Abstract:
An adaptive method of managing system configuration in either a rewritable or a write-once optical card with zones formed in combination with an emulated drive buffer to behave as a Direct-access device. In the card medium, zones are formed for recording user data and the capacity of each zone is variable according to the available volume capacity, partition capacity, and user requirement, a spare area for recording alternative sectors; a defect list area for recording a defect list and a table area for usage and definition of user zones.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     This invention relates generally to systems and method for controlling an optical pickup head for reading data from and writing data to data storage medium. More particularly, this invention is related to an improve method for optical disk tracking servo and focusing servo circuits enabled to compensate for either continuous or non-continuous track segments or prolonged defect data tracks.  
         [0003]     2. Description of the Prior Art  
         [0004]     The technologies as that commonly implemented in conventional Direct-Access information-recording and reproducing apparatuses, particularly those applied to “write-once” medium, cannot be conveniently applied to the optical data tracks supported on a card-shaped medium for recording data related to personal information such personal photo, biometric data and/or medical records, etc. Specifically, in a write-once optical disk, the recorded information cannot be rewritten; the contents stored in a file-allocation table (FAT) cannot be updated. The described file management technique is not valid and a rewritable optical disk does not have this type of problem. With it inherent very large capacity property, optical disk such as CDR, CDRW, DVDR, or DVDRW can use a multiple session method. This multiple session method allows a write-once optical disk to update information by creating a new session area and discarding the earlier sessions. Each session area has its own lead-in, data, and lead-out areas. The lead-in area has table of contents information and lead-out area indicates the end of data and end of this particular session information. The data area can use either 1988 ISO 9660 or OSTA Universal Data Format file management method. Comparatively, an optical write-once data card does not have the tremendous capacity provided by CDR, CDRW, DVDR, or DVDRW. The capacity of an optical card is not even enough to contain a convention CDR or CDRW lead-in area. A write once data card is therefore limited with options to update or correct data written on the cards. Even a rewritable data card capacity may not be enough for the conventional lead-in and lead out format requirement. Such limitations may unduly increases the operation costs and causes great deal of difficulties if a requirement for data update or error correction arises.  
         [0005]     The file structure in a recording medium contains significant information related to the file structure and status of these files to allow a data access device to efficiently access the data stored in different data tracks. Specifically, Direct-Access information-recording and reproducing apparatus such as a magnetic disk and floppy disk, the file management including the defective sector management, a directory area for recording management information and a data area for recording file data are formed on the disk. A file allocation table (FAT) area is also formed in the disk to record an FAT for controlling the status of the data area. In such a disk, a defective may occur due to flaws, contamination or deterioration of the recording material, an identification flag is recorded in the FAT entry corresponding to such a defect. When a disk is formatted to initialize FAT entries, an unused flag meaning that unused areas are recorded in FAT entries in addition to the defect area entries. When recording a new file, FAT entries are updated to reflect the new usage of the area. In this operation, FAT entries having the defect flag are skipped so that defective area will not be used in recording the new file. After the data of the new file are recorded in unused area, the FAT is updated by rewriting the information, which describes the new status.  
         [0006]     For optical disk configurations, U.S. Pat. No. 4,611,314 Ogata et al. Sep. 9, 1986 discussed a defect and data buffer management method of an optical disk, U.S. Pat. No. 4,682,318 Busby Jul. 21, 1987 discusses a multiple-zone methods with a temporary location for intermediate data, U.S. Pat. No. 4,677,606 Ogata et al. Jun. 30, 1987 discussed a multiple zones and blocks with pre-determined address assignment. U.S. Pat. No. 5,111,444 Fukushima et al. May 5, 1992 discussed a defect management of multiple zones. In U.S. Pat. No. 4,775,969, issued on Oct. 4, 1988, Osterlund discussed the emulation of a tape device with optical disk. These methods are not suitable for an optical write-once data card.  
         [0007]     These patented inventions however do not provide relevant or an effective solution to enable a card-sized optical recording medium formed with write-once and rewritable data storage data tracks to carry out data update or error corrections on the recording medium. Therefore, a need still exists in the art to provide improved and new configuration and data access process to overcome such limitations.  
       SUMMARY OF THE PRESENT INVENTION  
       [0008]     Therefore, an object of this invention is to provide a method and a system configuration to enable multiple sessions of data update operation in a non-rewritable information-recording medium supported on a card, e.g., a credit card or ID card and for a limited capacity rewritable data card that can not have conventional lead-in and lead-out type format. It is a further object to provide a method and system configuration to manage defective sectors in a non-rewritable information-recording medium, particularly for such medium supported on a card. Since the data tracks are formed as arc segments, it is further an object to provide a method for managing entries of starting sector and ending sector of a track in non-continuous track segment arrangement in a card-shaped information-recording medium. It is a further object to provide a method for detecting of starting sector of a track in non-continuous track segment arrangement in a card-shaped information-recording medium. In order to more conveniently carry out multiple sessions of data update operation, it is further an object to provide a method for managing a card-shaped information-recording medium as a direct-access device by implementing emulated buffer on a data access device and on a host computer. It is a further object of this invention to provide a data access device to format and process a plurality of optical data arcs ready for storing data and for a pickup head to access and update the data and to handle the defective data tracks with data stored in the formatted tracks.  
         [0009]     Briefly, in a preferred embodiment, the present invention discloses a data access device for accessing data stored in a card-shaped medium supporting a plurality of recording arc segments thereon. The data access device further includes a plurality of data tracks disposed on the non-rewritable card-shaped information-recording medium including a first segment of the data tracks storing an address pointing to a multiple session management location in said data tracks employed for carrying out multiple sessions of data updates on the non-rewritable or rewritable card-shaped recording medium. In a preferred embodiment, the non-rewritable card-shaped information-recording medium further includes a second segment of the data tracks for storing an address pointing to a defect management location in the data tracks for storing data employed for managing a defect in the data tracks. The format of a session applies to not only to a non-rewritable card shaped medium but also to a rewritable card shaped medium.  
         [0010]     In a preferred embodiment, this invention further discloses a method for enabling multiple sessions of data updates in a non-rewritable and rewritable card-shaped information-recording medium. The method includes a step of providing a plurality of data tracks on the non-rewritable or rewritable card-shaped information-recording medium and allocating a segment of the data tracks for providing an address pointing to a multiple session management location in the data tracks employed for carrying out the multiple sessions of data updates. The method further includes a step of allocating a segment of the data tracks for providing an address pointing to a defect management location in the data tracks for storing data employed for managing a defect in the data tracks.  
         [0011]     These and other objects and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment, which is illustrated in the various drawing figures. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1A  shows a non-rewritable and rewritable card-shaped information-recording medium with non-continuous track segment arrangement at an optical memory area and possible smart chip and magnetic stripe.  
         [0013]      FIG. 1B  shows a non-rewritable and rewritable card-shaped information-recording medium with circular continuous track arrangement at an optical memory area and a possible smart chip.  
         [0014]      FIG. 1C  shows a non-rewritable and rewritable card-shaped information-recording medium with circular continuous track arrangement at an optical memory area with possible smart chip and magnetic stripe.  
         [0015]      FIG. 2  shows the format of a logical optical track that can map to physical optical tracks.  
         [0016]      FIG. 3  shows separate areas allocated for different purpose in the segmented optical area.  
         [0017]      FIG. 4A  shows a starting sector map area and entries of sector address.  
         [0018]      FIG. 4B  shows a physical arrangement of tracks with starting sectors at each track aligned to each other.  
         [0019]      FIG. 4C  shows a physical arrangement of tracks with starting sectors at each track not aligned to each other.  
         [0020]      FIG. 5  shows a multiple session control table.  
         [0021]      FIG. 6  shows the mapping arrangement of the emulated direct-access buffer.  
         [0022]      FIG. 7  shows a defect entry table.  
         [0023]      FIG. 8  shows mapping method between host and the data access device that recognizes logical address and the physical address on the card.  
         [0024]      FIG. 9  shows a non-rewritable card and an emulated direct-access buffer built in with optical card reader/writer interface with a host system.  
         [0025]      FIG. 10  shows a non-rewritable card interfaces with a host system with an emulated direct-access buffer.  
         [0026]      FIG. 11  shows an emulated direct-access device buffer arrangement.  
         [0027]      FIG. 12  shows method to detect a starting sector of a segmented track.  
         [0028]      FIG. 13  shows the conversion of logical address to physical address.  
         [0029]      FIG. 14  shows method to update card information through the emulated  FIG. 15  shows method to generate defect map table.  
         [0030]      FIG. 16  shows method to use defect map sectors. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0031]     Referring to  FIGS. 1A, 1B , and  1 C for a data card  102 , e.g., a credit card, that supports an optical non-rewritable data storage area  101 . The data storage area  102  includes a plurality of optical data tracks and these data tracks are formed as circular arc segments or full circular tracks. Since these arc segments in  FIG. 1A  have a track starting point and a track ending point, unlike the data tracks disposed on a regular flat medium such as a compact disk (CD) or a floppy disk, these arc segments are not continuous from one track to the next. For this reason, the data access processes in reading or writing data to and from these data tracks must have special servo control to determine the beginning and the end of each arc segment employed for data storage.  FIG. 1B  or  1 C arranged with full circular concentric or spiral tracks does not need the special method to detect the beginning or ending points of track arc segments. Furthermore, these arc segments or circular tracks are implemented as non-rewritable data storage medium for storing personal information, e.g., medical records, biometric data, personal photos, etc. Since these data arcs or circle are formed as “write-once” medium, this invention discloses system configuration and data processing methods to perform multiple-session data updates or information corrections operations on these data arcs or circles as optical data tracks supported on the card-sized medium.  
         [0032]     In order to achieve these purposes, the present invention discloses special method to configure the optical data tracks formed as a plurality of arc segments or circular tracks with special formats. All data tracks in the following description can be physically in either arc segments or full circular or spiral tracks and logically arranged having track starting and ending points.  FIG. 2  shows the format arrangement of a physical optical track segment or a logical data track wherein the physical optical track can be arc segments, concentric circular or spiral circular configuration, or. A logical data track with logical sectors is logical units addressed by operating system for data accesses. Logical data tracks are mapped to physical data tracks that can be part of a physical track or can occupy one or more physical tracks. Operating system requests data from a specified logical sectors and tracks, device converts the requested logical sectors and tracks to physical sectors and tracks locations to retrieve or update data. Starting from the beginning of a data track, a certain length or area is for an optical data access device to turn on focusing, tracking and lock on track functions. This starting sector is for an optical data access device to verify the track, sector addresses, and prepare for actual data access at the data sectors following starting sector. This starting sector is also for an optical pickup head to turn on the writing power in writing that is usually higher the reading power. The number of data sectors in a track depends on the physical construction of an optical track; an exit area follows data sectors before the end of logical optical track. The exit area can be small in length comparing to a data sector. The exit area is for seeking to next track servo adjustment and is for the optical pickup head to turn off focusing and tracking functions at a controlled manner. A pickup head for reading/writing data from the data tacks is therefore provided with information to timely turn on and turn off at the beginning and end of each data track and to operate with proper control parameters based on the information provided on the beginning and end sectors of each data track. In the subsequent description, data tracks can be either logical or physical tracks and interchangeable in discussions.  
         [0033]     Referring to  FIG. 3  for data provided to manage multiple sessions and to handle data track defects, the starting address sector as shown in  FIG. 2  further includes a data for indicating a starting address per track table  401  a session management table  402 , a defect management table  403 . Separate areas, e.g., areas  404  and  405  are particularly reserved for data storage of different sessions and area  406  is reserved for defect sector alternative replacement process. Referring to  FIG. 4A  for more details of the starting address per track table  401  that is a table for a series of pointers  504 . Each pointer stores the physical address of the starting and ending sectors of each track.  FIG. 4B  shows the focusing and tracking initial sector  521  and the starting block region  522  wherein these sectors are aligned across different data tracks along a same radial line. Alternately,  FIG. 4C  shows that the starting points of first sector  532  across tracks in  101  are not aligned along a radial line. The aligned or non-aligned configuration depends on the optical memory manufacturing process.  
         [0034]     In order to perform multiple data access sections, the data track further provide data storage for storing data for different sessions.  FIG. 5  shows each entry points to an area of tracks in  101  the starting address and ending address of a session if the session has been defined, otherwise, the entry or sector has no data. Specifically, as shown in  FIG. 5 , Table  402  is a session management table that has a sequence of entries. Each entry occupies a sector or track since the media is non-rewritable. In this invention, data in each session is set as a self contained direct access device with complete operating system boot record, file allocation table, file directory entries and file data as shown in  FIG. 6  where a session pointer in table  402  points an area  1006  by a pointer  1007 . Area  1006  has complete information and structure of a direct access device. With the boot record file provided, each session can be conveniently initiated and operated as an independent session. The last entry is usually the latest up to date data since the sessions are created in sequence by updating process. All previous sessions become invalid and provide still a backup and restore of old data only. A rewritable data card may needs only one session instead of multiple sessions for a non-rewritable data card.  
         [0035]     For the purpose of managing defective data track or defective areas as a portion of a data track, special sectors with defective management data are provided.  FIG. 7  shows a table  403  with a series of defect sessions. Each entry  721  in table  403  has bad sector location addresses such as  704 ,  705 , etc. and their alternative or replacement assigned location in the data storage area  102 .  
         [0036]     As the physical length of each sector in optical memory process is usually constant, the number of sectors per each track in  101  varies from less number of sectors at an inner region to more number of sectors toward the outer region at a circular area. Under this constraint, the manufacturing process can usually align only one sector across the tracks on a radial line, or just randomly spread from track to track. Since the number of sectors per each track varies, the starting sector address  522  or  532  of each track depends on manufacturing process. The starting sector number  522  or  532  can be pre-set equal to a multiple of number of sectors of the longest track, or equal to a multiple of a number that is larger than the number of sectors of the longest track, or just spread them from track to track according to its physical length geometry. Table  401  records starting sector number  522  or  532  of each track for an optical data access device to use in address mapping purpose explained in  FIG. 8 . Using the data provided by a table  402 ,  FIG. 8  shows table  402  contains a series of session address pointers and table  401  has the starting address of each physical track  522  or  532 . The issues related to different number of sectors in each data track are therefore resolved.  
         [0037]     For the purpose of reading/writing data to the optical data tracks  101  supported on the data storage card  102 , an optical data access device  221  interfacing with a host computer  204  is shown in  FIG. 9 .  FIG. 9  shows a functional block diagram of the optical device  221  for carrying out data access operations to the data card  102  through an optical pickup head  208  driving by a spindle motor  209  and a stepper linear motor  207  controlled by a servo system  206  and a spindle motor control system  207 . The servo system  206  and the spindle motor control system  207  are part of a device controller  222  that further includes a microprocessor unit (MPU) as an intelligent processor to issue control command by receiving signals from the servo system  206  and the spindle motor control  207  and further by communicating with a memory system  210  and a data system  205  where data system  205  receives data and feedback signals directly from the pickup head  208 . The MPU  202  further communicates with a host computer  204  connected with data buses such as IDE parallel, IDE serial, SCSI, USB, etc between the MPU  211  and the host  204  and between the data system  205  and the host. Multiple sessions of data updates and corrections and defective data track managements are then processed through the cooperation between the MPU  202  and the host computer  204 . The MPU  202  also uses functions of data system  205  to encode and decode data accessed at data card  102  for retrieval or storage under the command of host  204 . The Memory system  210  provides temporary data storage and retrieval in controller functions for  205 ,  206 , and  207 . The memory system  210  further temporarily stores the instruction sequences of MPU  202  and provides the function as data buffers for various MPU and data access functions controlled by MPU  202 . For the purpose of achieving multiple sessions of data updates, the memory system further serve the function as an emulated disc buffer  211 . The details of the emulated buffers will be further described below in  FIGS. 10 and 11 . The emulated disc buffer  211  is under the control of MPU  202  to interface with the host  204 .  
         [0038]      FIG. 10  shows an equivalent buffer  311  of the buffer  211  in the memory system  210 . This equivalent buffer  311  is an emulated disc buffer  301  and is under the control of the host  204 . Instead of the MPU controlling the buffer  211  as the configuration shown in  FIG. 2 , the host  204  sets up the operation system boot record, the file allocation table, the file directory, and the files directly. In retrieving data, the host  204  updates data directly to buffer  301 . In updating data, host  204  gets data from device  221  and transfers to buffer  301 , updates the data to buffer  301  as needed. Once the updating of buffer  301  is complete, host  204  sends data from buffer  301  back to device  221 . Device  221  writes data back to  101 . The MPU  202  manages the buffer  211  in  FIG. 9  and the host  204  manages buffer  301  in  FIG. 10 . They are mutually independent when undergoing the processes of maintaining and updating the data contents of in these two different buffers but operate in sequential order in a coordinated manner to allow the optical data card  101  to have multiple sessions of data updates and data error corrections.  
         [0039]     A card-shaped information-recording medium is therefore disclosed in this invention. The card-shaped information-recording medium comprises a plurality of data tracks disposed in a data access area comprising data to enable a data handling system to process the card-shaped information-recording medium as a logic device. In a preferred embodiment, the plurality of data tracks further comprises data to enable a data handling system to process the non-rewritable card-shaped information-recording medium as a hard disk. In another preferred embodiment, the plurality of data tracks further comprising an operating system boot record, a file allocation table, a file directory and data file to enable a data handling system to process the card-shaped information-recording medium as a hard disk. In another preferred embodiment, the card-shaped information-recording medium further includes a first segment in the data tracks storing an address pointing to a multiple session management location in the data tracks employed for carrying out multiple sessions of data updates on the non-rewritable card-shaped recording medium. In another preferred embodiment, the card-shaped information-recording medium further includes a second segment in the data tracks for storing an address pointing to a defect management location in the data tracks for storing data employed for managing a defect in the data tracks. In another preferred embodiment, the plurality of data tracks comprises a plurality of data arc segments. In another preferred embodiment, the plurality of data tracks comprises a continuous data track having a beginning point and an end point, e.g., a circular track or a spiral track. In a preferred embodiment, the card-shaped information-recording medium is a non-rewritable card-shaped information-recording medium. In another preferred embodiment, the card-shaped information-recording medium is a rewritable card-shaped information-recording medium.  
         [0040]     According to above description, a data access device for accessing data stored card-shaped information-recording medium is disclosed. It includes a plurality of data tracks disposed on the card-shaped information-recording medium including a first segment in the data tracks storing an address pointing to a multiple session management location in the data tracks employed for carrying out multiple sessions of data updates on the card-shaped recording medium. In a preferred embodiment, the data access device further includes a second segment in the data tracks for storing an address pointing to a defect management location in the data tracks for storing data employed for managing a defect in the data tracks. In another preferred embodiment, the data access device further includes a beginning sector in each of the data tracks for storing data for the data access device to perform a focusing and tracking on the data tracks. In another preferred embodiment, the data access device further includes an ending sector in each of the data tracks for storing data for a data access device to exit from each of the data tracks and to end a data access operation. In another preferred embodiment, the data access device further includes a starting sector following a focusing and tracking sector disposed at a beginning of each of the data tracks sector, and the starting sector storing data for indicating number of sectors and an address of each of the sectors in each of the data tracks. In another preferred embodiment, the data access device further includes a focusing and tracking sector disposed at a beginning of each of the data tracks with each focusing and tracking sector in each of the data tracks aligned with each other. In another preferred embodiment, the data access device further includes a focusing and tracking sector disposed at a beginning of each of the data tracks with each focusing and tracking sector in each of the data tracks misaligned with each other. In another preferred embodiment, the data access device further includes a session management data including an operating system boot record, a file allocation table, a file directory and data file stored in the data tracks pointed by the address in the multiple session management location. In another preferred embodiment, the data access device further includes a bad block pointer and alternate block data stored in the defect management location. In another preferred embodiment, the data access device further includes a bad block pointer and alternate block data stored in the defect management location and a replacement data stored in the data tracks pointed by the alternate block data. In another preferred embodiment, the data access device further includes an emulated buffer in the data access device comprising an operating system boot record, a file allocation table, a file directory and data file for preparing to perform multiple session data updates in the card-shaped information-recording medium. In another preferred embodiment, the data access device further includes a host computer connected to the data access device and the data access device and the host computer each comprising an duplicated copy of an emulated buffer comprising an operating system boot record, a file allocation table, a file directory and data file for preparing to perform multiple session data updates in the card-shaped information-recording medium. In another preferred embodiment, the data access device further includes a first and a second duplicated copy of an emulated buffer comprising wherein the emulated buffer an operating system boot record, a file allocation table, a file directory and data file whereby the data access device is provided to process in the card-shaped information-recording medium as a logic device and ready to perform multiple-session data updates in the non-rewritable card-shaped information-recording medium. In a preferred embodiment, the card-shaped information-recording medium is a non-rewritable card-shaped information-recording medium. In another preferred embodiment, the card-shaped information-recording medium is a rewritable card-shaped information-recording medium  
         [0041]     For practical application, a computer system can set up a reading device  221  to access card medium  102  to retrieve data from  101  in a point of sale environment. To write or update data to optical data storage area  101 , the processes described above in  FIGS. 9 and 10  of this invention provide a system arrangement with a host  204  accessing data from card media  102  with an optical non-rewritable data storage area  101 . Host  204  also interfaces with an emulated disc memory  301  or  211  that stores the retrieved data from  101 . The Host  204  updates data as required. After finishing all updates, host  204  writes the updated data at  211  or  301  back to  101 . The host  204  can create data without any merging of data from  101 . In actual operations, the host  204  creates all the data at  211  or  301  first. After verifying and correcting data as necessary, host  204  transfers data from  211  or  301  to  101 . The configuration of an emulated disc  211  or  301  is set to duplicate in size and configuration of a session at  101  with operating system boot record, file allocation table, file directory, and files as shown in  FIG. 11 . As that shown in  FIG. 11 , the host  204  treats  211  or  311  as a direct access memory device that can be accessed as a logical device such as a hard disk drive in a computer system setup. Another preferred system configuration of this invention is to implement the functions perform by the host  204  in the MPU  202  by providing and invoking another MPU program to perform the functions with another duplicated emulated buffer set up in the memory  210  such that the data access device  221  can function as a stand alone unit to manage the data interface to the outside world of device  221  and the emulation of device disc buffer  211 . The data access device is enabled to carry out the multiple sessions of data updates or error corrections without relying on the availability of a host when the data access device is certified and qualified with sufficient security clearance levels or system management privileges.  
         [0042]      FIG. 12  shows the method to generate the starting and ending block table  401  as that shown in  FIG. 4A . Starting from the innermost track, the device  221  moves to the selected track N (step S 111 ) starts to detect the addresses of the starting sector  522  and  532  (Step S 112 ) by using the focus information. A determination is made based on the focus detection (step S 113 ), if the focus is found that changes from NO focusing signal to YES, the focus signal is a valid signal, then the process continue to activate a tracking process (step S 114 ), otherwise, the process loops back to step S 112 . The step S 114  activates the tracking servo to enable the optical pick-up unit  208  to follow the selected track. Then a determination is made (step S 115 ) to check if the tracking is locked. An “on track” condition indicates the system can proceed to S 116 ; otherwise system loops between S 114  and S 115  until the lock on track is valid. In step S 116  a physical address of a sector is acquired by decoding the signal followed by logging the decoded address (Step S 117 ). The in step S 118 , the physical address of next sector is calculated that allows a next step S 119  to compare two addresses decoded at S 117  and S 118 . When two addresses are in sequence, they are on the same track. If the determination made in step S 119  finds that the addresses are not valid then a jump is made to step S 165  to carry out a retry process S 165 . If the comparison made in step S 119  finds out that the addresses are in sequence, then another determination is carried out in step S 161  to verify the addresses are valid and in track N before the process proceed to step S 162  to log the starting block table with the starting sector address written to a buffer. The process proceeds by moving the pickup head to next track N+1 (step S 164 ). If it is determined in step S 161  that the track is not really the target track, a step S 163  is taken to perform a re-seek to the selected track referring to the decoded track address. At the end of the track, the tracking and focusing functions are turned of (step S 165 ) and finishing the data collections and ready for next step (step S 166 ). If all the tracks have been processed (Step S 167 ), the process proceeds to step S 168  to transfer the buffer data collected at S 162  to table  401  at card memory  101  or back to S 112  to start another process. Once the starting sector of a track is determined, device controller  222  can keep the OPU  208  on track between process S 162  and S 165  until reaches the end of track and lost the focusing and tracking to decode the ending sector address, the last valid address on this track is the end of the track address to fill the table  401  in  FIG. 4A .  
         [0043]     Referring to  FIG. 13  for the process that the optical device  221  converts a logical data block address requested by a host  204  to an actual physical address in the optical card  101 . Once the optical device  222  receives a logical address request at step S 151  either from the host  204  or from the internal generated request through the MPU  202 , the optical device uses table  402  to identify the current session and the session start address (step S 152 ) then proceeds with a step S 153  to apply table  401  to acquire the starting address of each track used in the session. The logic address to the data sector is mapped out one by one by starting from the first track of this session until the requested track address is reached (step S 154 ), The matched physical address is determined by adding the session address o the track address (step S 155 ) and the process is returned with a physical address.  
         [0044]     As described above, the emulated disc buffer  211  or  301  is a logical duplication of a session  1006  in configuration. The entries at table  402  are filled progressively as more sessions being created until the media is out of memory space.  FIG. 14  shows a method of using table  401  to fill the entries in Table  402 . As a session request reaches (step S 141 ), device  221  or host  204  activates an emulated disk buffer  211  or  301  (step S 142 ). A determination is made to determine Process the request is to update an existing session with files of to create a session with new data (step S 143 ). If the updating of a session is required, then the data for the current session is inputted for carrying out a data update (step S 145 ). Before any data is transferred back to device  221 , host  204  uses data buffer  211  or  301  to manipulate data, read or write like a direct device. Once all the data manipulations, readings and writings are completed (step S 144 ), host  204  and device  221  locate the next available session area from table  402  by searching table  402  to determine the last entry with valid data that are the starting and ending address of last session (step S 146 ). There should not be any session entry after this last entry. The next available session area pointer in table  402  is calculated from the ending address of the last session plus a predetermined offset, for example, two. With session address determined, all data in the emulated disc buffer  211  or  301  beginning with operating system boot record, file allocation table, file entry directory, and all file data are copied to the newly created session (step S 147 ). The size or the area of this session occupies and updates table  402  with starting address and ending address are recorded (step S 148 ). In copying data to a session area, device  221  also generates a defect table as needed at table  403 . Each session has a separate defect table in table  403 .  
         [0045]     Referring to  FIG. 15  for a method to generate table  721 . As S 131  a write block request is received (step S 131 ), the write request is processed and a write request is carried out (step S 132 ) then a check is made to determine if the write process is completed successfully (step S 133 ) followed by a read verification (step S 134 ) if the write process is checked out satisfactory. On the other hand, if it is detected that the write process fails, an alternate block is located (step S 135 ). Similarly, if the read verification cannot verify the written data with read verify, again, an alternate block is located (step S 135 ), otherwise, a successful read verification completes the process. In alternative process, an available sector IW in area  406  is located and tests are performed for the data written to IW and a read verification is performed (step S 136 ). If the tests failed, then the system repeats steps S 135  and S 136  processes until they are successful. The bad sector address and replacement address at a buffer are recorded for later copying to table  721  (step S 137 ). The operation of Table  721  writing to table  402  is done at the end of completion of a session.  
         [0046]      FIG. 16  shows the process to enter data into the defect Table  721  and how this table is used during a read request. The process begins with the receipt of a read request (step S 121 ) for data at address J. The current defect table  721  is retrieved and made available from the defect session table  403  (step S 122 ). A check is made to determine if the request block address J exists in Table  721  (step S 123 ), if it is not, the process proceeds with a read operation from the block J (step S 124 ) and the process is completed. If table  721  shows that the request block address J is a defect, then an alternate location IR is located (step S 125 ) and the data in block IR is read instead of the block J, and the process is returned with the data at IR as the data read from the address at the J block.  
         [0047]     Although the present invention has been described in terms of the presently preferred embodiment, it is to be understood that such disclosure is not to be interpreted as limiting. Various alternations and modifications will no doubt become apparent to those skilled in the art after reading the above disclosure. Accordingly, it is intended that the appended claims be interpreted as covering all alternations and modifications as fall within the true spirit and scope of the invention.