Abstract:
A system for exchanging digital data among a plurality of hand-held computer devices. Digital signals are written by a first hand-held device to a mini-cartridge that mini-cartridge is inter-operable among a class of hand-held device, each of which is equipped with a mini disk drive. A common digital data format is employed to further facilitate exchange of data between devices.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of prior U.S. application Ser. No. 09/912,822, filed Jul. 25, 2001, now U.S. Pat. No. 6,587,304, which is a continuation of U.S. application Ser. No. 09/083,766, filed May 22, 1998, now abandoned, which is a continuation of U.S. application Ser. No. 08/746,085, filed Nov. 6, 1996, now U.S. Pat. No. 5,809,520. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to an interchangeable cartridge data storage system and more particularly to a mirage system in which a mini-cartridge is compatible with devices generating signals representing different functions and the mini-cartridge is compatible, by use of a caddy, with a full size drive which can transfer signals between that drive and a host computer. 
     Microprocessors and supporting computer technologies are rapidly increasing in speed and computing power while decreasing in cost and size. These factors have led to the broad application of microprocessors to an array of electronic products, such as handheld computers, digital cameras, cellular phones and the like. All of these devices have, in effect, become computers with particular application-specific attributes. For this new breed of computer products, enormous flexibility is gained by the ability to exchange data files and store computer software. 
     A variety of proprietary storage devices have been used in computer products. For example, hand-held computers have used integrated circuit memory cards (“memory cards”) as the primary information storage media. Memory cards include memory storage elements, such as static random access memory (SRAM), or programmable and erasable non-volatile memory, such as “flash” memory. Memory cards each are typically the size of a conventional credit card and are used in portable computers in place of hard disk drives and floppy disk drives. Furthermore, memory cards enhance the significant advantages of the size, weight, and battery lifetime attributes of the portable computer and increase portability of the storage media. However, because of the limited memory density attainable in each memory card and the high cost of the specialized memory chips, using memory cards in hand-held computers imposes limitations not encountered in less portable computers, which typically use more power-consuming and heavier hard and floppy disk drives as their primary storage media. 
     Other of these computer products, such as the digital camera, have employed miniature video disks as the storage media. For example, U.S. Pat. No. 4,553,175 issued Nov. 12, 1985 to Baumeister discloses a digital camera configured to store information on a magnetic disk. In Baumeister, a signal processor receives signals representative of a picture from a photo sensor. Those signals are recorded on a magnetic disk for later processing. Unfortunately, the video disk storage product provides limited storage capacity. For that and other reasons (e.g., power consumption and cost), the video disk has not been used in other computer products. As a result, interchanging data from one of these digital cameras with other computer products, such as a hand-held computer, is not readily achieved. 
     Miniature hard disk drives have also been suggested for use in portable computer products. For example, U.S. Pat. No. 5,469,314 issued Nov. 21, 1995 to Morehouse et al. discloses a miniature hard drive for use in portable computer applications. In Morehouse, a hard disk drive is described that is approximately 50 mm in diameter. While addressing many of the problems presented by storage requirements in portable computers, the obvious problem of removability of the storage media is still present. 
     Thus, Applicants have recognized that there is a long-felt need for a storage media that has adequate storage capacity and that addresses the need for reduced size and interchangeability across a multitude of computer products. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention a mini-cartridge is provided for mini drives in a plurality of hand-held devices which generate signals representing different functions performed by different classes of the devices. For example, the devices include digital cameras, electronic books, global positioning systems, personal digital systems, portable games and cellular phones. Each of these devices has a mini drive for writing signals and reading signals representing the functions to and from a magnetic medium in the mini-cartridge. In this way, signals representing the diverse functions performed by the different classes of devices are recorded on the mini-cartridge. The hand-held devices incorporating the present invention provide and create a single means of capturing, moving and storing information across multiple products. 
     The mini-cartridge can be inserted into the mini drive of other devices. For example, a reporter could snap a photograph with a digital camera having a mini drive of the present invention, use a mini drive to save and transport the image to a mini drive equipped cell phone and then transmit the image to a news bureau, anywhere in the world. 
     The mini-cartridge from that cell phone can then be operated upon by a personal computer. Further by way of example, the mini-cartridge can be inserted into a caddy which accommodates the mini-cartridge to make it compatible with a full-size disk drive. The ZIP drive, marketed by Iomega Corporation, is typical of a full-size drive which can read the mini-cartridge because the caddy, in which the cartridge is inserted, makes it compatible with the full-size drive. 
     Full-size drives, such as the ZIP drive, are commonly included in personal computer systems. The full-size drive makes the signals recorded on a mini-cartridge readable. These signals are transmitted through the input/output channel and interface to a host computer which operates on the signals in the same manner as any other magnetically recorded signals. 
     As further example of the uses and advantages of the present invention, the mini-cartridge can be used in digital cameras similar to the way film is used in a traditional camera, capturing up to 70-80 images on a single disk at a low cost per disk. Currently, consumers must pay hundreds of dollars for a flash memory card holding the same number of images. 
     The mini drive and cartridge can be used to quickly transfer a phone number list from a PDA to a cell phone, or save a fax on a mini-cartridge and use it in a cell phone to transmit it wirelessly. 
     Hand-held gaming devices equipped with mini drives can also be an ideal means of distributing games for hand-held gaming devices at lower costs. There is an additional possibility of updating games via the Internet, saving the new version on a mini-cartridge and then using it in a hand-held game player. 
     GPS (global positioning systems) using a mini drive can download maps from the Internet, or a local map on a mini-cartridge can be purchased for use in a GPS system, while hiking or in a car equipped with a GPS device. 
     A PDA (personal digital assistant) with a mini drive is an affordable storage technology for PC companions and hand-held devices. They also serve as a high-capacity, affordable means to save and move applications to/from a PC and PDA. The present invention is designed to provide high capacity at a low cost for hand-held devices. The foregoing and other objects, features and advantages of the invention will be better understood from the following more detailed description and appending claims. 
    
    
     SHORT DESCRIPTION OF THE DRAWINGS 
     The foregoing summary, as well as the following detailed description of the preferred embody, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings embodiments that are presently preferred, it being understood, however, that the invention is not limited to the specific methods and instrumentalities disclosed. In the drawings: 
     FIG. 1 is a diagram of the interchangeable mini-cartridge of the present invention, including a plurality of devices each having a mini disk drive, and including a caddy to adapt the mini-cartridge to a full-size drive of a host computer; 
     FIG. 2A shows a top view of the mini-cartridge with the shutter retracted exposing a magnetic medium; 
     FIG. 2B shows a bottom view of the mini-cartridge with the shutter retracted exposing the magnetic medium; 
     FIG. 2C shows a top view of the magnetic medium; 
     FIG. 3A shows the mini-cartridge seated in the mini disk drive with the read/write heads retracted; 
     FIG. 3B shows the mini disk drive without the mini-cartridge; 
     FIGS. 4A,  4 B,  4 C and  4 D show the mini-cartridge at progressive stages of insertion into the mini disk drive; 
     FIG. 4E shows the mini-cartridge fully translated horizontally into the mini disk drive in an elevated, unseated position; 
     FIG. 5 shows the mini-cartridge seated in operational position in the mini disk drive with the heads engaging the magnetic medium; 
     FIG. 5 shows the top of the mini disk drive exterior; 
     FIG. 6A shows the male camming surface and the cartridge lock fully seated into the female camming surface and the cartridge lock mating surface, respectively; 
     FIG. 6B shows the sled tab engagement with the eject tab; 
     FIG. 7A shows a top perspective view of the caddy without a mini-cartridge; 
     FIG. 7B shows a top perspective view of the caddy with a mini-cartridge inserted; and 
     FIG. 8 shows the interface between the full-size drive and the host computer. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows a plurality of devices  10 - 15  which generate signals representing different functions performed by different classes of the devices. For example, the global positioning system  10  can generate signals representing navigational position. Electronic book  11 , digital camera  12 , personal digital assistant (PDA/Palmtop)  13 , portable game  14 , cellular phone  15 , and laptop computer  16  each generate signals representing the function performed by that particular device. 
     In accordance with the present invention, each of these devices has a mini drive  20  for writing the signals and reading the signals from a magnetic recording medium so that diverse functions performed by different classes are recorded on the devices. Each device has a mini drive  20 , i.e. a mini drive  20   f  for the global positioning system  10 , a mini drive  20   g  for the electronic book  11 , a mini drive  20   a  for the digital camera  12 , a mini drive  20   b  for the portable game  13 , a mini drive  20   c  for the PDA/palmtop  14 , a mini drive  20   d  for the cellular phone  15  and a mini drive  20   e  for the laptop computer  16 . 
     A mini-cartridge  30  has a magnetic recording medium on which the signals from the devices are recorded. The mini-cartridge  30  is compatible with the mini drives  20 . Standard file formats maintain compatibility between devices. In the preferred embodiment, mini drives  20  have a PCMCIA type 3 form factor. This form factor is commonly used in portable personal computers. For example, this form factor could be used for the modem port of a notebook computer. The PCMCIA type 3 form factor is quite small so the mini drive  20  readily fits into all of the portable, hand-held devices shown in FIG.  1 . The mini-drive  20  is insertable into and removable from the device just as the PCMCIA modem is insertable into and removable from the PCMCIA slot of a notebook computer. Alternatively, the drive  20  could be hard wired into the device. In both cases, the device generates a digital function signal which is connected to the magnetic heads of the drive so that the digital function signal can be written on the magnetic medium of the mini-cartridge  30 . As an example, a digital function signal representing a picture taken in a digital camera  12  is recorded on a mini-cartridge  30 . This digital function signal can be read; by other classes of devices when the cartridge  30  is inserted into other devices. 
     Referring to FIGS. 2A and 2B a mini-cartridge  30  in accordance with the present invention is depicted. FIG. 2A presents an isometric top view of mini-cartridge  30 , and FIG. 2B presents an isometric bottom view of mini-cartridge  30 . Mini-cartridge  30  is fabricated from a magnetic medium  29  disposed between a top shell portion  41  and a bottom shell portion  34 . Top shell portion  41  has four idly formed pods  42 , one at each corner. Bottom shell portion  34  attaches to top shell portion  41  within pads  42  and is formed from a substantially rigid materially, such as sheet steel. Both the top shell portion  41  and the bottom shell portion  34  have cut-outs such that aperture  60  is formed in one end of cartridge  30  when the shell halves are brought together. 
     Shutter  39  is connected over the aperture end of the mini-cartridge  30  to close the aperture and protect the magnetic medium  29  whenever cartridge  30  is outside of a mini drive  20 . As such, shutter  39  slides to a first position indicated by line B, revealing magnetic media  29 , and slides to a second position indicated by line A, closing the aperture and protecting magnetic media  29  from contamination and the like. When shutter  39  is closed (i.e., moved to the position as indicated by line A), shutter latch  62  engages the slot  64  and locks shutter  39  in place. Thus, in order to move shutter  39  to the open (B) position, the latch  62  must first be depressed to unlock shutter  39 . Four cam openings  59  are formed through the corresponding pads  42  of the top shell portion  41  and two cartridge lock cut-outs  57  are also formed in the top shelf. Additionally, the top shell portion  41  has a through hole to allow a thinner mini-cartridge  30  while accommodating a drive spindle (not shown). As such, a seal  36 , made of substantially thinner material than the material used to form top shell portion  41 , is attached to the shell to cover the hole. Magnetic medium  29 , as indicated by the dashed line in FIGS. 2A and 2B, is sandwiched between the shell portions  41 ,  34  and is allowed to float unattached to either shelf portion. 
     Magnetic medium  29  is best described with reference to FIG.  2 C. As shown, magnetic medium  29  is substantially circular in shape. Additionally, medium  29  is made from a single piece of flexible material, such as Mylar. As is well-Imam in the floppy disk arts, a magnetic coating is placed over both sides of the Mylar, malting it susceptible to storing data in the form of magnetically readable and erasable signals. A circular hub  32  is attached to the medium  29  and provides the mechanism for connecting the magnetic medium  29  to the drive spindle. Hub  32  is stamped from a single piece of ferrous material, such as sheet steel, forming circular lip  32   a . Hub  32  and magnetic medium  29  are permanently bonded together with a hot melt adhesive, such as bynel adhesive resin manufactured by DuPont Corp. 
     FIGS. 3A and 3B show a mini drive  20  with the top cover removed. FIG. 3A shows the mini drive with a mini-cartridge  30  inserted and in an operating position in the drive. FIG. 3B, by contrast, shows mini drive  20  without a cartridge  30 , revealing many of the internal drive components. Toward the back portion of the drive, a voice coil actuator  40  is coupled to drive platform  37 . Actuator  40  has two arms  42   a  and  42   b  that move linearly in the X axis direction in response to an electrical signal. A read/write head (not shown) is coupled to the distal end of each arm  42   a ,  426 . Thus, when a mini-cartridge  30  is inserted into the drive (as shown in FIG.  3 A), the heads in conjunction with arms  42   a ,  42   b  move over the surface of magnetic medium  29  reading and writing data. 
     The remaining internal components are best described with reference to FIG.  3 B. As shown, spindle  49  is disposed toward the Wont of the drive platform  37  and is centered about the width (i.e., the Y axis) of drive platform  37 . As with many disk drive spits, spindle  49  provides the rotational interface between the mini disk drive  20  and the magnetic medium  29 . As such, spindle  49  has an alignment pin  49   a  that engages the center of hub  32 , ensuring a consistent alignment of the medium  29  in the mini disk drive  20 . Additionally, spindle  49  has a magnetic top surface  49   b  that magnetically couples hub  32  to spindle  49 . To derive its rotational force, spindle  49  is fixed to the drive motor rotor  50 . Thus as the motor (only rotor portion shown) provides the rotational force to the motor rotor  50 , spindle  49  also rotates, causing inserted magnetic medium  29  to rotate. 
     Motor rotor  50  is magnetically coupled to the motor, which is a bushing type pancake motor. That is, motor rotor  50  can be removed from the motor merely by overcoming the magnetic force that holds the motor rotor to its associated motor. Moreover, as stated above, mini-cartridge  30  is magnetically coupled to spindle  49 . As a result, removal of mini-cartridge  30  from the drive  20  could cause motor rotor  50  to lift from the motor before the mini-cartridge  30  decouples from spindle  49 . Motor hold-down wings  48 , coupled to platform  37 , prevent motor rotor decoupling. Accordingly, hold-down wings  48  overhang motor rotor  50 . Clearance is provided between the overhanging hold-down wings  48  and the motor rotor  50  to allow motor rotor  50  to spin freely during normal operation. When a mini cartridge  30  is ejected from drive  20 , hold-down wings  48  will hold motor rotor  50  while hub  32  separates from spindle  49 . 
     A load/eject sled  45  is slidably disposed on drive platform  37  to facilitate cartridge loading and ejection in cooperation with other drive components. Cams  58  are attached to or, alternatively, integrally formal with, load/eject sled  45 . The entire sled  45 , in tandem with cams  58 , slides on drive platform  37  in a direction substantially parallel to the X axis. Initially in a no-cartridge condition, sled  45  and cams  58  are in the proximate position indicated by the line C. After a mini-cartridge  30  is inserted, sled  45  and cams  58  move to a proximate position indicated by line D. During cartridge  30  ejection, eject button  46  is pushed by a user and, as a result of the force supplied by the user, moves sled  45  from a position proximate to the line indicated by D to a position proximate to the line indicated by C. Accordingly, cams  58  are likewise forced to move to the position proximate to the line indicated by C. As is described more fully below, this movement of cams  58  causes a mini-cartridge  30  to eject from the drive  20 . Additionally, as is described more fully below, cartridge locks  56  are fixed on both sides of the drive platform  37  and are used to engage and lock a mini-cartridge  30  to drive platform  37  during the cartridge insertion process. These cartridge locks  56  cooperate with cams  58  to provide cartridge  30  insertion and ejection. 
     A head protect lever  52  is pivotally mounted at its proximate end to drive platform  37  and secures the read/write heads when no cartridge is in the drive  20 . Pivot pin  54  is connected to the proximate end of head protect lever  52  and rides in head release slot  51  of load/eject sled  45 . When no cartridge  30  is in the drive, head release slot  51  allows a spring to actuate head protect lever  52  rearwardly via pivot pin  54 . As a result, arms  42  are retracted. On the other hand, when a cartridge  30  is inserted into drive  20 , head release slot  51  forces head protect lever  52  forward, releasing arms  42  and enabling them to move over medium  29 . 
     A cartridge eject lever  47  is pivotally mounted proximately in the back of the drive platform  37  in front of actuator  40 . As is described more fully below, lever  47  provides two functions: Opening shutter  39  during cartridge  30  insertion; and ejecting cartridge  30  during cartridge ejection. 
     The insertion of a mini-cartridge  30  into mini drive  20  is best described with reference to FIGS. 4A through 4F and  5 . Starting with FIG. 4A, a mini-cartridge  30  is outside of drive  20  (with the cover and from panel removed for clarity) prior to insertion. At that moment, cams  58  are proximate to the position indicated by line C. Head protect lever  52  has arms  42  in a retracted position. Eject lever  47  is biased in a counter-clockwise position. And, sled  45  is locked into, the position proximate to line C, via eject lever tab  47  engaging sled tab  53 , and spring loaded by sled spring  66  (best viewed in FIG.  3 B). 
     Referring now to FIG. 4B, as mini-cartridge  30  enters drive  20 , it rides along the top of the forward set of male cams  58   c ,  58   d . Front female cam openings  59   a ,  59   b  in mini-cartridge  30  are sized and located such that they do not match-up with the first set of male cams  58   c ,  58   d  encountered by the mini-cartridge  30 . As a result, male cams  58   c ,  58   d  lift cartridge  30 , ensuring that it enters above and clears spindle  49  during mini-cartridge  30  insertion into drive  20 . 
     Referring next to FIG. 4C, as mini-cartridge  30  enters further into drive  20 , nose  47   a  of eject lever  47  enters shutter slot  64  and contacts the mini-cartridge shutter latch  62 . As mini-cartridge  30  is urged yet further into drive  20 , eject lever  47  pivots clockwise and moves shutter  39  away from media aperture  60 , exposing the magnetic medium  29  disposed within the mini-cartridge shell. Meanwhile, spring  43  provides a counter-clockwise bias on eject lever  47 . Thus, simultaneous to eject lever  47  opening shutter  39 , eject lever  47  is spring loaded. Additionally, as eject lever is rotated clockwise, eject lever tab  47   a , which is integrally formed with eject lever  47 , also begins to rotate clockwise. 
     FIG. 4D shows mini-cartridge  30  in the most forward position in drive  20 . At that moment, shutter  39  is fully open and eject lever  47  is pivoted fully clockwise and loaded against spring  43 . However, cartridge  30  is not yet seated on spindle  49  and head protect lever  52  has not yet released the heads. Eject lever tab  47   a  is now fully rotated clockwise, away from sled tab  53  (see FIG. 6H for best view of eject lever tab  47   a  and sled tab  53  engagement). 
     FIG. 4E shows the release of dad  45  and forward movement of sled  45 . After the eject lever tab  47   a  has moved away from sled tab  53 . The sled is free to move from a position proximate to line C to a position proximate to line D. With the sled now free, spring  66  provides the bias to move sled  45  accordingly. As a result of the sled movement, cams  58  are moved to the D position, providing proper alignment with corresponding cam openings  59  and head protect slot  51  moves forward engaging pin  54  and releasing head protect lever  52 . 
     FIG. 5 in conjunction with FIG. 4F, illustrates the final mini-cartridge  30  loading step. Referring first to FIG. 5, cantilever springs  55  are shown extending downwardly from drive cover  22 . These cantilever springs  55 , force mini-cartridge  30  down as cartridge  30  fully enters drive  20 . However, cartridge  30  is forced by cams  58  to a raised position until cam openings  59  on the mini-cartridge  30  are properly aligned with the matching male cams  58  on the sled  45 . At that moment, the cantilever springs  55  urge mini-cartridge  30  downwardly onto male cams  58 , as shown in FIG.  4 F. Substantially simultaneous to the cam engagement, drive spindle  49  enters the corresponding circular lip  32   a  on the mini-cartridge  30  and magnetically engages hub  32 . 
     According to an aspect of the invention, wedge locks  56  engage the corresponding wedge cut-outs  57  on the mini-cartridge shell. FIG. 6A provides an expanded view of the interlocking of wedge  56   b  with cut-out  57   b  in cartridge  30 . Wedges  56  provide a ramped surface on their front side and an acute angled surface on their back sides. The angled surface, as indicated by the angle α, is about 80° in the present embodiment. However, those skilled in the art will recognize that other angles could be substituted for 80 degrees while still providing satisfactory results. Eject lever  47  (shown in FIG. 4F) applies a translational bias to cartridge  30 , urging cartridge  30  outwardly. As a result, wedges  56  in cooperation with eject lever  47  lock cartridge  30  into place in drive  20 . Mini-cartridge  30  is now ready for access by the read/write heads. 
     When a user desires to eject a cartridge  30  from the drive, the process is substantially reversed. The user begins by pushing the eject button  46 . The force of this action causes cams  58  to move from their location proximate to the line indicated by D toward a point proximate to the line indicated by C. As best understood in conjunction with FIG. 6A, such lateral translation causes cams  58  to engage the corresponding female cammed surfaces  59 . As cams  58  move further toward a position proximate to the D line, cartridge  30  begins to lift vertically from drive  20  (in the Z axis direction). When cams  58  are moved substantially to the D line, the bottom of cartridge  30  lifts above the top of spindle  49  and the top of wedges  56 . Simultaneously, sled tab  53  is also moved toward the rear of the drive once sled  45  has moved to a position At that moment, spring  43  pivots the eject lever  47  counter-clockwise, simultaneously ejecting the cartridge  30  and closing shutter  39 . 
     In order to provide forward compatibility to the host computer  23 , a caddy  31  is provided. Caddy  31  adapts the mini-cartridge  23  to a full size drive  33 . The full size drive  25  is the aforementioned ZIP drive which is disclosed and claimed in U.S. Pat. No. 5,530,607, entitled “WING ATTACHMENT FOR HEAD LOAD/UNLOAD IN A DATA STORAGE DEVICE” by Jay Spendlove on Jun. 25, 1996 and U.S. Pat. No. 5,508,864 entitled “FLEXURES WHICH REDUCE FRICTION IN AN ACTUATOR FOR DATA STORAGE DEVICE” by John Briggs granted on Apr. 16, 996, and in U.S. application Ser. No. 08/398,576 filed Mar. 3, 1995 entitled “HEAD PARK MECHANISM IN A DATA STORAGE DEVICE FOR PREVENTING ACCIDENTAL DAMAGE” by David Jones and U.S. patent application Ser. No. 08/398,576 filed Mar. 3, 1995 entitled “Movable Internal Platform for a Disk Drive.” Them applications are incorporated herein by reference. 
     Obviously, a mini-cartridge  30  and a full-size cartridge have a number of differences that prevent the mini-cartridge from directly operating in a full-size drive. Perhaps, the most obvious of these differences is size. Mini-cartridge  30  has a much smaller form factor than a full-size drive cartridge. Whereas, a mini-cartridge is about 1⅞″ square and about {fraction (1/10)}″ high, a full size drive cartridge is about 3⅞″ square and ¼ ″high. Other differences between the cartridges and the drives also require adaptation to enable a mini-cartridge  30  to operate in a full-size drive. For example, the mini-cartridge rotates slightly faster than the rotation rate of a full size drive cartridge (e.g., 3267 rpms versus 2960 rpms for a full-size drive cartridge). Caddy  31 , described more fully below, accepts a mini-cartridge  30  and adapts it for use in a full-size drive. 
     Referring to FIGS. 7A and 7B, a presently preferred embodiment of caddy  31  is presented. FIG. 7A shows caddy  31  without a mini-cartridge  30 , revealing the internal components of caddy  31 . FIG. 7B shows caddy  31  with a mini-cartridge  30  snapped into place. As is best shown in FIG. 7A, caddy  31  comprises a caddy body  70  for carrying and adapting the mini-cartridge form factor to the full-size form factor, a drive mechanism  72 ,  74 ,  76  for translating power from the full-size drive axis of rotation to the mini-cartridge axis of rotation, a spindle  78  for rotating mini-cartridge  30 , and a gear cover  86  for securing main gear  72 . 
     Caddy body  70  is shaped and sized to substantially the same dimensions as a full-size ZIP cartridge and has special features added to adapt a mini-cartridge  30 . A depression  81  is formed in the top of caddy body  70 . Depression  81  has a rectangular footprint for accepting a mini cartridge  30 , and has an adjacent rectangular depression  84  to provide space for the insertion of main gear  72 . A cover  86  is disposed overtop depression  84  for holding main gear  72  in place, while allowing gear  72  to adjust to the full-size drive spindle. The depth of depression  81  is such that magnetic medium  29  is disposed at about half the height of caddy body  70 , thereby aligning the medium  29  with the height requirements of the full-size medium. Caddy body  70  also includes a lower depression  85 . Depression  85  provides space for the drive mechanism  72 ,  74 ,  76  to reside below the space occupied by mini-cartridge  30  and provides an opening for the lower full-size drive read/write head to enter the caddy  31  and access magnetic medium  29 . 
     The drive mechanism  72 ,  74 ,  76  translates power from the full-size drive motor and spindle to spindle  78  for rotating a mini-cartridge  30  placed in caddy  31 . Main gear  72  emulates a full-size cartridge hub and couples to the full-size drive spindle. As such, main gear  72  floats, as does a full-size cartridge hub, and adjusts its location to engage the full-size drive spindle. Thus, when caddy  31  is inserted into a full-size drive, the full-size drive spindle engages main gear  72  as if gear  72  were a full-size drive hub and the caddy were a full-size cartridge. As such, main gear  72  is formed of a ferrous material, or employs a ferrous material, to allow magnetic coupling with the full-size drive spindle. As the full-size spindle rotates main gear  72 , power is provided to the entire drive mechanism of caddy  31 . 
     Gears  74  and  76  translate power from main gear  72  to spindle  78 . Gears  74  and  76  are rotatably coupled to caddy body  70  by conventional methods, such as metal or plastic pins. Spindle  78  is fixed to spindle gear  76  such that when gear  76  rotates, spindle  78  also rotates. Furthermore, the center axes of spindle  78  and spindle gear  76  are coincident, ensuring that a stable axis of rotation is provided to a mini-cartridge  30  inserted into caddy  31 . Spindle  78  is located within the caddy body  70  such that it engages magnetic medium  29  (see FIG. 7B) at the appropriate height and plane (i.e., on the same plane as media for a full-size drive). Furthermore, spindle  78  emulates the spindle of a mini-drive  20  in engaging a mini-cartridge  30 . That is, spindle  78  magnetically couples with hub  32  of a mini-cartridge  30  inserted into caddy  31 . 
     During operation, main gear  72  rotates clockwise in accordance with the rotation of the full-size drive motor. Obviously, spindle  78  must also rotate clockwise so that medium  29  rotates properly in the full-size drive. Accordingly, intermediate gear  74 , is coupled between gear  72  and gear  76 . As Seat  72  rotates clockwise, gear  74  rotates counter-clockwise, causing gear  76  and spindle  78  to also rotate clockwise. Furthermore, as noted above, medium  29  of mini-cartridge  30  rotates within a mini drive  20  at the same angular rotation as a full-size cartridge medium rotates within a full-size drive. Because of the obvious size differences, the angular rotation of a mini-cartridge medium  29  translates to a rotational speed that is slightly faster than the rotational speed of a full-size medium. When operating in caddy  31 , the same proper rotation speed of a mini-cartridge  30  must be maintained. Accordingly, gear ratios of  72 ,  74 ,  76  must be selected such that the magnetic medium  29  rotates at an angular velocity approximately equal to the angular velocity of full-size drive magnetic medium, or about twice the rotational speed. 
     Additionally, a point on the circumference of the medium  29  farthest from the centroid of the main drive mechanism  72  defines a forward-most point  82 . The forward-most point  82  also lies on a center axis  80 , which is defined by points where the vertical center axes of the main drive mechanism  72  and of the spindle  78  bisect the plane defined by the medium  29 . The spindle  78  is located along the center axis  80  such that the forward-most point  82  of the mini cartridge medium  29  is coincident with a forward most point of a full-size medium of a standard, full-size disk cartridge. Such location of the mini cartridge medium  29  enables the heads of the full-size drive to properly engage the medium  29 . 
     Those skilled in the art will readily appreciate that many modifications to the caddy are possible within the scope of the invention. For example, a belt drive mechanism could be used in place of gears, or additional gears could be used to provide a more stable rotation. Accordingly, the caddy, is not limited to the single embodiment disclosed. 
     The ZIP drive  33  has an interface  24  for transferring signals between the full size drive  33  and the host computer  35 . The interface  34  is shown in FIG.  8 . 
     FIG. 8 shows the ZIP drive interface  26  between the read write channel for the disk (lower right side of diagram) and the host computer (upper left side of diagram). It includes an AIC chip  101  which performs the SCSI  102 , the DMA  103 , and disk formatter  104 . The interface also includes a PHAEDRUS  105  which includes an 8032 micro controller  106 , a 1 K Ram  107  and an ASIC  108 . The ZIP interface transfers data between the input/output channel of the ZIP drive and SCSI devices such as the host computer. 
     Although a particular embodiment of the invention has been shown and described, other embodiments and modifications will occur to those of ordinary skill in the art which fall within the scope of the appended claims.