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Modem-HOWTO
David S.Lawyer
mailto:dave@lafn.org
v0.12, December 2000
Help with selecting, connecting, configuring, trouble-shooting, and understanding modems for a PC. See Serial-HOWTO for multiport serial boards.
1.
Introduction
1.1 DSL, Cable, and ISDN Modems in other HOWTOs
1.2 Also not covered: PCMCIA Modems, PPP
1.3 Copyright, Disclaimer, Trademarks, & Credits
1.4 Contacting the Author
1.5 New Versions of this HOWTO
1.6 New in this Version
1.7 What is a Modem ?
1.8 Quick Install
2.
Modems for a Linux PC
2.1 External vs. Internal
2.2 External Modems
2.3 Internal Modems
2.4 Software-based Modems (winmodems)
2.5 PCI Modems
2.6 Which Internal Modems might not work with Linux
3.
Modem Pools, Digital Modems
3.1 Analog Modem Pools, Multiport Modem Cards
3.2 Digital Modems
4.
Serial Port and Modem Basics
4.1 Modem Converts Digital to Analog (and conversely)
4.2 What is a Serial Port ?
4.3 IO Address & IRQ
4.4 Names: ttyS0, ttyS1, etc.
4.5 Interrupts
4.6 Data Compression (by the Modem)
4.7 Error Correction
4.8 Data Flow (Speeds)
4.9 Flow Control
4.10 Data Flow Path; Buffers
4.11 Modem Commands
4.12 Serial Driver Module
5.
Configuring Overview
6.
Configuring the Serial Port
6.1 PCI Bus Support Underway
6.2 Configuring Overview
6.3 Common mistakes made re low-level configuring
6.4 I/O Address & IRQ: Boot-time messages
6.5 What is the current IO address and IRQ of my Serial Port ?
6.6 Choosing Serial IRQs
6.7 Choosing Addresses --Video card conflict with ttyS3
6.8 Set IO Address & IRQ in the hardware (mostly for PnP)
6.9 Giving the IRQ and IO Address to Setserial
6.10 Other Configuring
7.
Modem Configuration (excluding serial port)
7.1 Finding Your Modem
7.2 AT Commands
7.3 Init Strings: Saving and Recalling
7.4 Other Modem Commands
8.
Serial Port Devices /dev/ttyS2, etc.
8.1 Serial Port Device Names & Numbers
8.2 Link ttySN to /dev/modem ?
8.3 The cua Device
9.
Interesting Programs You Should Know About
9.1 What is setserial ?
9.2 What is isapnp ?
9.3 What is wvdialconf ?
9.4 What is stty ?
10.
Trying Out Your Modem (Dialing Out)
10.1 Are You Ready to Dial Out ?
10.2 Dialing Out with Minicom
10.3 Dialing Out with Kermit
11.
Dial-In
11.1 Overview
11.2 Getty
11.3 What Happens when Someone Dials In ?
11.4 Why Manual Answer is Best
11.5 Callback
11.6 Voice Mail
12.
Uugetty for Dial-In (from the old Serial-HOWTO)
12.1 Installing getty_ps
12.2 Setting up uugetty
12.3 Customizing uugetty
13.
What Speed Should I Use with My Modem?
13.1 Speed and Data Compression
13.2 Where do I Set Speed ?
13.3 Can't Set a High Enough Speed
13.4 Speed Table
14.
Communications Programs And Utilities
14.1 Minicom vs. Kermit
14.2 List of Communication Software
14.3 SLiRP and term
15.
Troubleshooting
15.1 My Modem is Physically There but Can't be Found
15.2 "Modem is busy"
15.3 I can't get near 56k on my 56k modem
15.4 Uploading (downloading) files is broken/slow
15.5 For Dial-in I Keep Getting "line NNN of inittab invalid"
15.6 I Keep Getting: ``Id "S3" respawning too fast: disabled for 5 minutes''
15.7 My Modem is Hosed after Someone Hangs Up, or uugetty doesn't respawn
15.8 uugetty Still Doesn't Work
15.9 (The following subsections are in both the Serial and Modem HOWTOs)
15.10 My Serial Port is Physically There but Can't be Found
15.11 Extremely Slow: Text appears on the screen slowly after long delays
15.12 Somewhat Slow: I expected it to be a few times faster
15.13 The Startup Screen Show Wrong IRQs for the Serial Ports.
15.14 "Cannot open /dev/ttyS?: Permission denied"
15.15 "Operation not supported by device" for ttyS?
15.16 "Cannot create lockfile. Sorry"
15.17 "Device /dev/ttyS? is locked."
15.18 "/dev/tty? Device or resource busy"
15.19 "Input/output error" from setserial or stty
15.20 Overrun errors on serial port
15.21 Modem doesn't pick up incoming calls
15.22 Troubleshooting Tools
16.
Flash Upgrades
17.
Other Sources of Information
17.1 Misc
17.2 Books
17.3 HOWTOs
17.4 Usenet newsgroups
17.5 Web Sites
18.
Appendix A: How Analog Modems Work (technical) (unfinished)
18.1 Modulation Details
18.2 56k Modems (v.90)
18.3 Full Duplex on One Circuit
18.4 Echo Cancellation
19.
Appendix B: Digital Modem Signal Processing (not done)
20.
Appendix C: "baud" vs. "bps"
20.1 A simple example
20.2 Real examples
21.
Appendix D: Terminal Server Connection
22.
Appendix E: Other Types of Modems
22.1 Digital-to-Digital "Modems"
22.2 ISDN "Modems"
22.3 Digital Subscriber Line (DSL)
22.4 56k Digital-Modems
22.5 Leased Line Modems
23.
Appendix F: Fax pixels (dots)
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