Abstract:
The present invention permits access to information stored on a remote device from a local device without requiring that a complete physical copy of the remote information be made. An enhanced and refined hash table permits access to the remote information in order or according to a search key with significant reduction in the memory requirements on the local device even though the remote information is not sorted. Scrolling through the remote data structure without accessing any unnecessary record on the remote device and hence reducing scroll response time is also achieved.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates generally to electronic devices capable of storing telephone book information such as names and phone numbers and, more particularly, a method and apparatus for providing alphanumerically sorted access to telephone book information stored in other electronic devices in an embedded system having crucial memory size restrictions with an application demanding immediate response to user initiated requests. 
   2. Background Art 
   Various electronic devices which store telephone book information, including names, telephone numbers, facsimile number, email addresses etc., are currently available to consumers and in increasingly common use. Such devices include conventional telephones, cellular or wireless telephones, Personal Digital Assistants (PDAs), portable email terminals and personal computers (PCs). Unfortunately, the information stored in one device often cannot be accessed by another device. For example, if a user stores telephone book information in a PDA, that telephone book information typically cannot be accessed from the user&#39;s cellular telephone. Rather, to locate and dial a telephone number the user must first look up the desired name and phone number on the PDA and then type the phone number into the telephone keypad. This can be a cumbersome task—especially when the user does not have both hands available or needs to make several telephone calls. 
   Certain prior art attempts have been made to address this problem. For example, some devices offer the user the ability “synchronize” with another device via and infrared (IR) link, a serial cable, a USB cable, or a wireless communications link whereby the data stored in one device is made to resemble the data stored in the other device and changes made to the data in either device are reflected in both devices. Accordingly an exact copy of the data is made to exist in each of the first and second devices. While useful, most methods of synchronization have some drawbacks. First, since these methods typically require that both devices dedicate enough memory to store the entirety of the synchronized data as the synchronization process copies each record completely between devices. Second, synchronization techniques typically require sophisticated software capable of translating between what are often proprietary data formats. Finally, records stored in a device are up to date only as of the last time the devices were synchronized. If a particular record has been updated on one of the devices since the last synchronization, the updated information will not be available to the other device. 
   In order to encourage interoperability between devices, manufacturers often publish interface specifications for interfacing with their devices. For example, Nokia Group Finland provides instructions for interfacing a NOKIA telephone with a personal computer in the document entitled  Nokia PC Connectivity SDK  2.1  Component Library Reference for Nokia Phones . Thus, techniques for accessing phonebook and other information stored by portable electronic devices are known in the art. 
   Many portable electronic devices, such as GSM cellular telephones which store phonebook information on SIM cards, also store phonebook entries in the order in which they are entered in the memory by the user. Thus, the entries are typically not sorted alphabetically or in any other orderly fashion within the device memory. In accordance with another aspect of the invention, unsorted information in the phonebook of a first device can be displayed in alphabetical sequence on another device without storing the entire contents of the phonebook information. 
   Thus, with typical prior art devices, a user must either (1) independently access and constantly juggle more than one device to “share” information, or (2) spend a great deal of time and effort entering, updating and synchronizing telephone book information in each device that the user owns. This is not only inconvenient, but in some cases increases the cost of the device, as well as the time and effort required to operate them. 
   Accordingly, one advantageous aspect of the invention provides for reduced memory costs and improved convenience by providing a method and apparatus for making telephone book information stored in a first electronic device available to other electronic devices without having to store the entirety of the first device&#39;s information in each of the other devices. 
   In some applications typical prior art synchronization techniques may also raise privacy and security concerns. For example, a visitor may desire to interface his cellular phone with the home telephone system of a personal being visited, so that the cellular phonebook is accessible via the home telephone system for the duration of the visit. However, it may not be desirable to provide the home telephone system with a permanent copy of the cellular user&#39;s entire phonebook. Therefore, another aspect of the present invention allows a user to interface an electronic device with other devices without the wholesale copying of private information. 
   Yet another aspect of the present invention allows the use of EEPROM memory because the need for fast read/write times is reduced. Home telephones or other access devices may also be constructed with smaller amounts of memory, thus lowering cost and improving reliability. 
   The prior art has included the use of software based hash tables to access stored data. A typical hash table comprises a data table storing items or keys in which keys are mapped to array positions by a hash function. The hash function typically maps keys to integers, such as to get an even distribution on a smaller set of values. 
   Conventional hash tables have significant drawbacks that have prevented their use in the context of the aforementioned application. In particular hash tables typically use linked lists that require more memory than tables. This may be undesirable for an embedded application in a consumer product. Moreover, hash tables are typically oversized to ensure that only few entries are made in each slot which again unfavorably impacts memory requirements. The access performance of a conventional hash table rapidly degrades when a single hash table slot contains numerous entries. In particular, scrolling in alphanumerical order through a “classic” hash table slows down proportionally to the number of entries of the slots. Similarly “unnecessary” redundant accesses to data pointed to by the hash table entries increase proportionally to the number of entries of the slots. 
   The present invention circumvents these limitations. A local data structure is implemented on a home phone to provide access to the address book stored in the memory of a cell phone from the comfort of a home phone (corded or cordless base or handset). Using the methods of the present invention the home phone can initialize and maintain the local data structures to the aforementioned purpose with a total memory size significantly smaller than that of the cell phone address book. 
   These and other desirable characteristics of the present invention will become apparent in view of the present specification and drawings. 
   SUMMARY OF THE INVENTION 
   The present invention allows data records such as telephone book entries stored on a first device, to be accessed by a second device such as a cordless telephone system, without storing the entirety of the accessed data on the second device. 
   The first device includes a storage medium which holds records of telephone book information. The first device communicates with the second device via an interface. The second device is able to access the storage medium in the first device via the interface. 
   The second device contains a memory that is built up to contain information referencing the entries in the phonebook storage medium of the first device. In accordance with one embodiment of the invention, the second device memory can specifically be built up as a modified Hash table. The table stores index values in a series of slots, each slot being further subdivided into a series of cells. At least some of the slots are preferably designated as “home slots” for particular alphanumeric sequences. 
   Upon initiating communications between the first and second device via the interface, the reference table within the second device can be populated. The index values may be stored in the appropriate home slot such that the home slot&#39;s alphanumeric sequence matches the alphanumeric sequence of the telephone book record identified by the index value. The index values may further be sorted within each home slot; in other words, when read in sequence the index values identify an alphabetically sorted list of records. 
   In an additional embodiment of the present invention, the index values may comprise an additional “update flag” bit, which may be used during synchronization to identify old records to be deleted. 
   An apparatus according to the present invention may comprise a cellular telephone and a cordless telephone connected by an interface. The cellular telephone contains telephone book records. The cordless telephone contains a sorted list of index values which point to a respective telephone book record. The index values may be stored in a series of slots and cells, such that the stored index values, when read in sequence, identify an alphabetical list of records. In all of the above embodiments, the telephone book records may be browsed or searched via the cordless telephone. The described algorithms and data structures circumvents the limitations of “traditional” hash tables that would prevent their application to an embedded system where memory requirements have to be minimized. Moreover, the described algorithms and data structures further minimize the number of accesses to the remote device holding the telephone book. In the present invention instantiation accesses to the cell phone address book are very slow. The desired response time for scrolling through the cell address book requires that the access to the cell address book be deterministic—i.e. get the desired “next” address in one shot (e.g. one access to cell phone to get the alphanumerically next address book entry). 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the present invention, reference may be had to the accompanying drawings in which: 
       FIG. 1  is a perspective view of one embodiment of the present invention comprising a cordless telephone system and a cellular telephone. 
       FIG. 2  is a block diagram representing the cordless telephone handset and the cellular telephone of FIG.  1 . 
       FIG. 3  is a block diagram illustrating the preferred memory structure for storing telephone book record index values. 
       FIG. 4  is a table containing sample telephone book data. 
       FIG. 5  is a block diagram illustrating the various states of memory slot “AN” as the data of  FIG. 4  is sorted. 
       FIG. 6  is a flowchart illustrating the logical process required to sort the index values of  FIG. 4  into the memory structure of FIG.  5 . 
       FIG. 7  is a flowchart illustrating the logical process required to perform a “quick search” of the second storage medium. 
       FIG. 8  is a flowchart illustrating the logical process required to perform a “full search” of the second storage medium. 
       FIG. 9  is a flowchart illustrating the logical process required to perform a “browse up” function in the second storage medium. 
       FIG. 10  is a flowchart illustrating the logical process required to perform a “browse down” function in the second storage medium. 
   

   DETAILED DESCRIPTION 
   While this invention is susceptible of embodiment in many different forms, there are shown in the drawings and will be described in detail, a preferred embodiment, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiments illustrated. 
   Particularly, the objects and advantages of the present invention can be achieved by providing a first electronic device and a second electronic device, wherein the first electronic device has telephone book information stored in non-volatile memory. The second electronic device may access the telephone book information stored in the first electronic device&#39;s memory via an interface. However, rather than copying the entirety of the data stored in the first electronic device&#39;s memory into the second electronic device&#39;s memory, the second electronic device merely stores an ordered list of “pointers” or addresses which indicate where in the first electronic device&#39;s memory each particular record is stored. This allows a second device to access the records of a first device in a real-time manner, without requiring the entire contents of each individual record in the first device to be transferred to the second device. 
   One skilled in the art will recognize that this technique may be applied among virtually any number of electronic devices. For purposes of simplicity, this specification discusses the proposed method in the context of using a cordless telephone to access information stored in a cellular or wireless telephone handset. However, it is intended that this invention could be applied in a number of contexts—for example, as between a PC and a cellular telephone, a PC and a PDA, and as between a PDA and a cellular telephone, etc. 
   An embodiment of the invention is disclosed in the context of the apparatus illustrated in FIG.  1 .  FIG. 1  shows a cordless telephone system having cordless handset  120  and base unit  122 . Handset  120  is a typical battery powered cordless telephone handset as is well known in the art, and comprises keypad  124  and Liquid Crystal Display (LCD)  126 . Keypad  124  may be used to manipulate menus governing phone settings or may be used to navigate telephone book information wherein names and numbers are stored in memory associated with the cordless handset. The corresponding menus and telephone book information are preferably displayed on LCD  126 . A similar menu is used to navigate the cell phone address book by means of keypad  124 . 
   Base unit  122  may include handset cradle  128  or the handset may have a standalone charger and cellular telephone cradle  130 . Data transfer can also be connectionless—e.g. through wireless communication standards such as Bluetooth™. Both handset cradle  128  and cellular telephone cradle  130  have electrical contacts (not shown) for interfacing the electrical circuitry in base unit  122  with handset  120  or cellular telephone handset  132 , respectively. While cellular cradle  130  is illustrated and being integrated into base unit  122  in the embodiment of  FIG. 1 , it is understood that in alternative embodiments, a physically separate cellular cradle unit could be provided, having an electrical link between the cellular cradle and base unit  122 . According to the foregoing device a user can elect to make or receive a telephone call by using the cordless handset  120  to access either the public switched telephone network (PSTN) to which the base unit  122  is physically connected, or when cellular telephone  132  resides in cradle  130 , the cellular or wireless telephone network to which cellular telephone  132  wirelessly connects. 
   In practice, and as will be described in more detail below, a user may store telephone book information in cellular telephone handset  132  by entering the information via cellular telephone handset keypad  136 . Alternatively large address books can be created by downloading from PC. For cellular telephones, phonebook entries are stored within telephone memory in the order in which each record or entry is entered, starting with the first available memory location within the phonebook memory. Thus, many cellular telephones build up a phonebook table that is not necessarily sorted in an alphabetical or other orderly fashion. 
   The user can typically view telephone book information via cellular telephone display  134 , and can place a call to that number via the cellular telephone network in an automated fashion. However, in some circumstances, a user may desire to place a call using the cordless telephone handset  120  rather than cellular telephone  132 . As described herein, the present invention functions, in part, to allow a user of cordless handset or a base station equipped with LCD and keypad  120  to access the telephone book information stored in cellular telephone  132 . 
   Specifically, when cellular telephone  132  is placed in cellular telephone cradle  130 , interface  112  (shown in  FIG. 2 ) is set up via electrical contacts within the cradle (not shown). As will be described in greater detail below, whenever the cellular telephone  132  is placed in cellular telephone cradle  130 , cordless telephone handset  120  initiates a software driven indexing routine. Particularly, cordless telephone handset  120  reads telephone book information from cellular telephone  132 , one entry at a time. 
   The entries are read sequentially by index number. Base unit  130  then stores the index number in an index table memory. Cordless telephone handset  120  stores only references to the telephone book information found in cellular telephone  132  but does not copy all of the data stored in cellular telephone  132 . When the user wishes to access the telephone book information, he may pick up cordless telephone handset  120  and use keypad  124  to browse or search the telephone book entries, while viewing the entries being browsed or searched on LCD  126 . Once a number is displayed on cordless handset the user may “use” this number to initiate a call on home or cell line or to store it in the local address book of the cordless handset. As will be described below, each time the user scrolls through the telephone book entries, cordless telephone handset  120  requests the required information from cellular telephone  132 , using the index previously created. Thus, the user may access his entire set of telephone book information without having to copy that information from cellular telephone  132  to cordless telephone  120 . This allows cordless telephone handset  120  to be manufactured at a lower cost, due to decreased memory requirement. This further prevents many of the headaches otherwise commonly associated with full record synchronization. In addition, according to the illustrated example, a user may cradle his or her cellular phone in another user&#39;s compatible cordless base unit toward making use of the cellular telephone&#39;s phonebook information while at another location, for example a friend&#39;s home, and may thereafter remove the cellular phone and not leave behind all of his or her telephone book data on the friend&#39;s telephone base unit. 
     FIG. 2  is a block diagram representing cordless telephone handset  120  and cellular telephone  122 . Cordless telephone handset  120  includes storage medium  104  and volatile storage medium  105 . Storage medium  104  is preferably a form of non-volatile memory, such as EEPROM, while volatile storage medium  105  is preferably Random Access Memory (RAM)  105 . Cordless telephone handset  120  also includes microprocessor  108 , which can read from and write to storage mediums  104  and  105 , as well as pass messages to cellular telephone  132  through interface  112 . In one embodiment, the hash table is stored once in the base. Each handset uses services of the base station to access the cell address book. As a result only one instance of the hash table exists regardless of the number of cordless handsets registered to the base station. 
   Cellular telephone  132  includes storage medium  106  as well as microprocessor  110 . As with storage medium  104 , storage medium  106  is a form of non-volatile memory, such as EEPROM, or in the case of GSM cell phones which store address books on a SIM card so that user can port his phone number and address book between different phones. Storage medium  106  includes at least some telephone book information. Microprocessor  110  can read information from storage medium  106  and pass information along to interface  112 , in response to a request from cordless telephone handset  120 . 
   Interface  112  between the base unit and cell phone generally comprises interface hardware and driver software. Specifically, it comprises the hardware and software required for microprocessor  108  and microprocessor  110  to exchange messages. Interface hardware is well known in the art and may include a form of UART connection, an RS232 cable, an infrared (IR) transceiver, a radio transceiver such as a Bluetooth™ transceiver, or even the electrical contacts of base unit  122 . Driver software is also well known in the art and is specific to a particular device. Typical specifications for cellular phone driver software may be found in the  Nokia PC Connectivity SDK  2.1  Component Library Reference for Nokia Phones  or the AT command specification supported by the GSM cell phone community. 
     FIG. 3  illustrates the structure of storage medium  104 . Particularly, storage medium  104  is organized into a series of slots  140 . Each slot is further subdivided into a fixed number of cells  142 . In the preferred embodiment of the present invention, each slot  140  comprises five cells  142 , each cell being sixteen bits wide. Some of the available slots are designated “home slots,” and are assigned to specific, two-character alphanumeric sequences, beginning with A 0  and ending with ZZ. Other slots are assigned to each of the numbers zero (0) through nine (9), one slot is assigned to “symbols,” and the remaining slots are designated as “free slots.” In the particular embodiment illustrated, there are seven hundred and two (702) slots assigned to the alphanumeric sequences A 0  through AZ, ten slots assigned to the digits zero (0) through nine (9), one slot assigned to symbols, and three hundred and eighty seven (387) slots designated as free slots for a total of one thousand one hundred (1100) slots. 
   The purpose of this particular organization of memory space is to provide a memory structure that is both efficient and is easily searchable. Thus, references to phone book entries with names beginning with “AA” may be placed in the “AA” home slot; references beginning with “AB” may be placed in the “AB” home slot, and so on. As will be described below, this allows the user to browse through the series of entries in alphabetical order. It is important to note that only references or “pointers” to the original telephone book data are stored in storage medium  104 —thus, cordless telephone handset  120  requires much less memory than it would require if it copied the entirety of each telephone book data record. It is, of course, well known to those skilled in the art that the particular combinations of available slots may take any form, depending on the size of the memory available and upon the particular application. According to the illustrated example, the first two letters of the name entry in the address book entry are used, but any other key can be used as is known in the art. For example, the home slots could be organized using three-letter alphanumeric sequences instead of two-letter sequences, at the expense of requiring additional storage space. Alternatively, the last two digits of the phone number can be used to achieve a lesser number of slots (i.e. 100). Numerous other variations are possible, such as varying the number of free slots, the number of cells per slot, or the size of the individual cells. 
   Turning to  FIG. 4 , the data structure of the cellular handset  132  telephone book information stored in storage medium  106  is shown. Telephone book data is preferably stored in table form, with each row representing one record of data. The records in this example will be referred to as Records 1 through 7. Each record comprises a series of fields—in this example, INDEX, NAME, and TELEPHONE. The data may or may not be in alphabetical order—in many cellular telephones, for example, telephone book information is indexed according to it&#39;s date of entry, not its alphabetical order. The INDEX value need not necessarily be a number; it can be any value which uniquely identifies a given record. The particular format of the data will vary depending on the particular device in which the data is stored. Accordingly, the data fields shown in  FIG. 4  are merely representative of data fields typically stored in such devices. 
   In order for cordless telephone handset  120  to access this data, it must know where to find each record of information—particularly, it must know the INDEX value of each Record 1-7. In addition, it is advantageous for the cordless telephone handset to store the INDEX values according to the alphabetical rank of the record, in order to allow more efficient browsing (scrolling up and down) of telephone book information. Because telephone book data is not stored alphabetically in cellular telephone  132  (sorting of the telephone book data is usually carried out by the telephone&#39;s firmware during operation or during initialization of the cell phone after power up), cordless telephone  120  must organize the records when storing the INDEX values of the records in some order, be it alphabetical or otherwise. 
   When a cordless telephone handset  132  is first placed in the base unit  122  an initialization process is executed by the base unit  122 . During this initialization, base unit microprocessor  108  systematically requests each record from the telephone book stored in cellular telephone  132 , determines the proper alphabetical location for that particular record, and stores that record&#39;s INDEX value in storage medium  104  within base unit  122 . This process is described in greater detail in connection with  FIGS. 5 and 6 .  FIGS. 5A-H  illustrate the “AN” home slot as it is filled with the data of  FIG. 3 , while  FIG. 6  illustrates the logical process used to sort the data. In discussing the slots illustrated in  FIG. 5 , the leftmost cell shall be considered the first cell in the slot and the rightmost cell shall be considered the fifth or last cell in the slot, with the cells in between being consecutively numbered as appropriate. 
   The initialization procedure begins with base unit microprocessor  108  requesting Record 1 from cellular telephone  132 , Step  200 . Specifically, microprocessor  108  passes this request to cellular telephone  132  via interface  112 , and specifically, cellular telephone microprocessor  110 . Cellular telephone microprocessor  110  receives the request from interface  112  and responds to the request by reading Record 1 from storage medium  104  and sending Record 1 back to microprocessor  108  across interface  112 . Microprocessor  108  receives Record 1 and stores it temporarily in RAM  105 . 
   Microprocessor  108  then determines the home slot of the record relative to the NAME field, Step  202 . For example, since the NAME value of Record 1 is “Anna Williams,” microprocessor  108  looks up the address of the “AN” slot. This address lookup can be accomplished by means of a lookup table stored within storage medium  104 , or in other cases may simply be calculated. Both methods for determining the slot&#39;s address are well known in the art. Microprocessor  108  then reads the first cell of the “AN” slot, Step  204 . Because the cell is empty, Step  206 , microprocessor  108  writes Record 1&#39;s INDEX value to the cell, Step  208 . Microprocessor  108  moves to the next record, Record 2, and requests that record from cellular telephone  132 , Steps  210 ,  200 . 
   The result of this operation is shown in FIG.  5 B. In  FIG. 5B , the first cell of slot “AN” contains the value “1,” which is the INDEX value of Record 1. The remaining cells are empty because no other records having a NAME field beginning with “AN” have been read in yet. 
   Microprocessor  108  begins to repeat these Steps for Record 2. Particularly, microprocessor  108  reads Record 2 from cellular telephone  132 , Step  200 , determines the home slot of that particular record, Step  202 , and reads the contents of the first cell in home slot “AN,” Step  204 . However, the first cell of slot “AN” is no longer empty, Step  206 , so microprocessor  108  must compare Record 2 to Record 1 in order to determine which one is “higher” alphabetically, Step  212 . While Record 2 is still stored in RAM  105 , Record 1 may no longer be in RAM  105 . If this is the case, microprocessor  108  must request Record 1 from cellular telephone  132  and store Record 1 in RAM  105  in order to perform the required comparison. With both Records 1 and 2 stored in RAM  105 , microprocessor  108  then compares the value of their respective NAME fields, using techniques well known in the art, in order to determine which record is alphabetically higher, Step  212 . Because Record 2 (“Androids R Us”) is higher than Record 1 (“Anna Williams”), microprocessor  108  shifts Record 1 down one cell (from the first cell to the second cell), Step  214 , and inserts Record 2 into the first cell of slot “AN,” Step  208 . Microprocessor  108  then requests the next record, Record 3, and reads that record into RAM  105 , Steps  210 ,  200 . 
   The results of this process are illustrated in FIG.  5 C. In  FIG. 5C , the first cell of slot “AN” contains the value “2” and the second cell of slot “AN” contains the value “1.” The remaining cells of slot “AN” are empty. 
   Microprocessor  108  next determines the home slot of Record 3 to be the “AN” slot, Step  202 , and reads the contents of the first cell, Step  204 . Because the first cell of the “AN” slot contains the value “2,” Step  206 , microprocessor  108  requests the record having an INDEX value of 2. Microprocessor  108  then compares the NAME value of Record 2 to the NAME value of Record 3 in order to determine which value is alphabetically higher, Step  212 . Because the NAME value of Record 3 is alphabetically lower than the NAME value of Record 2, microprocessor  108  leaves the first cell alone and looks at the second cell, Step  216 . The second cell is not the final cell in slot “AN,” Step  220 , so microprocessor  108  reads the contents of the cell, Step  218 , and determines that the second cell is not empty, Step  206 . Because the second cell contains a value of “1,” microprocessor  108  requests Record 1, and compares Record 1 to Record 3. Because Record 3 (“Anna Karenin”) is alphabetically higher than Record 1 (“Anna Williams”), microprocessor  108  moves the contents of the second cell to the third cell, and writes the INDEX value of Record 3 to the second cell, Steps  214 ,  208 . 
   The result of this operation is shown in FIG.  5 D. In  FIG. 5D , the first cell of slot “AN” contains the value “2,” which is the INDEX value of Record 2. The next cell contains the value “3,” which is the INDEX value of Record 3, and the third cell contains the value “1,” which is the INDEX value of Record 1. 
   Microprocessor  108  next reads in Record 4, and inserts its INDEX value into the second cell, shifting the remaining values down one cell as shown in FIG.  5 E. Microprocessor  108  then repeats the process for Record 5, inserting its INDEX value into the fourth cell and shifting the remaining values down one cell as shown in FIG.  5 F. 
   When microprocessor  108  reads in Record 6, it compares Record 6 to each of the records referenced in the five cells until it reaches the last cell. After reaching the last cell, Step  216 , microprocessor  108  determines that the fifth cell is the last cell in the “AN” slot, Step  220 . Because the fifth cell is not empty, Step  222 , and also does not contain a pointer, Step  224 , microprocessor starts a new slot, Step  226 . Starting a new slot requires three steps. First, microprocessor  108  inserts pointer &amp;FREE 37  into the last cell of slot “AN.” The purpose of this pointer is to provide the address of the next slot—in this case, slot FREE 37 , though it could be any available free slot. Next, microprocessor  108  inserts pointer &amp;AN into the first cell of slot FREE 37 . The purpose of this pointer is to assist browsing and will be explained in more detail later. Finally, microprocessor  108  compares Record 5 to Record 6 to determine their relative alphabetical rank, and accordingly inserts the INDEX value of Record 5 (which was previously in the fifth cell of slot “AN”) into the second cell of slot FREE 37 , and inserts the INDEX value of Record 6 into the third cell of slot FREE 37 . Microprocessor  108  can continue assigning additional slots as needed in this manner. The results of this operation are shown in FIG.  5 G. 
   Finally, microprocessor  108  reads in Record 7 and places that record in the second cell of slot “AN,” moving the remaining INDEX values down by one cell. The results of this operation are shown in FIG.  5 H. The foregoing example is likely to be a typical as address book entries are likely to be spread across many slots and is used to easily illustrate the algorithm and data structure. Moreover, additional FREE slots are “appended” if a free cell overflows such that the last cell of FREE 37  would point to FREE 38  and the first cell of FREE 38  would point back to FREE 37 . 
   In accordance with another aspect of the present invention, the steps described above may be modified so as to cache a greater amount of working data in RAM  105  which, in turn, will minimize the read/write access time and reduce the number of times the EEPROM is written to. Those skilled in the art will recognize that minimizing the number of read/write cycles to the EEPROM will enhance the longevity of the device. 
   Several functions can be carried out on the telephone book data now stored in cordless telephone handset  120 . For example, the user may perform a “quick search” by entering the first letter of a desired entry, wherein the cordless telephone handset  120  then displays the first matching entry. This “quick search” is explained in more detail in conjunction with FIG.  7 . In Step  300 , the user enters a single letter of the alphabet. For example, the user may enter the letter “A.” Microprocessor  108  looks up the first corresponding home slot in Step  302 —in the preferred embodiment described in this specification, the first home slot is “A 0 .” At Step  304 , microprocessor  108  reads the first cell of home slot “A 0 .” Microprocessor  108  then determines whether the first cell is empty, Step  306 . If the cell is empty, microprocessor proceeds to Step  308  where it determines whether any other home slots beginning with “A” exist. If other such slots exist, microprocessor  108  looks up the next consecutive home slot corresponding to “A” in Step  310 . In the preferred embodiment described above, the next consecutive home slot would be “AA.” Microprocessor  108  then repeats Steps  304 ,  306 ,  308  and  310  until a non-empty cell is found. 
   As soon as a non-empty cell is found, Step  306 , microprocessor  108  requests the full record information using the INDEX value stored in that cell, Step  312 . Microprocessor  108  then displays the record for the user in Step  314 . If no records starting with the desired letter are found, an appropriate message is presented to the user in Step  316 . 
   A “full search” may also be carried out as described in connection with FIG.  8 . The user inputs a search string in Step  400 . Microprocessor  108  stores the search string in RAM  105  and looks up the home slot corresponding to the first two characters in the search string, Step  402 . Microprocessor  108  selects the first cell of the home slot, Step  404 , and determines whether the cell is empty, Step  406 . If the first cell is empty, microprocessor  108  selects the next consecutive home slot until a non-empty slot is found, Step  408  (in general, whenever a record is not found, the microprocessor returns the next entry in the phonebook). Alternatively, microprocessor  108  may maintain a bitmap table indicating which slots are empty as a method of improving efficiency. 
   When microprocessor  108  finds a slot where the first cell is not empty, Step  406 , microprocessor  108  checks to ensure that the current cell is not the last cell in the slot, Step  410 . Of course, on the first pass after a slot has been selected, the current cell is always the first cell in the slot. Microprocessor  108  reads the contents of the current cell, Step  418 , and looks up the corresponding record, Step  420 . Microprocessor  108  then compares the record obtained in Step  420  to the user search string entered in Step  400 . If the record obtained in Step  420  is alphabetically lower or equal to the search string entered in Step  400 , microprocessor  108  displays the record. On the other hand, if the record obtained in Step  420  is alphabetically higher than the search string entered in Step  400 , microprocessor  108  repeats the process for the next cell, Step  424 . Microprocessor  108  thus sweeps each consecutive cell in each consecutive slot until it finds a record which is alphabetically lower than or equal to the search string. 
   Particularly, for each consecutive cell, microprocessor  108  checks to see if the cell is empty, Step  406 . If the cell is empty, microprocessor  108  moves to the first cell of the next consecutive home slot, Steps  408 ,  404 . Alternatively, if the current cell is the last cell in the slot, Step  410 , and the cell contains a pointer, microprocessor  108  selects the slot indicated by the pointer, Step  414 , and reads the next cell, Step  404 . Of course, because the first cell of a free slot always contains a pointer, Step  416 , microprocessor  108  must advance one more cell before reading the cell&#39;s value, Step  424 . 
   The user may also browse storage medium  104 . The steps for browsing storage medium  104  are shown in  FIGS. 9 and 10 .  FIG. 9  illustrates a method for browsing “up” through the data stored in storage medium  104 . Generally, a user may browse through the telephone book information using function keys or soft function keys (not shown). When the user presses the browse “up” key, the current cell is selected. If the current cell is empty, Step  500 , and if it is not the first cell in the slot, Step  502 , the previous cell is selected, Step  504 , and the process is repeated. If the first cell in the slot is empty, Step  502 , the last cell of the next alphabetically “higher” slot is selected, Steps  506 ,  508 . Once a non-empty cell is located, that cell is read out if it does not contain a pointer, Step  522 . If the cell to be read out contains a pointer, Step  510 , the type of pointer is determined, Step  512 . If the pointer points “up” (i.e., it is in the first cell of the current slot), the slot that the pointer points to is selected and the second-to-last cell of that slot is selected. On the other hand, if the pointer points “down,” the slot being pointed to is selected and the last cell of that slot is selected (thus ensuring that one always begins at the bottom of a slot.) 
   Browsing “down” is explained in connection with FIG.  10 . If microprocessor  108  encounters an empty cell, Step  602 , microprocessor  108  simply cycles through the consecutive home slots until it finds a non-empty slot, Steps  604 ,  600 . Of course, microprocessor  108  may also use the empty-slot bitmap described above for greater efficiency. Once microprocessor  108  encounters a non-empty slot, it checks to see if the cell contains a pointer, Step  606 . If it does not, microprocessor  108  uses the INDEX value stored in the cell to look up and display the corresponding record, Step  614 . If the cell does contain a pointer, microprocessor  108  either ignores it (if it is at the beginning of the slot, Step  608 ) and moves on to the next cell, Step  610 , or microprocessor  108  moves to the first cell of the slot indicated by the pointer (if the pointer is in the last cell of the slot), Step  612 . 
   When cellular telephone  132  is removed from its cradle  130 , the index data table may remain in cordless telephone handset  120 . Of course, cordless telephone handset  120  can not access the telephone book information stored in cellular telephone  132  when memory is not present to be accessed. However, the next time cellular telephone  132  is placed in cradle  130  (or interface  112  is otherwise enabled), cordless telephone handset  120  need not re-initiate the entire initialization process. Rather, microprocessor  108  again requests each consecutive record from cordless telephone  132 . When an identical INDEX value is determined to already exist in storage medium  104 , microprocessor merely updates the top bit of the INDEX value. Thus, the top bit of the INDEX value serves as an “update” flag. Any identical or new entries are given an “update” flag. All other entries are deleted after microprocessor  108  has completed inserting the new entries from cellular telephone  132 . New address book entries are inserted in the hash as described in initialization procedure above. The above refinement permits fast resynchronization if cell address book was not significantly modified while being uncradled. 
   The foregoing description and drawings merely explain and illustrate the invention and the invention is not limited thereto, as those skilled in the art who have the disclosure before them will be able to make modifications and variations therein without departing from the scope of the invention. For example, as pointed out earlier in this specification, interface  112  may be any suitable interface, and may even be a wireless interface such as a Bluetooth™ radio interface. One skilled in the art would easily recognize that such an interface provides greater flexibility since the user would not be required to dock his cell phone at any particular location. Furthermore, such an interface would allow multiple devices to interact and hence the user would be able to access multiple sources of data at once. In addition, the present invention could be used to perform other functions with respect to cellular telephone  132 . For example, one could delete entries from cellular telephone  132 &#39;s address book, or perform basic control functions. Those skilled in the art will recognize that the functions available are only limited by those which the manufacturer makes available via interface  112 . Finally, those skilled in the art will also recognize that the flowcharts and steps described above can be carried out in various manners while having the same result.