WO1997011413A1 - International time indicating system - Google Patents

Abstract

An international time indicating system is associated with a telephone, calculator, computer, software package, integrated circuit, real time clock or the like for automatically displaying a specific time and date of a called place upon entering the international access code, called country code, and called area code if necessary. A called time and date are calculated via time zone offsets stored in system memory by determining the difference in time between a time zone of a local place of a caller and a time zone of a called place. The offsets are defined with respect to a reference time zone. The difference in time is then offset in order to determine the called time. The system is also provided with a feature which calculates and displays the corresponding local time of the caller which is at the same moment as the entered time of day of a remote place to be called.

Description

INTERNATIONAL TIME INDICATING SYSTEM This invention relates in general to a real time clock and deals more particularly with an international time indicating system associated with a telephone, calculator, computer, software package, integrated circuit, clock or the like which is designed to display the time of a remote place, such as for a long distance telephone call, the specific time and date ofthe distant place the caller intends to reach as soon as the caller dials the country code ofthe distant place.

BACKCxROUND OF HE INVENTION A modern telephone unit offers many features like memory, timer, hold, automatic re-dialing, mute, volume adjustment, speaker, answering system, etc. As people scattered throughout distant countries are better able to do business with one another due to modern air transportation and communication systems, a growing number of people are conducting business with countries spaced far and wide. For example, consider a man working in a business office in the United

States (U.S.A.) who often needs to call parties in different countries such as Indonesia, Venezuela or Sweden, etc. The caller will likely use a telephone directory to find the appropriate telephone country code. However, the caller preferably needs to know the exact local time ofthe caller's destination in order to place the call during business hours at the remote destination. Since it is often inconvenient or impossible to find a catalog of time differences of various countries, the caller is compelled to make a call blindly. Such a blind call often results in wasted time and money because the call is not made during normal business hours in the foreign country.

To make more cost efficient telephone calls, it is desirable to have a feature associated with the telephone which will provide information regarding the time in a distant country by entering the country code. A simultaneous display of a caller's local time and the specific time ofthe called country will better enable the caller to place the telephone call at an appropriate time so as to eliminate the need to search out the call destination time. U.S. Patent No. 4,887,251 issued to Takada shows a world timepiece that is not associated with a telephone which provides time and date information of areas in different time zones by inputting "area code" infoπnation. However the timepiece of Takada is wasteful of hardware because it uses a separate internal timepiece where each timepiece is dedicated to one of at least twenty-four time zones.

Therefore, in response to the foregoing problems, it is an object ofthe present invention to provide a cost effective international time indicating system using a single timepiece which may be associated with or incorporated in a telephone, calculator, computer, software package, integrated circuit, real time clock or the like to provide information regarding the specific time and date of a remote place, such as the destination of a telephone call by means of entering the international access code followed by the country code and if necessary, followed by the area code.

It is also an object of the present invention to provide a simultaneous display of a local time, such as a telephone callers local time and date and the time and date ofthe destination ofthe telephone call.

SUMMARY OF THE INVENTION

According to the present invention, an international time indicating system is associated with a telephone, calculator, computer, software package, integrated circuit, real time clock or the like for automatically displaying a specific time and date of a called place. The international time indicating system comprises means for entering or adjusting information associated with a local place of a caller comprising a caller's local time, local date, international access code, local country code, and local area code if necessary. Means for entering a telephone number sequence is associated with a called place which may include telephone code information comprising an international access code, called country code, and a possible called area code. Means for pre-storing time-zone offsets of country and area codes is associated with places which may be called throughout the world. The offsets are defined with respect to a reference time zone. Means are provided for calculating a called time and date by determining the difference in time between a time zone of a local place of a caller and a time zone of a called place. The difference in time is then offset in order to determine the called time. A local time display for automatically displaying local information comprising a caller's local time, local date and international access code, local country code, and a possible local area code. A remote time display automatically displays remote information comprising a called time and a called date associated with the destination of a phone call as soon as the telephone code information is entered. Means is provided for displaying time, date and telephone code information on the appropriate local and remote time displays.

According to another aspect ofthe present invention, there is provided an international time indicating system associated with a telephone, calculator, computer, software package, integrated circuit, real time clock or the like, the system comprising electronic memory for storing locations throughout the world and relative time differences of the locations, means for entering a time of day and location of a remote place to be called, and means for calculating and displaying the corresponding local time ofthe caller which is at the same moment as the entered time of day ofthe remote place as a function ofthe relative time differences of a location of the caller and the remote place to be called. Preferably the location ofthe place to be called is defined by its telephone international access code, country code and possible area code.

According to yet another aspect of the present invention, there is provided a method for electronically deteπnining the local time of a telephone caller corresponding to a remote time of a place to be called, the method comprising the steps of storing in electronic memory data representing locations throughout the world and relative time differences ofthe locations, providing data representing a time of day and location of a remote place to be called, and automatically calculating and displaying by means of an electronic microprocessor the corresponding local time of the caller which is at the same moment as the entered time of day of the remote place as a function ofthe relative time differences ofthe location ofthe caller and the remote place to be called.

One advantage of the present invention is that if a caller is requested to make a telephone call at a specified time at a remote location, the caller need only enter the remote time and telephone number of the remote location, and the international time indicating system will automatically calculate and display the caller's local time at which the telephone call should be made.

Other advantages ofthe present invention will become apparent in view of the following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates the incorporation of an international time indicating system ofthe present invention in a telephone unit.

FIGS. 2A and 2B is an enlarged partial view of FIG. 1 respectively showing an inactivated display for the local time ofthe caller and an inactivated display for the remote time ofthe called place.

FIGS. 3A and 3B respectively illustrate an activation ofthe local time and remote time displays of the present invention.

FIG 4 is an example of initializing the local time display by entering an international access code, country code, and an area code.

FIG. 5 is a simplified map showing the problem of problematic area codes that may include more than one local time.

FIGS. 6A and 6B illustrate two possible ways of initializing the local display by a caller whose telephone area code covers two time zones. FIGS. 7A and 7B respectively show the remote time displays of distinct destination calls within a problematic area that are in different time zones from one another .

FIG. 8 is a block schematic diagram illustrating a preferred embodiment of the intemational time indicating system of the present invention.

FIG. 9 is a flow chart describing the initial operation of the time of day micro controller unit in the embodiment of FIG. 8.

FIG. 10 is the main flow chart ofthe operation of the present invention.

FIG. 11 is a flowchart of a major portion of a loop-back polling subroutine ofthe present invention.

FIG. 12 is a flowchart of a reprogramming subroutine of the present invention.

FIG. 13 is a flowchart of a time-register-update subroutine ofthe present invention. FIG. 14 is a flowchart of a time-set subroutine ofthe present invention.

FIG. 15 is a flowchart showing in greater detail a portion ofthe time-set subroutine of FIG. 14.

FIG. 16 is a flowchart showing a subroutine for deterrnining a local time corresponding to a known remote time. FIG. 17 is a flowchart showing an alternative subroutine for deteπnining a local time corresponding to a known remote time.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, a preferred embodiment ofthe international time indicating system of the present invention is incorporated in a telephone unit generally denoted by 10. The international time indicating system will be explained in conjunction with a telephone for illustrative purposes only, but may also be associated with other appropriate devices such as calculators, computers, software packages, integrated circuits, or real time clocks, to name a few. Furthermore, the international time indicating system may be in the form of an independent unit or an attachment to an existing device. The telephone unit 10 respectively includes local and remote time displays 12 and 14. The local and remote displays may each be incorporated in separate windows, as shown in FIG. 1, or may be incorporated within a single window. The local time display 12 is positioned near handset 16 and is designed to display a caller's local time preferably with an AM/PM indicator, and the caller's local date. For long distance calls, the local time display 12 may also include the international access code "00" when calling out of India, followed by the country code and area code ofthe caller's destination, with or without an asterisk, whose function will be explained later. The remote time display 14 is designed to display the called country's local specific time with or without an asterisk and the called country's date.

FIGS. 2A and 2B respectively show an enlarged view ofthe local and remote time displays 12 and 14. Referring to FIG. 2A, an upper line 18 in the local time display 12 displays the caller's local time in seven segment display, such as a light emitting diode display or a Uquid crystal display, in the sequence: hours / minutes

/ seconds which is continuously updated along with an AM/PM indicator 20. Of course other means for display may be used such as a dot matrix readout. A middle line 22 displays the local date in seven segment display, preferably in the sequence: month / date / year. A lower line 24 includes ten digits each comprising a seven segment display. The number of digits in the lower line can be increased beyond ten digits if needed. The segments are selectively activated to display the international access code followed by the caller's own country code with or without area code. An asterisk 26 is provided to the right of the digital segments for purposes to be explained later. Information entering buttons 28, 30 and 32, preferably located to the left side ofthe local time display 12, are designed to enter or adjust the caller's local time as displayed in the upper line 18 along with the AM/PM indicator 20, the caller's local date as displayed in the middle line 22, and the international access code followed by the caller's country code with or without area code and an asterisk when required. FIG. 2B shows an enlarged view ofthe remote time display 14 first shown in FIG. 1. An upper line 34 displays the called country's time in seven segment display in the sequence: hours / minutes / seconds which is continuously updated along with an AM/PM indicator 36 and an asterisk 38 whose function will be explained later. A lower line 40 displays the called country's date in seven segment display.

The information to be entered in the local time display 12 via the information entering buttons 28, 30 and 32 will now be explained in detail. Referring again to FIG. 2A, the caller will first enter the local time with AM/PM to be displayed in the upper line 18. The caller will then enter the local date in the middle line 22. In the lower line 24, the caller will enter the international access code followed by the local country code. If the caller is in a large country with more than one time zone, the caller will have to enter an area code after entering the country code. The caller may be in a problematic area having two time zones within a single area or country code. In this case, the caller can arbitrarily select a convention to determine whether he is in the western or eastern side ofthe time dividing line. For example, the caller can enter an asterisk at the right of the lower line 24 as shown in FIG. 6B to show he is in the western side ofthe time dividing line. Of course, the caller could have selected the eastern side of the time dividing line as the predetermined condition for entering an asterisk. The information to be entered in the local time display 12 will have to be done only once, at the time when the telephone unit 10 is installed. The local time display 12 will continuously display the local time, local date and local code with or without an asterisk for forming reference information for the computing system. Standard press buttons 42, as shown in FIG. 1, for "dialing" the telephone are included in the international time indicating system and are connected with an internal computing system such that the impulse generated by pressing the buttons passes to the computing system as well as to the telephone electronic exchange. An internal computing system, incorporating electronic components, utilizes the entered reference information in the local time display 12 to calculate the time and date ofthe desired remote place to be called, as soon as the caller dials the international access code followed by the country code with or without area code of the remote location to be called. The impulse generated by the dialing ofthe remote place is computed with the reference information so as to determine the exact time and date of the desired remote place which is displayed in the remote time display 14. The local time display 12 continuously shows the caller's local time, date and code with or without an asterisk, irrespective of a call. The remote time display 14, however, will be blank when the telephone is not in use, or when an incoming call is received, or when the caller makes a call to a place which lies in the caller's own standard time zone.

The local display shown in FIG. 2A and the remote display shown in FIG. 2B may be respectively provided in separate windows wherein each display can be simultaneously activated. However, the displays shown in FIGS. 2A and 2B may be provided within a single window wherein the local and remote displays shown in FIGS. 2A and 2B are non-simultaneously activated in alternating sequence with respect to one another. Also, the remote display may be modified so as to be substantially similar to the local display shown in FIG. 2A. Thus modified, the caller will be able to simultaneously see both the telephone number in the local display corresponding to the caller's location and the dialed telephone number in the remote display corresponding to the called place.

The remote time display 14 will display the specific time and date ofthe desired called place when the desired called place lies in a different time zone ~ giving an immense advantage to the caller, who can simultaneously visualize his own time and the time and date ofthe called distant place. The remote time display 14 will continue to function until the call is disconnected, thereupon which the remote time display 14 will become blank. Displaying the specific time and date ofthe desired distant place is useful when only dialing the international access code and country/area code. This allows the caller to access remote time and date information free of cost without going through with the call. The caller can plan his call such that the time will be suitable to the called party.

The function of local and remote time displays 12 and 14 will now be further clarified with reference to the following example as shown in FIGS. 3A and 3B. Say, for example, a caller is in Bombay, India and wishes to call someone in the United Kingdom (U.K.). The caller has already initialized the local time display 12 at the time of installation ofthe telephone, by entering the information as shown in FIG. 3A, namely, local Indian time, local Indian date, the international access code for calling out of India "00", and country code "91" which is specific for India. Since, India has only one standard time zone, there is no necessity of entering an area code or an asterisk. As the caller at Bombay dials the international access code "00", the international time indicating system is activated. Next, as the caller proceeds to dial the country code "44" for the U.K., the impulse received by the computing system interacts with the reference information shown in the local time display 12 in the following manner. First, the computing system with standard electronics, understands that "44" represents the U.K. and further understands that "44" represents the only time zone in the U.K. such that there is no need for further entering an area code for its computing. Second, the number "44" is further computed with the number "91" present in the lower line 24 ofthe initialized local time display 12, as shown in FIG. 3A, in order to define the time difference between the local and called time zones - which is five hours and thirty minutes in the present example. Third, the international time indicating system understands whether to add or subtract the defined time difference. In the present example the defined time difference is to be subtracted. The defined subtraction of time difference is computed with Indian time, 02:10:30 AM (as shown in FIG. 3 A) at that moment, with the resultant destination and display of the U.K. time, at that moment, which is 08:40:30 PM, in the remote time display 14, as shown in FIG. 3B. Fourth, the computing system defines the date in the U.K. with reference to the date in India displayed in the local time display 12. In this case, the date at Bombay is 5th October 1993, as shown in FIG. 3A and the defined and displayed date in the UK is 4th October 1993, as shown in FIG. 3B.

In smaller countries, where only one standard time zone exists, the country code alone is sufficient for the internal computing system to calculate the exact remote time. However, in large countries Uke the U.S.A. where more than one time zone exists, the large country must be further divided into smaller units which are represented by specific area codes.

For large countries like the U.S.A., which are conventionally subdivided into smaller areas represented by specific area codes, the computing system is initialized to understand a country code followed by an area code as a single unit, having a defined area and a specific time and date. The single unit functions like a small country having a single standard time ~ the only difference being that the small country is represented by a specific country code alone, while a place in the U.S.A. is represented by the country code followed by an area code. Let us use as an example an instance involving a caller staying outside of a large country like the U.S.A. (for example at London) who desires to call a distant place in the U.S.A. Here, the dialing ofthe international access code "00" activates the international time indicating system. Furthermore, dialing the number "1" is recognized by the computing system as representing the U.S. A. The computing system is now primed to wait and receive an area code. After entering the area code, the computing system will interact with the caller's country and area codes to define the time difference between the caller's local time (shown in the local time display 12) and the called location, and to define whether to add or subtract the time difference. Similarly, the date ofthe distant place in the U.S.A. is defined. The defined time and date of the desired distant place to be called in the U.S.A. is displayed in the remote time display 14.

A caller residing in a large country like the U.S.A. will have to first initialize, in the lower line 24 ofthe local time display 12, the international access code followed by the country code and the area code representing the caller's area. In the U.S.A., the international access code is "Oil". As an example, FIG. 4 shows, in the lower line 24 ofthe local time display 12, the entered number "0111415".

The convention for a caller residing in a large country like the U.S.A. when the caller desires to call a distant place in his own country lying in a different time zone is illustrated in the following example. The telephone unit 10 incorporating the international time indicating system is activated by the impulse generated by dialing "1". Here, the computing system recognizes that the caller is staying in the U.S.A. and is calling a location within the U.S.A. Further dialing the area code is recognized and computed with reference to the caller's time and date and code ofthe initialized local time display 12 with the resultant display ofthe specific time and date ofthe dialed place in the U.S.A. which is displayed in the remote time display 14. Thus, the international time indicating system is useful even when the caller residing in the U.S.A. is making a call to a location within the U.S.A. Here, the caller can immediately see the time and date of the called place in the U.S.A. as soon as he dials "1" followed by the appropriate area code. More generally, the international time indicating system can be initialized to recognize that a caller and called place are both within a single country or region covered by the country code by means of a national subscriber dialing (NSD) access code. In other words, the international time indicating system can recognize that dialing an NSD access code instead of the international access code means that a call is to be made within the country or region coπesponding to the NSD access code, and that an area code, if necessary, will immediately follow. For example, the region ofthe U.S.A. and Canada share an NSD access code "1" (which happens to be the same as the "country" code which is also shared by both the U.S.A. and Canada). Therefore, dialing the NSD access code "1" within the U.S. or Canada informs the initiaUzed international time indicating system that the call is to be made within the region covered by Canada and the United States, and that an area code will immediately follow.

In large countries Uke the U.S. A., certain areas have a specific area code which may cover two time zones, as shown in FIG. 5. Consider, for example, the area code of one of the problematic areas 44 is "XYZ". The time dividing line 46, as shown in FIG. 5, has spUt the area having the area code "XYZ" into an eastern part 48 and a western part 50. When the time in the eastern part of area "XYZ" is 8 AM, at the same moment, the western part of area "XYZ" is 7 AM.

The caller staying in a problematic area enters in the local time display 12 his own time, date and code and if necessary an asterisk. A caller in a predetermined side of a time dividing line, such as the western side, can alert the time indicating system of which time zone he is in by entering an asterisk. When the caller enters the international access code followed by the country code ("1" in U.S A.) followed by the appropriate area code "XYZ", the computing system is primed to understand that the time associated with the area code "XYZ" is the time of the eastern part of the problematic area. Such information is shown in the local time display 12 as illustrated in FIG. 6A. Here, it can be observed that the information entered in the local time display 12 is just Uke the information needed to be entered by any other caUer who is caUing from a non-problematic area in the U.S.A. A caUer, having an area code "XYZ" and calling from the western part ofthe time dividing line, as shown in FIG. 5, wiU need to enter the local time and date, with the international access code followed by the country code ("1" in U.S.A.), followed by the area code "XYZ", foUowed by an asterisk. Here, the asterisk wiU signal a one hour coπection for calculating the time and date of the desired distant place. A one hour coπection is needed because the computing system imderstands for its computing (according to convention) that the code containing "XYZ" without an asterisk means the eastern part time ofthe time dividing line of the problematic area having area code "XYZ".

With respect to the above-discussed convention, consider that a caller to the western part ofthe time dividing line enters the information in the local time display 12, as shown in FIG. 6B. Though the moment is the same for FIG. 6A and FIG. 6B, a one hour time difference is due to the caller of FIG. 6B being to the west of the time dividing line. To correct for this one hour time difference compared to the area east of the time dividing Une, an asterisk is entered so that the computing system will understand to conect the one hour time difference in its computations which otherwise will not be understood by the computing system. Now consider a caUer residing outside the U.S.A. -- say at Bombay, India - and calling a party in the U.S.A. having an area code "XYZ" associated with a problematic area. Here, the caUer must understand the possibiUty of a one hour error. According to the inventor's suggested convention, as the caUer dials "01 HXYZ", the computing system will display the eastern side time ofthe problematic area. Here, as shown in FIGS. 7A and 7B, the computing system will display an asterisk in the remote time display 14 because the system recognizes "0111XYZ" as a problematic area. Referring to FIG. 7 A, the time and date of a caUed destination residing in the eastern side ofthe problematic area having an area code "XYZ" is shown in the remote time display 14. Though the time displayed in this case is accurate, the computing system is unable to determine whether the called location is to the east or to the west of a time dividing Une which separates adjoining time zones in the problematic area. Therefore an asterisk is displayed to alert the caUer that the called place may be to the west ofthe time dividing line, and therefore, the remote time may be in eπor by as much as an hour. Referring to FIG. 7B, the time and date of a called destination residing in the western side ofthe problematic area having an area code "XYZ" is shown in the remote time display 14. The time displayed is one hour in error. The conect time is 04:40:10 AM while the time shown is 05:40:10 AM. The displayed asterisk informs the caUer ofthe possibiUty of a one hour eπor. Thus the display of an asterisk in the remote time display 14 informs the caller about the possibiUty of a one hour eπor in the display as weU as, in the rare case, a one day eπor in the date.

A schematic diagram of a prefeπed embodiment ofthe present invention is shown in FIG. 8. An international time indicating system 100 includes a keyboard 102 suitable to dial a desired telephone number consisting of a numeric digit string as required by a telephone system with international standards and sufficient to provide additional data entry as required by a time of day micro controller (TDM) 104. The TDM 104 may be built up around a single chip micro controller or any other suitable counterpart to implement different functional blocks as shown in FIG. 8. An interface 106 includes conventional circuitry to couple the keyboard 102 to a telephone 108 and the TDM 104 to enable continuous scanning ofthe keyboard 102 as weU as to output the scan code (a digital code unique to each key) upon every vaUd key entry to the TDM.

In summary, the interface 106 detects a single digit or string of digits to be dialed in a manner compatible to the telephone 108. The interface then transfers the same dialed string of digits or other suitable data as desired by the invented mechanism to either initialize the local time of day, date and location code at the local time display 12 or to enable and maintain alternate operations such as accepting country names or mnemonics of the distant place. The interface also re-transmits the single digit or string of digits to be dialed to the telephone 108 in a compatible manner. This digit transfer may be used in response to the country code names or mnemonics allowed to be entered from the keyboard 102 while a caller is attempting a long-distance call.

A display unit 110 includes a local time display 12 and a remote time display 14. The local display 12 displays local time of day, corresponding date and location code - that is the local area code and / or zone indication. The remote time display 14 displays current time of day, date and location code ofthe called number.

An area code decoder 112 retrieves the called location code from a dialed number that is received through a key buffer (not shown). The key buffer is a set of memory bytes used as a register to store the key scan codes of the keys pressed from the keyboard. The area code decoder extracts the location code from the intemational access code, country code and, if necessary, the area code when dialing the desired number.

A time keeping unit 114 uses a timer counter circuit and a crystal stabilized clock to continuously maintain the current time and other information as required by the local display 12 after the prior initiaUzation ofthe local display 12 through an independent initiaUzation routine. A time adjust unit 116, reading the remote location code obtained while diaUng a distant call, is used to process the data under a program control by the corresponding software resident in the program memory, conventionaUy known as read only memory / erasable programmable read only memory (ROM / EPROM) 118. The time adjust unit 116 may use necessary parameters and look-up tables stored in the ROM / EPROM 118 along with an image buffers, replica of the data bytes used to refresh the local and remote time displays 12 and 14, maintained in temporary storage memory, conventionally known as random access memory (RAM) 120.

Time difference due to different geographical locations is defined as offset in time and is stored in an offset time register. The time adjust unit 116 uses the location code to time offset look-up tables preprogrammed in the ROM / EPROM 118 to derive the data corresponding to the possible time difference (relative time offset) between the distant caUed place and the local place ofthe caU and to further compute the remote time from the local time. The time adjust unit 116 then continues to update the local and remote displays 12 and 14 by polling the time of day clock from the time keeping unit 114 and image buffers of corresponding displays in the RAM 120 until a remote abort command is received from the interface 106 subsequent to the end of dialing the distant caU. This inhibits the remote time display 14 while maintaining the local time display 12.

The area code decoder 112, the time adjust unit 116, the time keeping unit 114, the program storage ROM / EPROM 118 and the temporary storage RAM 120 may be implemented with micro controller techniques using single chip microcomputers such as the 87 CH51 (CHMOS version of the 8751) or application specific integrated circuit (ASIC) or Intel 8751 or its ROM-less equivalent version 8031 with standard Intel 2764 EPROM memory. Hence, any suitable and equivalent microcomputer chip set may be used in conjunction with the present invention.

Software implementation requires a number of program routines and procedure caUs to fulfill the system requirements. For example, FIG. 9 illustrates a power on initiaUzation routine 130 which consists of the sequential steps of power on initiaUzing devices (step 132), caUing a self check procedure (step 134) and displaying default or error status (step 136) and is foUowed by a loop back sequence of keyboard scan, display refresh and time register update cycles to be explained later. Local time initiaUzation is carried out with coπesponding key commands and parameters to set local time registers and display time of day, date and location code information at the local time display 12 thus enabling a time adjust procedure for the remote time display 14 whenever a distant call is dialed thereafter. A more detailed description of the above-mentioned software programs will be discussed below. FIG. 10 shows the main flow chart that assumes the following. First, a power-on condition with the system properly initialized and tested for equipment status has already taken place, as was described with reference to FIG. 9. Second, the local time is already initiaUzed to display all necessary data at the local display 12 including its location code. Third, the telephone circuit is appropriately enabled to transmit the digit string to be dialed for a distant caU. The keyboard interface holds such status to be read by the time of day micro controUer. Fourth, a polled routine in a known conventional manner may be assumed to test the time of day clock status which is a memory bit used as a normal status flag which is set active after each preset time interval generated by the time keeping unit 114 and is reset back by the micro controUer polled routine. It updates time registers whenever the status is found active. Fifth, no "caU over" or "abort caU" commands are received from the telephone unit before the execution of the main routine shown in FIG. 10. These assumptions help to understand the invention more clearly without branching to the secondary program routines. Keyboard scanning and key-status check is first performed (step 140).

Key detection implies a valid key entry with necessary Debounce time and key- status setting to indicate the type of data received at the key buffer. Thus, a command key or a function key or a simple digit number key can be distinguished to call an appropriate control routine. While dialing a distant call, key status further indicates the first digit entry or completion of a vaUd digit string. Step 142 indicates the corresponding test to enable further processing at step 144. A vaUd digit string stored at the key buffer is then passed to the procedure called "location decode program" wherein a necessary data like international access code, country code and, if required, an area code is retrieved to create a coπesponding location code which is a multi-bit unique code coπesponding to the remote location dialed. A location buffer in RAM 120 holds this code and decision step 146 tests its vaUdity as weU. Step 148 executes another caU for a remote adjust program where RAM data from the location buffer and local time registers are read to calculate relative time offset of the remote location with respect to the local location code. The look-up table in ROM / EPROM 118 is used to get the time offset as one ofthe computing variables. In step 150 the time offset buffer in RAM 120 is loaded with the relative time offset and the same is used to process the data for the remote time registers which is made possible due to the prior initialization ofthe local time registers. At step 152, the remote status of the remote time display 14 is set active as the corresponding image buffers in RAM are output to the remote time display.

The time keeping unit 114 shown in FIG. 8, can utilize different techniques to set and maintain a time of day. Micro controller designs use one or two timer/counter channels to reUeve the central processing unit (CPU) from this routine task. An 8/16 bit T/C channel may be programmed to pre-scale the system clock (1 MHz to about 16 MHz) down to 50/60 Hz. This precision time interval generator is used by another T/C channel or a real time clock (RTC) device working with smaU CPU overhead to update and maintain the time of day data.

Upon power-up, the CPU starts these T/C channels in appropriate modes - strobe / square wave generator in BCD counter mode - with suitable count divide ratios in auto reload fashion. The time of day clock thus initialized, either interrupts the CPU after every second or its sub multiple to enable the time register update service or to provide corresponding status to be read and cleared by the CPU. Approximately 16 bytes may be reserved per set to maintain the data from seconds to year of day and location code with special status in a packed or unpacked BCD mode. Each of the local time, remote time and set points during the year or day requires such 16 byte records in time register form. A single time of day clock and time offset data computed by the CPU is enough to maintain the time of day at different locations. Also through an appropriate and successive comparison, different additional functions may be performed. As an iUustration, such additional functions of the time keeping unit may include advancing or retarding the remote or local time by, for instance, one hour, on a specific day ofthe year for a specific location.

The time update cycle may be performed every second as indicated above or through successive steps every 50/100 msec, if the total time involved is excessive to cover in a single burst of execution.

A 16 byte record for any time register set provides one/two bytes each for storing current data regarding: seconds (0-59), minutes (0-59), hours (1-12 and AM/PM status), day/date (1-7/1-31), months (1-12), and the year in four digits. Additional data space is associated to store information such as: location code (6 digits with status), area code in conventional manner, relative time offset, and data set point which is a variable to compare total days of the current month, depending on the current month data (28/29/30/31) and current year data.

Status bits associated with the location code provide for specific coπection/indication of the predetermined area codes.

An update cycle starts with seconds data coπection and propagating the carry, if detected, through minutes data up to the last year register. Any status dependent comparison is further carried if so required. Similar updating may be performed for the remote time whenever the corresponding time registers are found initialized.

The time adjust unit 116 is responsible for several functions. One such function is local time initialization. Separate time set keys are used to select the time set function, to select "day", "date", "time", in sequence, to set data through the same digit dial keys and to enter the local area code with problematic zone declaration if so required. A second function is a time update cycle. The CPU overhead in incrementing the time registers is required in addition to T/C channels in the time keeping unit. A third function is the relative time offset calculation. One of the techniques used is to maintain a time offset for the local time as well as for a remote time depending on the location code derived by a location code decoder. The location code to time offset look-up table is stored in the ROM/EPROM memory area. The time adjust calculation may be carried out by the following procedure. This time adjust procedure requires necessary data such as found in the local time register. This provides time of day and area code data stored in the corresponding set of locations (memory bytes) with the status bits indicating that this register is appropriately loaded. Other data needed is found in the remote location register where a remote location code is stored by the area code decoder.

In EPROM, a stored program memory holds a look-up table to provide time offset and status bits coπesponding to each location code. Time of day information corresponding to any suitable location code (representing a geographical location describing, for instance, Mean Greenwich Time) is assumed as a reference time data and the required time offset, a signed value in time units is predetermined for every geographical location as impUed by the coπesponding location code. A sign is set so as to provide the appropriate time ofthe specified location by calculating a simple algebraic sum of reference time data and time offset data. Location codes of local and remote areas are first used to calculate a relative time offset of the remote location with respect to the local area as set in the local time display 12. The remote time registers are then set simply by finding an algebraic sum of the local time data and the relative time offset so calculated. The result is then displayed in the remote time display 14. Display information to both displays is repeated every time the time update cycle updates the time registers. Fig. 11 is a flowchart indicating a major part of a loop-back poUing routine 153 executed by the resident software of the system. It performs three repetitive operations in sequence. At step 154, the time keeping unit 114 (see FIG. 8) sets the time interval status active every time the preset time interval is over (e.g., one second). It is poUed continuously by the time adjust unit for executing the time register update (step 156). The display refresh step 158 is subsequently carried out and program control is transferred to a keyboard scan routine (step 160). If any key is found pressed, vaUd entry is tested at decision step 162 under the current condition ofthe system (e.g., dial digit string is accepted only under an off-hook handset condition). The coπesponding key-code is further decoded to distinguish command keys from data entries at step 164. Commands (e.g., Fl, a time set command), if detected, are processed as in step 166 and data is written into a key buffer with an updating of key status as shown in step 168.

The location code and time set operations wiU now be discussed in detail. The micro controller program requires the location code to fetch data from the look¬ up table stored in the ROM/EPROM memory. The look-up table provides aU necessary data specific to every location code. A typical entry requires several data bytes to hold aU of the information. It may be arranged in the form of an aπay of records, where each record is pointed by the location code to which it belongs. The time offset is used to adjust the remote time register. Status bits like "set point present", "display zone mark" and "read miscellaneous data" are selectively used for each location code. Additional data is preset as parameters to be used by the micro controUer whenever corresponding status bits are found active. Some of the status bits are described below. One status bit is "set point present". If a specific location requires a time coπection on a specific day of the year, then the record entry to this location code includes this status bit as active with the subsequent provision of the time set point and time correction offset representing the desired time correction on that day. A second status bit is "zone mark". If a specific location code derived from the dialed telephone number points to different time offsets on east/west zones, then an asterisk indication on the display may be provided while displaying remote time against this location code. This status bit is set active in the corresponding record entry. No further parameter is required.

A third status bit is "read miscellaneous data". Certain additional data along with the remote time is more helpful to the caUer trying an international caU. Displaying the status of the current date as, for instance, a national holiday of he called country can be useful for aborting the caU if so required. Provision of a number of set points representing national holidays as a parameter set is then stored in the corresponding record. HoUday status may be indicated as "H" in the corresponding display such as the remote time display. An array of records so described are preprogrammed in the permanent storage memory area (i.e., program memory 118). Any probable change in location code and/or the corresponding data may be reprogrammed by the user if EEPROM memory is used instead of ROM/EPROM memory devices. FIG. 12 refers to a flowchart to enable such reprogramming using the function keys Fl (time set function) and EN (data enter command keys) along with other numeric keys. The Fl key is used (step 170) to select area code programming or time set function and the same key is de selected by operating Fl (step 170) again.

Activating Fl suspends the time update operation with a steady colon segment and initiaUy blinks the hour display with the AM PM indicator (step 172). During the time set operation this data may be changed by the desired numeric entry. A single EN entry aUows continuation of the same time set operation (step 174). A multiple EN key entry (step 176) activates the area code reprogram function. Location code data in the local time display 12 blinks with the remaining display blanked (step 178). A "password data", a specific number different than any possible location code is required to be entered at this time. Any location code entry may transfer the control to the normal time set function.

With the appropriate password entry, the display 12 and 14 shown in FIG. 1 are now prepared for accepting the reprogrammed codes (step 180). The local display 12 represents old data and the remote display 14 indicates a new code and data upon subsequent entry (step 182). Initially the local time display 12 shows a local location code already present in the memory with a status bit "T" and time set point in place of day-date with time offset at the hours-minutes display position. BUnking data prompts as a cursor position indicating the next numeric entry position in the remote display 14. Entering new data with the EN key shifts the blinking data position to the local display 12 (step 184). This step prompts the user to the specific next location code to be modified. The process may continue until the Fl key is detected to exit this reprogram routine (step 186).

Thus for every location code to be modified, old data is displayed at the local time display 12 and a new data entry at the remote time display 14. Data bytes corresponding to the new location code, time set point and time coπection offset with status segment "T", zone setting with status segment "Z" and other data- like "national hoUday" set points with status "H" are to be loaded in succession. Only then does blinking shift to the local display 12 requiring the next location code to be changed.

FIG. 13 shows more details of the procedure call "time register update". A colon segment toggles every second along with the increment in the seconds register and the decimal adjust operation (step 188). Real time counting requires a carry generation and propagation during the count increment of seconds and minutes beyond 59, which is shown in the steps 190 to 200. The time set point is also tested by comparing the data from the time set point register with the current time of day every hour or every day. In FIG. 13, the testing is done every hour (steps 202-206). For example, once or twice a year a time coπection adjustment may be necessary to account for daylight savings time. The corresponding time correction refers to the specific correction requirement as described below.

The time correction offset for the location code is stored at the correction offset register and is loaded, when needed for a time adjustment, from the correction offset register into the cuπent time offset register (step 206) to be used to adjust the time registers at the end of the update cycle (step 230). Updating the hours data (steps 208-212) includes toggling of the AM PM display segment (step 212). Updating operation ofthe day register (steps 214-218) considers the days status register that stores the number of days for the current month. Change in the month (steps 220-224) then reloads the days status register with the new value from the corresponding look-up table (steps 222 or 224). During the adjustment of the year data at step 224, the possibility of having a leap year is checked at step 226 to alter the days ofthe month data to be 29 for the month of February (step 228). After completing the time register updating just explained, which is appUcable to both the local and remote time, the CPU control is transfened back to the main Une program to execute the next routine. A conventional time set operation may be achieved with the function keys Fl and EN as explained earlier and the numeric digit keys available for a telephone call. FIG. 14 shows a simplified flowchart for the same. Upon detecting the Fl key (step 232), the system branches to the time set program mode 248. The time update cycle stops (step 234) and the time registers display the current data from hours to area-code in a sequence. Blinking data prompts as a cursor position for the data entry and EN key operation enters the blinking data which is then stored back to the time register. As shown in steps 236 to 244, the time set sequence steps forward with each EN operation. The completion of step 244 or a multiple operation ofthe Fl key any time during this operation wiU exit the sequence and restart the time display (step 246).

FIG. 15 is a more detailed time update sequence of step 236 of FIG. 14 illustrating the data set operation ofthe set-hours-data operation (steps 250-260). Setting other parameters such as minutes, date, month, etc., is done in a similar manner. Referring again to FIG. 14, entering the last data corresponding to the location code step 244 automatically starts the time cycle update and local time is displayed at the local display 12 (step 246).

The international time indicating system of the present invention may also include the feature for determining a local time coπesponding to a known remote or destination time, as will be explained below with reference to FIGS. 16 and 17. Such a need arises when a caller has to make a long distance call at a specified time ofthe remote location to be called. The caUer usually has to determine the time difference between his own location and the remote location to be caUed, and then to further deteπnine whether to add or to subtract this time difference with the specific destination time so as to determine his own coπesponding local time at which the caU is to be made. For example, a caUer in New York, U.S.A. might be instructed by his cUent who is in Tokyo, Japan to make a call at 10:30 AM Japan time. The caller then has to determine his local time corresponding to 10:30 AM Japan time in which to make the caU.

With reference to the flowchart of FIG. 16, the international time indicating system of the present invention may include a manual find operation for determining a caUer's local time for making a telephone caU based on a known remote time in which the caUed person wishes to receive the telephone caU. Step 300 is the initial condition of vaUdly entering, on the international time indicating system ofthe present invention, digits including an international access code or NSD access code, a country code and an area code if required, as was previously explained fully in this specification. The manual find mode can be actuated regardless of whether the off- hook switch (OF-HKY) is in the on-hook or off-hook state. However, striking the OF- HKY switch aborts the current operation and returns the phone to an idle mode 302 in which the local time of day is displayed and the remote display is blank. After the initial condition (step 300) is satisfied, the international time indicating system waits (step 304) for the caUer to enter a function key, such as Fl, which initiates the remote time set mode and waits for an hours value of the remote time to be entered (step 306). The system then determines if any keys are being entered (step 308). The system will display numbers representing hours in the remote time display as they are being entered (step 310) and ignore any other types of information except Fl and OF-HKY information. If the OF-HKY switch is activated or a predetermined time period has elapsed, for example 10 to 15 seconds, (step 312) without information being entered, the system will revert to the idle mode (step 302) in the case of an OF-HKY condition, or revert to the initial condition (step 300) when no information has been entered within a predetermined time period. Once the hours value of the remote location has been entered, the system waits (step 308) until Fl is entered which fixes or sets the hours value in memory, and which initiates the minutes set mode (step 314) done in a sub-routine similar to that enclosed in the dashed box 316 for entering the hours value. After entering the minutes value ofthe caUed remote location, entering Fl sets the minutes value and initiates the AM/PM status set (step 318). This procedure of entering information and pressing Fl to advance to the next step in the procedure continues in a similar manner for setting the AM/PM status and initiating the month value (step 320), setting the month value and initiating the day value (step 322), and setting the day value and initiating the year value (step 324). Once Fl is entered after step 324, the system displays the entered remote time of day in the remote time display, and calculates and displays the coπesponding local time of day in the local time display (step 326). The system then proceeds to a wait mode (step 328). If Fl is entered, the system will branch to step 306 to re-initiate the time set mode. Upon activation ofthe OF-HKY switch, the system will branch to the idle mode (step 302). If no information is entered after a predetermined time period has elapsed, the system will branch to the initial condition (step 304).

With reference to the flowchart of FIG. 17, the international time indicating system ofthe present invention may include an auto find operation for determining a caUer's local time for making a telephone caU based on a known remote time in which the caUed person wishes to receive the telephone caU. Step 400 is the initial condition of vaUdly entering, on the international time indicating system ofthe present invention, digits including an international access code or NSD access code, a country code and an area code if required. The system then waits until either of two predetermined function keys (such as F4 or F5) are entered (step 402). Entering, in this instance, function key F4 initiates an hours scroll in the remote display (step 404) by generating a scroll request command signal (SCRL-REQ). Both local and remote displays increment by one hour (step 406) at a predetermined time interval such as around 1 to 4 seconds. Key operation may include a single depression of key F4 to start scrolling and a single depression of F4 to stop, or include continuous operation while holding the F4 key down, or a combination of both single and continuous depression features. The system determines (step 408) if the OF-HKY switch has been activated or if a predetermined time interval has elapsed without entering further information since the scroll was initiated. If the OF-HKY switch has been activated, the system terminates the operation (step 410). If the predetermined time interval has expired without further information being entered, the displays are restored to their initial conditions (step 412).

Absent an OF-HKY condition or the expiration ofthe predetermined time interval without entering further information, the system continues to scroU through the hour values at the local and remote time displays until the entering of function key F4 is detected (step 414) for freezing the hour values on the local and remote displays (step 416). The system wiU then determine whether there is an OF- HKY or time-out condition (step 418) and branch accordingly in a manner similar to that explained with the hourly scrolling feature. Entering, in this instance, function key F5 initiates an minutes scroU in the remote display (step 420) by generating a scroU request command signal (SCRL- REQ). Both local and remote displays increment by one minute (step 422) at a predetermined time interval. Preferably the number of increments is limited to 100 to 120 if the operation is left unattended. Key operation may include a single depression of key F5 to start scroUing and a single depression of F5 to stop, or include continuous operation while holding the F5 key down, or a combination of both single and continuous depression features. The system determines (step 424) if the OF- HKY switch has been activated or if a predetermined time interval has elapsed without entering further information since the scroU was initiated. If the OF-HKY switch has been activated, the system terminates the operation (step 410). If the predetermined time interval has expired without further information being entered, the displays are restored to their initial conditions (step 412).

Absent an OF-HKY condition or the expiration ofthe predetermined time interval without entering further information, the system continues to scroU through the minutes values at the local and remote time displays until the entering of function key F5 is detected (step 426) for freezing the minutes values on the local and remote displays (step 416). The system wiU then determine whether there is an OF- HKY or time-out condition (step 418) and branch accordingly in a manner similar to that explained with the hourly and minutes scroUing features. The above description thus indicates certain embodiments of the present invention, and it is apparent to those, expert and skiUed in the art, that numerous variations or modifications may be made without departing from the scope ofthe present invention as claimed.

Claims

WHAT IB CLAIMED IS:

1. An international time indicating system associated with an appropriate device such as a telephone, calculator, computer, software package, integrated circuit, real time clock or the like for automaticaUy displaying a specific time and date of a remote place such as a desired called place via a telephone, said international time indicating system comprising: means for entering or adjusting information associated with a local place such as that of a caller comprising a caUer's local time, local date, international access code, local country code, and local area code if necessary; means for entering a telephone number sequence associated with a desired caUed place which may include telephone code information comprising an international access code, called country code, and a possible caUed area code; means for pre-storing time-zone offsets of country and area codes associated with places throughout the world, the offsets defined with respect to a reference time zone; means for calculating a desired caUed time and date by determining the difference in time between a time zone of a local place of a caller and a time zone of a desired caUed place, and then offsetting the difference in time to the local time in order to determine the desired called time; a local time display for automaticaUy displaying local information such as a caUer's local time, local date and international access code, local country code, and a possible local area code; a remote time display for automaticaUy displaying remote information such as a desired caUed time and a called date associated with a remote place such as the destination of a phone call as soon as the telephone code information is entered; and means for displaying time, date and telephone code information on the appropriate local and remote time displays.

2. An international time indicating system as defined in claim 1, wherein the means for entering or adjusting information further includes means for entering problematic information associated with specific country or area codes that cover two time zones, and the system further includes local and remote problematic indicators respectively associated with the local and remote displays, the local problematic indicator being activated if a caUer is in a predetermined one of the two time zones associated with the local country or area code, the remote problematic indicator being activated when a caUed country or area code covers two time zones so as to warn a caller that the caUed time and date as displayed may be off by about an hour from that of the actual time in the caUed country.

3. An international time indicating system as defined in claim 1, wherein each ofthe local and remote displays include an AM/PM indicator.

4. An international time indicating system as defined in claim 1, wherein the local and remote displays are provided in a single display window and the local and remote information are non-simultaneously displayed in an alternating sequence.

5. An international time indicating system as defined in claim 1, wherein the local and remote displays are respectively provided in separate local and remote display windows, the local information being shown in the local display window and the remote information being shown in the remote display window.

6. An international time indicating system as defined in claim 1, further including means for sequentially entering letters for spelling a country, means for automatically associating a spelled country with its country code and possible area code, and means for displaying the time and date in the speUed country in the remote display so that a caUer can determine the caUed time and date of a destination call without having to memorize the country code and possible area code ofthe destination country.

7. An international time indicating system as defined in claim 1, further including means for sequentially entering letters for spelling a mnemonic of a country, means for automatically associating a spelled country with its country code and possible area code, and means for displaying the time and date in the speUed country in the remote display so that a caller can determine the called time and date of a destination caU without having to memorize the country code and possible area code of the destination country.

8. An international time indicating system as defined in claim 1, wherein the international time indicating system is in the form of an independent unit or an attachment to an appropriate device.

9. An international time indicating system as defined in claim 1, wherein the international time indicating system is incorporated in an appropriate device.

10. An international time indicating system as defined in claim 1, further including means for storing predetermined time adjustment dates throughout the year (usually twice a year) that are associated with time adjustments in specific countries, and for adjusting the local or remote time to be displayed accordingly.

11. An international time indicating system as defined in claim 1, wherein the local and remote information to be displayed is in seven segment form.

12. An international time indicating system as defmed in claim 1, wherein the local and remote information to be displayed is in dot matrix form.

13. An international time indicating system as defined in claim 1, further including means for suppressing the display ofthe international access code.

14. An international time indicating system as defined in claim 1, further including means for switching-off the display of the international access code, the local country code and the possible local area code information.

15. An international time indicating system as defined in claim 1, wherein the problematic indicator is in the form of an asterisk.

16. An international time indicating system as defined in claim 1, wherein the problematic indicator is in the form ofthe letter E.

17. An international time indicating system as defined in claim 1, further including means for storing national hoUday information associated with countries throughout the world and a hoUday status indicator for displaying such information, said hoUday status indicator being activated when there is a national hoUday in a caUed country.

18. An international time indicating system as defined in claim 17, wherein the hoUday status indicator is in the form ofthe letter H.

19. An international time indicating system as defined in claim 1, wherein the means for pre-storing time-zone offsets of country and area codes is in the form of EEPROM memory instead of standard ROM/EPROM memory so that any probable changes in country codes, area codes and/or coπesponding data may be reprogrammed by a user.

20. An international time indicating system as defined in claim 1, wherein the system is an independent unit which may be attached to an existing telephone or may be incorporated in other electronic devices such as calculators, computers, or software packages.

21. An international time indicating system as defined in claim 1, further induding: means for initiaUzing the international time indicating system with a national subscriber diaUng (NSD) access code so that the international time indicating system recognizes the country in which the system is installed, and that initially diaUng an NSD access code instead ofthe international access code signifies that a caUer and the caUed place are both within a country coπesponding to the dialed NSD access code such that an area code will immediately foUow; and means for displaying a remote time and remote date ofthe called place if the caUed place is in a different time zone than that of the caUer.

22. An international time indicating system as defined in claim 1, further including means for displaying a telephone number coπesponding to a caUer's location in the local time display, and means for displaying a telephone number conesponding to a caUed place in the remote time display.

23. An international time indicating system comprising: means for entering or adjusting a code sequence associated with a local place comprising a local time, local date; means for entering a code sequence associated with a remote place; means for pre-storing time-zone offsets associated with places throughout the world, the offsets defined with respect to a reference time zone; and means for calculating and displaying the time and date at a remote place by determining the difference in time between a time zone ofthe local place and a time zone ofthe remote place, and then offsetting the difference in time to the local time in order to determine the remote time.

24. An international time indicating system as defined in claim 23, further comprising: means for calculating and displaying the time and date at the local place.

25. An international time indicating system, the system comprising: electronic memory for storing locations throughout the world and relative time differences ofthe locations; means for entering a time of day and location of a remote place; and means for calculating and displaying the conesponding local time at a local place which is at the same moment as the entered time of day of the remote place as a function of the relative time differences of the local place and the remote place.

26. An international time indicating system as defined in claim 25, wherein the relative time differences are time zone offsets with respect to a reference time zone, and the means for calculating and displaying includes means for determining the coπesponding local time as a function of the differences in the time- zone offsets ofthe local place and the remote place.

27. An international time indicating system as defined in claim 25, wherein the locations throughout the world are represented by telephone international access codes, country codes, and possible area codes, and wherein the relative time differences of locations throughout the world are associated with the telephone international access codes, country codes, and possible area codes.

28. An international time indicating system as defined in claim 27, wherein the means for entering the location of a remote place includes means for entering a telephone international access code, caUed country code, and possible area code of the remote place.

29. An international time indicating system as defined in claim 25, wherein the entered time of day ofthe remote place and the corresponding local time ofthe local place include hours, minutes and date.

30. An international time indicating system as defined in claim 29, wherein the entering means includes means for entering a time of day of a remote place by one hour increments and one minute increments, the calculating and displaying means includes means for displaying the hourly increments of the remote time ofthe remote place and simultaneously calculating and displaying the hourly increments of the conesponding local time ofthe local place, and the calculating and displaying means includes means for displaying the minute increments of the remote time ofthe remote place and simultaneously calculating and displaying the minute increments ofthe corresponding local time ofthe local place.

31. An international time indicating system as defined in claim 25, wherein the calculating and displaying means displays the local time of the local place and the remote time of the remote place in multi-segment form.

32. An international time indicating system as defined in claim 25, further including means for selecting the location of the local place.

33. An international time indicating system as defined in claim 25, wherein the locations throughout the world are represented by telephone country codes, and possible area codes, and wherein the relative time differences of locations throughout the world are associated with the telephone country codes, and possible area codes.

34. An international time indicating system comprising: electronic memory for storing telephone international access codes, country codes, and possible area codes representing locations throughout the world, and for storing relative time differences associated with the telephone codes; means for selecting the location of a local place; means for entering a time of day and the telephone code of a remote place; and means for calculating and displaying the conesponding local time ofthe local place which is at the same moment as the entered time of day of the remote place as a function of the relative time differences of the location of the local place and the remote place.

35. An international time indicating system as defined in claim 34, wherein the relative time differences are time zone offsets with respect to a reference time zone, and the means for calculating and displaying includes means for deterrmning the conesponding local time as a function of the differences in the time- zone offsets of the location of the local place and the remote place.

36. A method for electronicaUy determining the local time of a local place conesponding to a remote time of a remote place, the method comprising the steps of: storing in electronic memory data representing locations throughout the world and relative time differences of the locations; providing data representing a time of day and location of a remote place; and automatically calculating and displaying by means of an electronic microprocessor the conesponding local time of a local place which is at the same moment as the entered time of day ofthe remote place as a function ofthe relative time differences ofthe local place and the remote place.

37. A method as defined in claim 36, wherein the locations in the storing step are defined by telephone international access codes, country codes, and possible area codes representing locations throughout the world.

38. A method as defined in claim 36, wherein the relative time differences are defined by time zone offsets with respect to a reference time zone.

39. A method as defined in claim 36, wherein the step of displaying is accompUshed in a form selected from the group comprising: seven segment form, Uquid crystal form, Ught emitting form and dot matrix form.

40. A method as defined in claim 36, wherein the locations in the storing step are defined by telephone country codes, and possible area codes representing locations throughout the world.