is not the first time to receive the LoginORB, that is, if access has already been requested, the process proceeds to step S42. That is, in this case, a LoginORB which does not include login_response is generated and the LoginORB is transmitted to the personal computer 1. Thus, access to the HDD 301 is not granted to the personal computer 1. 0157 The series of processes described above can be executed by hardware and also by software. When the series of processes are executed by software, the program constituting the software is installed from a program storing medium to a computer incorporated into a dedicated hardware or a general-purpose personal computer in which various functions can be performed by installing various programs. 0158 The program storing medium includes package media, which are separated from the personal computer and which are distributed to users for providing users with the program, such as the magnetic disk 121 (including a floppy disk), the optical disk 122 (including compact disk read-only memory (CD-ROM) and digital versatile disk (DVD)), the magnetooptical disk 123 (including a mini-disk (MD)), and the semiconductor memory 124 (including memory stick) to which the program is recorded. 0159 In this description, the steps forming the program recorded in the program storing medium, that is, the processes performed in time-series according to the described order, may be performed in parallel or independently. 0160 Also, in this description, the system refers to the whole apparatus including a plurality of devices. 0161 Industrial Applicability 0162 According to the present invention, control can be adequately allowed to a control device which requests control.