

************************************************************
                    U.S. ROBOTICS
      The Intelligent Choice in Data Communications
************************************************************






************************************************************
------------------------------------------------------------
                   REFERENCE GUIDE

                         for

              Sportster High Speed Modems
                    with V.42 bis
------------------------------------------------------------
************************************************************



















            Manual Revision Date:  12/30/93







          Copyright 1993 by U.S. Robotics, Inc.
              8100 North McCormick Blvd.
             Skokie, Illinois 60076-2999
                All Rights Reserved

************************************************************
TABLE OF CONTENTS
************************************************************


SPORTSTER CONFIGURATION
  Factory Configuration (&Fn and Yn)
    Permanent Configuration Templates (&Fn)
    Programmable Templates (Yn)
    Customizing Your Defaults (&Wn)
    Using AT Commands
    Resetting the Modem (Z)

PLACING CALLS
  Dial (D)
    Cancel Dialing
    Dial Command Options
      Dial Type-Pulse or Tone
      Adaptive Dialing (X2-X4)
      Wait for Another Dial Tone (W)
      Pause (,)
      Slash (/)
      Dial and Return to Command Mode (;)
      Dialing Letters (")
      Transferring Calls (!)
      Wait for an Answer (@)
      Reversing Originate/Answer Frequencies (R)
    Dialing Stored Numbers (DSn)
    Redialing
      Dial the Last Dialed Number (DL)
      Re-execute the Last Command (A/)
    Answering
      Suppressing Auto Answer
      Manual Answer
      Points to Remember
    Disconnecting and Hanging Up
      Escape Code Operations (+++)
        Modem Response to +++
      Returning Online (On)
      Hanging Up (Hn)
      Break Handling (&Yn)
    International Calls
      ITU-T/Bell Answer Sequence (Bn)
      Guard Tone (&Gn)
      Pulse Dial Make/Break Ratio (&Pn)
      ITU-T V.21-300 bps
      ITU-T V.23-1200/75 bps

TEMPORARILY CHANGING A SETTING
  Tone Dialing
  Audio Monitor
    Volume Control (Ln)
    Speaker Control (Mn)
  Local Echo
    Command Mode Local Echo (En)
    Online Local Echo (Fn)
  S-Registers
  Result Codes
    Response Modes (Vn)
    Quiet Mode (Qn)
    Result Code Options (Xn)
    Additional Result Code Options (&An)
  Error Control (&Mn)
    Auto Answer with Error Control
  Data Compression (&Kn)
  Data Rate Commands
      Software Requirements
    Serial Port Rate (&Bn)
    Connection Rate (&Nn)
  Flow Control
    Warning on Software Flow Control
      Software Flow Control Precautions
    Transmit Data Flow Control (&Hn)
      When it is Required
    Received Data Flow Control
      Hardware Control (&Rn)
       Software Control (&In)
  Serial Operations
    Carrier Detect (&Cn)
    Data Terminal Ready (&Dn)
    Data Set Ready (&Sn)

GETTING HELP
  Inquiries (In)
    S-Register Query (Sr?)
    Stored Phone Number Query (&Zn?)
    Last-Dialed Number Query (DL?)
  Help Screens
    Stop/Restart Display
    Cancel Display
    Basic Command Set ($)
    Ampersand Command Set (&$)
    Dialing (D$)
    S-Register Functions (S$)

TESTING THE MODEM
  Testing with &T
  Dial Test-S16=2

OTHER OPERATIONS
  Fax Operations
  Voice/Data Communications

TECHNICAL SPECIFICATIONS
  Compatibility
  The Serial Interface
  Default Settings

MODEM CONCEPTS
  How Modems Work
  Modem Configuration
  Line Travel
  Digital Data
  Flow Control
  Error Control
    ITU-T V.42 Handshaking
    MNP Handshaking
    Data Compression
    Flow Control
    Online Fallback/Fall Forward
  Throughput Guidelines
    Achievable Throughput Statistics








































************************************************************
SPORTSTER CONFIGURATION
************************************************************

The Sportster is preconfigured at the factory so you should
be able to connect the modem, set up your communications
software, and be ready to send and receive data.  Many users
won t need to change the default configurations, but if you
want to, this guide will tell you how.  Many of the
functions described below can be handled by your
communications software, but you also have the power to
place your computer in Terminal mode (via your
communications software) and control the modem directly.

NOTE:  Unless otherwise indicated, settings listed as
"default" are based on those set for the modem when it is
shipped.


============================================================
FACTORY CONFIGURATION (&Fn and Yn)
============================================================

The Sportster is preconfigured at the factory with three
permanent and two programmable templates.

============================================================
Permanent Configuration Templates (&Fn)

The following permanent templates come with your Sportster.
The default template consists of the most reliable settings,
but these settings may not work for all users.

&F0    This template does not include performance features,
       such as a fixed serial port rate or hardware flow
       control.  What it does offer is compatibility with
       nontypical computers or software that cannot handle
       flow control and other features.

&F1    Default.  This template sets the modem to
       hardware flow control, a fixed serial port rate, the
       highest level result codes, and the most complete
       result-code set.

       The &F1--Hardware Flow Control template is
       recommended for all IBM-compatible computers, as long
       as your communications software supports hardware
       flow control, a fixed serial port rate, and the
       advanced result-code subset.

       NOTE:  We also recommend that users of Macintosh
       computers invest in a Hardware Handshaking cable
       (instead of the standard cable), use this template,
       and use software that supports hardware flow control.

&F2    This is a software flow control template.  We
       recommend you do not use software flow control, and
       thus, this template.  However, if you use a
       Macintosh, see the note above.  In addition, some
       computers are limited to three-wire cables that do
       not support hardware flow control signals.  If this
       is the case, review the warning on software flow
       control later in this guide.

       To load the &F2--Software Flow Control template and
       save it as your power-on/reset default, enter the
       following command:

                 AT&F2&W <Enter>

       NOTE:  Refer to the "Programmable Templates" section
       for more information on selecting and modifying
       templates to save as your start-up configuration.

If you need a low performance template because of data-
transfer difficulties, flip DIP switch 7 ON and reset the
modem (ATZ command), or load the &F0--Low Performance
template by entering the following command:

                 AT&F <Enter>

NOTE:  When the modem receives the above command, it assumes
you want to load the &F0 template because there is no
position number indicated.  It is the same to enter AT&F as
to enter AT&F0.

This template allows you to communicate with nontypical
systems that cannot handle flow control and other features.

============================================================
Programmable Templates (Yn)

In addition to the &Fn permanent configuration templates,
two programmable templates are provided.  Your programmable
templates are located in nonvolatile, random access memory
(NVRAM).

The Sportster is shipped to load NVRAM template 0 (or Y0)
for its power-on/reset default settings.

Possible NVRAM templates:

Y0    Loads the NVRAM template 0 (stored with template
      &F1--Hardware Flow Control settings).  Default.

Y1    Loads the NVRAM template 1 (stored with template
      &F2--Software Flow Control settings).

If you want to switch the power-on/reset default NVRAM
template from Y0 to Y1, enter the Yn command, then reset the
modem with the Z command.

                 AT Y1 Z <Enter>

To customize other defaults you want to store in NVRAM as
part of your customized power-on/reset template, use the &Wn
command (below).

WARNING:  The Yn command, which selects template settings to
     use as the power-on/reset default, may select different
     power-on/reset default settings than those currently
     loaded (if you altered the settings during the current
     session).  Before changing a template, you may want to
     use option 4 of the Inquiry (I) command to display the
     current settings.

                 AT I4 <Enter>

     The Y setting on the ATI4 screen indicates if Y0 or Y1
     is the power-on/reset default.  If you want to check
     all the NVRAM settings in both Y0 and Y1 templates, use
     option 5 of the Inquiry command (I).

                 AT I5 <Enter>


============================================================
CUSTOMIZING YOUR DEFAULTS (&Wn)
============================================================

When the modem is shipped, it reads template 0 in NVRAM as
the power-on/reset default.  Template 0 (Y0) is initially
loaded with &F1 permanent configuration settings.  Although
you cannot alter the &F1 template, you can add, delete, or
modify the settings stored in your NVRAM templates.  It is
more likely, however, that you will want to keep your power-
on/reset default settings and simply change a setting for a
current session.  Refer to "Temporarily Changing a Setting"
in this guide for more information.

If  you want to modify your default configuration settings,
use the &Wn command.  Possible settings are:

&W0    Modifies the NVRAM 0 template (Y0).

&W1    Modifies the NVRAM 1 template (Y1).

Typically, users prefer the default settings stored in NVRAM
when the modem is shipped, but you may set up different
power-on/reset defaults.  For instance, if your system
supports hardware flow control, you can set your Y1 template
to the settings for hardware flow control so both templates
set the modem for hardware flow control.  (The Y0 template
is shipped with hardware flow control settings.)

                 AT &F1 &W1 <Enter>

NOTE:  Yn is unique because it writes itself to NVRAM-you do
not need to use the &Wn command.

Similarly, if your system only supports software flow
control, you can set your Y0 template to the settings for
software flow control so both templates set the modem for
software flow control.  (The Y1 template is shipped with
software flow control settings.)

                 AT &F2 &W <Enter>

You may also specify the entire configuration in a single
command string that ends with the &Wn command.  The
following example sets the modem for the current session and
stores the configuration in NVRAM 1 (or Y1).

                 AT &K3 &W1 <Enter>

After sending a configuration to NVRAM, you can change any
setting just for the current session, as in the following
example.  The NVRAM configuration remains intact.

                 AT &K3 <Enter>

But if you want the new setting to be a default, write it to
NVRAM at the same time, as in the following example, which
saves the setting to NVRAM template 0.

                 AT &K3 &W <Enter>

If you've sent the modem commands to change settings
throughout your session and want to save your current
configuration, send just the &Wn command.  The current
settings are then written to NVRAM 0 (or Y0) in the example
below.

                  AT&W <Enter>

If you cannot use hardware flow control and need to use
Xmodem-type file transfer protocols, use either Y0 or Y1 for
a no flow control configuration with no error control.

                 AT &F &M &W <Enter>
                        or
                 AT &F &M &W1 <Enter>




============================================================
USING AT COMMANDS
============================================================

To send commands directly to your modem, first put your
computer in Terminal mode.  Some communications programs do
this automatically upon loading.  Others require you to
display a communications terminal screen, press a Function
key, or perform some other operation.  If necessary, refer
to your communications software documentation for
instructions.

1.   Type all commands in either upper case (AT) or lower
     case (at), but not a combination (At).

2.   All commands except A/ (re-execute last command) and
     +++ (escape code) are preceded by the AT prefix and are
     executed with the Enter/Carriage Return key (<Enter>).

3.   Command string length = 40 characters, maximum.  The
     modem doesn't count the AT prefix, Carriage Return
     character, or spaces.  In a dial string, it counts--but
     doesn't act on--punctuation such as hyphens and
     parentheses.

4.   A missing numeric parameter is assumed to be zero, as
     in the command to hang up; ATH <Enter> is the same as
     ATH0 <Enter>.


============================================================
RESETTING THE MODEM (Z)
============================================================

If you've changed several current settings and want to reset
to your power-on defaults, type the following command.

                 ATZ <Enter>

The modem reads its DIP switch settings and resets to its
NVRAM defaults (DIP switch 7 OFF) or the &F0--Low
Performance template (DIP switch 7 ON) settings.

NOTE:  Use the ATZ command if you've changed the position of
DIP switches 1-7 while the modem is on, so that the modem
can read the new settings.  The only other way to initiate a
new setting for switches 1-7 is to turn the modem off and on
again.






************************************************************
PLACING CALLS
************************************************************

NOTE:  Unless otherwise indicated, settings listed as
"default" are based on the hardware flow control template
stored in NVRAM when the modem is shipped.


============================================================
DIAL (D)
============================================================

To dial a phone number and place a call without using your
software s dialing directory, first put the computer in
Terminal mode.  Then type the AT and D commands, the number
you wish to connect with, and press Enter.  Spaces in our
command examples are ignored by the modem and are only
included for readability.

                 ATD 1234567 <Enter>

Unless you lowered your modem s speaker volume, you will
hear the modem go off hook and dial the telephone number,
followed by a series of handshaking signals.

The Dial command string may include up to 40 characters.
The modem counts but ignores punctuation characters such as
parentheses and hyphens.  It does not count spaces, the AT
prefix, or the Carriage Return key (<Enter>) required to
execute the command.

The modem also executes any other commands or options
included in the command line.  The following Dial command
example instructs the modem to turn off the speaker (M0),
and dial (D) the phone number (1234567) using tone dialing
(T).

                 AT M0 DT 1234567 <Enter>

You may want to review the many options on the next several
pages that are available for tailoring Dial strings.  The
most typically used are the Dial Type--Pulse or Tone, and
the Pause options--comma, slash, and W.

============================================================
Cancel Dialing

To cancel Dial command execution, press <any key>.  If you
inadvertently hit a key on the keyboard while the modem is
dialing, the call is canceled.  If this occurs, type the A/
command, which re-executes the last command you entered.


============================================================
Dial Command Options

You can modify the dial string according to the needs of the
connection.  Listed below are options available to you when
entering the Dial string.

-----------------------
Dial Type-Pulse or Tone
-----------------------
The modem defaults to pulse (rotary) dialing.  To have the
modem use tone dialing, which includes the asterisk (*) and
pound sign (#), use the T command.

Dial type commands may be included in the Dial string (ATDT
number) or, issued separately (ATT or ATP).  However, if
you ll always use tone dialing, write tone dialing to NVRAM
as the modem s default and/or use adaptive dialing,
described below.

NOTE:  You can switch from one dial type to another within a
dialing sequence.  The modem remains set to the last dialing
type instruction until it is reset (ATZ command), or it
receives a different dial-type command.

--------------------------------
Adaptive Dialing (X2 through X4)
--------------------------------
When any of the X2 through X4 (default) result code options
is in effect and you do not issue a dial type in the Dial
string, the Sportster defaults to pulse dialing.  If you
issue a tone dial command,  the Sportster will default to
Hunt dialing, beginning with tone and adapting to pulse when
necessary.  For instance, if the phone company's central
office does not have tone-detection equipment, the modem
automatically reverts to pulse dialing.

------------------------------
Wait for Another Dial Tone (W)
------------------------------
This command is useful in situations where you must wait for
a second dial tone before continuing to dial.  For example,
if you need to dial for an outside line, as in the following
example, the Sportster continues to dial as soon as it
detects the next dial tone.

                 ATD9W1234567 <Enter>

NOTE:  This command executes only if result code option X3
or X4 (default) has been issued.  If the modem is set to X2
or lower, the modem interprets the W as a comma (two-second
pause).


---------
Pause (,)
---------
A comma causes a two-second delay in the dial sequence.  The
following example contains four-second delays at several
points.

         ATDP 9,,7654321,,55555,,1 312 1234567 <Enter>

The first four-second pause is to access an outside line
after dialing 9, but you may wish to use the W option, just
described.  The second pause is to make sure the remote
system is ready for the user's account number, and the
third, to delay before dialing the long-distance number.

Such pauses, however, may not be necessary.  Experiment and
use delays only as required.

---------
Slash (/)
---------
A slash (/) can be used in any command string to make the
modem pause for only 125 milliseconds.  Some users find it
helpful to have the shorter delay of a series of slashes,
rather than the 2-second comma pause.

-----------------------------------
Dial and Return to Command Mode (;)
-----------------------------------
If your phone is plugged into the modem, you can use this
option to have the modem Auto Dial a telephone rather than a
modem.  The Sportster dials, remains off hook, and returns
the OK message, indicating it is in Command mode.

For example, to have the modem place a voice call, enter the
Dial command with a semicolon.

                 ATDT5551234; <Enter>

When the modem returns the OK result, pick up your phone
receiver so you can talk to the other party, and send the
command that hangs up the modem.

                 ATH <Enter>

Similarly, if you can call a recorded weather or other
service, have the modem Dial, listen to the recording over
the modem's speaker and, when you are finished, instruct the
modem to hang up.





-------------------
Dialing Letters (")
-------------------
Quotation marks are used to make the modem dial
abbreviations and acronyms used as phone numbers, such as
DIAL USR (the U.S. Robotics Sales Department's 800 number).
This option is called Quote mode.  Quotation marks are
inserted at the beginning of the alphabetic string.

                 ATDT "BBS NEWS <Enter>

NOTE:  If you are including another command after the dial
string, use closing quotation marks before the additional
command.

                 ATDT "BBS NEWS",,,1234<Enter>

----------------------
Transferring Calls (!)
----------------------
This command is used for modems installed where other modems
share the phone line.  The modem flashes the switch-hook.
That is, it goes off hook 0.5 seconds, on hook for 0.5
seconds, and off hook again to dial the specified extension.
The following example includes instructions to return to
Command mode (;) and to hang up (H).

                 ATDT !1234;H <Enter>

----------------------
Wait for an Answer (@)
----------------------
Some online services answer the phone and return a tape-
recorded request for information before processing
transactions.  In such instances, the @ command can be used
in the Dial string to tell the modem to detect at least one
ring, wait for five seconds of silence at the other end of
the call, and then continue to execute the Dial string.

To use the @ command, set the modem result code option to X3
or X4 (default).  If the modem is set to X2 or lower, the
modem returns an ERROR message when encountering the @
character in a command string.

In the next example, the modem is set to the X3 result code
option and dials a banking service.  Each occurrence of @ in
the example indicates a five-second wait for silence.  That
is, for taped requests from the bank for a password (12345),
an account number (6789), and a transaction code (2).  The
transaction code might indicate, for example, a request for
an account balance.

           ATX3 DT5551234 @ 12345 @ 6789 @ 2 <Enter>

If the necessary conditions do not occur--no rings, or no
following five seconds of silence--the modem times out as it
normally would (after 60 seconds).  It then sends the
message NO ANSWER to the screen and aborts the call.

------------------------------------------
Reversing Originate/Answer Frequencies (R)
------------------------------------------
This command allows calls to an originate-only modem (a
modem set up to send only).  It reverses the modem's
originate/answer frequencies, forcing the Sportster to dial
out at the answer frequency.  The command follows the Dial
command, before or after the phone number.

                 AT D1234567R <Enter>
                 AT DR1234567 <Enter>

============================================================
Dialing Stored Numbers (DSn)

You can store up to four frequently used telephone numbers
in nonvolatile, random-access memory (NVRAM).  Use the &Zn=s
command to store telephone numbers, where n is the position
of the number in NVRAM (0-3) and s is the stored number.
The following command string stores the telephone number
(4441212) at position 1 in NVRAM.

                 AT&Z1=4441212 <Enter>

To dial a stored number, use the DSn command, where n is the
position of the number in NVRAM (0*3).  In the first
example, the modem dials the phone number stored at position
0.  In the second, the modem dials the phone number stored
at position 3.

                 ATDS0 <Enter>
                 ATDS3 <Enter>

You can also store a partial dial sequence.  If you often
call a set of phone numbers and only their last three or
four digits differ, it might be useful to store the other
digits.  The following example stores a partial phone number
at position 1.

                  AT&Z1 = 9W1 616 123 <Enter>

Once you have stored the partial phone number in NVRAM, use
the DSn command to dial the partial number, placing a slash
(/), then the remainder of the number after the DSn command.
The slash separates the DSn number from the remainder of the
string, yet maintains the dial command..

                  AT DS1/4567 <Enter>

NOTE:  Do not include modem settings in the &Zn=s string.
If the call requires modem settings, insert them in the
command string before the DSn command.  For example, &K3
(selective data compression) is inserted before the Dial
command to call the number stored at position 0.

                  AT&K3 DS0 <Enter>

This establishes &K3 as the current setting.  To return to
default data compression mode after the call, issue the
following command.

                  AT&K1 <Enter>


============================================================
REDIALING
============================================================

The most frequent reason for redialing is receipt of a busy
signal.  The Sportster modem provides two redialing options,
as follows.

============================================================
Dial the Last-Dialed Number (DL)

When you want to redial a number, enter the DL command.  The
modem dials the last-dialed number, which it has stored in a
special buffer.

                 ATDL <Enter>

To display the number stored in the last-dialed buffer, use
the following query.

                 ATDL? <Enter>

To write the last number dialed to NVRAM, use &Zn=L where n
is the position in NVRAM.  The following example stores the
last-dialed number at position 3.

                 &Z3=L <Enter>

If a number is already stored at position 3, that number is
overwritten with the last-dialed number.









============================================================
Re-execute the Last Command (A/)

Another option for redialing is to enter the A/ command.
This command does not require the AT prefix or a Carriage
Return.

                  A/

When the modem receives a command, it stores it in its
command buffer until it receives the next AT command.  Note
that if you've sent the modem an additional command since
the Dial command, A/ repeats that command instead of
redialing.


============================================================
ANSWERING
============================================================

Your Sportster modem is shipped with DIP switch 5 ON, Auto
Answer suppressed.  To set the modem to automatically answer
incoming calls, do one of the following.

Before powering on the modem...
*  Set DIP switch 5 OFF.  When you power on, the modem
   answers incoming calls on the first ring.

   If you want the modem to answer after several rings, set
   DIP switch 7 OFF.  Specify the ring you want the modem to
   answer on in NVRAM (default=1 ring).  The valid range is
   1-255 rings.  Power off the modem and power it on again
   with its new DIP switch and NVRAM settings..

During a current session...
*  Issue the following command to have the modem answer on
   the fourth ring:

                 ATS0=4 <Enter>

When the modem senses a call, it sends the RING result code
to your screen, goes off hook, and sends the remote modem a
high-pitched answer tone.  If there is no Carrier Detect
within 60 seconds, the modem hangs up.  If the connection is
made, the modem returns a CONNECT result code.  When the
call is disconnected by you or the remote user, the modem
hangs up and returns the NO CARRIER code.







============================================================
Suppressing Auto Answer

To disable Auto Answer, set DIP switch 5 ON before powering
on the modem, or set the modem to answer on zero (or no)
rings during the current session.

                 ATS0=0 <Enter>

NOTE:  The S-Register setting S0=0 cannot be saved to NVRAM.

============================================================
Manual Answer
If you've disabled Auto Answer but are expecting an incoming
data call, use the Manual Answer command.  Send the modem
the following command after the RING result code appears on
your screen.

                 ATA <Enter>

When the call is disconnected, the modem returns to its
original state, Auto Answer disabled.

------------------
Points to Remember
------------------
1.  You can set the modem to receive calls when you're not
    at your computer.  Load your communications software as
    you normally do, and set the modem to Auto Answer.  Also
    set your software's file-save function to save incoming
    messages and/or files.

2.  If you've attached your phone so it can be used for
    conventional calls, disable Auto Answer when you are not
    expecting incoming data calls.  Otherwise, your modem
    may answer the phone before you do, greeting a voice
    caller with a high-pitched, irritating answer tone.


============================================================
DISCONNECTING AND HANGING UP
============================================================

The commands outlined below describe how you can instruct
the modem to disconnect the call and hang up the line.

============================================================
Escape Code Operations (+++)

Once the modem is online to another system, the only command
it recognizes is an escape code of three plus symbols that
forces the modem into Online-Command mode.  Issue the
escape command in the following sequence.

*  Wait one second after sending the last item of data.
*  Type three plus symbols (+++).
*  Wait one second before typing any data.

Do not type the AT prefix or a Carriage Return.  The guard
time of one second before and after prevents the modem from
misinterpreting the presence of the +++ symbols in the
transmitted data stream.

If necessary, the character used in the escape code or the
duration of the guard time can be changed by resetting
Register S2 or S12.  See the "Quick Installation Guide" for
more information.

---------------------
Modem Response to +++
---------------------
When the modem receives +++, by default it enters Online-
Command mode and returns the OK result code.  It maintains
the connection and is ready to act on commands.  You may
then choose one of the following options.

*  Issue commands to the modem and then return it online.
*  Hang up the modem.

Alternatively, if you want the modem automatically to hang
up on receiving the +++ escape code, set Register S14 to 1
and write the command to your NVRAM templates.

                 ATS14=1 &W &W1 <Enter>

The modem disconnects and sends the NO CARRIER result code
to the screen.

============================================================
Returning Online (On)

After forcing the modem into Online-Command mode with the
escape code sequence, you can issue commands and then toggle
the modem back online with the O command, as in the
following example.

                 AT Q1 O <Enter>

O0   Return online (normal).

O1   Return online and retrain.  If errors occur during a
     non-ARQ connection, try this option.  The modem returns
     online and requests that both modems resynchronize.





============================================================
Hanging Up (Hn)

At its default setting, the escape code forces the modem
into Online-Command mode but leaves the line open.  To hang
up the modem, issue the following command once the modem
sends the OK result code.

                ATH <Enter>

H0   Hang up (go on hook).

H1   Go off hook.

============================================================
Break Handling (&Yn)

This command lets you send a Break to abort data transfer
without disconnecting from the phone line interface.

&Y0  Destructive, no Break transmitted:  the modem clears
     the data from its transmit buffer (all data is lost)
     but does not transmit the Break to the remote modem.

&Y1  Destructive, expedited:  the modem clears the buffer
     and immediately sends a Break to the remote modem.
     Default.

&Y2  Nondestructive, expedited:  the modem retains data in
     the transmit buffer, but immediately sends a Break to
     the remote modem.

&Y3  Nondestructive, unexpedited (send Break in sequence):
     the modem transmits any buffer data received before the
     Break, sends the Break, and then sends any subsequent
     input from the computer.

NOTE:  If the call is under MNP5 data compression,
destructive Breaks cause both modems to reset their data
compression tables.  When transmission resumes, the modems
build new tables, and the result is lower than normal
throughput.












============================================================
INTERNATIONAL CALLS
============================================================

The following commands apply to international calls.

============================================================
ITU-T/Bell Answer Sequence (Bn)

To answer international calls, use the default B0 setting.

B0   Default.  This setting is required for V.32 or higher
     modems to answer V.32 or higher calls.  It also selects
     the ITU-T V.25 answer sequence, used outside of North
     America.

B1   This setting selects the Bell 2225 Hz answer tone used
     in the U.S. and Canada and may be used when the remote
     modem operates at only 2400 bps or lower.  However, if
     the modem is set to B1, it won t be recognized by V.32
     or higher modems and can t answer calls at 9600 and
     14,400.

============================================================
Guard Tone (&Gn)

The United Kingdom and some Commonwealth countries use phone
switching systems that require answering modems to send an
1800 Hz guard tone after they send an answer tone.  Some
other European phone networks require a 550 Hz guard tone.
Guard tones are not used in the United States or Canada.

&G0  No guard tone, U.S./Canada.  Default.

&G1  550 Hz guard tone follows answer tone.  Requires B0
     setting.

&G2  1800 Hz guard tone follows answer tone, United Kingdom
     and some Commonwealth countries.  Requires B0 setting.

============================================================
Pulse Dial Make/Break Ratio (&Pn)

This command sets the ratio of the off-hook/on-hook
(make/break) interval for pulse dialing.  The default sets
the modem for use in North America.  The ratio must be
changed if the modem is used to dial out in the United
Kingdom and some Commonwealth countries.

&P0  Make/break ratio, U.S./Canada:  39%/61%.  Default.

&P1  Make/break ratio, United Kingdom, some Commonwealth
     countries:  33%/67%.

============================================================
ITU-T V.21-300 bps

Select this option to call or answer overseas modems at 300
bps.  In V.21 mode, the modem answers Bell 103/V.21 calls,
but only originates V.21 calls.  This option is enabled in
Register S27 with the following command.

                  ATS27=1 <Enter>

============================================================
ITU-T V.23-1200/75 bps

Some United Kingdom and European systems require a 1200-bps
speed with a 75-bps back channel.  This option is enabled in
Register S34 with the following command.

                  ATS34=8 <Enter>




































************************************************************
TEMPORARILY CHANGING A SETTING
************************************************************

When you change a setting, the modem retains it until you do
one of the following.

*  Change the setting again.
*  Issue the ATZ command to reset the modem.
*  Turn the modem off and power it on again.

The parameters described in this section are organized in
the order of their likely use.  That is, those you are most
likely to use appear at the beginning of the section, and
those you are least likely to use appear toward the end.

============================================================
TONE DIALING
============================================================

The modem defaults to pulse (rotary) dialing.  To have the
modem use tone dialing, which includes the asterisk (*) and
pound sign (#), use the T command.

                 ATDT 4445555 <Enter>

To have the modem always use tone dialing, use the T and &W
commands:

                 AT T &W &W1 <Enter>

============================================================
AUDIO MONITOR
============================================================

The modem's speaker enables you to monitor the dial-connect
process.  There are several ways to make use of this
feature.  After the Sportster modem dials a number, it waits
up to 60 seconds for a high-pitched answer tone from the
other modem, immediately followed by data signals, called a
"carrier."  These signals must occur before a data link is
established.

At the default X4 setting, the modem sends your screen the
NO CARRIER message after 60 seconds.  If you listen to the
speaker and realize you have received a voice answer, you
can respond immediately, instead of waiting for the modem to
time out, by pressing any key on the keyboard.  This cancels
the call.

You can also hear if dialing is proceeding too quickly for
the system.  Terminate the call (press any key) and retype
the Dial command, but insert a comma (,) or a couple of
slashes (/), to have the modem pause during the dialing
process.


============================================================
Volume Control (Ln)

The following options allow you to adjust the speaker volume
if you have an internal modem.  You can adjust an external
modem s volume via its volume switch.

L0   Low.

L1   Low.

L2   Medium.  Default.

L3   High.


============================================================
Speaker Control (Mn)

This command disables the speaker entirely or sets the
speaker to monitor different segments of the dial-connect
sequence.

M0   Disables the speaker entirely so that you don't hear
     the modem go off hook, dial, etc.

M1   The speaker is on until Carrier Detect.  Default.  You
     can monitor call progress until the Sportster detects
     the remote modem's carrier signals, or until the 60-
     second timeout and result code display.  At Carrier
     Detect, the modem disconnects the speaker and data-
     transmission sounds are suppressed.

M2   The speaker is on continuously, including during data
     transmission.

M3   The speaker doesn't go on until after the last digit is
     dialed, then goes off at Carrier Detect.


============================================================
LOCAL ECHO
============================================================

Local echo is the display of what you type at the keyboard
and online echo display of data the Sportster transmits to
another modem.  The En command controls the display of your
typed commands, when the Sportster is in Command mode.  The
Fn command controls the display of data when your modem is
online to another system.


============================================================
Command Mode Local Echo (En)

The power-on/reset default for command mode local echo is
set with DIP switch 4.  The Sportster modem is shipped with
DIP switch 4 OFF, enabling local echo of your typed
commands.

Use the En command to control the local echo for a current
session, independent of the switch setting.  This command
may not be stored in NVRAM.

E0   Command mode echo OFF.  The modem does not display
     keyboard commands.

E1   Command mode echo ON.

NOTE:  If double characters appear on the screen, both the
modem's and software's local echo are on.

============================================================
Online Local Echo (Fn)

This command causes the modem to display a copy of the data
it is transmitting to another system.  Many systems,
however, return a copy of received data, which is called a
remote echo.  If the modem's online echo is ON and there is
also remote echoing, double characters appear on the screen.

In some microcomputer documentation, the term "duplex" is
applied to online local echoing, although the term is not
technically accurate.

F0   Online echo ON.  Sometimes called "half duplex."  As
     the modem transmits data to a remote system, it also
     sends a copy of the data to the screen.

F1   Online echo OFF.  Sometimes called "full duplex."
     Default.


============================================================
S-REGISTERS
============================================================

The S-Registers are used to set various timing parameters
and to redefine selected ASCII characters and other
configuration options.  Refer to the "Quick Installation
Guide" for a summary of S-Register functions and setting
options.

Users typically require the default values.  To change a
setting, use the ATSr=n command, where r is the register and
n is a decimal value from 0-255 (unless otherwise
indicated).

The example below sets the modem's test timer (S-Register
18) to 10 seconds.

                 ATS18=10 <Enter>

The modem does not perform a value-range check.  Some values
you select may not work with some equipment, and you'll have
to readjust the settings.

Use ATSr? to display the contents of a register, as follows.

                 ATS18? <Enter>


============================================================
RESULT CODES
============================================================

Four commands control the result codes that the modem
returns to the screen.

Vn   Numeric/verbal response mode

Qn   Display/suppress all result codes

Xn   Result code options

&An  Display/suppress additional result code options

============================================================
Response Modes (Vn)

Result codes are sent to the screen in words (Verbal mode)
or numbers (Numeric mode).

The power-on/reset default for response modes is set with
DIP switch 2.  The Sportster modem is shipped with DIP
switch 2 OFF, enabling Verbal mode.

Use the Vn command to select verbal or numeric result codes
for a current session, independent of the DIP switch
setting.  This command may not be stored in NVRAM.

V0   Numeric mode.  Numeric result codes are followed by a
     Carriage Return but no Line Feed, as in the following
     example, where a 3 is returned (for NO CARRIER).

                 ATD1234567 <Enter>
                      becomes
                 3TD1234567 <Enter>

V1   Verbal mode.  Verbal responses are preceded and
     followed by a Carriage Return and a Line Feed, as shown
     below.

                 ATD1234567 <Enter>
                 NO CARRIER

============================================================
Quiet Mode (Qn)

Enable/suppress the display of result codes.

The power-on/reset default for response modes is set with
DIP switch 3.  The Sportster modem is shipped with DIP
switch 2 ON, to display result codes.

Use the Qn command to control the display for a current
session, independent of the DIP switch setting.  This
command may not be stored in NVRAM.

Q0   Result codes are displayed.

Q1   Result codes are suppressed (made quiet).

Q2   Result codes are suppressed only in Answer mode.


============================================================
Result Code Options (Xn)

You have five options, X0 through X4, for selecting the
result-code set best suited to your applications, as shown
in the tables below.

X0   Basic set, returns the first five codes (0-4) in the
     following table.

X1   Extended set, codes 0-5, 10, 13 and 18, that adds rate-
     specific CONNECT messages to the Basic set.  This set
     also includes all &An result codes.

X2-4 The default is X4.  These options include the X1 set,
     call-progress codes 6 or 7, and 8, and the functions
     listed in the following table.

NOTE:  By default, the modem is also set to &A3, which
selects additional results that report the protocols used in
the connection.






                   Result Code Options

                                       Setting
Result Codes              X0      X1      X2      X3      X4
0/OK                      o       o       o       o       o
1/CONNECT                 o       o       o       o       o
2/RING                    o       o       o       o       o
3/NO CARRIER              o       o       o       o       o
4/ERROR                   o       o       o       o       o
5/CONNECT 1200                    o       o       o       o
6/NO DIAL TONE                            o               o
7/BUSY                                            o       o
8/NO ANSWER                                       o       o
10/CONNECT 2400                   o       o       o       o
13/CONNECT 9600                   o       o       o       o
18/CONNECT 4800                   o       o       o       o
20/CONNECT 7200*                  o       o       o       o
21/CONNECT 12000*                 o       o       o       o
25/CONNECT 14400*                 o       o       o       o
-----------------------------------------------------------
Functions
-----------------------------------------------------------
Adaptive Dialing                          o       o       o
Wait for 2nd Dial Tone (W)                        o       o
Wait for Answer (@)                               o       o
Fast Dial                                 o               o

* 14.4K only

NOTE:  More CONNECT messages indicate an error control
connection, the call modulation, or the error control and
data compression used.  See Additional Result Code Options
(&An), after this section.




















               Result Code Definitions

Result Code          Meaning

0/OK                 Command has been executed.
1/CONNECT            Connection established with another
                     modem; if set to X0, connection may be
                     at 300, 1200, 2400, 7200, 9600, 12K or
                     14.4K bps; if X1 or higher, connection
                     is at 300 bps.
2/RING               Incoming ring detected.

3/NO CARRIER         Carrier detect has failed or carrier
                     has been dropped due to disconnect.

4/ERROR              Command is invalid.

5/CONNECT 1200       Connection established with another
                     modem at 1200 bps.

6/NO DIAL TONE       Dial tone not detected during the
                     normal 2 seconds, set in Register S6.

7/BUSY               Busy signal detect; modem hangs up.

8/NO ANSWER          After waiting 5 seconds for an answer,
                     modem hangs up; returned instead of
                     NO CARRIER when the @ option is used.

10/CONNECT 2400      Connection established with another
                     modem at 2400 bps.

13/CONNECT 9600      Connection established with another
                     modem at 9600 bps.

18/CONNECT 4800      Connection established with another
                     modem at 4800 bps

20*/CONNECT 7200     Connection established with another
                     modem at 7200 bps.

21*/CONNECT 12K      Connection established with another
                     modem at 12,000 bps.

25*/CONNECT 14.4K    Connection established with another
                     modem at 14,400 bps.

Adaptive (Hunt)      The modem attempts to use tone
Dailing              dialing and, if that doesn't work,
                     reverts to rotary (pulse) dialing.


Wait for Another     The modem continues dialing as soon as
Dail Tone (W)        it detects another dial tone.

Wait for an          The modem continues dialing when it
Answer (@)           detects 5 seconds of silence on the
                     line.

Fast Dial            The modem dials immediately on dial-
                     tone detect, instead of waiting the
                     normal 2 seconds set in Register S6.

*14.4K only



============================================================
Additional Result Code Options (&An)

Use this command to enable/disable one of the following sets
of error control, modulation, or protocol result codes.
If you encounter software problems, it may be because your
software expects to find different result codes from those
the modem is sending.  (The modem defaults to &A3.)  Review
your software documentation or try &A2, &A1, or &A0.  You
may need to call your software s technical support to find
out which &An setting they support.

&A0  ARQ (error control) codes are disabled.  This setting
     does not affect an error control connection; the modem
     returns standard CONNECT messages if result codes are
     enabled.

&A1  ARQ codes are enabled.  Default.  One of the results
     below is shown when a successful error control
     connection is established.  CONNECT/ARQ is displayed if
     the modem is set to X0 and the connection is between
     1200 to 14.4K bps.  The remaining results indicate
     connection rate and require X1 or above.  If your
     software cannot handle the ARQ codes, select &A0.


        14/CONNECT/ARQ              19/CONNECT 4800/ARQ
        15/CONNECT 1200/ARQ         24/CONNECT 7200/ARQ
        16/CONNECT 2400/ARQ         22/CONNECT 12000/ARQ
        17/CONNECT 9600/ARQ         26/CONNECT 14400/ARQ

&A2  V.32 modulation codes are enabled.  These results
     require a setting of X1 or higher.  If your software
     cannot handle the added modulation information, select
     &A1 or &A0.

        33/CONNECT 9600/V32         41/CONNECT 12000/V32
        37/CONNECT 9600/ARQ/V32     42/CONNECT 12000/ARQ/V32
        38/CONNECT 4800/V32         44/CONNECT 7200/ARQ/V32
        39/CONNECT 4800/ARQ/V32     45/CONNECT 14400/V32
        40/CONNECT 7200/V32         46/CONNECT 14400/ARQ/V32

&A3  Protocol codes are enabled.  Default.  Error control
     protocols reported are LAPM or MNP.  When the call is
     not under one of those protocols (and ARQ is not
     included in the result code), the modem reports NONE,
     for no protocol.

     If the modems are using data compression, the type of
     compression-V42BIS or MNP5-is added to the result code.
     In the first of the following examples, the modems
     negotiated error control for the call (ARQ), used
     V.32 bis modulation, are using the LAPM error control
     protocol, and are using V.42 bis compression.

     CONNECT 14400/ARQ/V32/LAPM/V42BIS        [or MNP/MNP5]
     CONNECT 2400/ARQ/MNP/MNP5             [or LAPM/V42BIS]
     CONNECT 2400/NONE

     If your software cannot handle the added protocol
     information, select &A2, &A1, or &A0.

     Although these codes will return numeric identifiers if
     DIP switch 2 is ON or you've set the modem to V0, they
     are the same numeric identifiers used for &A2 result
     codes.  If you want &A3 protocol indicators, use Verbal
     mode (V1), and not Numeric mode (V0).


============================================================
ERROR CONTROL (&Mn)
============================================================

By default, the Sportster first attempts a connection using
V.42 (LAPM) error control and, if that doesn't succeed, it
attempts an MNP connection.  If that doesn't succeed, the
modem tries to connect without error control.

Error control is possible at rates of 1200 bps and above.

The following options are available.

NOTE:  ARQ is U.S. Robotics  term for error control
protocols that feature error detection and automatic
retransmission of corrupted blocks of data.

&M0  Normal mode, no error control.  Because of the nature
     of phone-line channels, this is never recommended for
     calls above 2400 bps unless you're using an error-
     correcting file-transfer protocol.

&M1  Reserved.

&M2  Reserved.

&M3  Reserved.

&M4  Normal/ARQ mode.  Default.  If the remote modem doesn't
     recognize the Sportster's error control signals--V.42
     or MNP--the modem operates in Normal mode, as though it
     were set to &M0.

&M5  ARQ mode.  If the remote modem doesn't recognize the
     error control request--V.42 or MNP--the Sportster hangs
     up.

Always set the Sportster for error control, &M4 (default) or
&M5, for calls at speeds over 2400 bps.  Most users
communicating with V.42- or MNP-compatible modems will want
error control at 2400 and 1200 bps, as well.

If you're dialing out and have trouble connecting, it may be
because the remote modem doesn't have either MNP capability,
and it misinterprets your modem s MNP error control request.
If you know the remote modem doesn't support MNP, disable
MNP handshaking by setting Register S27 to 16 (ATS27=16).
The Sportster still connects, but without MNP error control.

To reset the modem for normal operations after the
call, issue the ATZ (reset) command, or set Register
S27 to zero.

============================================================
Auto Answer with Error Control

When set to &M4 or &M5 and a call comes in, the modem goes
off hook and responds to received error control signals.  If
the Sportster doesn't receive those signals and is set to
Normal/ARQ mode (&M4), it answers the call in Normal mode
(&M0).  If it doesn't receive the signals and is set to ARQ
mode (&M5), it hangs up.


============================================================
DATA COMPRESSION (&Kn)
============================================================

When data compression is enabled, the transmitting modem
detects redundant units of data and recodes them into
shorter units of fewer bits.  The receiving modem
decompresses the redundant data units before passing them to
the receiving computer.

Compression does not occur unless the modems can establish
an error control connection.

If the Sportster makes a V.42 connection, it negotiates V.42
bis compression.  If V.42 bis is not feasible, the
connection remains under error control, but without data
compression.

If the Sportster makes an MNP connection, it negotiates for
MNP Level 5 (MNP5) data compression.  If the remote modem
does not have MNP5 capability, the connection remains
under MNP error control, but without compression.

&K0  Data compression disabled.

&K1  Auto enable/disable.  Default.  The modem enables
     compression if the serial port rate is fixed (&B1) and
     disables compression if the serial port rate follows
     the connection rate (&B0).  (Compression offers no
     throughput advantage when serial port and connection
     rates are equal, and may even degrade throughput.)

&K2  Data compression enabled.  Use this setting to keep the
     modem from disabling compression.

&K3  Selective data compression.  The modem negotiates only
     for V.42 bis compression, and disables MNP Level 5
     (MNP5) compression.  See the following note.

NOTE:  MNP5 compression is not useful when transferring
already compressed files, such as the .ZIP files downloaded
from Bulletin Boards and 8-bit binary files that appear
already compressed to the modem.  MNP5 tends to add data to
these files, and throughput over the phone link degrades.

V.42 bis compression detects when data is already compressed
and turns off until it detects that compression will be
advantageous.  The special &K3 setting allows the best
throughput for already compressed and 8-bit binary files.


============================================================
DATA RATE COMMANDS
============================================================

The &Bn and &Nn commands control data rates at the serial
port and phone line interfaces.

The Sportster defaults to a fixed rate at the serial port
interface (&B1) to keep the serial port rate higher than the
connection rate.  You'll get greater throughput regardless
of the connection rate.  Your software, however, must
support this feature and you must set your software to use a
fixed rate.

For the phone line, however, we recommend variable
connection rates (&N0).  This lets the modem switch its
connection rate to match the rate of a remote modem, no
matter what that rate is.  If the connection rate is fixed,
for example, at 9600 bps (&N6), the modem only connects with
modems operating at that rate.  Of course, if your
application requires connections with modems at only one
rate, you may wish to set the modem to a fixed connection
rate.

---------------------
Software Requirements
---------------------
Both variable and fixed serial port rates require
communications software support.  Most communications
programs support variable or fixed rates.  Check your
software manual.  Set your software BEFORE making calls.

============================================================
Serial Port Rate (&Bn)

Initially, the modem's serial port rate depends on your
software setting.  The modem uses the rate at which it
receives the AT command to determine the serial port rate;
after that it depends on its &B setting.

&B0  Variable serial port rates.  The modem switches its
     serial port rate to follow the connection rate
     established with a remote modem.  If your software has
     Auto Baud Detect, turn it on.  The software will switch
     its serial port rate to match the connection rate.

&B1  Fixed serial port rate.  Default.  The modem detects
     its serial port rate from your last AT command and
     maintains it, whatever the connection rate.

     Set your software to 57.6K, 38.4K, or 19.2K bps, then
     set the modem to &B1 for the best throughput.  Some
     programs require that you turn off Auto Baud Detect to
     fix the serial port rate.  Others use the term Serial
     Port Lock (yes or no).

     The serial port rate MUST EQUAL OR EXCEED the
     connection rate.  Also, this setting requires
     flow control, preferably hardware (&H1), to avoid
     buffer overflow.

&B2  Fixed for ARQ calls/Variable for non-ARQ calls, Answer
     mode only.  When the modem goes off hook and answers in
     ARQ mode, it shifts its serial port rate to the one
     written to NVRAM, for example, 38.4K bps.  In non-ARQ
     mode, it acts as if set to &B0 when answering, and
     switches its serial port rate to match the call's
     connection rate.

     This option is designed for installations such as
     Bulletin Boards that receive calls from a wide variety
     of modems, ranging from the very slow to those with the
     Sportster 's advanced design.

============================================================
Connection Rate (&Nn)

Use the &Nn command to select variable or fixed rates at the
phone-line interface.  Variable rates let the modem connect
with a variety of remote modems, while fixed rates limit
calls to one connection rate.

&N0  Variable rates.  Default.  The Sportster negotiates
     with the remote modem for the highest possible
     connection rate, depending on the capabilities of the
     remote modem.  This is the recommended setting.

&N   Fixed rate.  The Sportster only connects if the remote
1-8  modem is operating at the same rate.  If not, the
     Sportster hangs up.

     The fixed rate options are as follows.

       &N1  300 bps       &N5  7200 bps (14,400 only)
       &N2  1200 bps      &N6  9600 bps
       &N3  2400 bps      &N7  12K bps (14,400 only)
       &N4  4800 bps      &N8  14.4K bps (14,400 only)

By fixing the connection rate, you can filter out calls at
other than a specific rate, for security or other reasons.

============================================================
FLOW CONTROL
============================================================

The modem uses either hardware or software flow control to
manage the amount of data stored in the buffers, thus
preventing buffer overflow.

The Sportster defaults to hardware flow control.  This type
of flow control is performed between the modem and computer
with serial signaling.

Software flow control uses the standard ASCII Transmit OFF
(XOFF) character, Ctrl-S, and the Transmit ON (XON)
character, Ctrl-Q.

ASCII definitions are as follows.

XON    Ctrl-Q      ASCII 17 Decimal, 11 Hex
XOFF   Ctrl-S      ASCII 19 Decimal, 13 Hex

NOTE:  Both your software and computer must support the flow
control you select.  All 100% IBM PC-compatible computers
support hardware flow control, as do Apple computers
equipped with a Hardware Handshaking cable.  However,
hardware flow control requires software support.  Refer to
your software documentation to see what your software
supports.

When you have determined the type of flow control your
system supports, be sure to set your software appropriately
BEFORE transferring files.


============================================================
Warning on Software Flow Control

In ordinary operations, the only characters the modem
recognizes during a call are the three plus symbols (+++) of
the escape code that return it to Command mode.  But when
software flow control is enabled, the modem or computer also
looks for Ctrl-S or Ctrl-Q characters.  IF THESE CHARACTERS
OCCUR IN A FILE OR AS PART OF A PROTOCOL, it reads them as
XON/XOFF characters and acts on them.

For example, XON/XOFF characters occur in binary files, and
are used by Xmodem-type protocols.  They may also come from
the remote system.  An XON from the remote system, after
your modem has sent an XOFF, can result in buffer overflow.

Software flow control may prove satisfactory if you're only
transferring text files; however, you may lose data if
XON/XOFF characters occur in the data stream from other
sources.

To select software flow control, write the &F2 configuration
template to Y1.

                 AT &F2 &W <Enter>

---------------------------------
Software Flow Control Precautions
---------------------------------
If you can t use hardware flow control and are doing Xmodem-
type protocol or binary file transfers, select a protocol
that performs error correction, and turn off the modem's
error control (AT&M0).

============================================================
Transmit Data Flow Control (&Hn)

This type of flow control regulates data your computer
transmits to the modem for transmission over the phone link.
The modem monitors its Transmit Data buffer as data comes
in.  If the buffer nears 90% capacity, the modem signals
the computer to stop transmitting.  When it has sent enough
data over the link to empty half the buffer, it signals the
computer to resume transmitting.



-------------------
When it is Required
-------------------
Transmit Data flow control should be enabled in the
following situations.

*  You're using error control (any allowable rate above
   300 bps), with or without data compression.  If data is
   resent due to errors, a continuous stream of data from
   the computer could overflow the modem's buffer.

*  The serial port rate is higher than the connection rate.
   For example, the serial port rate is 38.4K bps and the
   connection rate is 14.4K bps.

NOTE:  Set your software to either hardware or software flow
control.  Some programs also require that you turn off the
type you are not using.

&H0  Transmit Data flow control disabled.

&H1  Hardware flow control.  Default.  Your computer and
     software must support Clear to Send (CTS).  The modem
     drops the Clear to Send (CTS) signal to the computer
     when its buffer nears 90% capacity, and starts sending
     CTS again when the buffer is about half full.

&H2  Software flow control.  Your software must support
     XON/XOFF signaling.  The modem sends an XOFF to the
     terminal when its buffer nears 90% capacity, and sends
     an XON when the buffer is about half full.  Default in
     the &F2-Software Flow Control template.

&H3  Use both hardware and software flow control.  Select
     this option if you're not sure what your computer
     supports.

NOTE:  If possible, use hardware flow control.  See "Warning
on Software Flow Control," earlier in this guide for
details.


============================================================
Received Data Flow Control

Two commands--&Rn (hardware) and &In (software)--control the
flow of received data passed by the modem to your computer.
Because computers handle incoming data more quickly than the
modem receives it over the phone line, most applications
won't need this.




----------------------
Hardware Control (&Rn)
----------------------
When your computer drops its Request to Send (RTS) signal,
the modem stops passing along received data.  The computer
sends RTS again when it is ready to receive more data.

Your computer and software must support RTS.  You cannot use
this type of flow control, however, if your software
requires a constant RTS signal.

NOTE:  Use only for ARQ (error control) calls, because the
V.42 and MNP protocols control the data flow across the
phone link.  During non-ARQ calls, however, there is no way
to signal the remote modem to stop sending data.  If your
modem stops passing data to your computer and the remote
modem keeps sending, the Received Data buffer will overflow.

&R0  Reserved.

&R1  The modem ignores Request to Send (RTS).  This setting
     is required if your software does not support RTS.

&R2  Hardware flow control of received data enabled.
     Default.  The modem passes received data to your
     computer only on receipt of the RTS signal.

----------------------
Software Control (&In)
----------------------
When you send the modem a Ctrl-S (XOFF) command from the
keyboard, the modem stops passing received data to your
computer.  When you send a Ctrl-Q (XON) command, it resumes.

NOTE:  Because of the risk of data loss, &I1-5 are
recommended only if your data does not have XON/XOFF control
characters.  See "Warning on Software Flow Control" for
details.

&I0  Disables XON/XOFF flow control of received data.
     Recommended for non-ARQ calls.

&I1  The modem acts on your typed Ctrl-S/Ctrl-Q commands and
     passes them to the remote computer.  Not recommended
     for non-ARQ calls.  Use in ARQ mode only, but keep in
     mind that XON/XOFF characters sent to the remote
     computer may interfere with XON/XOFF signaling between
     it and the remote modem.  &I2 is preferred for ARQ
     calls.

&I2  The modem acts on your XON/XOFF commands, but removes
     them before sending data to the remote computer.
     Default in the &F2--Software Flow Control template.
     Recommended setting for ARQ mode, only.  It ensures
     that the remote computer does not confuse its modem's
     XON/XOFF characters with yours.

     If the call is not in ARQ mode, there is no flow
     control on the phone link.  If you send an XOFF to your
     modem and it stops passing data, it has no way to tell
     the remote computer and modem to stop sending for a
     while, and your modem's buffer may overflow.  See &I5
     for another alternative.

&I3  Host Mode.  Applies only to modems attached to HP
     mainframes using the ENQ/ACK protocol.  ARQ mode only.

&I4  Terminal Mode.  Applies only to modems attached to HP
     system terminals using the ENQ/ACK protocol.  ARQ mode
     only.

&I5  Enables phone link flow control when the connection is
     not under error control.  Both modems must use &I5.  In
     ARQ mode, the modem operates as if set to &I2.  It acts
     on XON/XOFF commands, but does not pass them on to the
     remote system.

     In non-ARQ mode, the modem acts as if set to &I0.  It
     does not look for local XON/OFF commands, but does look
     for any XON/XOFF characters coming in over the phone
     link from the remote computer.  The modem acts upon
     them and drops them from the data stream.

     Operators can signal the other modem to stop sending
     and control phone link data flow to keep their modem's
     buffer from overflowing, if both are set to &I5.


============================================================
SERIAL OPERATIONS
============================================================

The parameters described below are directly affected by the
serial connection and DIP switch settings, and apply to
external modems only.

============================================================
Carrier Detect (&Cn)

Like DIP switch 6, this command controls Carrier Detect (CD)
signaling from the modem to the computer.

The power-on/reset default for response modes is set with
DIP switch 6.  The Sportster modem is shipped with DIP
switch 6 OFF, disabling override for normal operations.

Use the &Cn command to control Carrier Detect for a current
session, independent of the DIP switch setting.  This
command may not be stored in NVRAM.

Check your communications software manual to find the
required setting.

&C0  CD override, CD always ON.

&C1  Normal CD operations.  The modem sends a CD signal when
     connecting with another modem and drops CD upon
     disconnecting.  Most communications software programs
     require this setting.

============================================================
Data Terminal Ready (&Dn)

Like DIP switch 1, this command controls the Data Terminal
Ready (DTR) signaling from the computer to the modem.

The power-on/reset default for DTR is set with DIP switch 1.
The Sportster modem is shipped with DIP switch 1 OFF,
disabling override for normal operations.

Use the &Dn command to DTR for a current session,
independent of the DIP switch setting.  This command may not
be stored in NVRAM.

Check your communications software manual to find the
required setting.

&D0  DTR override, modem ignores DTR.

&D1  Reserved.

&D2  Normal DTR operations.  The computer or terminal must
     send a DTR signal or the modem won't accept commands.
     Dropping DTR terminates a call.  Most communications
     software programs require this setting.

============================================================
Data Set Ready (&Sn)

The modem sends your computer a Data Set Ready (DSR) signal.
(Data Set is industry jargon for modem.)  Few, if any,
commercial communications programs require the modem to
control DSR (&S1).  Leave the modem set for DSR override
(&S0), unless you know that your installation requires a
different setting.

&S0  DSR is always ON (override).  Default.

&S1  In Originate mode, the modem sends DSR after dialing,
     when it detects the remote modem's answer tone.  In
     Answer mode, it sends DSR after sending an answer tone.


************************************************************
GETTING HELP
************************************************************

Checking the Help screens is the first step to recovery.
These screens give you the information you ll need to
identify a problem.  Once a problem is identified, it can
easily be solved.


============================================================
INQUIRIES (In)
============================================================

The Inquiry command has eight options.  The most commonly
used options display the following information.

ATI4  Current settings

ATI5  NVRAM settings

ATI6  Link diagnostics

I0   The modem returns a product code.  If you have a
     problem and call U.S. Robotics' Technical Support
     Department, you may be asked for this product code.

I1   The modem performs a checksum of its read-only memory
     (ROM) and returns the result to the screen.  This
     function is used only in factory testing.  The modem
     should always read the same number.

I2   The modem performs a test of its random-access memory
     (RAM) and returns either the OK (0) or ERROR (4) result
     code, followed by OK when the test is completed.  You
     may want to use this command as a checkpoint if the
     modem appears to be malfunctioning.

I3   Reserved.

I4   The modem displays its current configuration.

I5   The modem displays the stored phone numbers and two
     templates (Y0 and Y1) stored in nonvolatile random
     access memory (NVRAM).  Activate the second screen by
     pressing any key.

I6   During a connection, the modem monitors and stores
     information about link operations.  When the call is
     ended, you can request a diagnostic summary.

     For calls under data compression, the number of
     characters sent may be less than the number of octets
     sent, due to buffering operations.

     Most terms used in the display are self explanatory
     except for  the following:

     Octets:  Compressed data units.  If the number of
              octets is greater than the  number of
              characters sent, the modems probably used MNP5
              compression on an already compressed file, and
              the result was expanded data.

     Blers:   Errors in data and protocol blocks.  If there
              were many block errors, your receiver may have
              experienced problems on the line.

     Blocks Resent:  These represent blocks the remote modem
              resent due to the previous category, Blers.

     Link Timeouts:  Protocol detection problems;
              communications were severed momentarily and
              the modems probably recovered.  This does
              not indicate the retry timeout.

     Link Naks:  Negative acknowledgments (one or more
              blocks).

     Data Compression:  Indicates the type of data
              compression negotiated for the call (V42BIS or
              MNP5) or NONE.  A V42BIS response includes the
              size of the dictionary and the maximum string
              length used, for example, 2048/32.

     Fallback:  Enabled/Disabled:  indicates whether or not
              the modems negotiated online fallback during
              the connection sequence.

     Protocol:  Indicates the error control protocol
              negotiated (LAPM, MNP, NONE).

     Speed:   The last rates at which the  receiver/
              transmitter were operating before
              disconnecting.

     Disconnect Reason:  Possible reasons the modem hung up
              are as follows:

              *  DTR dropped--The DTE dropped the Data
                 Terminal Ready signal, terminating the
                 call.

              *  Escape code--The operator sent the modem
                 the +++ escape code.

              *  Loss of carrier--The modem detected loss of
                 the remote modem s carrier and waited the
                 duration specified in Register S10 (default
                 is 0.7 seconds).

              *  Inactivity timeout--The modem detected no
                 activity on the line for the duration
                 specified in Register S19 (default is 0,
                 timer disabled).

              *  MNP incompatibility--The modem is set to
                 &M5 and the remote modem does not have MNP
                 compatibility, or there was an MNP
                 negotiation procedure error.

              *  Retransmit limit--The modems reached the
                 maximum of 12 attempts to transfer a data
                 frame without error.

              *  LD received--The remote modem sent an MNP
                 error control Link Disconnect request.

              *  DISC--The remote modem sent a V.42
                 Disconnect frame.

              *  Loop loss disconnect--The modem detected a
                 loss of current on the loop connecting
                 it with the telephone company central
                 office.  This usually occurs because the
                 remote modem has hung up:  the central
                 office drops current momentarily when
                 there is a disconnect at the other end of a
                 call.  Unless Register S38 is set higher
                 than 0, the modem immediately hangs up at
                 loop loss.

              *  Unable to retrain--After several attempts,
                 disturbances on the phone line prevented
                 the modems from retraining
                 (resynchronizing), and they could no longer
                 transmit or receive data.

              *  Invalid speed--The modem is set to &N1 or
                 higher, for a fixed link rate, and the
                 remote modem is not operating at the same
                 rate.

              *  XID timeout--The modems failed to negotiate
                 the V.42 Detection (XID Exchange) phase.

              *  SABME (Set Asynchronous Balance Mode
                 Extended) timeout--The modems failed this
                 part of V.42 link negotiation.

              *  Break timeout--Incompatible processing of a
                 Break signal occurred.

              *  Invalid codeword--The modem received an
                 invalid V.42 bis (compression) frame.

              *  A rootless tree--The modem received an
                 invalid V.42 bis (compression) frame.

              *  Illegal command code--The modem received an
                 invalid V.42 bis (compression) frame.

              *  Extra stepup--The modem received an invalid
                 V.42 bis (compression) frame.

I7   The modem returns a product configuration.  If you have
     a problem and call U.S. Robotics' Technical Support
     staff, you may be asked to read this screen.


============================================================
S-REGISTER QUERY (SR?)
============================================================

This command allows you to view the contents of a particular
S-Register, as in the following example that requests the
contents of Register S0 ("On what ring will the modem
answer?").

                 ATS0? <Enter>


============================================================
STORED PHONE NUMBER QUERY (&Zn?)
============================================================

At this command, the modem returns the phone number stored
in NVRAM at position n, as in the following example that
includes a sample modem response.

                 AT&Z3? <Enter>
                 5551234


============================================================
LAST-DIALED NUMBER QUERY (DL?)
============================================================

At this command the modem displays the number stored in the
last-dialed number buffer.

                 ATDL? <Enter>



============================================================
HELP SCREENS
============================================================

Sportster modems provide four Help screens:  summaries of
the basic AT command set, extended ampersand (&) command
set, Dial command options, and S-Register functions.

--------------------
Stop/Restart Display
--------------------
The following command stops the display.  Hold down the
Control key and type S.

                <Ctrl>-S

To restart the display, use the same command or press <any
key>.

--------------
Cancel Display
--------------
Either of the following commands cancels the display.

                 <Ctrl>-C
                 <Ctrl>-K

============================================================
Basic Command Set ($)

At AT$, the Sportster displays a screen that shows a partial
summary of the command set.  A second screen, activated by
pressing any key, shows the remaining commands.

============================================================
Ampersand Command Set (&$)

At AT&$, the Sportster displays a screen that shows a
partial summary of the extended ampersand command set.  A
second screen, activated by pressing any key, shows the
remaining command set.

============================================================
Dialing (D$)

At ATD$, the Sportster displays the Dial command summary.

============================================================
S-Register Functions (S$)

At ATS$, the Sportster displays a screen that shows a
partial summary of the S-Register functions.  A second
screen, activated by pressing any key, shows the remaining
registers.

************************************************************
TESTING THE MODEM
************************************************************

Modem testing is available with the &Tn command and Register
16 (Dial test).  All loopback testing conforms to ITU-T
Recommendation V.54.

NOTE:  Only one test can be performed at a given time.  If
you send a test command while the modem is in Test mode,
you'll receive an ERROR message.


============================================================
TESTING WITH &Tn
============================================================

The tests supported through the &Tn command include Analog
Loopback, Digital Loopback, and Remote Digital Loopback.
You can key in your own data during testing, or use the
modem's internal test pattern and error detector.

Always disable error control before testing.  If the modem
is detecting errors and retransmitting the affected data,
your test results will be invalid.

============================================================
Ending a Test--&T0, S18

Issue the &T0 command to terminate a test.  Alternatively,
set Register S18 to a specified number of seconds, for
example, S18=10.  When the 10 seconds are up, the modem
automatically ends the test and returns to Command mode.  If
the test was Analog Loopback, the &T0 command hangs the
modem up.  If the test was Digital or Remote Digital
Loopback, issue an ATH command to hang up the modem, or an
ATZ command to hang up the modem and reset it to its
defaults.

NOTE:  If you use the S18 test timer, but in the process of
testing you issue an ATZ command, S18 resets to zero and the
timer is disabled.  Also, you cannot store a value for S18
in nonvolatile memory;  its power-on and reset default is
always zero.

============================================================
Analog Loopback-&T1, &T8

This test checks the operation of the modem's transmitter
and receiver.



---
&T1
---
This AL option requires that you type data you can later
verify at your screen.

1.  The modem should be on hook in Command mode.  If you
    wish, set Register S18 as a test timer.  For example,
    insert S18=10 in the following command string before
    &T1.

                 AT &M0 S18=10 &T1 <Enter>

    The modem disables error control, sets the timer, enters
    Analog Loopback (AL) mode, and sends a CONNECT message.

2.  Type recognizable data so that you can verify it when
    it is looped back to the screen.

3.  End the test.  If you set S18, the modem automatically
    stops the test at the timeout, exits AL mode and
    responds OK.

    If you didn't set Register S18, wait one second and type
    +++ to end the test and return the modem to Command
    mode.  When the modem responds OK, type AT&T0 to
    terminate AL mode and hang up the modem.  (Typing ATH
    has the same effect.  Typing ATZ also has the same
    effect, but also resets the modem and restores your &M
    default.)

    The modem responds OK.  If the modem sends an ERROR
    message, you have issued an invalid command.

4.  If there were no errors, reset the modem to &M4, for
    error control, unless you've issued the ATZ reset
    command.

    NOTE:  If the modem is in Online-Command mode--that is,
    still connected to a remote modem--and you send it an
    &T1 or &T8 command, it drops the call, enters AL mode,
    sends a CONNECT result and waits for loopback
    characters.

---
&T8
---
This AL option causes the modem to send an internal test
pattern to its transmitter and loop it back to the receiver.
An internal error detector counts any errors and, when the
test is ended, sends the number of errors or 000 (no errors)
to the screen.

Since you don't type anything during this test, and the
modem does not send anything to the screen, this option
verifies only the modem.  If there are no errors but your
problem continues, it may be at the computer interface.

1.  The modem should be on hook in Command mode.  If you
    wish, set Register S18 as a test timer.  For example,
    insert S18=10 in the following command string before
    &T8.

                 AT &M0 S18=10 &T8 <Enter>

    The modem disables error control, sets the timer, and
    enters AL mode.  The modem sends its internal test
    pattern to the transmitter, and loops the pattern back
    to the receiver.  You will not see any data on your
    screen.

2.  End the test.  If you set S18, the modem automatically
    stops the test at the timeout.  If you didn't set
    Register S18, type AT&T0 to end the test.  Or use ATH
    or the command that resets the modem, ATZ.  Both of the
    latter end the test and hang up the modem.

    When the modem hangs up, it returns a three-digit code,
    followed by OK.  A code of 000 indicates no errors were
    found.  A code of 255 indicates 255 or more errors.  An
    ERROR message indicates that you issued an invalid
    command.

3.  If there were no errors, reset the modem to &M4 for
    error control unless you issued the ATZ command.

============================================================
&T2

This option is reserved.

============================================================
Digital Loopback-&T3

If your modem has passed the Analog Loopback (AL) test, this
test can help you locate a problem with a remote modem or
the telephone channel.

1.  Set the modem to &M0 to disable error control.
    Establish a connection with the remote modem.

2.  Bring the modem back to Online-Command mode with the
    +++ escape code.  Then send it the AT&T3 command.  The
    modem enters Digital Loopback (DL) mode.

3.  The remote user should type a short message.  It will
    be looped back by your modem's transmitter for
    verification on the remote screen.  You will not see the
    message or any other data.

4.  When the remote user has completed the test,  issue the
    AT&T0 command to end the test.  If you wish, return the
    modem online (ATO) to resume Data mode.  Or type either
    ATH or the command that resets the modem, ATZ.  The
    latter two commands end the test and hang up the modem.
    The modem responds OK.  If the modem sends an ERROR
    message, you have issued an invalid command.

============================================================
&T4, &T5

The &T4 option grants a remote modem's request for a Remote
Digital Loopback test.

The &T5 option cancels &T4 and your modem will not recognize
a request for a Remote Digital Loopback test from a remote
modem.  This is the default so that your modem isn't subject
to another user calling and tying up your modem without your
permission.

============================================================
Remote Digital Loopback-&T6, &T7

This test, like the local Digital Loopback test, verifies
the condition of both modems and the phone link.

The request for and granting of Remote Digital Loopback
testing requires that both modems use ITU-T V.54 standard
signaling.  The test MUST be performed at 2400 or 1200 bps.
If the remote modem does not have the capability or is not
set to respond, you will get an ERROR result code.

---
&T6
---
This RDL option requires that you send keyboard data to the
modem and verify it when it is returned over the phone lines
and to your screen.

1.  Set your software to 2400 or 1200 bps.  Set the modem to
    &M0.  If you wish, set the S18 timer.

    Establish a connection with the remote modem.  If you
    haven't already done so, arrange with the remote user to
    cooperate with your testing.  The remote user should set
    his or her modem to acknowledge the RDL request, for
    example, AT&T4.

2.  Bring the modem back to Online-Command mode with the
    +++ escape code.  Send it the AT&T6 command.  The modem
    enters RDL mode.

3.  Type a short message.  It will be looped back to your
    modem by the remote modem and to your screen for
    verification.  (The remote user will not see your data.)

4.  End the test.  If you set Register S18 the modem
    automatically ends the test when the test timeout is
    reached.  If you didn't set S18, type AT&T0 to end the
    test.  If you wish, return the modem online (ATO) to
    resume Data mode.  Or send either ATH or the command
    that resets the modem, ATZ.  The latter two commands end
    the test and hang up the modem.  The modem responds OK.
    If you issue an invalid command, the modem sends an
    ERROR message.

    Data errors indicate a problem with the remote modem or
    the phone link.  If you have not performed analog loop-
    back testing with your modem, the problem may also lie
    with your modem.

5.  Reset the modem to &M4 unless you used the reset
    command, ATZ.

---
&T7
---
This test option causes the modem to send an internal test
pattern through the Remote Digital Loopback.  An internal
error detector counts any errors and, when the test is
ended, sends the number of errors or 000 (no errors) to the
screen.

You don't need to type anything during this test.  The modem
sends only its final error count to your screen.

1.  Set your software to 2400 or 1200 bps.  Set the modem
    to &M0.  If you wish, set the S18 timer.

    Establish a connection with the remote modem.  If you
    haven't already done so, arrange with the remote user to
    cooperate with your testing.  The remote user should set
    his or her modem to acknowledge the RDL request, for
    example, AT&T4.

2.  Bring the modem back to Online-Command mode with the
    +++ escape code.  Then send it the AT&T7 command.  The
    modem enters RDL mode.  The modem sends its internal
test
    pattern to the remote modem, which loops it back to
    your modem.  You will not see the data on your screen.

3.  End the test.  If you set S18, the modem automatically
    stops the test when the timer times out.  If you didn't
    set Register S18, type AT&T0 to end the test.  After you
    view the test results (next paragraph), return the modem
    online if you wish (ATO) and resume Data mode.  Or send
    either ATH or the command that resets the modem, ATZ.
    The latter two commands end the test and hang up the
    modem.

    When you terminate the test, the modem returns a three-
    digit code, followed by OK.  A code of 000 indicates no
    errors were found.  A code of 255 indicates 255 or more
    errors.  If you issue an invalid command, the modem
    sends an ERROR message.

    If you've performed an Analog Loopback and know your
    modem is working properly, errors indicate a problem
    with either the phone connection or the remote modem.

4.  Reset the modem to &M4 unless you've sent it the ATZ
    reset command.


============================================================
DIAL TEST-S16=2

The Dial test is used for factory-testing the frequencies of
tone dialing values.  When S-Register 16 is set to 2 and a
single tone is dialed (for example, ATD7 <Enter>), the modem
continues to transmit that tone until you press Enter again.





























************************************************************
OTHER OPERATIONS
************************************************************

============================================================
FAX OPERATIONS
============================================================

============================================================
Fax Modem Guidelines

Fax operations require facsimile-compatible software that
can send or receive Group III faxes.  Follow the
instructions in your fax software manual.

The modem's normal operating mode is Data mode.  If your fax
software is typical, it automatically switches the modem to
Fax mode when you run the program, and resets the modem to
Data mode when you exit the program.

If you have a problem, however, and think the modem may be
in the wrong mode, you can use one of the following AT
commands to manually switch the modem.

Most users will never need to use these commands.

         AT+FCLASS=0 <Enter>   (Switch to Data mode)
         AT+FCLASS=1 <Enter>   (Switch to Fax mode)

If you are not sure whether the modem is in Data or Fax
mode, type the following command.

                 AT+FCLASS? <Enter>

The modem returns a 0 to indicate Data mode or a 1 to
indicate Fax mode.

NOTE:  Whenever the fax modem is reset using the ATZ
command, toggling the DTR signal, or turning the power off
and on, the modem will be set to Data mode.

============================================================
Fax Mode Flow Control Setting

Many facsimile software products use software flow control
when the modem is in Fax mode.  To allow compatibility with
software products that use software flow control by default,
U.S. Robotics fax modems switch to software flow control
when entering Fax mode.

For the best information on modem settings, see your Fax
software manual.

============================================================
FCC Notice

FCC part 68, rules regarding fax operation, has been amended
as follows:

   Telephone facsimile machines--identification of the
   sender of the message:  It shall be unlawful for any
   person within the United States to use a computer or
   other electronic device to send any message via a
   telephone facsimile machine unless such a message clearly
   contains, in a margin at the top or bottom of each
   transmitted page or on the first page of the
   transmission, the date and time it is sent and an
   identification of the business, other entity, or
   individual sending the message and the telephone number
   of the sending machine or of such business, other entity,
   or individual.  Telephone facsimile machines manufactured
   on and after December 20, 1992 must clearly mark such
   identifying information on each transmitted page.


============================================================
A Note to Programmers

If you want to know more about the supported fax commands,
refer to the standard for the Service Class 1 fax protocol.

     ANSI/EIA/TIA-578-1990 (EIA-578)
     Asynchronous Facsimile DCE Control Standard
     November, 1990  Approved:  October 22, 1990

You can obtain a copy of this standard by contacting Global
Engineering Documents, at 1-800-854-7179.


============================================================
VOICE/DATA COMMUNICATIONS
============================================================

When you install the Sportster, you have the option of
plugging your phone into the second modular jack of the
modem so it's available for voice calls.  You can also use
the phone to set up communications with another user whose
modem uses the AT command set, such as a U.S. Robotics or
U.S. Robotics-compatible modem.

============================================================
Preparation

First call the other user to establish the parity, word
length, and number of Stop bits the other person's modem
accepts.  Then turn the call over to your modems, as
follows.

============================================================
Procedures

1.  Without hanging up the phone, have your modem go off
    hook in Originate mode.  Type the following command.

                 ATD <Enter>

    NOTE:  Be sure the modem is NOT set to X2 or X4, or it
    will return the NO DIAL TONE result code and hang up.

2.  The other party should have the remote modem go off
    hook in Answer mode.  The following command is used to
    do this.

                 ATA <Enter>

3.  Now both of you can hang up your respective phones
    while the two modems establish the data link.  They will
    maintain the link until one of you gives your modem a
    command to disconnect.

    Either party's device can be the originate or answer
    modem; it doesn't matter who made the phone call.  But
    one modem must enter Originate mode and the other Answer
    mode.  You and the other party, therefore, must agree on
    which command, ATD or ATA, you will each use.


























************************************************************
TECHNICAL SPECIFICATIONS
************************************************************

============================================================
COMPATIBILITY
============================================================

The Sportster modem conforms to the following standards,
ensuring compatibility with a wide base of installed modems.
ITU-T is the new signifier of what was formerly the CCITT
international standards body.

ITU-T V.32 bis         14.4K/12K/9600/7200/4800 bps
                          (14,400 modems only)

ITU-T V.32             9600/4800 bps

ITU-T V.22 bis         2400 bps

Bell 212A              1200 bps (also ITU-T V.22)

ITU-T V.23             1200 bps with 75 bps back channel
                          (Some United Kingdom and
                           European phone systems)

Bell 103               300 bps (ITU-T V.21 optional)

ITU-T V.42             LAPM error control, 1200 bps and
                           higher

ITU-T V.42 bis         Data compression, 1200 bps and higher

MNP                    Levels 2, 3 and 4 error control,
                           level 5 data compression,
                           1200 bps and higher

ITU-T V.54             Analog, digital, and remote digital
                           loopback testing


------------------------------------------------------------
Fax Modems
------------------------------------------------------------
TIA/EIA-578            Service Class 1 Asynchronous
                           Facsimile DCE Control
                           Standard

ITU-T V.17             14.4K/12K bps

ITU-T V.29             9600/7200 bps

ITU-T V.27 ter         4800/2400 bps

ITU-T V.21             300 bps

============================================================
THE SERIAL INTERFACE
============================================================

The serial interface information below applies only to
external modems.

============================================================
Description

The serial interface is a standard developed by the
Electronic Industries Association (EIA).  It defines the
signals and voltages used when data is exchanged
between a computer and a modem or serial printer.

The entire standard covers many more functions than are used
in most data communications applications.  Data is
transmitted between the devices over a shielded serial cable
with a 25-pin male (DB-25P) connector to the modem and a 25-
pin, 9-pin, 8-pin, or custom-built connector to the
computer.

NOTE:  FCC regulations require the use of shielded cable
when connecting a modem to a computer to ensure minimal
interference with radio and television.

============================================================
Pin Assignments

Pin assignments are factory-set in the Sportster modem to
match the standard DB-25 assignments in the following table.
DB-9 connectors for IBM PC/AT-compatible computers should be
wired at the computer end of the cable as shown in the DB-9
column.






              Serial Interface Pin Definitions

                                             Signal Source
DB-25    DB-9    Circuit   Function        Computer -- Modem

  1       *       AA       Chassis Ground          Both
  2       3       BA       Transmitted Data      Computer
  3       2       BB       Received Data          Modem
  4       7       CA       Request to Send       Computer
  5       8       CB       Clear to Send          Modem
  6       6       CC       Data Set Ready         Modem
  7       5       AB       Signal Ground           Both
  8       1       CF       Carrier Detect         Modem
 12       *       SCF      Speed Indicate         Modem
 20       4       CD       Data Terminal Ready   Computer
 22       9       CE       Ring Indicate          Modem

If you're using a Macintosh computer, ask your dealer for
the correct modem cable; we recommend a Hardware Handshaking
cable.


                    Macintosh 8-Pin DIN

                                            Signal Source
DB-25    MAC        Function               Computer -- Modem

20/5*     1         Output Handshake*        Computer/Modem*
4         2**       Input Handshake              Computer
2         3**       Transmit Data Negative***    Computer
7         4         Ground                          Both
3         5         Receive Data Negative          Modem
--        6         Transmit Data Positive****       --
--        7         Not connected                    --
--        8         Receive Data Positive            --

*     Adds CTS capability when in Hardware mode.
**    Hardware handshaking lines.
***   To do this, you must ground pin 6.
****  To do this, you must ground pin 8.

NOTE:  A three-wire interface consists of Receive, Transmit,
and Ground wires and does not support hardware flow control.
Systems requiring three-wire interfaces must use software
flow control.  If your system doesn t support software flow
control, use no flow control but be sure to use an error-
correcting protocol.






============================================================
Minimum Requirements

Some computer equipment supports only a few of the serial
signal functions set in the Sportster modem.  The minimum
required for the modem to operate is as follows.

                Minimum Required Pins

DB-25      DB-9       8-Pin
Pin        Pin        DIN           Function

 2          3          3            Transmitted Data
 3          2          5            Received Data
 7          5          4            Signal Ground
20          4          1            Data Terminal Ready*

* Required if DIP switch 1 is OFF for normal DTR operations,
  override disabled.


---------------------------------
Additional Flow Control Functions
---------------------------------
If your computer and software support Clear to Send (CTS)
and you wish to use Transmit Data hardware flow control
(&H1), Pin 5 (DB-25) or Pin 8 (DB-9) is required.

If your computer and software support Request to Send (RTS)
and you wish to use Received Data hardware flow control
(&R2), Pin 4 (DB-25) or Pin 7 (DB-9) is required.

----------------------------------------
For 57.6K and 38.4K bps Serial Port Rate
----------------------------------------
Your software and computer must support the 57.6K or 38.4K
bps rate.  Make sure the serial cable is shielded.  Cables
are normally six feet long, but longer lengths are possible.
If you encounter problems with signal degradation, try a
shorter cable.

If you decide to build your own cable, use a
low-capacitance cable.  To further minimize the capacitance,
connect only those functions (pins) that your application
requires.









============================================================
DEFAULT SETTINGS
============================================================


============================================================
Data Format

Both your software and the remote system must use the same
10-bit data format.  If you don t know the setup of the
remote computer s modem, phone ahead to find out what
combination of word length, parity, and Stop bit is
required.

Set your communications software to the required scheme.
Some communications programs use a kind of shorthand for
formats, such as 7-E-1 or 8-N-1.  The modem detects the
format from the AT prefix of the next command it receives
from your keyboard or from your software.

                 Allowable Data Formats

             Word         Parity          Stop
            Length        (1 Bit)         Bits

              7          Even, Odd,         1
                        Mark, Space
              7            None             2
              8            None             1


============================================================
Template Settings

You can create one or two customized configurations and
store one of them at a time in nonvolatile random-access
memory (NVRAM) as your power-on/reset default using the
&Wn command.  As long as DIP switch 7 is OFF when you power-
on or reset the modem, your defaults are loaded into the
modem's random-access memory (RAM).  To view your NVRAM
settings, use the ATI5 command.

The Sportster modem is preconfigured in the factory for the
&F1--Hardware Flow Control template settings in NVRAM as Y0,
and the &F2--Software Flow Control template settings in
NVRAM as Y1.

Tables on the next pages list the settings of the permanent
configuration templates &F1 (default), &F2, and &F0, as well
as
parameters you can modify and store in the NVRAM
configuration templates.


            &F1--Hardware Flow Control Template
                   Factory Default

Feature                             &F1  Settings

ITU-T/Bell Answer Sequence           B0  ITU-T sequence
Online Echo                          F1  Online Echo OFF
Speaker Control                      M1  Speaker ON until
                                            CONNECT
Pulse/Tone Dialing                   P   Pulse Dialing
Result Code Options                  X4  All Result codes
ARQ Result Codes                     &A3 All protocol codes
                                            enabled
Serial port Rate                     &B1 Fixed serial port
                                            rate
Guard Tone                           &G0 No guard tone
Transmit Data Flow Control           &H1 Hardware flow
                                            control
Modem Testing                        &T5 Deny remote digital
                                            loopback
Received Data Hardware Flow Control  &R2 Enabled
Received Data Software Flow Control  &I0 Disabled
Data Compression                     &K1 Auto enable/disable
Error Control                        &M4 Auto select
Connection Rate                      &N0 Variable connection
                                            rate
Make/Break Ratio                     &P0 U.S./Canada ratio
Volume Control (internal)            L2  Medium volume
Data Set Ready (DSR)                 &S0 DSR always on
Break Handling                       &Y1 Break clears
                                            buffer; break
                                            then goes to
                                            remote modem

The following parameters are changed via your communications
software:

Stored Phone Numbers                &Zn=s
Word Length                         8 bits*
Parity                              None*
Serial port Rate                    19.2 kbps*

* Initial Settings; match software settings of subsequent &W
commands.

The &F2 and &F0 templates largely resemble the &F1 template.
The tables below list only those settings that differ from
the &F1 template.






               &F2--Software Flow Control Template

Feature                             &F2  Settings

Transmit Data Flow Control          &H2  Transmit data
                                            software
                                            flow control
Receive Data Flow Control           &R0  Received data
                                            hardware
                                            flow control
                                            disabled
                                    &I2  Received data
                                            software
                                            flow control
                                            enabled


               &F0--Low Performance Template

Feature                             &F0  Settings

Result Code Options                 X1   Basic subset
ARQ Result Codes                    &A1  ARQ codes enabled
Serial port Rate                    &B0  Variable serial
                                            port rate
Transmit Data Flow Control          &H0  Disabled
Receive Data Flow Control           &R1  Disabled

The following parameters are changed via your communications
software:

Word Length                         7 bits*
Parity                              Even*
Serial port Rate                    9600 bps*

* Initial Settings; match software settings of subsequent &W
commands.


















            NVRAM S-Register Options

NVRAM S-Register Options                  Template Settings

S0*  Number of rings to answer on                   1
S2   Escape code character                          43
S3   Carriage Return character                      13
S4   Line Feed character                            10
S5   Backspace character                            8
S6   Dial wait-time, sec.                           2
S7   Carrier wait-time, sec.                        60
S8   Dial pause, sec.                               2
S9   Carrier Detect time, 1/10th sec.               6
S10  Carrier loss wait-time, 1/10th sec.            7
S11  Tone duration, spacing, msec.                  70
S12  Escape code guard time, 1/50th sec.            50
S13  Bit-mapped functions                           0
S14  Bit-mapped functions                           0
S15  Bit-mapped functions                           0
S19  Inactivity/hang up timer                       0
S21  Break length, 1/100th msec.                    10
S22  XON character                                  17
S23  XOFF character                                 19
S25  DTR recognition time, 1/100th sec.             5
S27  Bit-mapped functions                           0
S28  V.21/V.23 fallback delay, 1/10th msec.         8
S34  Bit-mapped functions                           6
S38  Disconnect wait time, sec.                     0

NOTE:  Bit-mapped registers have up to eight functions.  See
instructions under S13 in Appendix A of the "Quick
Installation Guide."

* The valid range of rings that can be stored in NVRAM for
S0 is 1-255.  S0=0 cannot be stored in NVRAM.  Regardless of
the NVRAM setting, DIP switch 5 must be OFF for the modem to
be in Auto Answer mode at power-on/reset.
















************************************************************
MODEM CONCEPTS
************************************************************


============================================================
HOW MODEMS WORK
============================================================

Modem is a term based on the concept of MOdulation and
DEModulation.  A modem modulates (converts) digital data
(computer information) to analog data (fluctuations in tones
carried over a copper telephone wire).  The information is
carried over a telephone network until it reaches its
destination, where another modem demodulates the analog
signals and converts them back to digital data so the
computer there can use the information.

This ability to use the telephone network for quick,
inexpensive data exchange is a powerful tool used by
businesses and individuals worldwide to expand
business and personal networks.


============================================================
MODEM CONFIGURATION
============================================================

Modems come in all shapes and sizes and their ability to
communicate is based on the protocols they use, or rules
they follow to perform operations in identical ways.  They
may be preset or reset physically (DIP switches) and
logically (communications software) to best communicate with
the modem they are transferring information to and receiving
information from.

Much of this is done automatically by the modems when they
initially contact each other.  The calling modem contacts
the answering modem and introduces itself.  The modems
communicate via a series of signals to identify the
appropriate protocol and speed for efficient data transfer.
The answering modem either accepts the call or rejects the
call.  This transaction is called a "handshake."

Successful handshaking results in what is called "carrier."
When modems establish carrier, your modem sends a Carrier
Detect signal to your computer, indicating that the modems
are ready to transfer data.  If they fail to connect, your
modem sends your computer a No Carrier message.





============================================================
LINE TRAVEL
============================================================

Poor line quality may cause a decrease in efficient data
transmission.  In order to ensure the data sent and received
is reliable, error control was introduced by modem
manufacturers.  The modems check each data block received,
and if something went wrong between locations, the receiving
device instructs the sending device to resend the affected
block.

Modems send information at different rates, measured in bits
per second (bps).  Today, the figures can be staggering.  In
the most optimal situation, the Sportster can exchange data
as fast as 57,600 bps.

In most cases, though, the speed relies heavily on the
ability to adapt to line conditions at high speed.  This
adaptability is the most important feature of the Sportster.


============================================================
DIGITAL DATA
============================================================

Modems send data via asynchronous communication.  The
smallest data unit sent is made up of a defined word length
(7 or 8 bits each), a Start bit (a 0 that indicates where
the data unit begins), and one or two Stop bits.

Parity bits were the typical method of controlling errors
before cyclic redundancy check (CRC) error correction,
described below under :Error Control."  A parity bit is
either a 1 (odd parity) or a 0 (even parity), depending upon
whether the data segment has an odd or even number of binary
digits.  Some systems allow mark parity (parity is always
1--odd) or space parity (parity is always 0--even).  Parity
bits are used less often now that CRC is common.

The setting 8-N-1 (word length=8, parity=None, stop bits=1)
has become the most common data format in data
communications.  Both computers involved in a data transfer
must use the same parity, word length, and number of Stop
bits or connection isn t possible and garbage characters
will display.  The software must first be set the same on
the computers at both ends of the data transfer before the
modems can operate effectively.  A simple phone call
to determine the settings at the other end can clear this up
quickly and easily.

The requirement to specify parity setting, even if it is
None (*-N-1), assures that users with older systems can
still communicate with newer modems.

============================================================
FLOW CONTROL
============================================================

Another important aspect of modem communications is flow
control, which manages the amount of data stored in buffers.
Buffers are used to store information temporarily before it
is passed on to a computer or modem.  Flow control is used
to prevent buffer overflow.  The system uses either hardware
or software (control characters) flow control.  U.S.
Robotics recommends the use of hardware flow control,
because actual data may be mistaken for the control
characters used in software flow control and the data may be
distorted.


============================================================
ERROR CONTROL
============================================================

Error control protects the integrity of data transferred
over phone channels and is available for calls at 1200 bps
and above.  It can be disabled, although high-speed calls
(above 2400 bps) should always be under error control.  The
operations defined in an error control protocol include the
following.

*  Establishment of compatibility

*  Data formatting into blocks

*  Error detection through Cyclic Redundancy Checking (CRC)
   CRC is based on algorithms that calculate a value for an
   entire block of data.  The CRC value attached to each
   block sent must match the receiving modem s calculation.
   If not, the remote modem sends a negative acknowledgment
   to the sending modem.

*  Positive acknowledgment of error-free blocks and
   negative acknowledgment of corrupted data blocks

*  Retransmission of corrupted data blocks

Always set the Sportster for error control, &M4 (default) or
&M5, for calls at speeds over 2400 bps.

The Sportster is set at the factory to &M4, causing it to
try for an error control connection and, if that isn t
possible, to proceed with the call in Normal mode.  The
modem first tries for a V.42 connection, then an MNP
connection.  The information below is based on the
Sportster's setting of &M4.



============================================================
ITU-T V.42 Handshaking

The exchange of signals between two devices in order to
establish a communications link is called handshaking.
ITU-T V.42 includes a two-stage handshaking process.

*  A Detection phase that is based on an exchange of
   predefined characters.

*  LAPM (Link Access Procedures for Modems) Negotiation.
   In this phase, the modems identify their capabilities
   concerning maximum data-block size and the number of
   outstanding data blocks allowed before an acknowledgment
   is required.

============================================================
MNP Handshaking

This protocol is supported by the ITU-T V.42 Recommendation.
It was originally developed by Microcom, Inc., and is now in
the public domain.

MNP handshaking begins with an MNP Link Request sent by the
calling modem.  If the remote modem doesn't recognize the
request, error control isn't possible.

============================================================
Data Compression

If the modems successfully establish a V.42 connection, they
also negotiate for V.42 bis data compression.  If they
successfully establish an MNP connection, they negotiate for
MNP5 data compression.

Modems using V.42 bis compression negotiate the following
options.

*  Dictionary size--that is, the amount of memory available
   for compression table entries.  (Entries are codes
   devised for redundant data.  The data is packed into
   shorter data units, called code words, and unpacked by
   the receiving modem.)

   Possible sizes are as follows.  U.S. Robotics modems use
   11-bit, or 2048-entry dictionaries, but drop down if the
   remote modem uses a 512- or 1024-entry dictionary.

               Bits        Entries
                9           512
                10          1024
                11          2048

*  Maximum string length of each entry.

As the dictionary fills, the modem deletes the oldest unused
strings.  V.42 bis compression is more efficient than MNP5
compression, in part because it dynamically deletes unusable
strings.  In addition, it works better with files that are
already compressed.  These include .ZIP files downloaded
from many Bulletin Boards and 8-bit binary files, which
appear to the modem to be compressed.

MNP5 compression should not be used with such files because
it adds data to them, which lessens throughput.  (The
additional data is stripped when the file is decompressed by
the remote modem.)  When transferring such files, it's best
to set the modem to &K3.  This allows V.42 bis compression
to work dynamically with the compressed data, but disables
MNP5.

============================================================
Flow Control

Flow control of data from the computer is required under
error control for two reasons.

1.  The transmitting modem buffers a copy of each frame it
    transmits to the remote end until it is acknowledged by
    the receiving modem.

2.  If errors are encountered, the transmitting modem must
    resend the corrupted data.  This retransmission
    activity, combined with the steady stream of data from
    the computer, can overflow the buffer.

============================================================
Online Fallback/Fall Forward

Under error control, if a disturbance on the phone line
causes an error to a data block, the receiving modem replies
with a negative acknowledgment.  In response, the
transmitting modem retrieves a copy of the original data
block from its Transmit buffer, and every block it sent
after that block, and retransmits them.  This keeps
the data error-free and in sequence.

However, there is a retransmit limit:  the modems hang up if
line disturbances are so severe that one of the modems has
retransmitted the same block of data twelve times without a
positive acknowledgment.

Because high-rate calls are more vulnerable than
transmissions at 2400 bps and below, V.32 bis modems risk
reaching the retransmit limit and hanging up.  To prevent
this, one of the modems requests that they fall back--that
is, they reduce their rate from 14.4K to 12K bps, and then
to 9600 bps or lower, if necessary.  When line conditions
improve, the modems fall forward to the next higher rate, up
to the link rate of the call.

Online fallback/fall forward is defined in ITU-T
recommendation V.32 bis for modems with top connection rates
of 14.4K bps.  The Sportster 9600, however, is a V.32 modem.
V.32 modems fallback to 4800 bps and stay at that rate.


============================================================
THROUGHPUT GUIDELINES
============================================================

The following guidelines should help you to make the most of
your modem's advanced performance features.  In many
instances, experimentation and experience will indicate what
works best for your applications.

Throughput is the volume of user information transferred per
second, without Start and Stop bits and other overhead
information.  You'll obtain optimal throughput under the
following conditions.

1.  Your communications software supports a fixed serial
    port rate higher than the connection rate (for example,
    setting your software to lock into the 38.4K bps rate,
    and retaining the default &B1 setting).

2.  The call is under data compression.

3.  You're transmitting text files.  Throughput is higher
    for text files than other types of files, such as .EXE
    or .COM binary files.

4.  File transfer may be slowed down by a file-transfer
    protocol.  Many non-text files require a file-transfer
    protocol, but throughput results vary.  Certain public
    domain file-transfer protocols, for example, have the
    following effects.

    Kermit     Newer versions of Kermit support packets up
               to 9K and a sliding window design to
               eliminate turnaround delay.  With earlier
               versions, however, throughput may be severely
               reduced due to short block lengths (possibly
               under 128 bytes) and acknowledgment
               turnaround time.

    Xmodem     Throughput may be reduced if your version
               uses short block lengths, for example 128
               bytes.  Some versions use blocks of 1K byte,
               which is much better, although overhead
               (error control protocol information) still
               affects overall throughput.

    Ymodem     This protocol is similar to Xmodem with 1K
               byte block lengths, and allows multiple files
               to be sent in one transfer.

The above protocols further reduce throughput during error-
control (ARQ) connections.  The accuracy of the data is
checked twice, by the file-transfer protocol and the modem.
To avoid redundancy, disable modem error control by setting
the modem to &M0.

The most current version of Zmodem can yield the most
efficiency.  Leave the modem at its error control default
(&M4) and data compression default, &K1.  Zmodem performs
the same kind of compression as V.42 bis; it turns off its
compression if files are already compressed.

An alternative protocol is Ymodem-G, with the modem left at
its error control default, &M4.  Ymodem-G assumes the modems
are handling error control.  Overhead is minimal, with
throughput almost equal to that obtained with no file-
transfer protocol.

However, keep in mind that Ymodem-G is only useful if the
modems are using error control.  In addition, follow this
recommendation only if your machine and software support
hardware flow control.

NOTE:  Both modems must use the same protocol for data
transfer to take place.

WARNING:  If you are using an X-, Y- or Zmodem-type
     protocol, do NOT use the modem's software flow control.

============================================================
Achievable Throughput Statistics

The table below indicates the maximum throughput, in
characters per second (cps), that can be expected under the
following optimal conditions:

*  Serial port rate set at 57.6K bps; modem set to &B1
   Your software and computer must support 57.6K bps in
   order to use that rate.)

*  Connection (link) rate of 14.4K bps (assuming no
   protective fallback to a lower speed is necessary)

*  V.42 bis compression negotiated for the call, and the
   default size 11-bit, 2048-entry dictionary

*  Straight data (that is, not already compressed, and no
   file-transfer protocol)

*  Transmission from a fast (for example, 386) computer



            Throughput (cps) if set to 14.4K bps

File Type                            MNP5         V.42 bis

Assembler or Compiler listing        2880         3840
Text file                            2325-2625    3400-5760
Binary file:  .EXE                   2175-2400    2030-2600
Binary file:  .COM                   2100-2250    2050-2300
.ZIP files (common on BBS s)*        1500-1650    1700
Random binary 8-bit*                 1460-1575    1700

* These files are already compressed or appear to the modem
to be compressed.  Additional MNP5 compression causes
throughput lower than what can be expected using MNP without
compression.  We recommend setting the modem to &K3 when
transferring these files, to allow V.42 bis but disable
MNP5.



The following table indicates the maximum throughput, in
characters per second (cps), that can normally be expected
in the same conditions as the previous table, but with a
serial port rate of 38.4K bps.

            Throughput (cps) if set to 14.4K bps

File Type                            MNP5         V.42 bis

Assembler or Compiler listing        2880         3840
Text file                            2325-2625    3400-3840
Binary file:  .EXE                   2175-2400    2030-2600
Binary file:  .COM                   2100-2250    2050-2300
.ZIP files (common on BBS s)*        1500-1650    1700
Random binary 8-bit*                 1460-1575    1700








