Abstract:
An external load port magazine for use with a storage unit includes a casing detachably mountable on an exterior of the storage unit and defining therein a space for holding at least one item to be loaded into the storage unit. An opening is formed in the casing for enabling automatic withdrawal or insertion of the at least one item from or into the space when the casing is mounted on the exterior of the storage unit. A mechanism is provided for moving the at least one stored item towards the opening.

Description:
TECHNICAL FIELD 
       [0001]    The disclosure relates to an external load port magazine for use with a storage unit, and a method of using the same. 
       BACKGROUND 
       [0002]    Magnetic disks, optical disks and magnetic tape cartridges have been all widely used as peripheral digital data storage devices for computer systems. Large computer systems are usually connected with external libraries of multiple such digital data storage devices. Originally, digital data storage devices, such as tape cartridges, were loaded manually. Automated libraries were subsequently developed to expedite the handling of the tape cartridges. Such automated libraries include robotic pickers for accessing, transferring and loading a desired tape cartridge into a reader/writer, and hold the tape cartridges in magazines. Each magazine may hold several tape cartridges in respective slots. Once the library has been up and running, there will be a need to add/remove tape cartridges to/from the library. 
         [0003]    In accordance with a prior approach, a magazine is loaded with tape cartridges outside the library, and then the magazine is inserted into the library as a unit and, similarly, removed as a unit. In accordance with another approach, tape cartridges can be inserted individually into the library via a mail-slot. 
         [0004]    A further approach is to provide the library with load port specific hardware built into the library. The slots in such load port specific hardware can be configured either as load port slots for adding or removing tape cartridges or as regular storage slots. This arrangement creates a tradeoff between having more load port slots or more storage slots. Also, the built in load ports require different hardware than normal storage slots, because the load port slots need to be accessible by the user while the library is active, and because the load port magazines usually need to be removable. Another problem with built in load ports is that it is difficult to predict how many load port slots a customer may require. In addition, with the built in hardware it is difficult to provide enough flexibility, because the choices of the customer are limited to a range inside the predefined number of configurable load port slots the vendor picks. 
         [0005]    Another attempt at making the load port more flexible is to allow each row of slots to be configured as load ports which provides some flexibility in the number of load port slots. Still, this approach causes a trade off between the number of storage slots and the number of load port slots. 
       SUMMARY 
       [0006]    In an aspect, an external load port magazine for use with a storage unit comprises a casing detachably mountable on an exterior of the storage unit and defining therein a space for holding at least one item to be loaded into the storage unit. An opening is formed in the casing for enabling automatic withdrawal or insertion of the at least one item from or into the space when the casing is mounted on the exterior of the storage unit. A mechanism is provided for moving the at least one stored item towards the opening. 
         [0007]    In a further aspect, a storage system comprises a storage unit for storing a plurality of items, and at least an external load port magazine detachably mountable on an exterior of the storage unit for loading and unloading at least one item into and from the storage unit. The storage unit comprises a housing having therein a plurality of locations each capable of receiving and storing one of the items, and at least a receiving slot extending through a wall of the housing. The external load port magazine comprises a casing detachably mountable on the exterior of the housing and defining therein a space for holding the at least one item, and an opening in the casing to be aligned with the receiving slot when the casing is mounted on the exterior of the housing for enabling automatic transfer of the at least one item, one at a time, from the space into the housing and vice versa through the aligned opening and receiving slot. 
         [0008]    In a further aspect, a method of bulk loading and unloading of digital data storage devices to and from a digital data storage device library having therein a plurality of storage locations each being capable of receiving and storing one of the digital data storage devices, comprises: detachably mounting an external load port magazine to an exterior of the library so that an opening of the external load port magazine is aligned with a corresponding receiving slot of the library to define a passage between an interior of the external load port magazine and the storage locations within the library; and automatically transferring one or more of the digital data storage devices, one at a time, through the passage. 
         [0009]    In a further aspect, a storage unit for storing a plurality of items, comprises a housing having an internal space in which a plurality of locations each capable of receiving and storing one of the items are arranged. The housing is configured for allowing at least an external load port magazine to be detachably mountable on an exterior thereof. At least a receiving slot extends through a wall of said housing and is alignable with an opening of the external load port magazine, when the external load port magazine is mounted on the housing, for transfer of at least one of the items between the external load port magazine and the internal space of the storage unit. The storage unit further comprises a robotic picker for gripping and moving said at least one of the items through said receiving slot for transferring said at least one of the items between the internal space of the storage unit and the external load port magazine when the external load port magazine is mounted on the exterior of the storage unit. 
         [0010]    Additional aspects and advantages of the disclosed embodiments are set forth in part in the description which follows, and in part are obvious from the description, or may be learned by practice of the disclosed embodiments. The aspects and advantages of the disclosed embodiments may also be realized and attained by the means of the instrumentalities and combinations particularly pointed out in the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The disclosed embodiments are illustrated by way of example, and not by limitation, in the figures of the accompanying drawings, wherein elements having the same reference numeral designations represent like elements throughout. 
           [0012]      FIG. 1  is a schematic front view of a library configured for use with one or more external load port magazines in accordance with an embodiment. 
           [0013]      FIG. 2  is a schematic, cut-away side view showing the interior of the library and external load port magazine of  FIG. 1 . 
           [0014]      FIGS. 3A-3D  are schematic, cut-away side views of an external load port magazine in accordance with an embodiment at various states. 
           [0015]      FIG. 4  is a schematic, cut-away side view of an external load port magazine in accordance with another embodiment. 
           [0016]      FIGS. 5A-5B  are flow charts showing loading and unloading processes in accordance with further embodiments. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0017]    In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. It will be apparent, however, that the embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing. 
         [0018]      FIG. 1  is a schematic front view of a library  100  configured for use with one or more external load port magazines  150  in accordance with an embodiment  FIG. 2  is a schematic, cut-away side view showing the interior of library  100  and external load port magazine(s)  150  of  FIG. 1 . The following description will be given with reference to both  FIGS. 1 and 2 . 
         [0019]    In particular, library  100  includes a housing  102  defining an internal space for storing one or more digital data storage devices  104 . Digital data storage devices  104  can be stored in individual storage locations or cells  106  of one or more magazines  108 . Library  100  further includes a reader/writer  110  for reading and/or writing the contents of digital data storage devices  104  and a robotic picker  112  for transferring digital data storage devices  104  between cells  106  and reader/writer  110 . A controller  114  is also provided for processing data read/written by reader/writer  110  and/or controlling operation of robotic picker  112  and/or handling communication between library  100  and external equipment such as a host computer (not shown). 
         [0020]    It is within the scope of the present invention to provide various configurations for library  100 . For example, library  100  may include any number of reader/writers  110  and magazines  108  depending on the storage desired and the sophistication of data processing. Library  100  may, alternatively, include only magazines  108  and no reader/writer  110 . Further, magazines  108  may be of the modular type which can be stacked one upon another as designated at  108 A and  108 B, thereby providing some flexibility in configuring the storage capability of library  100  as the modular type magazines  108  can be easily added to or removed from library  100  to meet a particular user need. Additionally or alternatively, magazines  108  can be of the built-in type or include mounting brackets, as designated at  108 C, which has a fixed configuration and, generally, provides more storage space but is less flexible than the modular type magazines  108 A-B. 
         [0021]    In an embodiment, library  100  includes one or more robotic pickers  112  which travel(s), e.g., along a track (not shown), for carrying digital data storage devices  104  between magazines  108  and reader/writer  110 , if provided. Robotic picker  112  is configured to be able to insert and withdraw digital data storage devices  104  from either cells  106  of magazines  108  or reader/writer  110 . In a further embodiment, robotic picker  112  is moveable in any necessary manner, e.g., linearly and/or rotationally, under control of controller  114 . In another embodiment, control of library operation including operation of reader/writer  110  and/or robotic picker  112  can be performed via external equipment, such as a host computer (not shown). In the description herein below, control performed by library  100  should be understood to be performed by controller  114  or a host computer or combinations or equivalents thereof. 
         [0022]    Further embodiments provide library  100  with an user interface  116  for allowing an operator to control some or all aspects of library operation. As schematically shown in  FIG. 1 , user interface  116  includes a screen  118 , e.g., a liquid crystal display (LCD) screen, and control buttons  120 . Regular computer monitors and input devices, such as mice, keyboards, styluses, touch screens etc. can also be used as user interface  116 . Reference numeral  122  in  FIG. 1  designates an optional see-through window that gives the operator a direct view of the interior of library  100  without opening a wall of housing  102 , and/or ventilation holes. 
         [0023]    It will be appreciated that library  100  allows for placing digital data storage devices  104  into the library and removing digital data storage devices  104  from the library when a user so desires. In one embodiment, library  100  may include one or more mail-slots (not shown) or magazine slots (not shown) to allow individual digital data storage devices  104  and/or magazines  108  to be remove from or placed to library  100 . Examples of such mail-slots and magazine slots are provided in U.S. Patent Application Publication No. 2005/0004703 which is incorporated by reference herein in its entirety. 
         [0024]    One or more internal load port magazines  124  can be also be used in accordance with another embodiment. Internal load port magazine  124  can be configured as a drawer as schematically shown in  FIG. 1  at panels  126 . Like magazines  108 , internal load port magazine  124  also has slots  106  for holding digital data storage devices  104 . However, one or more or all of slots of internal load port magazine  124  are configured (hardware) and/or defined (software) by the manufacturer, operator or library  100  as load port slots  128  rather than regular storage slots  106 . Internal load port magazine  124  is normally retracted within library  100  as the name “internal” suggests. Internal load port magazine  124  slides out for loading load port slots  128  with digital data storage devices  104 , and is then retracted again within library  100  for unloading load port slots  128 . Examples of such internal load port magazines are provided in U.S. Patent Application Publication No. 2004/0254647 which is incorporated by reference herein in its entirety. 
         [0025]    As discussed above, internal load port magazines  124  require a tradeoff between having more load port slots  128  or more storage slots  106 . In addition, load port slots  128  may require different hardware than normal storage slots  106  because load port slots  128  need to be accessible while the library is active, and because internal load port magazines  124  usually need to be removable. Another problem with built in or internal load port magazines  124  is that it is difficult to predict how many load port slots  128  and/or internal load port magazines  124  a customer may require, and with the built in hardware it is difficult to provide enough flexibility. 
         [0026]    Disclosed embodiments of the present invention provide an external load port magazine  150  to solve one or more of the above and other problems. Specifically, library  100  may include one or more external load port magazines  150  in lieu of or in addition to one or more mail-slots, magazine slots, and internal load port magazines of the types disclosed above and/or other types. 
         [0027]    Unlike internal load port magazine  124  which normally resides within library  100 , external load port magazine  150  is always located outside library  100 . In an embodiment, external load port magazine  150  is removably attached to the outer wall, e.g., the front panel, of housing  102  of library  100  by any appropriate means, for example, snap connectors schematically shown at  352  in  FIG. 3A . External load port magazine  150  as illustrated in  FIGS. 3A-3D  further includes a casing  354  carrying connectors  352  and defining therein a space  356  for holding at least one digital data storage device  104  to be loaded into library  100 . 
         [0028]    Casing  354  further has an opening  358  through which the digital data storage devices  104  can be withdrawn from or inserted into space  356  of casing  354  when casing  354  is mounted on the exterior of housing  102  of library  100 . For this purpose, the outer wall, e.g., the front panel, of housing  102  includes a matching receiving slot  152  ( FIG. 1 ) which is adapted to be aligned with opening  358  when external load port magazine  150  is attached to library  100 . In the specific embodiment illustrated in  FIGS. 3A-3D , connectors  352  are arranged around opening  358  to releasably engage edges of receiving slot  152 . In other embodiments, connectors  352  or any other attaching means engage housing  102  outside receiving slot  152 . 
         [0029]    Within space  356  of casing  354 , there is further provided a mechanism  360  for moving and/or guiding digital data storage devices  104  towards and/or away from opening  358 . Mechanism  360  can be mechanically and/or electrically and/or magnetically and/or pneumatically and/or gravity-driven or can have any suitable configuration. In the specific, exemplary embodiment of  FIGS. 3A-3D , mechanism  360  includes a spring-loaded platform  364  and a spring  362  biasing platform  364  towards opening  358 . A stop  366  is provided at or about the level of opening  358  for stopping the uppermost digital data storage device  104 U at a desired position corresponding to opening  358  and receiving slot  152  and ready for removal by robotic picker  112 . 
         [0030]    In  FIG. 3A , the uppermost digital data storage device  104 U is shown in the state of being withdrawn (or inserted) half way by robotic picker  112  (not shown in  FIG. 3A ). After the uppermost digital data storage device  104 U has been completely removed from the stack of digital data storage devices  104  as shown in  FIG. 3B , the next digital data storage device  104 V is pressed upwardly by spring  362  against stop  366  and becomes the uppermost digital data storage device ready to be picked up by robotic picker  112 . The described unloading process is repeated until the last digital data storage device  104 L ( FIG. 3D ) has been removed from external load port magazine  150  or until the unloading process is stopped by library  100  and/or the operator. 
         [0031]      FIG. 3C  illustrates digital data storage device  104 U being inserted into opening  358  in a reversed, loading process. In particular, digital data storage device  104 U is pushed by robotic picker  112  against a lead-in ramp  368  which is continuous to stop  366 . Lead-in ramp  368  will guide digital data storage device  104 U downwardly, thereby compressing spring  362  and moving the whole stack of digital data storage devices  104  already in external load port magazine  150  downwardly. When digital data storage device  104 U has passed lead-in ramp  368  and reached the level of stop  366  as shown in  FIG. 3A , further pushing by robotic picker  112  will move digital data storage device  104 U, now the uppermost digital data storage device in the stack, horizontally until robotic picker  112  stops pushing and/or until the uppermost digital data storage device  104 U hits a further stop (not shown) arranged for aligning digital data storage devices  104  properly within external load port magazine  150 . The described loading process is repeated until external load port magazine  150  is full or until the loading process is stopped by library  100  and/or the operator. 
         [0032]    To notify library  100  and/or the operator that external load port magazine  150  is full or empty, one or more indicators are provided. For example, when external load port magazine  150  is empty as shown in  FIG. 3D , platform  364  assumes a position at which it activates an empty indicator  370  which, in turn, notifies library  100  or the operator of the empty status of external load port magazine  150 . In an embodiment, empty indicator  370  can be a sensor which transmits a signal corresponding to the empty status of external load port magazine  150  to any of library  100 , robotic picker  112  and the operator. For example, empty indicator  370  may include a proximity (e.g., magnetic) or contact (e.g., electric) sensor. Then, the presence of platform  364  near the sensor or the contact of platform  364  with the sensor will trigger the sensor to send an electrical, or optical, or acoustic, or RF signal to library  100  which will notify the operator accordingly, either by ways of user interface  116  or other indicators (not shown) on the outer wall of housing  102  near the attached external load port magazine  150 . Empty indicator  370  may also directly indicate the empty status on casing  354  of external load port magazine  150  itself. 
         [0033]    In another embodiment, the presence of platform  364  near empty indicator  370  interrupts a communication between empty indicator  370  and robotic picker  112  or another component of library  100 , thereby indicating the empty status of external load port magazine  150 . For example, platform  364  may block a direct view between empty indicator  370  and robotic picker  112  when robotic picker  112  is in the position ready for picking up the next available digital data storage device  104 . A light source, e.g., an LED, and an optical sensor can be provided in any or both of empty indicator  370  and robotic picker  112  to notify library  100  that the direct view has been blocked and that external load port magazine  150  is empty. Of course, the light source and optical sensor should be arranged such that their direct view can be blocked only by platform  364 , and not by any digital data storage devices  104  disposed on platform  364 . 
         [0034]    In a further embodiment, empty indicator  370  can be a mechanical switch which is switched by platform  364  to prevent further access by robotic picker  112  to space  356  of external load port magazine  150 . For example, the switch may close a door (not shown) of opening  358 . Other arrangements are, however, not excluded. 
         [0035]    Similar to empty indicator  370 , a full indicator  372  ( FIG. 3D ) is also provided to notify library  100  and/or the operator that external load port magazine  150  is full. Full indicator  372  can be configured similar to or different from empty indicator  370  or in any suitable manner. 
         [0036]    In an alternative embodiment to that of  FIGS. 3A-3D , a gravity-loaded external load port magazine is provided. Such gravity-loaded external load port magazine is similar to external load port magazine  150  in the upside-down state. Spring  362  may be omitted in this embodiment as digital data storage devices  104  automatically fall under gravity to the “botton”  366  of the external load port magazine to be removed by robotic picker  112 . A digital data storage device can be inserted in the gravity-loaded external load port magazine by a process similar to  FIGS. 3C and 3A . 
         [0037]      FIG. 4  illustrates an external load port magazine  450  in accordance with another exemplary embodiment. External load port magazine  450  is basically similar to external load port magazine  150  of  FIGS. 3A-3D , except for the following. Most significantly, external load port magazine  450  uses a motor  462 , rather than spring  362 , for moving the stored digital data storage devices  104  either towards or away from opening  358 . In particular, platform  364  in external load port magazine  450  is moveable along a track  465  and is driven by motor  462  to go up and down depending on the unloading or loading action of robotic picker  112 . A control  463  can be provided to control motor  462 . In an embodiment, control  463  is omitted and motor  462  is directly controlled by library  100  via communication link  467  which can be wired or wireless. In the former case, communication link  467  can be connected to a contact or contacts provided on one of connectors  352 , at a portion where such contact or contacts are contactable with corresponding contacts of library  100  when external load port magazine  450  is detachably mounted on housing  102  of library  100 . In the latter case, control  463  and/or motor  462  can be optically or RF controlled by library  100  or robotic picker  112 . In either case, motor  462  is controlled to move platform  364  and hence the stack of digital data storage devices  104  supported thereon one step down every time robotic picker  112  or library  100  indicates that a loading operation is in process or that robotic picker  112  is going to place another digital data storage device in external load port magazine  450 . Similarly, motor  462  is controlled to move platform  364  one step up after robotic picker  112  has removed a digital data storage device from external load port magazine  450 . The position of platform  364  can be determined by empty and/or full indicators such as  370  and  372  described with reference to  FIG. 3D , but can also be determined by control  463 , library  100  or motor  462  itself based on the numbers of step-ups and/or step-downs made by platform  364 . 
         [0038]    In a further embodiment (not shown), motor  462  or an equivalent driving mechanism is placed inside library  100  and is arranged to transmit driving power to move platform  364  up and down along track  465 . The power transmission can be done in any suitable manner, e.g., by pulleys, belts, gear wheels, pinion racks etc. 
         [0039]      FIGS. 5A and 5B  are flow charts showing exemplary loading and unloading processes using the disclosed external load port magazines. The physical positions of the external load port magazines and components of library  100  are schematically illustrated in  FIGS. 1 and 2 . 
         [0040]    In the process of loading digital data storage devices into library  100 , the user first loads digital data storage devices  104 , e.g., in space  356  of external load port magazine  150 , as shown at step  502  in  FIG. 5A . Opening  358  can be used for manual loading of external load port magazine  150 . However, one of the wall of casing  354  of external load port magazine  150 , for example back wall  392  ( FIG. 3A ), or a larger opening on that wall can be opened to allow the user to load several digital data storage devices  104  in external load port magazine  150  at a time. The back wall  392  can be opened or another opening such as  193  in  FIGS. 1 ,  2  can be provided to allow the operator to add one or more digital data storage devices to the external load port magazine  150  being attached to library  100  without detaching external load port magazine  150 . 
         [0041]    The user next attaches, at step  504  in  FIG. 5A , the loaded external load port magazine  150  to housing  102  so that opening  358  is aligned with one of receiving slots  152  ( FIG. 1 ) of library  100 . The user then instructs library  100 , e.g., via user interface  116 , to unload digital data storage devices  104  from the attached external load port magazine  150 . Alternatively, library  100  may be configured to automatically detect the presence of the attached external load port magazine  150  and to automatically initiate the unloading of external load port magazine  150 , as shown at step  505  in  FIG. 5A . The detection of external load port magazine  150  at one of receiving slots  152  can be arranged using sensors or switches as discussed with respect to empty indicator  370 . Additionally or alternatively, other technologies such as bar codes or smart cards can be used. In an embodiment, library  100  locks external load port magazine  150  to its housing  102  to prevent undesired detachment of external load port magazine  150  during the unloading thereof. 
         [0042]    In response to initiation of the unloading process, either manually by the user or automatically by library  100 , robotic picker  112  approaches receiving slot  152  where external load port magazine  150  is positioned, as shown at K in  FIG. 2 . Robotic picker  112  extends, e.g., its fingers, in to space  356  of external load port magazine  150  through receiving slot  152  and opening  358 , grips one of digital data storage devices  104  (in the embodiment of  FIG. 3A , the uppermost digital data storage device  104 U), and withdraws the gripped digital data storage device  104  out of external load port magazine  150 . This step is indicated at  506  in  FIG. 5A . 
         [0043]    Robotic picker  112  then transfers the gripped digital data storage device  104  to one of the slots  106  within library  100  as shown at M in  FIG. 2  and indicated at step  508  in  FIG. 5A . In a further embodiment, robotic picker  112  first transfers the gripped digital data storage device  104  to reader/writer  110  as illustrated at L in  FIG. 2 , so that the content of the gripped digital data storage device  104  can be read and/or cataloged and/or updated and/or added by library  100 , as designated at step  507  in  FIG. 5A . Thereafter, robotic picker  112  removes the read/updated digital data storage device  104  from reader/writer  110  and moves it to the designated storage slot illustrated at M in  FIG. 2 . 
         [0044]    Subsequently, if external load port magazine  150  does not indicate or is not determined by library  100  to be empty (step  510  in  FIG. 5A ), the steps  506 ,  508  or  506 - 508  will be repeated until external load port magazine  150  is empty or until the operator of library  100  interrupts the process, as indicated at step  512  in  FIG. 5A . In an embodiment, library  100  or external load port magazine  150  will notify the operator, at step  513 , by audible or visible signals, that external load port magazine  150  is empty and ready for a new load. 
         [0045]    In the process of unloading digital data storage devices from library  100  as shown in  FIG. 5B , the user first attaches, at step  552 , an external load port magazine  150 , for example an empty external load port magazine, to one of the receiving slots  152  of library  100  if no external load port magazine is currently attached to library  100  or if no attached external load port magazine is currently available for unloading. 
         [0046]    Robotic picker  112  then removes a designated digital data storage device from its storage slot in accordance with instructions of library  100 , as illustrated at N in  FIG. 2 . Since reader/writer  110  already knows the content of the removed digital data storage device  104 , the digital data storage device need not be transferred to reader/writer  110 . However, it is not excluded that some data need to be added to or erased from the digital data storage device, in which case robotic picker  112  will first transfer the digital data storage device to reader/writer  110 . 
         [0047]    In the next step  554  in  FIG. 5B , robotic picker  112  inserts the digital data storage device into external load port magazine  150  through receiving slot  152  and opening  358 . If external load port magazine  150  does not indicate or is not determined by library  100  to be full (step  556  in  FIG. 5B ), the above steps simplified at  554  in  FIG. 5B  will be repeated until external load port magazine  150  is full or until the operator of library  100  interrupts the process, as indicated at step  558  in  FIG. 5B . In an embodiment, library  100  or external load port magazine  150  will notify the operator, at step  559 , by audible or visible signals, that external load port magazine  150  is full or contains all digital data storage devices required to be removed from library  100 , and can now be detached from library  100 . 
         [0048]    In an embodiment of the method of the present invention, the external load port magazine needs to be discovered upon power up and initialization of library  100  to let the library know to add the external load port magazine to its element list. An inventory of the external load port magazine would not be needed, nor possible, since only the first digital data storage device (e.g.,  104 U) in the external load port magazine is accessible to robotic picker  112 . 
         [0049]    It should be noted that in accordance with the present invention, receiving slots  152  need not be provided on the front of library  100 , they can be arranged any where on the outer walls of library  100 , for example, the side walls. Likewise, receiving slots  152  and/or openings  358  need not be horizontal as depicted in the drawings and can have any shape that allows passage of digital data storage devices therethrough. For example, receiving slots  152  and/or openings  358  can be vertical or slanted. Digital data storage devices can therefore be arranged within the external load port magazine in any manner suitable for their removal through the receiving slots  152  and openings  358 , and need not be placed horizontally as illustrated. For example, digital data storage devices can be placed vertically or obliquely inside the external load port magazine. As a result, the direction in which digital data storage devices are moved towards and/or away from opening  358  can be varied depending on the nature of mechanism  360  and/or orientations of receiving slots  152 , openings  358  and the digital data storage devices themselves. 
         [0050]    Embodiments of the present invention further include one or more of the following features. 
         [0051]    The disclosed external load port magazine has only a single opening, such as opening  358 , through which robotic picker  112  can access, remove and insert digital data storage devices in the external load port magazine. In an embodiment, robotic picker  112  can only remove or insert one digital data storage device at a time from or to the external load port magazine. This arrangement simplifies control of robotic picker  112 , because robotic picker  112  has to move always to the same physical location, which requires only a single logical load port address and corresponds to receiving slot  152 , to pick up the next digital data storage device from the external load port magazine. In contrast, to unload digital data storage devices from internal load port magazine  124 , robotic picker  112  must move each time to a different load port slot  128  as shown at B in  FIG. 2  to pick up the next digital data storage device. 
         [0052]    The disclosed external load port magazine also saves storage space inside library  100 . If an internal load port magazine, such as  124 , is used, load port slots  128  cannot be immediately used as regular storage slots  106 ; the operator has to reconfigure, either physically or logically load port slot  128 , before they can be used as regular storage slots  106 . At any given time, the slots configured as load port slot  128  are a waste of storage space inside library  100 . In contrast, if the disclosed external load port magazine is used, all that is required is a receiving slot  152  on the outer wall of the housing of library  100  and a small clearance ( 288  in  FIG. 2 ) inside library  100  and near receiving slot  152  for robotic picker  112  to maneuver. The space below clearance  288  can be used as regular storage slots as schematically indicated by magazine  289  in  FIG. 2 . The load port slots in each internal load port magazine, if used together with the external load port magazines, can be minimized or converted to storage slots. 
         [0053]    The disclosed external load port magazine further requires minimal changes to the pre-existing library configuration. Besides a slight rearrangement, if indeed necessary, of the storage space inside library  100  to provide clearances  288 , library  100  only requires the provision of one or more receiving slots  152  on the outer wall thereof. This can be done by, e.g., replacing each front panel  161 - 164  of the preexisting housing  102  with a corresponding panel having a receiving slot  152  and, if necessary, connecting members for engagement with connectors  352  and/or contacts for connection to any sensors or switches inside the external load port magazine. The receiving slots can be arranged at one or more places with minimal disturbance to interior mechanics and real estate. 
         [0054]    The disclosed external load port magazine adds greater flexibility to the library configuration. For example, the user can choose to use none or some or all of the built-in receiving slots  152  with external load port magazines for loading the unloading digital data storage devices to and from library  100 , without having to reconfiguring hardware or software of the load port slots as it was the case with internal load port magazine  124 . Simply attaching an external load port magazine to one of receiving slots  152  will trigger the library to recognize that receiving slot as a load port slot, whereas any unused receiving slots can be disabled, e.g., by software, or left idle without sacrificing excessive storage space within the library. The user&#39;s need for load port slots can be met simply by using more or less external load port magazines at the same time. 
         [0055]    The disclosed external load port magazine reduces hardware and/or software costs generally associated with the provision of built-in internal load port magazines. 
         [0056]    The disclosed external load port magazine simplifies bulk loading/unloading, as the customer would just have to attached one or more external load port magazine(s), and issue commands to load/unload digital data storage devices to/from the attached external load port magazine(s). When the external load port magazine is full or empty, they simply attach another external load port magazine and repeat the process. 
         [0057]    While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. For example, those of skill in the art will appreciate that embodiments of the present invention have application to all types of digital data storage devices including but not limited to optical disks, magnetic disks, memory devices and magnetic tape cartridges. Embodiments of the invention are also applicable to other items and their storage units regardless of how the items are to be stored within the storage units. The items are not restricted to digital data storage devices and can comprise items which do not themselves store data. 
         [0058]    Additional advantages and modifications could be made herein without departing from the scope of the described embodiments as defined by the appended claims.