.
`
`lllllllllllllllllIllllllll!IlllllllllHillllllllllllIllllllllllllllllllllll
`U5005535242A
`
`United States Patent
`
`[19]
`
`[11] Patent Number:
`
`5,535,242
`
`Brigida et al.
`[45] Date of Patent:
`Jul. 9, 1996
`
`
`[54] METHOD AND SYSTEM FOR MODEM
`COMMAND PROCESSING DURING DATA
`TRANSFER
`
`[75]
`
`Inventors: David J. Brigida, Boca Raton; Victor
`’
`S. Moore, Delray Beach; Thomas K.
`Pate, Boca Raton, all of Fla.
`
`[73]
`
`Assignee:
`
`International Business Machines
`Corporation, Armonk, NY.
`
`[21]
`
`[22]
`
`[63]
`
`[51]
`[52]
`[58]
`
`[56]
`
`Appl. No.: 427,768
`
`Filed:
`
`Apr. 25, 1995
`
`Related US. Application Data
`
`Continuation of Ser. No. 860,383, Mar. 30, 1992.
`Int. Cl.6 ....................................................... H04B 1/38
`US. Cl. ...........
`. 375/222; 375/377; 379/98
`
`Field of Search ..................................... 375/222, 377;
`379/93, 97, 98
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`375/365
`3,825,905
`7/1974 Allen, Jr.
`................
`375/222
`4,387,440
`6/1983 Eaton ..............
`
`375/222
`4,549,302 10/1985 Heatherington .
`
`375/222
`4,718,082
`1/1988 Parker et a1.
`375/222
`.
`4,922,534
`5/1990 Gomiak et a1.
`............................. 375/377
`4,926,448
`5/1990 Kraul et al.
`
`4,928,305
`5,170,470
`
`.......................................... 375/222
`5/1990 Yui
`..... .. 375/222
`12/1992 Pindar et a].
`
`Primary Examiner—Stephen Chin
`Assistant Examiner—T. Ghebretinsae
`Attorney, Agent, or Firm—Richard A. Tomlin; Andrew J.
`Dillon
`
`[57]
`
`ABSTRACT
`
`A method and system are disclosed for permitting selected
`command sequences to be processed by a modem during
`data transfer operations. A preselected escape character is
`designated and inserted into a data stream to be applied to a
`modem in order to identify a selected command sequence
`which follows. A termination character is inserted into the
`data stream following the selected command sequence.
`Upon detection of the preselected escape character,
`the
`selected command sequence is coupled to a command
`processor within the modem and processed. In applications
`in which the modem is coupled between a data processing
`system and a cellular telephone communication channel, the
`selected command sequence may be utilized to transmit
`communication channel parameter status queries to a cellu-
`lar telephone associated with the modem. In this manner, the
`Received Signal Strength Indicator (RSSI), bit error rate, or
`other indications of communication channel status may be
`queried. An identical technique may be utilized to transmit
`a response to each such query to the data processing system,
`permitting real time display of cellular communication chan—
`nel status information during data transfer.
`
`7 Claims, 4 Drawing Sheets
`
`
`
`P
`
` EXHIBIT
`
`Petitioner - Kyocera
`
`
`
`PX 1016
`
`
`
`Kyocera PX 1016__1
`
`

`

`US. Patent
`
`Jul. 9, 1996
`
`Sheet 1 of 4
`
`5,535,242
`
`
`TELEPHONESYSTEM
`
`
`Fig.1
`
`
`
`Kyocera PX 1016_2
`
`Kyocera PX 1016_2
`
`

`

`US. Patent
`
`Jul. 9, 1996
`
`Sheet 2 of 4
`
`5,535,242
`
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`
`
`
`__________._.____.._________..______
`
`Kyocera PX 1016_3
`
`Kyocera PX 1016_3
`
`
`
`

`

`US. Patent
`
`Jul. 9, 1996
`
`Sheet 3 of 4
`
`5,535,242
`
`DATA PUMP
`
`18
`
`9215
`
`CH =1234
`
`EMULATOR TEXT
`
` BER=123
`
`PKT#=123/123
`
`CHQ=123 “
`
`94
`
`96
`
`Fig
`
`. 5
`
`Kyocera PX 1016_4
`
`Kyocera PX 1016_4
`
`
`
`
`

`

`US. Patent
`
`Jul. 9, 1996
`
`Sheet 4 of 4
`
`5,535,242
`
`RETRIEVE NEXT
`CHARACTER
`
`
`
`TECR
`RAH
`
`ER
`
`VA
`
`Tl
`
`XRENETEC
`
`RETRIEVE NEXT
`CHARACTER
`
`Kyocera PX 1016_5
`
`Kyocera PX 1016_5
`
`

`

`1
`METHOD AND SYSTEM FOR MODEM
`COMIMAND PROCESSING DURING DATA
`TRANSFER
`
`This is a continuation of application Ser. No. 07/860,383,
`filed 30 Mar. 1992 now pending.
`
`BACKGROUND OF THE INVENTION
`
`1. Technical Field
`
`The present invention relates in general to improvements
`in communication in a distributed data processing system
`and in particular to methods and systems for enhancing the
`efficiency of modem operation in a data processing system.
`Still more particularly, the present invention relates to meth-
`ods and systems for permitting command processing by a
`modem during data transfer, wherein communication chan-
`nel parameters may be monitored.
`2. Description of the Related Art
`Data communication between modern computer devices
`is typically accomplished utilizing a modulator/demodulator
`or so-called “modem” which is utilized to convert digital
`signals within a data processing system to analog signals for
`transmittal over existing communication links. Additionally,
`such devices convert received analog signals to digital
`signals for utilization by a data processing system. In the
`past most distributed computer networks have been coupled
`together utilizing existing telephone land line systems or
`specialized wiring; however, modern distributed data pro-
`cessing systems often utilize more sophisticated means of
`communication.
`
`For example, the decreasing cost of cellular communica-
`tion equipment has resulted in the utilization of that tech-
`nology to couple together computers without the necessity
`of access to a telephone line outlet. This particular technol-
`ogy is particularly effective in combination with small
`portable battery powered laptop or notebook computers in
`which the necessary modem and cellular communication
`circuitry are miniaturized and provided in an integral fashion
`within the computer itself. Thus, an operator utilizing such
`a computer may initiate communications and transfer data
`between his or her computer and a distributed data process-
`ing system without the necessity of access to either tele-
`phone lines or power lines. Examples of such portable
`computers include the International Business Machines Cor-
`poration LX40 and the Model 9075 PCradio, which may be
`utilized for wireless communication by attaching a radio
`device. Radio devices such as a cellular telephone, or
`ARDIS radio devices may be utilized.
`These radio devices communicate with the portable com—
`puter via a conventional communication port. These devices
`are typically configured and controlled in the same manner
`as a Hayes compatible modem. For example, a series of
`preselected commands, typically known as “AT” commands
`may be utilized to set internal parameters for these devices
`and instruct the devices in operation. Known modems or
`combination modem/radio systems typically operate in one
`of two different modes of operation. In a first mode of
`operation, the device recognizes all characters transmitted to
`the device as commands. This mode of operation is referred
`to as the command mode. The other mode treats characters
`received at
`the device as data to be transmitted via a
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`communications link. This mode of operation is referred to
`as the data mode. Typically, a special sequence of data bytes
`may be utilized to toggle the device from the data mode to
`the command mode. Generally this sequence consists of one
`
`65
`
`5,535,242
`
`2
`
`second with no data followed by the key sequence “-H—t,”
`followed by another second of no data.
`This manner of transferring back and forth between
`command and data modes of operation has proven to be
`quite adequate for devices which communicate via tele-
`phone landlines. Such devices have been widely accepted
`within the industry. This toggling concept works largely
`because the command mode and data mode are substantially
`divorced from one another, without the need to share data
`from one mode with the second mode. This is generally due
`to the low bit error rates present within landline systems and
`the fact that a standard modern has little information to
`
`provide to the data processing system regarding modem or
`line operation while the modem is operating in a data mode.
`In contrast, modem/radio systems possess
`substantial
`amounts of information regarding the modem and commu-
`nications channel operation.
`For example, when utilizing a cellular telephone/modem
`to transmit data it would be helpful to the operator to possess
`information regarding how well the cellular telephone radio
`link is operating at a particular moment. This information
`may be utilized by the operator to make decisions regarding
`data throughput. If data throughput is low, the operator may
`choose to select a different transmission protocol or to
`increase the power of the radio transmitter. For example, a
`low Received Signal Strength Indicator (RSSI) may alert the
`operator to increase the transmitter power so that the receiv—
`ing station may receive a clear signal. The Received Signal
`Strength Indicator (R881) and a Service Access Tone (SAT)
`are two indications of cellular telephone channel quality
`which are typically present within a known cellular tele-
`phone system. Additionally, information about the bit error
`rate experienced within the cellular telephone transmission
`channel may also be utilized by the operator to choose
`protocols that enhance the efiiciency of data transfer.
`While existing cellular telephone systems may provide
`channel
`information, such as Received Signal Strength
`Indicator (RSSI), Service Access Tone (SAT), bit error rates
`and packet counts, these important operational parameters
`are not generally available to data radio operators during
`data transmission. In order to access this information utiliz—
`ing known data radio devices, the data transmission mode
`must be terminated and the operator must enter the com-
`mand mode in order to query the status of these various
`parameters.
`
`It should therefore be apparent that a need exists for a
`method and system whereby modem commands may be
`selectively processed during data transfer, resulting in the
`ability to poll communication charmel parameters during
`actual data transfer.
`
`SUMMARY OF THE INVENTION
`
`It is therefore one object of the present invention to
`provide an improved system for communication in a dis-
`tributed data processing system.
`It is another object of the present invention to provide an
`improved method and system for enhancing the efficiency of
`modem operation in a distributed data processing system.
`It is yet another object of the present invention to provide
`an improved method and system for permitting selected
`command processing by a modem during data transfer
`wherein communication channel parameters may be moni-
`tored during modem operation.
`~The foregoing objects are achieved as is now described.
`The method and system of the present invention may be
`
`Kyocera PX 1016_6
`
`Kyocera PX 1016_6
`
`

`

`3
`
`4
`
`5,535,242
`
`utilized to permit selected command sequences to be pro-
`cessed by a modem during data transfer operations. A
`preselected escape character is designated and inserted into
`a data stream to be applied to a modem in order to identify
`a selected command sequence which follows. A termination
`character is inserted into the data stream following the
`selected command sequence. Upon detection of the prese-
`lected escape character, the selected command sequence is
`coupled to a command processor within the modem and
`processed. In applications in which the modem is coupled
`betWeen a data processing system and a cellular telephone
`communication channel, the selected command sequence
`may be utilized to transmit communication channel param-
`eter status queries to a cellular telephone associated with the
`modem. In this manner, the Received Signal Strength Indi-
`cator (RSS1), bit error rate, or other indications of commu-
`nication channel status may be queried. An identical tech—
`nique may be utilized to transmit a response to each such
`query to the data processing system, permitting real time
`display of cellular communication channel status informa-
`tion during data transfer.
`
`BRIEF DESCRIPTION OF THE DRAWING
`
`The novel features believed characteristic of the invention
`are set forth in the appended claims. The invention itself
`however, as well as a preferred mode of use, further objects
`and advantages thereof, will best be understood by reference
`to the following detailed description of an illustrative
`embodiment when read in conjunction with the accompa-
`nying drawings, wherein:
`FIG. 1 is a partially schematic pictorial representation of
`a distributed data processing system which may be utilized
`to implement the method and system of the present inven-
`tion.
`
`FIG. 2 is a partial high level block diagram of a computer
`within the distributed data processing system of FIG. 1
`which may be utilized to implement the method and system
`of the present invention;
`FIG. 3 is a high level block diagram of a modem/cellular
`telephone which may be utilized to implement the method
`and system of the present invention;
`FIG. 4 is a high level
`logic flowchart which depicts
`command processing in a modem during data transfer in
`accordance with the method and system of the present
`invention; and
`
`FIG. 5 is a pictorial representation of a computer display
`depicting the display of communication channel status data
`obtained utilizing the method and system of the present
`invention.
`
`DETAILED DESCRIPTION OF PREFERRED
`EMBODIMENT
`
`With reference now to the figures and in particular with
`reference to FIG. 1, there is depicted a partially schematic
`pictorial representation of a distributed data processing
`system 10 which may be utilized to implement the method
`and system of the present invention. Upon reference to the
`foregoing those skilled in the art will appreciate that while
`distributed data processing system 10 is illustrated as includ-
`ing only two computers,
`typically such distributed data
`processing systems include a large number of computers
`distributed over a wide geographic area. As illustrated, one
`of the computers within distributed data processing system
`10 is a portable computer 12. Portable computer 12 is
`typically a battery powered computer which includes a low
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`power display system 16 which preferably provides a dis-
`play screen 18 which may be implemented utilizing a liquid
`crystal displays (LCDS), a gas plasma display or any other
`suitable technology. The keyboard 14 is provided which
`enables the user to access and modify data stored within
`portable computer 12 in a manner well known in the art.
`As those skilled in the art will appreciate it is increasingly
`common for computers such as portable computer 12 to
`include therein a miniature cellular telephone system (not
`shown) which is provided in conjunction with a modem.
`One example of a portable computer equipped with a
`combination modem/cellular telephone which may be uti-
`lized to implement portable computer 12 is the International
`Business Machines Corporation Model 9075 PCradio.
`Those skilled in the art will appreciate that a modem is a
`device which may be utilized to convert digital data from a
`computer to an analog signal which may be transmitted via
`a telecommunications system. Additionally, such devices
`convert received analog signals from the telecommunica-
`tions line to digital data which may be utilized by a com-
`puter. As is typical in such systems, a cellular telephone
`transmits a radio frequency signal via antenna 20 which may
`be received and relayed via multiple cellular system anten-
`nae 22. Thus, digital data within portable computer 12 may
`be converted into a series of analog signals and transmitted,
`via a cellular telephone system and multiple intervening
`repeaters to a telephone system 24, in a manner well known
`to those skilled in this art.
`
`Analog signals thus transmitted may be received by the
`telephone system and transmitted, via an ordinary telephone
`land line 26 to a computer 28 within distributed data
`processing system 10. While computer 28 is depicted as a
`personal computer, those skilled in the art will appreciate
`that computer 28 may be implemented utilizing a worksta-
`tion, terminal or mainframe computer, as desired. Typically,
`computer 28 will also include a modem device permitting
`data from portable computer 12 to be transmitted to and
`received by computer 28 and computer 28 may also be
`linked to portable computer 12 utilizing cellular technology,
`rather than telephone land lines.
`Referring now to FIG. 2, there is depicted a partial high
`level block diagram of portable computer 12 within distrib-
`uted data processing system 10 of FIG. 1 which may be
`utilized to implement the method and system of the present
`invention. As illustrated, portable computer 12 preferably
`includes a processor 30 which is coupled to a bus 32. Serial
`port 34, coupled to bus 32, is utilized to serialize data from
`processor 30 and couple that data to modem 36. Modern 36,
`as described above, converts that data into a series of analog
`signals which are coupled to cellular telephone 38 and
`transmitted, via antenna 30 in the manner described above.
`Of course, those skilled in the art will appreciate that in a
`modern miniature portable computer modem 36 and cellular
`telephone 38 may be implemented utilizing a single subas-
`sembly within portable computer 12.
`With reference now to FIG. 3, there is depicted a high
`level block diagram of a modem/cellular telephone which
`may be utilized to implement the method and system of the
`present invention. As is typical in such devices, the modem
`is coupled via communication port 52 to data processing
`system 12. In known combination modem/cellular telephone
`systems of this type, the digital data from the data processing
`system is converted to an analog signal and coupled to
`communication channel 54 via data pump 58. In the depicted
`embodiment of the present invention two additional fea-
`tures, switch 56 and control
`logic 60 are provided. In
`accordance with the method and system of the present
`
`Kyocera PX 1016_7
`
`Kyocera PX 1016_7
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`

`

`5,535,242
`
`5
`invention, switch 56 and control logic 60 are utilized to
`temporarily divert data within a data stream applied to the
`modem to the command processor 50. Command processor
`50 is, as those skilled in the art will appreciate, typically
`present within each modem and utilized to decode and
`process the various commands which may be coupled to the
`modem while the modem is operating in the command
`mode.
`
`As will be explained in greater detail herein, the method
`and system of the present invention selectively inserts a
`designated escape character into the data stream being
`coupled through the modem and, upon a detection of this
`designated escape character by control logic 60, switch 56 is
`utilized to couple the characters which follow the designated
`escape character to command processor 50, allowing the
`modem to process selected commands while maintaining
`operation in the data transfer mode. In a similar manner, as
`will be explained in greater detail herein, command proces-
`sor 50 may also transmit responses to selected commands to
`data processing system 12 by inserting into the data stream
`passing through the modem a response to a selected com—
`mand following a designated escape character, indicating
`that the data which follows is not part of the normal data
`stream. In this manner, a data processing system may
`transmit selected command sequences to the command
`processor of the modem without breaking away from the
`data transfer mode. These command sequences may then be
`processed and requested data may be returned to the data
`processing system via communication port 52, by inserting
`the response data into the data stream utilizing the desig-
`nated escape character to isolate the response data from
`received data being transmitted to data processing system
`12.
`
`Of course, those skilled in the art will appreciate that this
`method and system will not find application with all possible
`commands in the command set utilized for a typical modern;
`however, selected command sequences, as will be described
`in detail below, may be utilized to permit the operator to
`receive certain communication channel parameter informa-
`tion in a real time basis, without requiring the operator to
`toggle the modern from the data transfer mode to the
`command mode. As will be illustrated below, examples of
`various communication channel parameters such as cellular
`signal strength, Service Access Tone (SAT) frequency, cel-
`lular channel, packet number, number of packet retries,
`retraining status and data buffer utilization may all be
`obtained from the modem utilizing the method and system
`of the present invention.
`Referring now to FIG. 4, there is depicted a high level
`flowchart which illustrates the processing of commands by
`a modem during data transfer,
`in accordance with the
`method and system of the present invention. Of course, the
`process depicted within FIG. 4 illustrates a data stream
`flowing from the data processing system to the communi—
`cation channel; however,
`the identical process may be
`utilized to embed responses to selected command sequences
`in a data stream flowing from the communication channel to
`the data processing system.
`The process, as illustrated, begins at block 70 and there-
`after passes to block 72. Block 72 illustrates the retrieval of
`the next character within the data stream and the process
`then passes to block 74. Block 74 depicts a determination of
`whether or not the character retrieved is the designated
`escape character. As will become apparent to those skilled in
`the art upon reference to the foregoing,
`the designated
`escape character may be any character within the data
`processing system; however, the efficiency of the system
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`will be greatly enhanced by selecting an escape character
`which is not often present within normal data stream trans-
`fers. For example, the “escape” key may be utilized. It is
`anticipated that a selected AT command may be utilized to
`place the modem/cellular telephone system into a shared
`command/data state of operation and that a second com—
`mand may thereafter be utilized to designate a selected
`escape character for utilization with the method and system
`of the present invention.
`Referring again to block 74, in the event the character just
`retrieved is not the designated escape character, the process
`passes to block 76. Block 76 illustrates the transmittal of that
`character to the data pump for transmittal via the modem/
`cellular telephone system. However, in the event the char-
`acter encountered is the designated escape character, as
`determined at block 74, the process passes to block 78.
`Block 78 illustrates the retrieval of the next character and
`thereafter, the process passes to block 80. Block 80 depicts
`a determination of whether or not
`the next character
`retrieved is the designated escape character. This step in the
`process is utilized, as should be apparent, to permit the
`transmittal of the designated escape character within an
`ordinary data stream context by searching out each occur-
`rence of the designated escape character within the data
`stream which is not followed by a command sequence and
`inserting at that point a second occurrence of the designated
`escape character. Thus, the occurrence of 'two consecutive
`designated escape characters will indicate to the method and
`system of the present invention that a single escape character
`is to be transmitted to the data pump, as depicted at block 76
`of FIG. 4.
`
`Referring again to block 80, in the event the next char-
`acter retrieved is not the designated escape character, the
`process passes to block 82. Block 82 illustrates a determi-
`nation of whether or not the next character is the designated
`termination character. In the depicted embodiment of the
`present invention each command sequence which follows a
`designated escape character is terminated by utilizing a
`carriage return. However, any other unique character may be
`utilized to designate the termination of a command sequence
`which follows a designated escape character, in accordance
`with the method and system of the present invention. If the
`next character is a carriage return, the process passes back
`to block 72 to retrieve the next character and begin trans-
`mitting data via the data pump until the next designated
`escape character occurs.
`Referring again to block 82, in the event the next char-
`acter encountered is not a caniage return, or alternate
`designated termination character, the process passes to block
`84. Block 84 illustrates the transmittal of that character to
`the command processor and the process then passes to block -
`86. Block 86 illustrates the retrieval of the next character and
`
`the process then returns iteratively to block 82 until such
`time as the designated termination character occurs. In this
`manner, data within a data stream applied to the modem is
`continually analyzed to locate a designated escape character
`within that data stream and thereafter, the subsequent char-
`acter is checked to determine if a duplicate designated
`escape character has been transmitted. In the event a second
`designated escape character has not been transmitted, the
`data which follows the designated escape character is con-
`tinuously coupled to the command processor until such time
`as the designated termination character (a carriage return in
`the depicted embodiment) occurs. In this manner, selected
`command sequences may be coupled to the command pro-
`cessor 50 (see FIG. 3) for processing without terminating the
`data transfer mode.
`
`Kyocera PX 1016_8
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`With reference now to FIG. 5, there is depicted a pictorial
`representation of a computer display 18 which depicts the
`display of communication status data obtained utilizing the
`method and system of the present invention. As illustrated,
`a window 90 is provided which may be utilized to display
`the text associated with the emulator application. Addition-
`ally, various communication channel status data may be
`displayed within computer display 18 in the manner illus-
`trated within FIG. 5. For example,
`the Received Signal
`Strength Indicator (RSSI) may be obtained from the modem/
`cellular telephone assembly and be graphically depicted as
`illustrated at reference numeral 92, as a bar graph which
`varies in length according to the amplitude of the Received
`Signal Strength Indicator (RSSI) received from the cellular
`system. Additionally, various other communications channel
`parameters may be established by querying the command
`processor 50 (see FIG. 3) utilizing embedded command
`sequences in the, manner described herein and subsequently
`returning the response to those command sequences to the
`data processing system for display. For example, a bit error
`rate may be displayed, as indicated at reference numeral 94.
`Additionally, various packet numbers, channel quality indi-
`cators, carrier status indicators and channel numbers may be
`displayed as depicted at reference numerals 96, 98, 100 and
`102.
`
`Upon reference to the foregoing those skilled in the art
`will appreciate that the Applicants herein have provided a
`novel and unobvious method whereby selected command
`sequences may be addressed to a command processor within
`a modem while that modem is in the data transfer mode,
`without requiring the modem to be toggled to the command
`mode. These command sequences may then be processed
`and a response to each command sequence may be embed-
`ded within the data being transferred to the data processing
`system in a similar manner. Thus, the user of a battery
`powered portable computer device having an integrated
`modern/cellular telephone communication capability may be
`continually apprised'of the status of the communication
`channel, in real time, without the necessity of continually
`toggling the modem between the data transfer mode and the
`command mode.
`
`While the invention has been particularly shown and
`described with reference to a preferred embodiment, it will
`be understood by those skilled in the art that various changes
`in form and detail may be made therein without departing
`from the spirit and scope of the invention.
`We claim:
`
`1. A method in a data processing system for enhancing the
`efliciency of operation of a modern coupled between a
`communication channel and said data processing system,
`said modem having a command processor, a data'transfer
`mode and a command mode, said method comprising the
`steps of:
`coupling a stream of data from said data processing
`system to said modem while said modem is operating
`in said data transfer mode;
`selectively inserting within said stream of data a prese-
`lected escape character followed by a selected com-
`mand sequence which initiates a communication chan-
`nel status query;
`detecting said preselected escape character within said
`stream of data; and
`
`command
`selected
`said
`processing
`automatically
`sequence within said command processor of said
`modem in response to a detection of said preselected
`escape character while said modern continues to oper—
`ate in said data transfer mode and is directly connected
`to the data processing system such that communication
`channel status may be determined during data transfer.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`4s
`
`50
`
`55
`
`60
`
`65
`
`2. The method in a data processing system for enhancing
`the efliciency of operation of a modem according to claim 1,
`further including the steps of:
`coupling a second stream of data from said modem to said
`data processing system while said modem is operating
`in said data transfer mode;
`selectively inserting within said second stream of data a
`preselected escape character followed by a response to
`said selected command sequence; and
`automatically processing said response within said data
`processing system in response to a detection of said
`preselected escape character while said modern contin-
`ues to operate in said data transfer mode.
`3. The method in a data processing system for enhancing
`the efliciency of operation of a modem according to claim 1,
`further including the step of detecting each occurrence of
`said preselected escape character within said stream of data
`not followed by a selected command sequence and inserting
`a second preselected escape character following each such
`occurrence.
`
`4. The method in a data processing system for enhancing
`the efliciency of operation of a modem according to claim 1,
`further including the step of inserting within said stream of
`data a preselected termination character following said
`selected command sequence.
`5. A data processing system for enhancing the efliciency
`of operation of a modern coupled between a communication
`channel and said data processing system, said modem hav-
`ing a command processor, a data transfer mode and a
`command mode, said data processing system comprising:
`means for coupling a stream of data from said data
`processing system to said modem while said modem is
`operating in said data transfer mode;
`means for selectively inserting within said stream of data
`a preselected escape character followed by a selected
`command sequence which initiates a communication
`channel status query;
`means for detecting said preselected escape character
`within said stream of data; and
`means for automatically processing said selected com-
`mand sequence within said command processor of said
`modem in response to a detection of said preselected
`escape character while said modem continues to oper-
`ate in said data transfer mode and is directly connected
`to the data processing system such that communication
`channel status may be determined during data transfer.
`6. The data processing system for enhancing the efficiency
`of operation of a modem according to claim 5, further
`including:
`means for coupling a second stream of data from said
`modem to said data processing system while said
`modem is operating in said data transfer mode;
`means for selectively inserting within said second stream
`of data a preselected escape character followed by a
`response to said selected command sequence; and
`means for automatically processing said response within
`said data processing system in response to a detection
`of said preselected escape character while said modem
`continues to operate in said data transfer mode.
`7. The data processing system for enhancing the efficiency
`of operation of a modem according to claim 5, further
`including means for inserting within said stream of data a
`preselected termination character following said selected
`command sequence.
`
`Kyocera PX 1016_9
`
`Kyocera PX 1016_9
`
`