Abstract:
A connection unit for a computer, which is connectable to a network, is configured such that in response to a receipt by the connection unit of a predetermined wake-up packet via the network, a predetermined signal is generated. Following which, in response to the predetermined signal, the receipt of the predetermined wake-up packet is persistently displayed utilizing a dedicated display. With these means, a user of the computer is enabled to recognize the fact execution of WOL has been carried out or attempted, without running a specific application (adapted for informing the user of the fact that WOL was executed) on the computer, or even where the computer is not connected to the connection unit.

Description:
BACKGROUND OF THE INVENTION 
   1. Technical Field 
   This invention relates to a connection unit such as an expansion unit for expanding functions of an information processing system such as a personal computer mounted thereon and, more particularly, to an expansion unit for offering a LAN connection environment to an information processing system mounted thereon. More specifically, this invention relates to an expansion unit for offering a WOL (Wake-up On LAN) history displaying function to an information processing system. 
   2. Description of the Prior Art 
   Recently, the term “network computing” frequently appears in a variety of media such as newspapers, periodicals and the like. “Network computing” literally means an environment, wherein a plurality of computers and/or peripheral devices are coupled together by a communication medium (whether it be a wired or wireless medium). Also, “network” means a communication network for transmitting data among computers. There are diverse forms of networks, which range from a local area type such as a LAN (Local Area Network) to a wide area type such as a public switched telephone network (PSTN), and further to the “Internet” that has grown into an enormous collection of global networks as a result of interconnecting respective servers. A computer system as a DTE (Data Terminal Equipment) is connected to a network via a DCE (Data Circuit-Terminating Equipment). A DCE is either one of a modem (Modulator/Demodulator), a TA (Terminal Adapter) and a LAN adapter (e.g., Ethernet card or token ring card) depending on whether the network involved is an analog type such as PSTN, ISDN (Integrated Services Digital Network) or a LAN. Also, a DTE may be a general purpose computer system (e.g., an IBM PC/AT compatible machine (“PC/AT” is a trademark of International Business Machines Corporation), besides any dedicated terminal connected to the network via a DCE. 
   A LAN is a smallest unit of a network, which is autonomously operated/managed by an independent organization such as a college or a research institution to cover a relatively narrow area such as a single campus or the like. Supported with the price reduction of communication equipment reflecting the evolution of semiconductor technologies and the enhanced functions of communication software, LANs have been primarily and deeply used in research/development arenas for the purpose of sharing computer resources, sharing/distribution of information and the like. 
   The forms of LANs are generally categorized as a peer-to-peer type and a client/server type. In the peer-to-peer LAN, interconnected DTEs have no master/slave relationship among them so that they are treated equally. More particularly, in the peer-to-peer LAN, there exists such relationship among the interconnected DTEs that allows each of them to share a resource of another DTE respectively, whereby a disk and/or a printer owned by a user of a given DTE may be used by another LAN user as it is. On the other hand, in the client/server LAN, a single machine on the LAN is dedicated to be a server, which is to be shared by other LAN users (i.e., clients). In the client/server LAN, the server for offering service and clients for accepting service are synchronized each other by using a remote procedure call (RPC) to continue respective processing. 
   Today, the client/server LAN that has general purpose personal computers (PCs) interconnected is becoming the mainstream of network computing. This is primarily intended for enjoying the advantages of this scheme as described below. 
   (1) Installing software that is necessary for each client PC, each user is allowed to freely perform his own work. (2) Data/files to be shared are placed on a server&#39;s side. Also, a printer is connected to the server such that each user can share it via the network. (3) Installing software such as groupware onto the server, it is possible to perform processing corresponding to a group work. 
   However, as a result of excessively distributing information toward a client&#39;s side (i.e., client PC is overgrown), it has been found problematic in that maintenance and/or management of the client system requires a vast amount of costs. For example, whenever an OS or an application is to be upgraded, there has been no way to avoid cumbersome manual works such as installation and/or setup for each PC. It is, therefore, mandatory to reduce costs of an entire network, i.e., total cost of ownership (TCO). 
   One of the known concepts for reducing TCO is to use a server for centrally managing software resources on a network. For example, by simply updating a program on the server, those programs available at clients&#39; sides are automatically updated. By centrally managing from the server&#39;s side in this way, it becomes possible to prevent any trouble due to an operational miss on a client&#39;s side from occurring, which will in turn lead to reduction of TCO. 
   As one of the techniques for reducing TCO, it is possible to apply WOL (“Wake-up ON LAN”) in such a way that a system configuration of a client&#39;s side can be managed via the network. By automatically activating each client system, which has been powered off, via the network during a convenient time zone such as at night where the office changes to an unattended environment, it becomes possible to install a new application onto each system or to replace an older one with a new one. 
   In order to implement WOL, it is essential that a DCE to be connected to a network or a LAN is provided with the WOL function. When a DTE as a user terminal is a general purpose computer system, a DCE is provided in the form of a LAN adapter card, for example. The adapter card is insertable into a “bus slot”, which is generally formed on a computer&#39;s system unit (at its mother board). 
   The WOL function is implemented by a function for automatically starting up a computer system via a network or a LAN. In  FIG. 6 , there is schematically shown a configuration of a WOL compatible computer system. A WOL compatible LAN adapter  610  is connected to a LAN and, upon recognition of a frame packet (hereafter called “wake-up packet”) for indicating activation (i.e., “Wake-up”) of the system that is currently in a stopped state, asserts a WOL signal  660  to the system&#39;s side. Also, the WOL compatible computer system is provided with an auxiliary power supply  625 , which continually feeds power to the LAN adapter  610  such that a WOL operation is enabled while the system itself is in a power-off state. Further, the computer system is provided with a WOL logic circuit  640 , which is responsive to detection of the WOL signal asserted by the WOL compatible LAN adapter  610  for issuing a power-on indication to a power supply circuit  620  for the entire system. 
   The term “expansion unit” means herein such equipment that is used for expanding a peripheral environment of a notebook PC by simply mounting the PC thereon. In  FIG. 7 , there is shown a manner of mounting a notebook PC  720  onto an expansion unit  710 . For ensuring portability, the notebook PC  720  is designed and manufactured to have a smaller size and a lighter weight at the sacrifice of its peripheral environment. For example, the notebook PC  720  is capable of accommodating a limited number of external storage devices alone, and only PC cards may be inserted therein since it has no bus slot for mounting an adapter card thereon. Note in this respect that it is extremely cumbersome for a user, who carries the notebook PC  720 , to attach/detach connection cables for a variety of equipment used in an office environment such as a printer, a CRT (Cathode Ray Tube) display, an external keyboard and the like. The expansion unit  710  is such equipment that offers the same working environment as a desktop PC whenever the notebook PC  720  is used in an office. For this purpose, the expansion unit  710  has a “Port Replication function” and a “Bus Expansion function”. 
   The port replication function is implemented by having extensions of connection port signals in the notebook PC  720 &#39;s system unit. If, at the expansion unit  710 &#39;s side, peripheral devices (not shown) such as a printer, a CRT display and an external keyboard are previously cable connected, a user will be allowed to immediately make use of these peripheral devices by simply mounting the notebook PC  720  onto the expansion unit  710 . Also, if these peripheral devices are kept connected to the expansion unit  710 , these peripheral devices will be immediately available to another notebook PC  720  mounted on the expansion unit  710  without worrying about the cumbersome works to attach/detach cables. Such a function for centrally managing cable connections may be called a “cable management function”. 
   On the other hand, the “bus expansion function” is implemented by having at the expansion unit  710 &#39;s side extensions of buses in the notebook PC  720 &#39;s system unit (e.g., a PCI (Peripheral Component Interconnect) bus as a local bus and an ISA (Industry Standard Architecture) bus as a system bus). The expansion unit  710  has a space for accommodating one or more external storage devices to be connected to a bus, along with one or more bus slots for mounting one or more adapter cards thereon. Attaching a HDD, a SCSI (Small Computer System Interface) adapter card and a LAN adapter card onto the expansion unit  710 , it is possible to offer a file subsystem or a network subsystem to a user of the notebook PC  720 . Incidentally, the expansion unit  710  may be called a “docking station”. Also, an expansion unit having the port replication function alone may be called a “port replicator”. 
   Generally, the expansion unit  710  is used in a “single user mode” or a “multi user mode”. The former means that a single PC user exclusively owns the expansion unit  710 , i.e., only a particular notebook PC is exclusively mounted on a single expansion unit  710 . On the other hand, the multi user mode means that a plurality of PC users share a single expansion unit  710 , i.e., a notebook PC of each user may be interchangeably mounted on the expansion unit  710 . In the multi user mode, it may frequently happen that policies and/or strategies differ from user to user. 
   Incidentally, an expansion unit per se is disclosed, for example, in JA patent application 5-181593 (JA patent publication 7-36577) and JA patent application 6-134124 (JA patent publication 8-6668), each being assigned to the present applicant. 
   Now, with reference to  FIG. 4 , operations of a prior system will be described. (1) In a first case where a note PC  409  is connected to a docking station  407 : A system administrator sends a WOL packet to a note PC system  410  for activating the system. While, at this point of time, a power supply for the notebook PC  409  of the note PC system  410  is in an off state, its LAN feature section is continually driven by an auxiliary power supply to wait for arrival of a WOL packet. Whenever a WOL packet sent from a server  403  via a network  401  arrives at the notebook PC system  410 , a signal (PME# or the like) for activating the system is asserted to start up the power supply for the note PC  409 , thereby activating the system. After the system is activated, the system administrator performs maintenance or the like of the note PC  409  using remote control software or the like and, subsequent to termination thereof, shuts down the system to complete a sequence of operations. 
   (2) In a second case where a note PC  409  is not connected to a docking station  405 : The system administrator sends a WOL packet to the docking station  405  for activating the system. Since, at this point of time, the note PC  409  is not connected to the docking station  405 , an auxiliary power supply for a LAN feature section within the docking station  405  is in an off state. Accordingly, even if a WOL packet is received, no event will occur at all. Because the note PC  409  is not activated despite sending of the WOL packet, the system administrator will resend the WOL packet. However, the same result will be iterated and, thus, operations will be terminated without completing the intended maintenance or the like. 
   In many occasions, such WOL operations are executed at night where the office changes to an unattended environment, thereby to prevent routine jobs from being obstructed. In the first case (1) above (where a computer is connected), if it is arranged to activate an application after starting up the system on the next morning to inform the execution of WOL, a user of the PC system  409  to be managed will be able to recognize that its maintenance or the like has been performed by the system administrator. However, with this approach, there is no way to know, before activating the system, whether or not any work such as maintenance has been carried out, nor are all applications designed to inform a user of the fact that such maintenance work has been performed. 
   Also, in the second case (2) above (where a computer is not connected), while the system administrator has required to manage the PC system  409 , nevertheless there is no way for a user of the PC system  409  to know such a situation. On the other hand, in either case (1) or (2) above, there is no way for a user of the PC system  409  to know any history that a malicious third party has either remotely activated or has attempted to remotely activate the system, which may lead to a security problem. 
   SUMMARY OF THE INVENTION 
   It is, therefore, an object of this invention to provide an information processing system for displaying a history of WOL operations to an information processing system that is provided with the WOL function. 
   It is another object of this invention to provide an information processing system that is capable of displaying whether or not the current system activation is caused by WOL. 
   This invention is concerned with a connection unit for a computer, said connection unit being connectable to a network comprising: (a) means, responsive to receipt of a predetermined packet via the network, for generating a predetermined signal; and (b) means, responsive to the predetermined signal, for displaying the receipt of the predetermined packet, whereby a user of said computer is enabled to recognize the fact that execution of WOL has been carried out or attempted, without running an application on said computer (adapted for informing the user of the fact that WOL was executed), or even where the computer is not connected to the connection unit. 
   The expansion unit for an information processing system of this invention is provided with a network adapter (e.g., LAN adapter) for connecting to a network. This network adapter has the automatic startup function (so-called WOL (Wake-up ON LAN)). That is, the network adapter is continually fed power from a power supply circuit (e.g., auxiliary power supply) even when the expansion unit (and an information processing system mounted thereon) are powered off, whereby it generates a wake signal (WOL signal) in response to receipt of a wake-up packet via the network, and displays the receipt of the wake-up packet in a manner recognizable by a user. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a block diagram schematically showing a hardware configuration of a typical personal computer (PC) adapted for implementing this invention; 
       FIG. 2  is a diagram schematically showing a hardware configuration of an expansion unit that is provided for practicing this invention; 
       FIG. 3  is a system configuration diagram centering around the WOL function; 
       FIG. 4  is a diagram showing an entire network adapted for practicing this invention; 
       FIG. 5  is a flowchart illustrating a WOL sequence (first embodiment) that is cooperatively performed by a computer&#39;s system unit and expansion unit; 
       FIG. 6  is a diagram schematically showing a configuration of a WOL compatible computer system; 
       FIG. 7  is a schematic diagram showing a computer and an expansion unit adapted for practicing this invention; 
       FIG. 8  is a circuitry diagram showing a WOL display circuit and its associated circuits within a computer system adapted for practicing this invention; and 
       FIG. 9  is a flowchart illustrating a WOL sequence (second embodiment) that is cooperatively performed by a computer&#39;s system unit and expansion unit. 
   

   DETAILED DESCRIPTION 
   Now, with reference to the drawings, an embodiment of this invention will be described in detail. 
   A. Hardware Configuration of Computer System 
   In  FIG. 1 , there is schematically shown a hardware configuration of a typical personal computer (PC)  100 . An example for implementing this invention is a notebook PC, which conforms to the specifications of OADG (PC Open Architecture Developer&#39;s Group) and incorporates an operating system (OS) such as “Windows95, 98” of Microsoft Corp. or “OS/2” of IBM Corp. This notebook PC  100  is provided with a docking connector  150  on a rear side of its system unit, for example, for use in electrically connecting to an expansion unit  200  (to be described below) as a connection unit. Hereinafter, each component will be described. 
   CPU  11  acting as a main controller executes a variety of programs under the control of OS. CPU  11  may be a CPU chip called “Pentium”, “MMX Technology Pentium”, “Pentium II”, or “Pentium Pro” made by Intel Corp., or alternatively it may be another company&#39;s compatible CPU. 
   CPU  11  interconnects with each hardware component (to be described below) through a hierarchical bus structure of three levels, which comprises a processor bus  12  directly coupled to its own external pins, a PCI (Peripheral Component Interconnect) bus  16  as a local bus and an ISA (Industry Standard Architecture) bus  18  as a system bus. 
   Processor bus  12  and PCI bus  16  are interconnected by a bridge circuit (host-PCI bridge)  13 . The bridge circuit  13  of the present embodiment comprises a memory controller for controlling access operations to a main memory  14 , a data buffer for absorbing a speed difference between both buses  12  and  16 . 
   The main memory  14  is a writable memory used as read-in areas of executed programs of CPU  11  or working areas for writing processed data of the executed programs. In general, the main memory  14  comprises a plurality of DRAM (dynamic RAM) chips such that its basic capacity is typically 32 MB and extendable up to 256 MB. The executed programs include an OS such as “Windows98”, a variety of device drivers for manipulating peripheral devices under hardware control, application programs adapted for use in specific jobs and firmware stored in a ROM  17  (to be described below). 
   L2 (Level 2)-cache  15  is a high speed memory for absorbing CPU  11 &#39;s access time to the main memory  14  and is used for temporarily storing limited code and data to be frequently accessed by CPU  11 . In general, L2-cache  15  comprises SRAM (static RAM) chips and its typical capacity is 512 KB. 
   PCI bus  16  is a type of bus that enables to transfer data at a relatively high rate (bus width: 32/64 bits, maximum operating frequency: 33/66 MHz, maximum data transfer rate: 132/264 MBps), and is used for connecting relatively fast PCI devices such as a video controller  20  and a card bus controller  23 . As well known in the art, the PCI architecture is based on the proposal of Intel Corp. and implements the so-called “PnP” (Plug and Play) function. 
   The video controller  20  is a dedicated controller for actually processing drawing instructions from CPU  11 . In operation, it temporarily stores the processed drawing information into a video memory (VRAM)  21 , reads the drawing information from VRAM  21  and provides the same as a video output to a liquid crystal display (LCD)  22 . Also, the video controller  20  is capable of converting a video signal to an analog form using its associated digital-analog converter (DAC). The analog video signal so converted is output to a CRT port  51  via a signal line  20   a . Also, the signal line  20   a  is branched halfway toward the docking connector  150 . 
   The card bus controller  23  is a dedicated controller for directly coupling those bus signals on PCI bus  16  to an interface connector (card bus) of a PC card slot  24 . This PC card slot  24  may be provided at a wall surface P-P′ of the computer  100 &#39;s system unit for accepting a PC card (not shown), which conforms to the industry standard (e.g., “PC Card Standard 951”) defined by PCMCIA (Personal Computer Memory Card International Association)/JEIDA (Japan Electronic Industry Development Association). 
   At a substantial end of PCI bus  16 , there is provided a bridge circuit (PCI-PCI bridge)  60 . This bridge circuit  60  is interconnecting a secondary PCI bus at the downstream of PCI bus (primary PCI bus)  16 . The secondary PCI bus is provided internally to the expansion unit  200  that is connected via the docking connector  150 . Incidentally, if any PCI bus is not connected at the downstream, the bridge circuit  60  is arranged to disable each PCI bus signal at its substantial end respectively. 
   Also, PCI bus  16  and ISA bus  18  are interconnected by a bridge circuit (PCI-ISA bridge)  19 . This bridge circuit  19  of the present embodiment is constructed to contain a DMA controller, a programmable interrupt controller (PIC) and a programmable interval timer (PIT). DMA controller is a dedicated controller for executing a data transfer between a peripheral device (e.g., FDD) and the main memory  14  without an intervention of CPU  11 . PIC is a dedicated controller that is responsive to an interruption request (IRQ) from a peripheral device for causing a predetermined program (interrupt handler) to be executed. PIT is an apparatus for generating timer signals at predetermined frequencies that are programmable. 
   Also, the bridge circuit  19  of the present embodiment is provided with an IDE interface for connecting external storage devices, which conform to the IDE (Integrated Drive Electronics). To this IDE interface, an IDE hard disk drive (HDD)  25  and an IDE CD-ROM drive  26  may be connected through ATAPI (AT Attachment Packet Interface). In place of IDE CD-ROM drive  26 , another type of IDE device such as a DVD (Digital video Disc or Digital Versatile Disc) drive may be connected. An external storage device such as HDD  25  and/or CD-ROM drive  26  is accommodated in the so-called “media bay” or “device bay” within the computer  100 &#39;s system unit. These standard external storage devices may be mounted interchangeably with another equipment such as an FDD and/or a battery pack, or they may be mounted exclusively of such equipment. 
   Further, the bridge circuit  19  of the present embodiment contains therein a USB (Universal Serial Bus) route controller for connecting a USB as a general purpose bus, and has a USB port. This USB port  27  is provided, for example, at the wall surface Q-Q′ of the computer  100 &#39;s system unit. USB supports the “hot plug function” that allows a new peripheral device (USB device) to be attached/detached without shutting down its power, as well as the “Plug and Play function” that allows a newly connected peripheral device to be automatically recognized and a system configuration to be set up again accordingly. To a single USB port, up to 63 USB devices can be connected in a daisy-chain manner. Exemplary USB devices include, but not limited to, a keyboard, a mouse, a joystick, a scanner, a printer, a modem, a display monitor and a tablet. 
   ISA bus  18  has a slower data transfer rate than PCI bus  16  (bus width: 16 bits, maximum data transfer rate: 4 Mbps) and, thus, it is used for connecting relatively slower peripheral devices such as ROM  17 , a real time clock (RTC)  29 , an I/O controller  30 , a keyboard/mouse controller (KMC)  34  and an audio CODEC  37 . 
   ROM  17  is a nonvolatile memory, which permanently stores code groups (BIOS: Basic Input/Output System) for controlling I/O operations of respective hardware components such as a floppy disk drive (FDD)  31 , in addition to firmware such as a POST (Power On Self Test) program to be executed at a power-on time. 
   RTC  29  is a device for measuring the current time-of-day. In general, RTC  29  is mounted on a single chip with a CMOS memory (not shown). Typically, this CMOS memory is used for temporarily storing critical information to security/safety of the system  100  such as system configuration information (setup values of BIOS) and a power-on password. RTC/CMOS  29  is backed up by a reserve battery (normally a coin battery, not shown) so that the measured/stored contents are not lost even after the system  100  goes to its power-off state. In the present embodiment, such information indicating whether the system  100  permits or prohibits the automatic startup via a network, i.e., WOL (Wake-up ON LAN) is also written into RTC/CMOS  29 . 
   I/O controller  30  is a peripheral controller for controlling operations of FDD  31 , I/O operations of parallel data (PIO) via a parallel port  55 , and I/O operations of serial data (SIO) via a serial port  56 . A printer may be connected to the parallel port  55 , whereas a modem may be connected to the serial port  56 . A parallel signal line  30   a  not only extends to the parallel port  55  but also branches toward the docking connector  150 . Further, a serial signal line  30   b  not only extends to the serial port  56  but also branches toward the docking connector  150 . Similarly, a signal line  30   c  for the FDD  31  not only extends to an external FDD port  57  but also branches toward the docking connector  150 . 
   The keyboard/mouse controller (KMC)  34  is a dedicated controller for capturing input scan codes from a keyboard  35 , or input coordinate values from a TrackPoint  36  as computer data. Track Point  36  is a pointing device of a stick like shape, which is embedded near the center of the keyboard unit. A signal line  34   a  for the keyboard  35  and a signal line  34   b  for the mouse not only extend to an external keyboard port  53  and an external mouse port  54  but also branch toward the docking connector  150  respectively. 
   The audio CODEC  37  is a dedicated controller for performing input/output of audio signals, which comprises a CODEC circuit (COder-DECoder: namely AD, DA converters provided with mixing functions) for digitally recording/reproducing audio signals. The audio CODEC  37  is also capable of processing MIDI (Musical Instrument Digital Interface) data. A signal line  37   a  for MIDI is assigned to a portion of the docking connector  150 . Further, a signal line  37   b  for audio output not only extends to a line output terminal  52  but also branches toward the docking connector  150 . 
   An analog switch  61  is operated to connect/disconnect the end of ISA bus  18  to/from the docking connector  150 . For example, when a secondary PCI bus (to be described below) is connected via the docking connector  150 , the analog switch  61  disables an end of each bus signal, thereby to disconnect ISA bus  18  from the docking connector  150 . On the other hand, when ISA bus  18  is extended via the docking connector  150 , the analog switch  61  enables an end of each signal line, thereby to connect ISA bus  18  to the docking connector  150 . 
   A DC inlet  71  is a jack for accepting an AC adapter that converts an external AC power source to a DC voltage. A DC/DC converter  70  drops/regulates the external DC voltage accepted via the DC inlet  71  and feeds its outputs to each component within the system  100 . In case of accepting power from the expansion unit  200 &#39;s side, it is fed to the DC/DC converter  70  via a power line  70   a.    
   As shown, each bus signal of PCI bus  16 /ISA bus  18 , as well as other port signals  20   a ,  30   a ,  30   b , . . . , and power line  70   a  are assigned to respective connector pins of the docking connector  150 . Electrical and mechanical specifications of the docking connector  150  are matching with those of docking connector  250  provided at the expansion unit  200 &#39;s side. By docking the system  100  with the expansion unit  200 , each bus signal of PCI bus  16 /ISA bus  18 , as well as other port signals  20   a ,  30   a ,  30   b  on the computer  100 &#39;s system unit may be expanded within the expansion unit  200 . 
   Incidentally, the broken line Q-Q′ in  FIG. 1  is imaging the rear side of the notebook PC  100 &#39;s system unit. The notebook PC  100  is connected to the expansion unit  200  at the docking connector  150  of its rear side. As a result of this connection at the rear side, respective ports  51 ,  52 ,  53 , . . . provided at the rear side are concealed by the housing of the expansion unit  200  and they become unavailable for use. However, this does not raise any problems since each external device is available by means of the port replication function (aforementioned) of the expansion unit  200 . 
   Incidentally, additional electronic circuits or the like other than those shown in  FIG. 1  are required to construct the computer system  100 . However, these components are not described in the present specification, since they are well known in the art and yet they do not pertain to the gist of this invention. Also, it should be noted that for brevity of the drawings, only a portion of the connections between the illustrated hardware blocks is shown in the drawings. 
   B. Hardware Configuration of Expansion Unit 
   In  FIG. 2 , there is schematically shown a hardware configuration of the expansion unit  200  that is provided for practicing this invention. The expansion unit  200  is provided with a communication adapter such as a LAN adapter card or the like as a network subsystem, whereby a user of the notebook PC  100  is enabled to enjoy a network environment such as LAN or the like by simply docking the PC  100  with the expansion unit  200 . It is assumed that the LAN adapter of the present embodiment has the WOL (Wake-up ON LAN) function. 
   The expansion unit  200  is provided with the docking connector  250 , which has electrical and mechanical specifications compatible with those of the docking connector  150  provided at the computer  100 &#39;s system unit, thereby to accept all of the bus signals and port signals via the connectors  150 ,  250 . 
   CPU  211  at the expansion unit  200 &#39;s side (DockCPU) is a main controller for coordinating operations of each component within the unit  200 . DockCPU  211  contains a RAM (not shown) to be used as working areas and a ROM (not shown) for storing an executable program code (firmware). DockCPU  211  controls operations of various components, including but not limited to an LCD indicator  212  for displaying states of the unit  200 , an eject lock  213  for mechanically prohibiting a removal of the computer  100 &#39;s system unit and a beeper  214  for generating an operational alert sound. 
   From the computer  100 &#39;s system unit (i.e., CPU  11 ), DockCPU  211  appears to be one of the peripheral devices connected to a bus, and it contains an I/O accessible I/O register. A portion of the I/O register is used as a WOL state register (to be described below). Incidentally, DockCPU  211  is fed power by the auxiliary power supply even when the computer  100  and the expansion unit  200  have been powered off. 
   EEPROM  215  is a rewritable, nonvolatile memory. EEPROM  215  is used for saving a small amount of data (such as a serial number of the expansion unit  200 , a user&#39;s password, system configuration information and the like) for assuring security/system operations at the time of docking/undocking of the computer  100 &#39;s system unit. The stored content of EEPROM  215  is referable to DockCPU  211  and/or the computer  100 &#39;s system unit. 
   A DC/DC converter  272  is a device for dropping/regulating an external DC voltage inputted via a DC inlet  271  and for distributing power toward both of the expansion unit  200  and the computer  100 &#39;s system unit. The DC inlet  271  is arranged to accept an AC adapter for converting an commercial AC voltage to a DC voltage. Note that the DC/DC converter  272  of the present embodiment includes the auxiliary power supply (to be described below) for continually feeding power to DockCPU  211  and a LAN adapter  300  even when the computer  100 &#39;s system unit and the expansion unit  200  have been powered off. 
   All of the port signals and the like accepted via the docking connector  250  branch toward a CRT port  251 , a line output terminal  252 , an external keyboard port  253 , an external mouse port  254 , a parallel port  255 , a serial port  256  and a MIDI port  260  respectively. Also, to an FDD signal line, an FDD  232  is connected. 
   To a secondary PCI bus  216  that is expanded at the expansion unit  200 &#39;s side, those devices requiring relatively faster data transfers such as a SCSI (Small Computer System Interface) controller  220  and a card bus controller  223  are connected. 
   The SCSI controller  220  is a dedicated controller for performing a protocol conversion between PCI-SCSI, and a SCSI bus appears outside of the unit  200  at a SCSI port  220 A. To the SCSI port  220 A, SCSI external devices are connected by a SCSI cable in a daisy chain manner. Examples of the SCSI devices are an HDD, an MO drive, a DVD drive, a printer, a scanner and the like. 
   Similarly to the aforesaid hardware component  23 , the card bus controller  223  is a dedicated controller for directly coupling PCI bus signals to a card slot  24 . 
   Also, at the end of PCI bus  216 , there are provided one or more PCI bus slots  216 A. To one of the PCI bus slots  216 A, a PCI compatible expansion adapter card may be mounted. In the present embodiment, at least the LAN adapter  300  with the WOL (Wake-up ON LAN) function is mounted on one of the bus slots  216 A. The LAN adapter  300  is continually kept in its operable state by means of the auxiliary power source, thereby to assert a WOL signal in response to receipt of a wake-up packet via a network (to be fully described below). 
   Within the expansion unit  200 , there is also provided a secondary ISA bus  218 . The secondary ISA bus  218  is interconnected with the secondary PCI bus  216  by means of a bridge circuit (PCI-ISA bridge)  219 . Provision of the secondary ISA bus  218  is intended to inherit the plentiful ISA legacies. 
   The bridge circuit  219  is configured in substantially the same manner as the aforesaid hardware component  18 . The bridge circuit  219  includes an IDE interface for connecting an IDE device  231  such as an HDD and/or a CD-ROM drive. The IDE device  231  may be interchangeably accommodated in a “media bay” within the expansion unit  200  along with the FDD  232 . 
   Further, at the end of the secondary ISA bus  218 , there are provided one or more ISA bus slots  218 A. To one of the ISA bus slots  218 A, an ISA compatible expansion adapter card may be mounted. 
   While  FIG. 2  shows a type of the expansion unit  200  that extends a PCI bus, the expansion unit  200  is not limited thereto. For example, it may be another type of an expansion unit that extends an ISA bus. In an extreme case, it may be a certain type of an expansion unit that extends only the LAN adapter card  300  with the WOL function. 
   C. Network Subsystem for Implementing WOL Function 
     FIG. 3  is a system configuration diagram centering around the WOL (Wake-up ON LAN) function of a network subsystem. In order to implement security for the WOL function, at the expansion unit  200 &#39;s side, cooperative actions of DockCPU  211  and the LAN adapter  300  are essential. DockCPU  211  and the LAN adapter  300  are continually fed power by an auxiliary power supply within a DC/DC converter  370  and, thus, they are kept in their operable states even when the computer  100 &#39;s system unit and/or the expansion unit  200  have been powered off (aforementioned). 
   In the present embodiment, the LAN adapter  300  is provided to the expansion unit  200  in the form of a PCI compatible adapter card (aforementioned). The LAN adapter  300  has the WOL function and generates a WOL signal to DockCPU  211 . When the LAN adapter  300  receives a packet frame or a wake-up packet representing a power-on indication via the network while the expansion unit  200  is being powered off, it responds thereto and asserts a WOL signal. Incidentally, the wake-up packet is generated on the network by a server machine, for example, which manages the entire network. 
   DockCPU  211  operates in accordance with the firmware that is stored in its internal ROM. From the computer  100 &#39;s system unit, DockCPU  211  appears to be one of the peripheral devices, and it contains an I/O register that is I/O accessible via the bus  16  (or  18 ). A portion of the I/O register is allocated to a WOL state register. To the WOL state register, such information indicating whether the system  100  permits or prohibits automatic startup by WOL is written. CPU  11  on the computer  100 &#39;s system unit is capable of permitting or prohibiting WOL by means of writing a predetermined value into this WOL state register. 
   DockCPU  211  operates in response to assertion of the WOL signal. If a value of the WOL state register indicates permission of WOL, DockCPU  211  asserts a power-on indication, i.e., a power-on signal to the computer  100 &#39;s system unit. Conversely, if a value of the WOL state register indicates prohibition of WOL, DockCPU  211  ignores the WOL signal and does not assert a power-on signal to the computer  100 &#39;s system unit. In other words, the WOL state register has a function for masking the WOL signal. 
   Also, on the computer  100 &#39;s system unit, CPU  11  executes firmware stored in ROM  17 , for example, to implement security for the WOL function. An example of this firmware is POST (Power On Self Test: self-diagnostic program) as an activation sequence that is executed by the system  100  at its power-on time. 
   As described above, the CMOS memory  29  not only stores critical information to security/safety of the system  100  in a nonvolatile manner but also such information of network security indicating that automatic startup by WOL is permitted or prohibited. By way of example, if a predetermined utility program is executed on the system  100  to set up “WOL permission”, its related information is written into the CMOS memory  29 . Conversely, if “WOL non-permission (prohibition)” is set up, its related information is written into the CMOS memory  29 . This information of WOL permission/prohibition is saved and it is referred to at the time of executing the startup sequence, for example (to be described below). 
   The DC/DC converter  70  on the side of the computer  100 &#39;s system unit may be fed power from either an AC adapter that is attached to the computer  100 &#39;s system unit or the DC/DC converter  370  on the side of the expansion unit  200 . In addition to starting/stopping power-on of the computer  100 &#39;s system unit in response to manipulation of its power switch (not shown), the DC/DC converter  70  responds to assertion of a power-on signal from DockCPU  211  for starting power-on of the computer  100 &#39;s system unit. Also, it shuts down the power supply for the computer  100 &#39;s system unit in accordance with an instruction from CPU  11 . 
   Incidentally, an implementation of a WOL sequence of this invention (to be described below) does not depend on network topology of a LAN. The LAN may be Ethernet, token ring or another network scheme. 
   D. WOL Sequence 
   Up to the previous section, we have described a hardware configuration adapted for implementing this invention. In this section, we will now describe a sequence of the WOL function in detail that is implemented by cooperative operations of the computer  100 &#39;s system unit and the network subsystem on the side of the expansion unit  200 . 
   In  FIG. 4 , there is shown an entire network that includes one embodiment of this invention. A note type PC is not connected to a docking station (expansion unit) # 1  ( 405 ), whereas a note type PC  409  is connected to a docking station (expansion unit) # 2  ( 407 ). Each of the docking stations # 1  ( 405 ) and # 2  ( 407 ) is connected to a network  401  such as token ring type or the like via a communication adapter and a communication cable. To this network  401 , a server  403  and the like are connected as well. 
   The server  403  is capable of sending a WOL packet to the docking station # 1  ( 405 ) or # 2  ( 407 ) that supports the WOL (Wake-up ON LAN) function, whereas the docking station # 1  ( 405 ) or # 2  ( 407 ) is capable of receiving the WOL packet sent from the server  403  and performing wake-up (i.e., power-on). The server  403  sends a WOL packet to a note type PC (alternatively called “note PC”) during a convenient time zone such as midnight, where a user of the note PC is unlikely to use the same, for causing the note PC to be remotely powered on, thereby attempting to update all kinds of software stored in the note PC such as applications and/or BIOS. 
   In  FIG. 5 , there are shown cooperative operations (first embodiment) in the form of a flowchart, which are performed by the computer  100 &#39;s system unit (or  409 ) and the expansion unit  200  (or  407 ) upon receipt of a WOL packet. It is assumed, however, that the LAN adapter  300  and DockCPU  211  are kept in their operative states by means of the auxiliary power supply, whereas other components are powered off. 
   If the LAN adapter  300  receives a wake-up packet via the network (step S 20 ), it asserts a WOL signal (step S 22 ). The wake-up packet is generated on the network by a server machine, for example, which manages the entire network. 
   In response to the WOL signal, the WOL indicator is turned on to indicate that the WOL packet has been received by the docking station (step S 23 ). By this operation, it becomes possible for a user of the PC system to directly recognize that the WOL packet has arrived. 
   Also, as a condition for turning on the WOL indicator, it is possible to use a logical AND operation of “WOL signal&#39;s generation” and “no computer being connected to the docking station”. That is, in this case, the WOL indicator is turned on only if the docking station receives a WOL packet while no computer is connected to the docking station, whereas the WOL indicator is not turned on if the docking station receives a WOL packet while a computer is connected to the docking station. 
   DockCPU  211  asserts a power-on signal (step S 30 ). On the side of the computer  100 &#39;s system unit, in response to assertion of the power-on signal, POST program is executed in the same manner as the normal power-on time and, subsequent thereto, the computer  100 &#39;s system unit enters into its operable state (step S 32 ). 
   Then, processing requested from the server by means of WOL packets or the like is performed (step S 34 ). For example, such processing may include updating of application programs, OS and/or BIOS stored in a nonvolatile memory and/or a hard disk apparatus within the computer  100 . 
   After completing such processing requested from the server by means of WOL packets, the computer  100 &#39;s system unit performs power-off processing (step S 36 ) and, then, a sequence of processing is terminated (step S 38 ). 
   In  FIG. 6 , there is shown a computer system  600 , which comprises a docking station as an expansion unit of this invention combined with a system unit  630 . Aside from the system unit  630 , the docking station comprises a power supply circuit  620  including an auxiliary power supply  625  that is continually powered on as described with reference to  FIG. 3 , a WOL compatible LAN adapter  610 , a WOL logic circuit  640 , a WOL display circuit  650  and the like. 
   The auxiliary power supply  625  continually feeds power to the WOL compatible LAN adapter  610 , WOL logic circuit  640 , WOL display circuit  650  and the like even when the system unit  630  is being powered off. The WOL compatible LAN adapter  610  is connected to a network such as a LAN and if it receives a WOL packet sent from a server connected to the same network, it will responds to the WOL packet for generating a WOL signal  660 . 
   Upon receipt of the WOL signal  660 , the WOL logic circuit  640  outputs a power-on indication signal  690  to the power supply circuit  620 , thereby causing the power supply circuit  620  to start power feeding to the system unit  630 . Also, the WOL display circuit  650  responds to receipt of the WOL signal  660  for displaying the fact that the a WOL packet has been received in a manner recognizable to a user. 
   In  FIG. 7 , there is shown a docking station  710  as an expansion unit and a note type PC  720  as a computer connected to the docking station  710 , which comprise one embodiment of this invention. This docking station  710  and the note type PC  720  are connected together via a connector  730 . 
   In this drawing, there is shown a WOL display means  701 , which is a portion of the WOL display circuit  650  shown in FIG.  6 . The WOL display means  701  may be comprised of a light emitting element such as an LED (light emitting diode) or another element so long as it is recognizable to a user. Using a conventional LED that emits an orange or green color, a user is able to immediately know receipt of a WOL packet by noticing the LED that emits an orange or green colored light. 
   As an example, it is preferable to describe characters such as “Wake on LAN”  703 , “Wake-up packet received” or an icon at a periphery of the WOL display means  701  so that a user can readily understand the situation at a glance, but it is not necessarily required to provide such character displays or the like. Also, in case of using a light emitting element such as an LED or the like as the WOL display means  701 , it is possible to exploit a “method of continuously turning on LED” or a “method of flashing LED at a regular interval” as a manner for showing receipt of a WOL packet. 
   Further, while  FIG. 7  shows the WOL display means  701  alone, it is possible to add a dock state indicator (not shown) along with the WOL display means  701 , as described below with reference to FIG.  9 . Moreover, it is possible to display information such as WOL and/or a dock state onto an LCD (liquid crystal display). 
   In  FIG. 8 , there is shown in detail the WOL display circuit  650  and its associated circuits in accordance with this invention. While an expansion unit (docking station)  810  and a note type PC  890  are normally connected by a certain bus, in the present embodiment, the note type PC  890  and the expansion unit  810  are connected by a PCI bus  835 . The expansion unit  810  includes a PCI-PCI bridge circuit  821  for connecting the PCI (primary) bus  835 , which connects the note type PC  890  and the expansion unit  810 , to a PCI (secondary) bus  833  within the expansion unit  810 . 
   To the PCI (secondary) bus  833 , a LAN subsystem  832  as a PCI device is connected. The LAN subsystem  832  includes the LAN communication adapter  610 . Upon receipt of a WOL packet from a server or the like via a network, the LAN subsystem  832  outputs a Wake-on-LAN-PME# signal that indicates receipt of the WOL packet. In order to conform to the specifications of a PCI bus, this Wake-on-LAN-PME# signal is outputted on the side of the note PC  890  via a drive circuit such as an open collector  831  or the like. In so doing, it becomes possible to distinguish a PME# signal derived by a WOL packet and a PME# signal derived by another factor other than a WOL packet from each other. 
   While the description herein is based on the PCI Management Specifications (Power Management Specifications), this invention may be based on another incompatible method other than PCI. In accordance with the PCI specifications, only one PME# signal for waking up the system exists in the same, and all of the functions connected to a PCI bus for enabling to wake up the system are defined to share this signal. 
   In such a case, a plurality of sources for activating this PME# signal may exist in the system and, thus, it is not possible to use this PME# signal as a condition for displaying a WOL state. Accordingly, it is necessary to separate a PME# signal  838  of the LAN subsystem  832  from a PME# signal  834  of the system. 
   Also, the Wake-on-LAN-PME# signal is sent to a clock (CLK) input terminal of a D-type flipflop (FF)  825  and an input terminal of an inverter  810  as well. When the D-type flipflop (FF)  825  receives the Wake-on-LAN-PME# signal, its output (Q) generates a LOW ( 0 ) output since its data input (D) terminal is grounded. A NAND circuit  826  performs a logical NAND operation of a System Reset# signal from the note PC  890  and an inverted signal of the Wake-on-LAN-PME# signal, thereby generating a HIGH ( 1 ) output and presetting the D-type FF  825  only if both input signals are HIGH ( 1 ). 
   The Q output of the D-type FF  825  is connected to a transistor  823 , which is in turn connected to an LED  824 . Thus, when the Qoutput is LOW ( 0 ), the LED  824  is turned on to display that the expansion unit  810  has received a WOL packet. 
   After receipt of a WOL packet, the LED  824  is in principle rendered to continually emit a light until it is reset by a next LAN Reset# signal. While this LAN Reset# signal is normally generated as a result of a logical OR operation of a System Reset# signal  837  from the note PC  890  and a DOCKED# signal indicating that the note PC  890  has been connected to the docking station  810 , it is possible to generate this LAN Reset# signal in accordance with another alternative condition. 
   Using the circuitry configuration as shown in  FIG. 8  in detail, when a WOL packet is received in such a situation where the docking station (expansion unit)  810  is not connected to the note PC  890  or the like, the LED  824  is caused to be turned on or flashed, thereby enabling to inform a user of receipt of the WOL packet. 
   In  FIG. 9 , there are shown cooperative operations (second embodiment) in the form of a flowchart, which are performed by the computer  100 &#39;s system unit (or  409 ) and the expansion unit  200  (or  407 ) upon receipt of a WOL packet. It is assumed, however, that the LAN adapter  300  and DockCPU  211  are kept in their operative states by means of the auxiliary power supply, whereas other components are powered off. 
   Of the steps shown in  FIG. 9 , steps S 20 , S 22 , S 30 , S 32 , S 34  and S 36  are not explained below since they are identical to those shown in FIG.  5 . 
   At step S 23 , in response to the WOL signal, the WOL indicator is turned on to indicate that the WOL packet has been received by the docking station (step S 23 ). By this operation, it becomes possible for a user of the PC system to directly recognize that the WOL packet has arrived. 
   At step S 91 , it is determined whether or not the computer (PC)  100  has been connected to the docking station  200 . If the computer has been connected, the process proceeds to step S 92 . Otherwise, the process branches to step S 94 . 
   At step S 92 , a dock state indicator is turned on to display the connected state of the PC  100  and the docking station  200 . In response to assertion of the WOL signal, DockCPU  211  refers to its own WOL state register, if any (step S 94 ) to determine whether or not WOL is permitted (step S 96 ). However, it is not an essential requirement of this invention that the expansion unit has a WOL state register. Thus, in a case where the expansion unit does not have a WOL state register, steps S 94  and S 96  may be skipped. 
   If a predetermined value representing “WOL prohibition” is already set up in the WOL state register, the process proceeds to step S 98 , where DockCPU  211  masks the WOL signal. In this case, a power-on indication is not issued to the computer  100 &#39;s system unit and, thus, the computer  100 &#39;s system unit is kept in its power-off state. As a result, the server on the network that originated the wake-up packet is not capable of accessing the computer  100  nor is it enabled to manage the computer  100 &#39;s system configuration. In this case, a record of inaccessibility may be kept on the server. 
   Conversely, if a predetermined value representing “WOL permission” is continually held in the WOL state  15 ′ register, or if the expansion unit  200  does not have a WOL state register, DockCPU  211  asserts a power-on signal (step S 30 ). Even if the computer  100 &#39;s system unit has already prohibited WOL (i.e., information of “WOL prohibition” is written into the CMOS memory  29 ), the WOL state register may still exhibit “WOL permission” at certain occasions, such as immediately after the computer  100  is connected to the expansion unit  200  or the WOL state register is initialized, without precisely reflecting the intention of the computer  100 &#39;s system unit. 
   The computer  100 &#39;s system unit responds to assertion of the power-on signal for executing POST program in the same manner as the normal power-on time. Subsequent thereto, it enters into its operable state (step S 32 ), performs a sequence of operations of steps S 34 , S 36 , and its operation is terminated (step S 38 ). 
   In the above, this invention has been described in detail with reference to a specific embodiment. However, it is apparent that various changes or substitutions in this embodiment may be made by those skilled in the art without departing from the gist of this invention. 
   While the present embodiment has been described on the basis of the so-called PC/AT compatible machines (“PC/AT” is a trademark of IBM Corp.) conforming to the OADG specifications, it is apparent that this invention may be implemented in other machines as well (e.g., the PC  98  series of NEC Corp., Macintosh of Apple Computer, Inc. and compatible machines thereof). 
   In summary, this invention has been disclosed in an exemplary manner and, thus, this invention is not to be limited except as proscribed by the claims. As described above, in accordance with this invention, it is possible to provide an improved expansion unit, which offers a function for displaying receipt of a WOL (Make-up ON LAN) packet to an information processing system mounted on the expansion unit.