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       # 3COM CORPORATION
       
          COURIER HST WITH ASL
       
          Modem Type                   Data (synchronous/asynchronous)   
          Maximum Data Rate            14.4Kbps                          
          Data Bus                     External                          
          Data Modulation Protocol     Bell 103A/212A                    
                                                                         
                                       ITU-T V.22, V.22bis, V.23         
          Error Correction/Compression MNP5, V.42, V.42bis               
       
 (IMG) IMG 1
          
       
          +------------------------------------------------------------+
          |                        CONNECTIONS                         |
          |------------------------------------------------------------|
          |     Purpose      | Location |      Purpose      | Location |
          |------------------+----------+-------------------+----------|
          | Line out         |   CN1    | DC power          |   CN4    |
          |------------------+----------+-------------------+----------|
          | Line in          |   CN2    | Volume            |    R1    |
          |------------------+----------+-------------------+----------|
          | RS-232/422       |   CN3    | Power switch      |   SW2    |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                      MI/MIC POLARITY                       |
          |------------------------------------------------------------|
          | Setting          |         J6         |         J8         |
          |------------------+--------------------+--------------------|
          | » Normal         | Pins 1 & 2 closed  | Pins 1 & 2 closed  |
          |------------------+--------------------+--------------------|
          | Reversed         | Pins 2 & 3 closed  | Pins 2 & 3 closed  |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                    TX/RX PIN ASSIGNMENT                    |
          |------------------------------------------------------------|
          | Setting                       |            SW3             |
          |-------------------------------+----------------------------|
          |       Normal operation        | » Off                      |
          |-------------------------------+----------------------------|
          | Reverse TX/RX pin assignments | On                         |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                         DTR SIGNAL                         |
          |------------------------------------------------------------|
          | Setting                       |           SW1/1            |
          |-------------------------------+----------------------------|
          | DTR forced high               |             On             |
          |-------------------------------+----------------------------|
          | » DTR normal                  |            Off             |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                        RESULT CODES                        |
          |------------------------------------------------------------|
          | Setting                        |           SW1/2           |
          |--------------------------------+---------------------------|
          | » Verbose result codes enabled |            Off            |
          |--------------------------------+---------------------------|
          | Numeric result codes enabled   |            On             |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                    RESULT CODES DISPLAY                    |
          |------------------------------------------------------------|
          | Setting                       |           SW1/3            |
          |-------------------------------+----------------------------|
          | » Display enabled             |             On             |
          |-------------------------------+----------------------------|
          | Display disabled              |            Off             |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                   ECHO COMMANDS DISPLAY                    |
          |------------------------------------------------------------|
          | Setting                       |           SW1/4            |
          |-------------------------------+----------------------------|
          | » Local echo enabled          |            Off             |
          |-------------------------------+----------------------------|
          | Local echo disabled           |             On             |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                        AUTO ANSWER                         |
          |------------------------------------------------------------|
          | Setting                             |        SW1/5         |
          |-------------------------------------+----------------------|
          | » Modem answers on first ring       |          On          |
          |-------------------------------------+----------------------|
          | Modem does not answer on first ring |         Off          |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                       CARRIER DETECT                       |
          |------------------------------------------------------------|
          | Setting                       |           SW1/6            |
          |-------------------------------+----------------------------|
          | » CD normal                   |            Off             |
          |-------------------------------+----------------------------|
          | CD forced high                |             On             |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                    RESULT CODES DISPLAY                    |
          |------------------------------------------------------------|
          | Setting                                            | SW1/7 |
          |----------------------------------------------------+-------|
          | » Display result codes in originate and answer     |  Off  |
          | modes                                              |       |
          |----------------------------------------------------+-------|
          | Display result codes in Answer mode                |  On   |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                       AT COMMAND SET                       |
          |------------------------------------------------------------|
          | Setting                       |           SW1/8            |
          |-------------------------------+----------------------------|
          | » AT command set enabled      |             On             |
          |-------------------------------+----------------------------|
          | AT command set disabled       |            Off             |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                        ESCAPE CODE                         |
          |------------------------------------------------------------|
          | Setting |                      SW1/9                       |
          |---------+--------------------------------------------------|
          | » Off   |  Disconnect, go to command mode and display NO   |
          |         |    CARRIER when escape character is received     |
          |---------+--------------------------------------------------|
          | On      |  Go to command mode and display OK result code   |
          |         |        when escape character is received         |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                        USER PROFILE                        |
          |------------------------------------------------------------|
          | Setting                    |            SW1/10             |
          |----------------------------+-------------------------------|
          | » Off                      |      Use stored profile       |
          |----------------------------+-------------------------------|
          | On                         |      Use factory default      |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                         VOICE/DATA                         |
          |------------------------------------------------------------|
          |            Setting            |            SW4             |
          |------------------------------------------------------------|
          | Note: for switch functions see table for register S32.     |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                     DIAGNOSTIC LED(S)                      |
          |------------------------------------------------------------|
          | LED | Color |  Status  |             Condition             |
          |-----+-------+----------+-----------------------------------|
          | HS  |  Red  |    On    | Modem is operating at 4800bps or  |
          |     |       |          |              faster               |
          |-----+-------+----------+-----------------------------------|
          | HS  |  Red  |   Off    | Modem is operating at slower than |
          |     |       |          |              4800bps              |
          |-----+-------+----------+-----------------------------------|
          | AA  |  Red  |    On    |        Auto-answer enabled        |
          |-----+-------+----------+-----------------------------------|
          | AA  |  Red  |   Off    |       Auto-answer disabled        |
          |-----+-------+----------+-----------------------------------|
          | CD  |  Red  |    On    |      Carrier signal detected      |
          |-----+-------+----------+-----------------------------------|
          | CD  |  Red  |   Off    |    Carrier signal not detected    |
          |-----+-------+----------+-----------------------------------|
          | OH  |  Red  |    On    |         Modem is off-hook         |
          |-----+-------+----------+-----------------------------------|
          | OH  |  Red  |   Off    |         Modem is on-hook          |
          |-----+-------+----------+-----------------------------------|
          | RD  |  Red  | Blinking |      Modem is receiving data      |
          |-----+-------+----------+-----------------------------------|
          | RD  |  Red  |   Off    |    Modem is not receiving data    |
          |-----+-------+----------+-----------------------------------|
          | TD  |  Red  | Blinking |    Modem is transmitting data     |
          |-----+-------+----------+-----------------------------------|
          | TD  |  Red  |   Off    |  Modem is not transmitting data   |
          |-----+-------+----------+-----------------------------------|
          | TR  |  Red  |    On    |        DTR signal is high         |
          |-----+-------+----------+-----------------------------------|
          | TR  |  Red  |   Off    |         DTR signal is low         |
          |-----+-------+----------+-----------------------------------|
          | MR  |  Red  |    On    |            Power is on            |
          |-----+-------+----------+-----------------------------------|
          | MR  |  Red  |   Off    |           Power is off            |
          |-----+-------+----------+-----------------------------------|
          | MR  |  Red  | Blinking |       Retraining/test mode        |
          |-----+-------+----------+-----------------------------------|
          | RS  |  Red  |    On    |        RTS signal is high         |
          |-----+-------+----------+-----------------------------------|
          | RS  |  Red  |   Off    |         RTS signal is low         |
          |-----+-------+----------+-----------------------------------|
          | CS  |  Red  |    On    |        CTS signal is high         |
          |-----+-------+----------+-----------------------------------|
          | CS  |  Red  |   Off    |         CTS signal is low         |
          |-----+-------+----------+-----------------------------------|
          | EC  |  Red  |    On    |       Error control enabled       |
          |-----+-------+----------+-----------------------------------|
          | EC  |  Red  |   Off    |      Error control disabled       |
          |-----+-------+----------+-----------------------------------|
          | EC  |  Red  | Blinking |   Modem is retransmitting data    |
          |-----+-------+----------+-----------------------------------|
          | SYN |  Red  |    On    |         Synchronous mode          |
          |-----+-------+----------+-----------------------------------|
          | SYN |  Red  |   Off    |         Asynchronous mode         |
          +------------------------------------------------------------+
       
                            Proprietary AT Command Set
       
          +------------------------------------------------------------+
          |                  BIT-MAPPED REGISTER S13                   |
          |------------------------------------------------------------|
          | Format        | AT [cmds] S13=n [cmds]                     |
          |---------------+--------------------------------------------|
          | Example:      | ATS13=139<CR>                              |
          |---------------+--------------------------------------------|
          | Default:      | 0                                          |
          |---------------+--------------------------------------------|
          | Range:        | 0 - 255                                    |
          |---------------+--------------------------------------------|
          | Unit:         | Bit-mapped                                 |
          |---------------+--------------------------------------------|
          | Description:  | Controls DTR reset, DTR dialing, auto      |
          |               | answer, result code delay, reset dialing,  |
          |               | HST and MNP3.                              |
          |------------------------------------------------------------|
          |   Bit   | Value |                 Function                 |
          |---------+-------+------------------------------------------|
          |    0    | » 0 1 | DTR normal.                              |
          |         |       |                                          |
          |         |       | Reset on low DTR.                        |
          |---------+-------+------------------------------------------|
          |    1    | » 0 1 | Auto answer operation normal.            |
          |         |       |                                          |
          |         |       | When ring detected, enter originate mode |
          |         |       | and listen for answer tone.              |
          |---------+-------+------------------------------------------|
          |    2    | » 0 1 | Pause 250 msec. before displaying result |
          |         |       | codes.                                   |
          |         |       |                                          |
          |         |       | Display result codes immediately.        |
          |---------+-------+------------------------------------------|
          |    3    | » 0 1 | DTR dialing disabled.                    |
          |         |       |                                          |
          |         |       | DTR dialing enabled.                     |
          |---------+-------+------------------------------------------|
          |    4    | » 0 1 | Reset dialing disabled.                  |
          |         |       |                                          |
          |         |       | Reset dialing enabled.                   |
          |---------+-------+------------------------------------------|
          |    5    | » 0 1 | HST enabled.                             |
          |         |       |                                          |
          |         |       | HST disabled.                            |
          |---------+-------+------------------------------------------|
          |    6    | » 0 1 | MNP 3 enabled.                           |
          |         |       |                                          |
          |         |       | MNP 3 disabled.                          |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                  BIT-MAPPED REGISTER S15                   |
          |------------------------------------------------------------|
          | Format:        | AT [cmds] S15=n [cmds]                    |
          |----------------+-------------------------------------------|
          | Example:       | ATS15=139<CR>                             |
          |----------------+-------------------------------------------|
          | Default:       | 0                                         |
          |----------------+-------------------------------------------|
          | Range:         | 0 - 127                                   |
          |----------------+-------------------------------------------|
          | Unit:          | Bit-mapped                                |
          |----------------+-------------------------------------------|
          | Description:   | Controls HST high frequency equalization, |
          |                | online fallback, back channel,            |
          |                | non-error-correcting mode buffer, MNP4,   |
          |                | and BS/DEL switch and MNP compliance      |
          |------------------------------------------------------------|
          |   Bit    | Value |                Function                 |
          |----------+-------+-----------------------------------------|
          |    0     | » 0 1 | HST high frequency equalization         |
          |          |       | enabled.                                |
          |          |       |                                         |
          |          |       | HST high frequency equalization         |
          |          |       | disabled.                               |
          |----------+-------+-----------------------------------------|
          |    1     | » 0 1 | Online fallback enabled.                |
          |          |       |                                         |
          |          |       | Online fallback disabled.               |
          |----------+-------+-----------------------------------------|
          |    2     | » 0 1 | 450bps back channel enabled.            |
          |          |       |                                         |
          |          |       | 450bps back channel disabled.           |
          |----------+-------+-----------------------------------------|
          |    3     | » 0 1 | Non-error-correcting mode transmit      |
          |          |       | buffer set to 1.5KB.                    |
          |          |       |                                         |
          |          |       | Non-error-correcting mode transmit      |
          |          |       | buffer set to 128 bytes.                |
          |----------+-------+-----------------------------------------|
          |    4     | » 0 1 | MNP 4 enabled.                          |
          |          |       |                                         |
          |          |       | MNP 4 disabled.                         |
          |----------+-------+-----------------------------------------|
          |    5     | » 0 1 | Use backspace key for delete disabled.  |
          |          |       |                                         |
          |          |       | Use backspace key for delete enabled.   |
          |----------+-------+-----------------------------------------|
          |    6     | » 0 1 | MNP normal.                             |
          |          |       |                                         |
          |          |       | MNP adjusted for non compliant modems.  |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                  BIT-MAPPED REGISTER S27                   |
          |------------------------------------------------------------|
          | Format:         | AT [cmds] S27=n [cmds]                   |
          |-----------------+------------------------------------------|
          | Example:        | ATS27=139<CR>                            |
          |-----------------+------------------------------------------|
          | Default:        | 0                                        |
          |-----------------+------------------------------------------|
          | Range:          | 0 - 191                                  |
          |-----------------+------------------------------------------|
          | Unit:           | Bit-mapped                               |
          |-----------------+------------------------------------------|
          | Description:    | Controls V.21, V.42 answer tone and      |
          |                 | handshake, and 9600 result codes.        |
          |------------------------------------------------------------|
          |    Bit    | Value  |               Function                |
          |-----------+--------+---------------------------------------|
          |     0     | » 0 1  | V.21 disabled.                        |
          |           |        |                                       |
          |           |        | V.21 enabled.                         |
          |-----------+--------+---------------------------------------|
          |     1     | » 0    | Not used.                             |
          |-----------+--------+---------------------------------------|
          |     2     | » 0    | Not used.                             |
          |-----------+--------+---------------------------------------|
          |     3     | » 0 1  | 2100Hz answer tone enabled.           |
          |           |        |                                       |
          |           |        | 2100Hz answer tone disabled.          |
          |-----------+--------+---------------------------------------|
          |   5, 4    | » 00   | V.42 detect, LAPM and MNP enabled.    |
          |           | 01 10  |                                       |
          |           | 11     | V.42 detect and LAPM enabled.         |
          |           |        |                                       |
          |           |        | MNP enabled.                          |
          |           |        |                                       |
          |           |        | LAPM enabled.                         |
          |-----------+--------+---------------------------------------|
          |     6     | » 0    | Not used.                             |
          |-----------+--------+---------------------------------------|
          |     7     | » 0 1  | Actual result codes displayed.        |
          |           |        |                                       |
          |           |        | Force 9600 result codes.              |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                        BREAK LENGTH                        |
          |------------------------------------------------------------|
          | Type:        | Register                                    |
          |--------------+---------------------------------------------|
          | Format:      | AT [cmds] S21=n [cmds]                      |
          |--------------+---------------------------------------------|
          | Example:     | ATS21=20<CR>                                |
          |--------------+---------------------------------------------|
          | Default:     | 10                                          |
          |--------------+---------------------------------------------|
          | Range:       | Unidentified                                |
          |--------------+---------------------------------------------|
          | Unit:        | 10 ms                                       |
          |--------------+---------------------------------------------|
          | Description: | Sets the length of error control mode       |
          |              | breaks sent from DCE to DTE.                |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                         BREAK TYPE                         |
          |------------------------------------------------------------|
          | Type:        | Configuration                               |
          |--------------+---------------------------------------------|
          | Format:      | AT [cmds] &Yn [cmds]                        |
          |--------------+---------------------------------------------|
          | Example:     | AT &Y0<CR>                                  |
          |--------------+---------------------------------------------|
          | Description: | Configures action of break signal.          |
          |--------------+---------------------------------------------|
          | Command      |                  Function                   |
          |--------------+---------------------------------------------|
          | &Y0          | Break empties buffer.                       |
          |--------------+---------------------------------------------|
          | » &Y1        | Break empties buffer and is sent            |
          |              | immediately.                                |
          |--------------+---------------------------------------------|
          | &Y2          | Break does not empty buffer and is sent     |
          |              | immediately.                                |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                        COMPRESSION                         |
          |------------------------------------------------------------|
          | Type:        | Configuration                               |
          |--------------+---------------------------------------------|
          | Format:      | AT [cmds] &Kn [cmds]                        |
          |--------------+---------------------------------------------|
          | Example:     | AT &K1<CR>                                  |
          |--------------+---------------------------------------------|
          | Description: | Controls data compression.                  |
          |--------------+---------------------------------------------|
          |   Command    |                  Function                   |
          |--------------+---------------------------------------------|
          |     &K0      | Data compression disabled.                  |
          |--------------+---------------------------------------------|
          |     &K1      | Data compression disabled when serial port  |
          |              | is locked.                                  |
          |--------------+---------------------------------------------|
          |     &K2      | Data compression enabled.                   |
          |--------------+---------------------------------------------|
          |     &K3      | MNP 5 disabled.                             |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                CONNECTION SPEED UPPER LIMIT                |
          |------------------------------------------------------------|
          | Type:        | Configuration                               |
          |--------------+---------------------------------------------|
          | Format:      | AT [cmds] &Nn [cmds]                        |
          |--------------+---------------------------------------------|
          | Example:     | AT &N1 DT555-1212<CR>                       |
          |--------------+---------------------------------------------|
          | Description: | Sets required connection speed if &U is set |
          |              | to 0. Otherwise, sets fastest allowed       |
          |              | connection speed.                           |
          |--------------+---------------------------------------------|
          | Command      |                  Function                   |
          |--------------+---------------------------------------------|
          | » &N0        | Variable.                                   |
          |--------------+---------------------------------------------|
          | &N1          | 300bps                                      |
          |--------------+---------------------------------------------|
          | &N2          | 1200bps                                     |
          |--------------+---------------------------------------------|
          | &N3          | 2400bps                                     |
          |--------------+---------------------------------------------|
          | &N4          | 4800bps                                     |
          |--------------+---------------------------------------------|
          | &N5          | 7200bps                                     |
          |--------------+---------------------------------------------|
          | &N6          | 9600bps                                     |
          |--------------+---------------------------------------------|
          | &N7          | 12Kbps                                      |
          |--------------+---------------------------------------------|
          | &N8          | 14.4Kbps                                    |
          |--------------+---------------------------------------------|
          | &N9          | 16.8Kbps                                    |
          |--------------+---------------------------------------------|
          | &N10         | 19.2Kbps                                    |
          |--------------+---------------------------------------------|
          | &N11         | 21.6Kbps                                    |
          |--------------+---------------------------------------------|
          | &N12         | 24Kbps                                      |
          |--------------+---------------------------------------------|
          | &N13         | 26.4Kbps                                    |
          |--------------+---------------------------------------------|
          | &N14         | 28.8Kbps                                    |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                   EXTENDED RESULT CODES                    |
          |------------------------------------------------------------|
          | Type:        | Configuration                               |
          |--------------+---------------------------------------------|
          | Format:      | AT [cmds] &An [cmds]                        |
          |--------------+---------------------------------------------|
          | Example:     | AT &A1 %C1<CR>                              |
          |--------------+---------------------------------------------|
          | Description: | Selects extended result codes.              |
          |--------------+---------------------------------------------|
          | Command      |                  Function                   |
          |--------------+---------------------------------------------|
          | &A0          | Extended result codes disabled.             |
          |--------------+---------------------------------------------|
          | &A1          | ARQ result codes enabled.                   |
          |--------------+---------------------------------------------|
          | » &A3        | Error control and compression result codes  |
          |              | enabled.                                    |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                FLOW CONTROL CHARACTER - XON                |
          |------------------------------------------------------------|
          | Type:        | Register                                    |
          |--------------+---------------------------------------------|
          | Format:      | AT [cmds] S22=n [cmds]                      |
          |--------------+---------------------------------------------|
          | Example:     | ATS22=20<CR>                                |
          |--------------+---------------------------------------------|
          | Default:     | 17                                          |
          |--------------+---------------------------------------------|
          | Range:       | 11-127                                      |
          |--------------+---------------------------------------------|
          | Unit:        | ASCII                                       |
          |--------------+---------------------------------------------|
          | Description: | Sets the character used to represent XON.   |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |               FLOW CONTROL CHARACTER - XOFF                |
          |------------------------------------------------------------|
          | Type:        | Register                                    |
          |--------------+---------------------------------------------|
          | Format:      | AT [cmds] S23=n [cmds]                      |
          |--------------+---------------------------------------------|
          | Example:     | ATS23=20<CR>                                |
          |--------------+---------------------------------------------|
          | Default:     | 19                                          |
          |--------------+---------------------------------------------|
          | Range:       | 11-127                                      |
          |--------------+---------------------------------------------|
          | Unit:        | ASCII                                       |
          |--------------+---------------------------------------------|
          | Description: | Sets the character used to represent XOFF.  |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                  FLOW CONTROL PASSTHROUGH                  |
          |------------------------------------------------------------|
          | Type:        | Configuration                               |
          |--------------+---------------------------------------------|
          | Format:      | AT [cmds] &In [cmds]                        |
          |--------------+---------------------------------------------|
          | Example:     | AT &I0 &W<CR>                               |
          |--------------+---------------------------------------------|
          | Description: | Allows modem to act on, then transmit       |
          |              | XON/XOFF characters.                        |
          |--------------+---------------------------------------------|
          | Command      |                  Function                   |
          |--------------+---------------------------------------------|
          | » &I0        | Software flow control disabled.             |
          |--------------+---------------------------------------------|
          | &I1          | XON/XOFF passthrough enabled.               |
          |--------------+---------------------------------------------|
          | &I2          | XON/XOFF passthrough disabled.              |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                     FLOW CONTROL TYPE                      |
          |------------------------------------------------------------|
          | Type:        | Configuration                               |
          |--------------+---------------------------------------------|
          | Format:      | AT [cmds] &Hn [cmds]                        |
          |--------------+---------------------------------------------|
          | Example:     | AT &H0 A<CR>                                |
          |--------------+---------------------------------------------|
          | Description: | Sets type of flow control used by modem.    |
          |--------------+---------------------------------------------|
          | Command      |                  Function                   |
          |--------------+---------------------------------------------|
          | &H0          | Flow control disabled.                      |
          |--------------+---------------------------------------------|
          | » &H1        | CTS/RTS flow control enabled.               |
          |--------------+---------------------------------------------|
          | &H2          | XON/XOFF flow control enabled.              |
          |--------------+---------------------------------------------|
          | &H3          | CTS/RTS and XON/XOFF flow control enabled.  |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                        HELP SCREENS                        |
          |------------------------------------------------------------|
          | Type:        | Immediate                                   |
          |--------------+---------------------------------------------|
          | Format:      | AT <prefix>$                                |
          |--------------+---------------------------------------------|
          | Example:     | AT &$<CR>                                   |
          |--------------+---------------------------------------------|
          | Description: | Shows command help screens for all commands |
          |              | beginning with the given prefix, or no      |
          |              | prefix if none is given.                    |
          |--------------+---------------------------------------------|
          |   Command    |                  Function                   |
          |--------------+---------------------------------------------|
          |      $       | Shows ATx help screen.                      |
          |--------------+---------------------------------------------|
          |      &$      | Shows AT&x help screen.                     |
          |--------------+---------------------------------------------|
          |      D$      | Shows ATDx help screen.                     |
          |--------------+---------------------------------------------|
          |      S$      | Shows S-register help screen.               |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                      INACTIVITY TIMER                      |
          |------------------------------------------------------------|
          | Type:        | Register                                    |
          |--------------+---------------------------------------------|
          | Format:      | AT [cmds] S19=n [cmds]                      |
          |--------------+---------------------------------------------|
          | Example:     | ATS19=20<CR>                                |
          |--------------+---------------------------------------------|
          | Default:     | 0                                           |
          |--------------+---------------------------------------------|
          | Range:       | Unidentified                                |
          |--------------+---------------------------------------------|
          | Unit:        | 1 minute                                    |
          |--------------+---------------------------------------------|
          | Description: | Sets the length of time that the modem does |
          |              | not receive information before it           |
          |              | disconnects.                                |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                       NETWORK ACCESS                       |
          |------------------------------------------------------------|
          | Type:        | Configuration                               |
          |--------------+---------------------------------------------|
          | Format:      | AT [cmds] %Rn [cmds]                        |
          |--------------+---------------------------------------------|
          | Example:     | AT %R1 &W<CR>                               |
          |--------------+---------------------------------------------|
          | Description: | Used with USR network management system.    |
          |--------------+---------------------------------------------|
          | Command      |                  Function                   |
          |--------------+---------------------------------------------|
          | » %R0        | Network access disabled.                    |
          |--------------+---------------------------------------------|
          |     %R1      | Network access enabled.                     |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                   REPEAT COMMAND STRING                    |
          |------------------------------------------------------------|
          | Type:        | Configuration                               |
          |--------------+---------------------------------------------|
          | Format:      | AT [cmds] > [cmds]                          |
          |--------------+---------------------------------------------|
          | Example:     | AT *D1 > #E1<CR>                            |
          |--------------+---------------------------------------------|
          | Description: | Causes modem to repeat command string until |
          |              | a keyboard key is pressed.                  |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                     REPORT INFORMATION                     |
          |------------------------------------------------------------|
          | Type:        | Immediate                                   |
          |--------------+---------------------------------------------|
          | Format:      | AT [cmds] In [cmds]                         |
          |--------------+---------------------------------------------|
          | Example:     | AT I1 O<CR>                                 |
          |--------------+---------------------------------------------|
          | Description: | Displays modem properties.                  |
          |--------------+---------------------------------------------|
          |   Command    |                  Function                   |
          |--------------+---------------------------------------------|
          |      I0      | Reports product code.                       |
          |--------------+---------------------------------------------|
          |      I1      | Reports ROM checksum result.                |
          |--------------+---------------------------------------------|
          |      I2      | Reports RAM checksum result.                |
          |--------------+---------------------------------------------|
          |      I3      | Reports firmware version.                   |
          |--------------+---------------------------------------------|
          |      I4      | Reports current command settings.           |
          |--------------+---------------------------------------------|
          |      I5      | Reports current NVRAM settings.             |
          |--------------+---------------------------------------------|
          |      I6      | Reports current connection’s statistics.    |
          |--------------+---------------------------------------------|
          |      I7      | Reports configuration.                      |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                    STATUS REGISTER BIT                     |
          |------------------------------------------------------------|
          | Type:        | Configuration                               |
          |--------------+---------------------------------------------|
          | Format:      | Read: AT [cmds] Sn.m=0 or 1 [cmds]          |
          |              |                                             |
          |              | Write: AT [cmds] Sn.m=? [cmds]              |
          |--------------+---------------------------------------------|
          | Example:     | AT S40.4=1 S51.3?<CR>                       |
          |--------------+---------------------------------------------|
          | Description: | Sets/clears or reads bit m of register n.   |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                          TESTING                           |
          |------------------------------------------------------------|
          | Format          | AT [cmds] S16=n [cmds]                   |
          |-----------------+------------------------------------------|
          | Example:        | ATS16=32<CR>                             |
          |-----------------+------------------------------------------|
          | Default:        | 0                                        |
          |-----------------+------------------------------------------|
          | Range:          | 0 - 15                                   |
          |-----------------+------------------------------------------|
          | Unit:           | Bit-mapped                               |
          |-----------------+------------------------------------------|
          | Description:    | Enables loopback tests.                  |
          |-----------------+------------------------------------------|
          | Note:           | Bit 3 is read-only.                      |
          |------------------------------------------------------------|
          |   Bit    | Value  |                Function                |
          |----------+--------+----------------------------------------|
          |    0     | » 0 1  | Analog loopback test disabled.         |
          |          |        |                                        |
          |          |        | Analog loopback test enabled.          |
          |----------+--------+----------------------------------------|
          |    1     | » 0 1  | Dial test disabled.                    |
          |          |        |                                        |
          |          |        | Dial test enabled.                     |
          |----------+--------+----------------------------------------|
          |    2     | » 0 1  | Test pattern disabled.                 |
          |          |        |                                        |
          |          |        | Test pattern enabled.                  |
          |----------+--------+----------------------------------------|
          |    3     | » 0 1  | Remote digital loopback test disabled. |
          |          |        |                                        |
          |          |        | Remote digital loopback test enabled.  |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                        TIME DISPLAY                        |
          |------------------------------------------------------------|
          | Type:        | Immediate                                   |
          |--------------+---------------------------------------------|
          | Format:      | AT [cmds] Kn [cmds]                         |
          |--------------+---------------------------------------------|
          | Example:     | AT K1 *L2 #E1<CR>                           |
          |--------------+---------------------------------------------|
          | Description: | Displays the current call time or clock     |
          |              | time.                                       |
          |--------------+---------------------------------------------|
          |   Command    |                  Function                   |
          |--------------+---------------------------------------------|
          |      K0      | Display length of last call.                |
          |--------------+---------------------------------------------|
          |      K1      | Display actual time.                        |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                   TOUCH TONE RECOGNITION                   |
          |------------------------------------------------------------|
          | Type:        | Configuration                               |
          |--------------+---------------------------------------------|
          | Format:      | AT [cmds] %Tn [cmds]                        |
          |--------------+---------------------------------------------|
          | Example:     | AT %T &W<CR>                                |
          |--------------+---------------------------------------------|
          | Description: | Controls recognition of touch tones while   |
          |              | off hook.                                   |
          |--------------+---------------------------------------------|
          | Command      |                  Function                   |
          |--------------+---------------------------------------------|
          |      %T      | Enabled.                                    |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                  BIT MAPPED REGISTER S34                   |
          |------------------------------------------------------------|
          | Format:        | AT [cmds] S34=n [cmds]                    |
          |----------------+-------------------------------------------|
          | Example:       | ATS34=139<CR>                             |
          |----------------+-------------------------------------------|
          | Default:       | 0                                         |
          |----------------+-------------------------------------------|
          | Range:         | 0 - 56                                    |
          |----------------+-------------------------------------------|
          | Unit:          | Bit-mapped                                |
          |----------------+-------------------------------------------|
          | Description:   | Controls V.23, MR LED function and        |
          |                | MI/MIC.                                   |
          |------------------------------------------------------------|
          |   Bit    |    Value    |             Function              |
          |----------+-------------+-----------------------------------|
          |    3     | » 0 1       | V.23 disabled.                    |
          |          |             |                                   |
          |          |             | V.23 enabled.                     |
          |----------+-------------+-----------------------------------|
          |    4     | » 0 1       | MR LED normal.                    |
          |          |             |                                   |
          |          |             | MR LED reflects DSR signal.       |
          |----------+-------------+-----------------------------------|
          |    5     | » 0 1       | MI/MIC disabled.                  |
          |          |             |                                   |
          |          |             | MI/MIC enabled.                   |
          +------------------------------------------------------------+
       
          +------------------------------------------------------------+
          |                     VOICE/DATA SWITCH                      |
          |------------------------------------------------------------|
          | Type:        | Register                                    |
          |--------------+---------------------------------------------|
          | Format:      | AT [cmds] S32=n [cmds]                      |
          |--------------+---------------------------------------------|
          | Example:     | ATS32=6<CR>                                 |
          |--------------+---------------------------------------------|
          | Default:     | 1                                           |
          |--------------+---------------------------------------------|
          | Unit:        | 1-7                                         |
          |--------------+---------------------------------------------|
          | Description: | Controls the function of SW4.               |
          |--------------+---------------------------------------------|
          | Command      |                  Function                   |
          |--------------+---------------------------------------------|
          |      0       | Disabled.                                   |
          |--------------+---------------------------------------------|
          |      1       | Switch between voice and originate mode.    |
          |--------------+---------------------------------------------|
          |      2       | Switch between voice and answer mode.       |
          |--------------+---------------------------------------------|
          |      3       | Redial.                                     |
          |--------------+---------------------------------------------|
          |      4       | Dial number stored at position 0.           |
          |--------------+---------------------------------------------|
          |      5       | Enable and disable Auto Answer.             |
          |--------------+---------------------------------------------|
          |      6       | Reset.                                      |
          |--------------+---------------------------------------------|
          |      7       | Start remote digital loopback test.         |
          +------------------------------------------------------------+