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Using the modem: Mini PCI Type 3B Data Fax Modem by 3Com User's Guide

Overview • Transferring Data • Faxing

Overview

Your modem allows you to send and receive both data and fax files using your communications software. Your modem can also be used for data

communications with an online service, the Internet, an electronic Bulletin Board System (BBS), or another modem, at up to V.90 speeds.

Your modem can connect at speeds up to 56,000 bits per second (bps), and send or receive faxes at speeds up to 14,400 bps. With V.90

technology, your modem is capable of receiving at up to 56 Kbps and sending at up to 31.2 Kbps. Actual download speeds you experience may

be lower due to varying line conditions. Compatible phone line and server equipment are required.

Your modem supports class 1 faxing. If problems arise when you attempt to fax, we suggest you try changing the fax class.

Transferring Data

Because your modem is optimized for Windows, it takes advantage of the Windows interface and the capabilities of your computer to achieve

faster data transfers than a regular modem.

Terminal Emulation Protocols

You may be required to designate a terminal emulation protocol to use for data transmission. Various computer systems use different types of

terminal emulation, such as IBM 3270, TTY, DEC, or ANSI. Contact the system operator of the host modem you are dialing into to determine the

type of emulation to use for that connection. If the system operator is unknown, try using the ANSI terminal emulation protocol.

File Transfer Protocols

File transfer is the ability to transport files between two computers via two modems. The modem must use a file transfer protocol (ftp), which can

correct errors in transmission and begin the file transfer process. Both modems must use the same file transfer protocol.

At the time you set up a file transfer, your communications software will prompt you to designate a file transfer protocol. The following table

describes some of the most common protocols:

Protocol

Description

ZMODEM

Transfers files in a streaming protocol, making it very fast even with error correction. Also provides an automatic receive function

that saves you steps when receiving data.

YMODEM-

A variation of YMODEM designed for modems that support error control. Does not provide error correction or recovery, but relies

on the modem to provide it. If any block is unsuccessfully transferred, the entire transfer is canceled.

YMODEM

An error correcting file transfer data transmission protocol that sends information in 1024-byte (1k) blocks. Checksums are done

on each block and the result is sent along with the block. If the result does not check out at the receiving end, a NAK (Negative

AcKnowledgement) is sent to retransmit that block. If the block checks out, an ACK (ACKnowledgement) is sent.

XMODEM

An error correcting file transfer protocol that sends informaton in 128-byte blocks. Checksums are done on each block and the

result is sent along with the block. If the result does not check out at the receiving end, a NAK (Negative AcKnowledgement) is sent

to retransmit that block. If the block checks out, an ACK (ACKnowledgement) is sent.

KERMIT

A very reliable asynchronous file transfer protocol that can communicate successfully with virtually any system. Because of this

portability, throughput is significantly reduced.

ASCII

Sends TEXT ONLY files directly to the computer screen. Is very slow. Binary or graphics files cannot be transferred using the ASCII

protocol.

Rules for Using File Transfer Protocols

For the best results when sending or receiving a file, follow these basic rules:

If both systems support ZMODEM, use it!

Both the sending and receiving modem must use the same file transfer protocol. BBS or online services usually inform you which protocols

are available.

Most communications software packages must be informed of the name of the sending (uploading) or receiving (downloading) file before file

transfer can begin, and when a file transfer is about to take place. See your communications software manual for specific information.

CAUTION: When files are shared, the risk of getting a computer virus always exists. We recommend the use of virus scanning

software to make sure the files you receive and send do not contain viruses.

Sending a Data Transmission

All communications software allows for automatic dialing. See your software documentation for instructions.