  
 
 
SPORTSTER HIGH SPEED MODEMS
with V.42 bis
Reference Guide 
1994 by U.S. Robotics, Inc.
8100 North McCormick Blvd.
Skokie, Illinois 60076-2999
All Rights Reserved
Revision Date:  9/9/94 
 
TABLE OF CONTENTS 
 
Sportster Configuration 

Factory Configuration (&Fn and Yn)              5 
Permanent Configuration Templates (&Fn)         5 
Programmable Templates (Yn)                     6 
Customizing Your Defaults (&Wn)                 6 
Using AT Commands                               7 
Resetting the Modem (Z)                         8 
 
Placing Calls 

Dial (D)                                        9 
Cancel Dialing                                  9 
Dial Command Options                            9 
Dial Type_Pulse or Tone                         9 
Adaptive Dialing (X2-X4)                       10 
Wait for Another Dial Tone (W)                 10 
Pause (,)                                      10 
Slash (/)                                      10 
Dial and Return to Command Mode (;)            10 
Dialing Letters (")                            11
Transferring Calls (!)                         11 
Wait for an Answer (@)                         11 
Reversing Originate/Answer Frequencies(R)      11 
Dialing Stored Numbers (DSn)                   12 
Redialing                                      12 
Dial the Last Dialed Number (DL)               12 
Re-execute the Last Command (A/)               13 
Answering                                      13 
Suppressing Auto Answer                        13 
Manual Answer                                  13 
Points to Remember                             14 
Disconnecting and Hanging Up                   14 
Escape Code Operations (+++)                   14 
Modem Response to +++                          14 
Returning Online (On)                          14 
Hanging Up (Hn)                                15 
Break Handling (&Yn)                           15 
International Calls                            15 
ITU-T/Bell Answer Sequence (Bn)                15 
Guard Tone (&Gn)                               15 
Pulse Dial Make/Break Ratio (&Pn)              16 
ITU-T V.21_300 bps                             16 
ITU-T V.23_1200/75 bps                         16 
 
Temporarily Changing a Setting 

Tone Dialing                                   17 
Speaker                                        17 
Volume Control (Ln)                            17 
Speaker Control (Mn)                           18 
Local Echo                                     18 
Command Mode Local Echo (En)                   18 
Online Local Echo (Fn)                         18 
S-Registers                                    18 
Result Codes                                   19 
Response Modes (Vn)                            19 
Quiet Mode (Qn)                                19 
Result Code Options (Xn)                       20 
Additional Result Code Options (&An)           21 
Error Control (&Mn)                            22 
Auto Answer with Error Control                 22 
Data Compression (&Kn)                         23 
Data Rate Commands                             23 
Software Requirements                          23 
Serial Port Rate (&Bn)                         24 
Connection Rate (&Nn)                          24 
Flow Control                                   24 
Warning on Software Flow Control               25 
Software Flow Control Precautions              25 
Transmit Data Flow Control (&Hn)               25 
When it is Required                            25 
Received Data Flow Control                     26 
Hardware Control (&Rn)                         26 
Software Control (&In)                         26 
Serial Operations                              27 
Carrier Detect (&Cn)                           27 
Data Terminal Ready (&Dn)                      27 
Data Set Ready (&Sn)                           28 
 
Getting Help 

Inquiries (In)                                 29 
S-Register Query (Sr?)                         31 
Stored Phone Number Query (&Zn?)               31 
Last-Dialed Number Query (DL?)                 31 
Help Screens                                   31 
Stop/Restart Display                           31 
Cancel Display                                 31 
Basic Command Set ($)                          31 
Ampersand Command Set (&$)                     31 
Dialing (D$)                                   31 
S-Register Functions (S$)                      31 
 
Testing the Modem 

Testing with &T                                32 
Dial Test_S16=2                                35 
 
Other Operations 

Fax Operations                                 36 
Voice/Data Communications                      37 
 
Technical Specifications 

Compatibility                                  38 
The Serial Interface                           38 
Default Settings                               40 
 
Modem Concepts 

How Modems Work                                43 
Modem Configuration                            43 
Line Travel                                    43 
Digital Data                                   43 
Flow Control                                   44 
Error Control                                  44 
ITU-T V.42 Handshaking                         44 
MNP Handshaking                                45 
Data Compression                               45 
Flow Control                                   45 
Online Fallback/Fall Forward                   46 
Throughput Guidelines                          46 
Achievable Throughput Statistics               47 
 
			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. (Sportster Mac&Fax modems come with this hardware 
	handshaking cable)
	
&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 &F2Software 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.  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 the 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 to load a programmable template. 

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 
modem, use the following command. 

ATZn <Enter> 

Z0      Resets modem to NVRAM profile selected by Y command 
Z1      Resets modem to NVRAM profile 0 
Z2      Resets modem to NVRAM profile 1 
Z3      Resets modem to factory default profile 0 (&F0) 
Z4      Resets modem to factory default profile 1 (&F1) 
Z5      Resets modem to factory default profile 2 (&F2)  

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.

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.

NOTE:  You cannot issue additional commands on the same line with the 
Z command for the modem will ignore everything following the Z parameter.  
For example:  ATZE1Q0 would be an invalid command.  The modem will ignore 
the E1Q0 portion of the command string. 
 

			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.  The duration of the 
	delay can be changed by using the S8 register.  The default duration 
	of the delay is 2 seconds. 


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 "DIAL USR <Enter> 

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

				ATDT "DIAL USR",,,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 (03) 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 (03).  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.  You can also use a comma (,) 
	to insert a 2-second delay that separates the number. 

			AT DS1/4567 <Enter> 
	
	NOTE:  Do not include modem settings in the &Zn=s string.  If 
	the call requires special 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 
		bis modems and can't answer calls at 9600 bps and above. 


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 with Register S34=8. It is 
also recommended that you force 1200 connections with &N2 and disable 
error correction with &M0 to establish a V.23 connection with the 
following command. 
			AT &M0 &N2 S34=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> 
 

SPEAKER 

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 echoes 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 3 ON, to display result codes.   

Use the Qn command to control the display for a current session, independent 
of the DIP switch setting. NOTE: 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             *      *       *       *       *                   
1/CONNECT        *      *       *       *       *      
2/RING           *      *       *       *       *
3/NO CARRIER     *      *       *       *       *      
4/ERROR          *      *       *       *       *
5/CONNECT 1200          *       *       *       *
6/NO DIAL TONE                  *               *   
7/BUSY                                  *       *
8/NO ANSWER                             *       *   
10/CONNECT 2400$        *       *       *       *             
13/CONNECT 9600$        *       *       *       *             
18/CONNECT 4800$        *       *       *       *             
20/CONNECT 7200$        *       *       *       *             
21/CONNECT 12000$       *       *       *       *             
25/CONNECT 14400$+      *       *       *       *
43/CONNECT 16800$+      *       *       *       *
85/CONNECT 19200$+      *       *       *       *             
91/CONNECT 21600$+      *       *       *       *             
99/CONNECT 24000$+      *       *       *       *             
103/CONNECT 26400$+     *       *       *       *             
107/CONNECT 28800$+     *       *       *       *             

Functions 
			       
Adaptive Dialing                *       *      *             
Wait for 2nd Dial Tone (W)              *      *                    
Wait for Answer (@)                     *      *            
Fast Dial                       *              *    

+ V.FC modems  
$ V.34 modems 

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 30028.8K 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 at reported rate.  Same for results of 
			4800 (18), 9600 (13), 7200 (20), 12K (21), 14.4K 
			(25), 16.8K (43), 19.2K (85), 21.6K (91), 24K (99), 
			26.4K (103), 28.8K (107).  NOTE:  Connections over 
			9600 bps apply to V.32 bis and V.FC modems only.  
			Connections over 14.4K bps apply to V.FC modems only. 

Adaptive Dialing (HUNT) The modem attempts to use tone dialing and, if that 
			doesn't work, reverts to rotary (pulse) dialing. 
Wait for Another        The modem continues dialing as soon as it detects 
    Dial Tone (W)       another dial tone. 
	  
Wait for an             The modem continues dialing when it detects 5 
    Answer (@)          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. 
 

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.  CONNECT/ARQ is displayed if the modem 
	is set to X0 and the connection is 1200 bps and above.  The 
	remaining results indicate connection rate and require X1 or above.  
	If your software cannot handle the ARQ codes, select &A0. 

&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. 

&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.  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 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 115.2K, 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 modem is 
	operating at the same rate.  If not, the Sportster hangs up. 
	The fixed rate options are as follows. 

&N1      300 bps     
&N2     1200 bps         
&N3     2400 bps         
&N4     4800 bps         
&N5     7200 bps 
&N6     9600 bps 
&N7     12,000 bps 
&N8     14,400 bps 
&N9     16,800 bps (V.FC/V.34 only) 
&N10    19,200 bps (V.FC/V.34 only) 
&N11    21,600 bps (V.FC/V.34 only) 
&N12    24,000 bps (V.FC/V.34 only) 
&N13    26,400 bps (V.FC/V.34 only) 
&N14    28,800 bps (V.FC/V.34 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 &F2Software 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, &I15 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) 

The power-on/reset default for Carrier Detect 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 switch setting.  Check your communications software 
manual to find the required setting.  This command may not be stored in NVRAM.   

&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) 

The power-on/reset default for Data Terminal Ready 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 control DTR for a current session, independent of 
the switch setting.  Check your communications software manual to find the 
required setting.  This command may not be stored in NVRAM.   

&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. 

&D3     Reset when DTR drops (toggles).  This  command is the equivalent 
	to S13=1, however it is NOT savable to NVRAM.  If you need to save 
	this command to NVRAM, use S13=1 
 

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      The modem returns a product identifiication string. 

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 S16 (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 modethat is, still connected 
	to a remote modemand 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 loopback 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 Class 1 Fax mode) 
		AT+FCLASS=2.0 <Enter> (Switch to Class 2.0 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, a 1 to indicate Class 1 Fax 
mode or a 2.0 to indicate Class 2.0 Fax Class mode.  Sportster modems are 
not compliant with TR-29 (SSP-2388-A)  Class 2 facsimilie control. 

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 or 303-792-2181 or by fax at 303-843-9880.  

For more information on supported Class 2.0 fax commands, refer to the 
standard for the Service Class 2.0 fax protocol. 
	
	ANSI/EIA/TIA-592-1993 (EIA-592) 
	Asynchronous Facsimile DCE Control Standard 
	May, 1993 


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.  

NOTE:  If the modem is off-hook, the handset will appear to be dead, no sound 
will be heard through the handset.  


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. 

V.34            28.8K/26.4K/24K/21.6K/19.2K/16.8K/14.4K/12K/9600/ 
		7200/4800  /2400 bps (V.34 only) 

V.Fast Class    28.8K/26.4K/24K/21.6K/19.2K/16.8K bps (V.FC/V.34 only) 

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 

EIA/TIA-592     Service Class 2.0 Asynchronous Facsimile DCE Control Standard (V.FC/V.34 only) 

EIA/TIA-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 a 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
	
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. 
 
If you're using a Macintosh computer, ask your dealer for the correct modem 
cable; we recommend a Hardware Handshaking cable. (This cable is included 
with the Sportster Mac&Fax modem)

			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.

Minimum RequirementsSome 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 115.2K, 57.6K and 38.4K bps Serial Port Rates 

	Your software and computer must support the 115.2K, 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. 

	NOTE:  Only V.FC and V.34 modems will support a rate of 115.2K bps. 
 

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 &F2Software 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 Setting 

	Transmit Data Flow Control      &H2 Transmit data software flow 
					    control 
	Receive Data Flow Control       &R1 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                Factory Setting 

	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 
	S51     Bit-mapped functions                    0    (V.FC/V.34 only) 
	S54     Bit-mapped functions                    0    (V.FC/V.34 only) 
	S55     Bit-mapped functions                    0    (V.FC/V.34 only) 
	S56     Bit-mapped functions                    0    (V.FC/V.34 only) 
 
 
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 115,200 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 1odd) 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 (8-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.  Most users communicating with V.42- or 
MNP-compatible modems will want error control at 2400 and 1200 bps, as well.   

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/V.FC modems risk reaching the retransmit limit and 
hanging up.  To prevent this, one of the modems requests that they fall back 
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 V.FC and ITU-T recommendation 
V.32 bis for modems.  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 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 
 
 
 
 

