WO1991002434A1

WO1991002434A1 - Automatic message protection for selected addresses in a selective call receiver

Info

Publication number: WO1991002434A1
Application number: PCT/US1990/003792
Authority: WO
Inventors: Patrick Shuang Kung
Original assignee: Motorola, Inc.
Priority date: 1989-08-09
Filing date: 1990-07-09
Publication date: 1991-02-21

Abstract

A method is disclosed for automatically protecting messages (403, 405) associated with selected receiver addresses (403) and stored within the memory (107, 108) of a selective call receiver from inadvertent deletion.

Description

AUTOMATIC MESSAGE PROTECTION FOR SELECTED ADDRESSES IN A SELECTIVE CALL RECEIVER

Field of the Invention

This invention relates in general to electronic message storage devices such as selective call receivers and, more specifically, to a method of automatically protecting certain messages contained therein from being overwritten.

Background of the Invention

Typical modern selective call receivers such as numeric and alphanumeric pagers are capable of receiving and storing several information messages in an internal random access memory (RAM). In a paging system, most paging transmissions comprise a receiver address portion and, immediately following a message portion. Each pager in the system is identified by at least one specific receiver address. Upon receipt of a valid receiver address, the pager stores the associated message in RAM and a message address identifying where in RAM that message is stored is placed within a plurality of slots within memory. After receipt and storage, messages are available for review on demand by the user on a visual display. Usually, the received messages are stored in memory on a first in, first out basis. That is, if all of the pager's message address slots in memory are full upon receipt of a new message, the oldest message in memory is overwritten (in other words, deleted from memory) to make room for the new message. Most of today's pagers comprise some means for locking (protecting) selected messages stored in memory to avoid their potential deletion in the event of memory overflow. Typically this protection means is achieved by manual actuation of a switch while the message to be protected is displayed on the pager's visual display. After this locking step, the protected message cannot be overwritten by a subsequently received message unless unlocked. Unlocking is performed when messages that were previously locked lose their "important" status and is usually executed by manual actuation of the same switch as in the locking process. To summarize, actuation of the switch will lock an unlocked displayed message or vice versa.

In some cases, the current art for locking selected messages stored in memory is not sufficient for users' needs. For example, in the case where a user receives multiple messages within a relatively short period of time, the potential exists for received messages to be overwritten and thus, deleted, before they are read by the user. Additionally, the manual locking scheme of the current art can be cumbersome and confusing for the user since he is expected to perpetually manage locking of important received messages and unlocking of messages that were once, but are no longer, important. This issue is exacerbated as pagers continually evolve with the capability to store a greater number of messages.

Thus, what is needed is an improved method for protecting selected messages in the memory of a selective call receiver from being overwritten and deleted by subsequently received messages.

Summary of the Invention

Accordingly, it is an object of the present invention to provide an improved method for protecting messages in the memoiy of a selective call receiver from being overwritten by subsequently received messages.

In carrying out the above and other objects of the invention in one form, there is provided an electronic device comprising a first element for receiving and storing messages associated with a received first receiver address or a received second receiver address, the first element comprising a memory, each of the stored messages having attributes, the attributes comprising at least one bit in the memoiy, and a second element for protecting the stored messages associated with the received first receiver address from being overwritten, at least one of the attribute bits of the messages associated with the received first receiver address being set to a predetermined state.

Brief Description of the Drawings

FIG. 1 is a block diagram of a selective call receiver in accordance with the preferred embodiment of the invention.

FIG. 2 is a diagram of the relevant constituents of the random access memory (RAM) of a selective call receiver in accordance with the preferred embodiment.

FIG. 3 is a diagram of the pertinent section of the message information array portion of the RAM.

FIG.4 is a flow diagram of the address decoding and message protection process.

Detailed Description of the Invention

Referring to FIG. 1, a selective call receiver comprises an antenna 102 that provides a received modulated radio frequency signal to the receiver/ demodulation circuitry 109. The receiver /demodulation circuitry 109, in conjunction with the central processing unit (CPU) 101 and the control 105, performs the conversion of the received modulated radio frequency signal to digital data and the address portion of this digital data is compared to the digital addresses stored in the read only memory (ROM) 108. Should the address portion of the decoded digital data match one of the addresses of the pager, the alert 104 is activated to notify the product user of a received page through means such as audible or visual. In the case of an information page (numeric, for example), the received, decoded message is stored in the random access memory (RAM) 107 and a message address identifying where in the RAM 107 that message is stored is placed in one of a plurality of available slots within the RAM 107. The message is then available for review by the user on the display 106. The control 105 comprises switches for performing pager functions that are well known in the art such as message read, alert reset, display backlighting etc The battery 103 supplies power to all active circuits within the selective call receiver (for simplicity, only the connections from the battery to the receiver/ demodulation circuitry 109 and the CPU 101 are shown).

In the preferred embodiment of the invention, the ROM 108 has certain ones of the pager's receiver addresses designated as being protective. In other words, messages sent to these protective receiver addresses will be locked upon receipt of the message by the pager. This allows the user to receive his "critical" messages on the protective receiver addresses, thereby automatically protecting these messages from being inadvertently deleted. In another embodiment of the invention, the protective receiver addresses are designated in the RAM 107, rather than the ROM 108, to permit the user to more easily change receiver addresses from unprotective to protective and vice versa.

Referring to FIG. 2, the random access memory (RAM) 107 of the selective call receiver of the preferred embodiment comprises the message addresses 201, a message information array 202, and the message storage 203. The purpose of the message addresses 201 is to store the exact location of particular messages within the message storage 203 and the message information array 202. The message addresses 201 comprises a plurality of slots; each for storing the location of one particular message. For example, in FIG. 2, the first line 204 of the message addresses 201 indicates that message 1 is stored in location d of the message storage 203 and that information about message 1 is stored within the message information array 202 location d. Similarly, the second line 205 indicates that message 2 and information about it are stored in location c, the third line 206 indicates that message 3 and information about it are stored in location a, and the fourth line 207 indicates that message 4 and information about it are stored in location b.

Referring to FIG. 3, the message information array 202 of the RAM 107 comprises a table in which attributes are stored for each message resident in the message storage 203. In accordance with the preferred embodiment of the invention, one such attribute is a message protection bit that is set to a predetermined state to indicate whether a stored message is locked (protected from being overwritten). For example, if a "one" bit in the message protection bit column 302 indicates that the associated message is locked and a "zero" bit indicates that it is not locked, message 3 is locked 303, message 4 is unlocked 304, message 2 is unlocked 305, and message 1 is locked 306.

Referring to FIG. 4, the steps of the address decoding and message protection process comprise decoding a received receiver address, step 401, then comparing the decoded receiver address to those resident in the ROM 108 to see if there is a match 402. If there is not a match found in step 402, the process reverts back to decoding the next received receiver address, step 401. If there is a match found in step 402, the receiver address is checked to see if it is a protective receiver address (in other words, the received receiver address is compared to those designated as "protective" in the ROM 108), step 403. If the receiver address is not protective, the process proceeds to step 404, in which the CPU 101 decodes the received data, activates the alert 104, and stores the data in the RAM 107, after which the process returns to step 401. If, in step 403, it is found that the address is protective, a protection bit 302 is set 405 within the message information array 202 of the RAM 107 to designate the stored message as protected from overwriting and the process then proceeds to step 404

Claims

1. An electronic device comprising first means for receiving and storing messages associated with a received first receiver address or a received second receiver address, said first means comprising a memory, each of said stored messages having attributes, said attributes comprising at least one bit in said memory; and second means for protecting said stored messages associated with said received first receiver address from being overwritten, at least one of said attribute bits of said messages associated with said received first receiver address being set to a predetermined state.

2. The apparatus of claim 1 wherein said electronic device comprises a selective call receiver.

3. A method for protecting stored messages within a selective call receiver from being overwritten by subsequently received messages comprising the steps of. receiving a modulated radio frequency transmission; and protecting Selected ones of said stored messages from said overwriting based upon said modulation.

4. The method according to claim 3 wherein said modulation is a receiver address of said selective call receiver.

5. A method for protecting stored messages within a selective call receiver from being overwritten wherein said selective call receiver is responsive to at least one receiver address and comprising the steps of. receiving a first receiver address; and automatically protecting said stored messages associated with said first receiver address from being overwritten.

6. The method according to claim 5 wherein said automatically protecting said stored messages comprises setting the state of at least one memory bit.

7. A method comprising the step of automatically protecting a stored message in a selective call receiver from being overwritten.