Next Previous Contents v2.12, July 2001

This document describes serial port features other than those which should be covered by Modem-HOWTO, PPP-HOWTO, Serial-Programming-HOWTO, or Text-Terminal-HOWTO. It does not cover the Universal Serial Bus (see the kernel documentation for USB). It lists info on multiport serial cards. It contains technical info about the serial port itself in more detail than found in the above HOWTOs and should be best for troubleshooting when the problem is the serial port itself. If you are dealing with a Modem, PPP (used for Internet access on a phone line), or a Text-Terminal, those HOWTOs should be consulted first.

1. Introduction

2. How the Hardware Transfers Bytes

• 2.1 Transmitting
• 2.2 Receiving
• 2.3 The Large Serial Buffers

3. Serial Port Basics

4. Is the Serial Port Obsolete?

5. Multiport Serial Boards/Cards/Adapters

6. Configuring the Serial Port

7. Serial Port Devices /dev/ttyS2, etc.

8. Interesting Programs You Should Know About

9. Speed (Flow Rate)

• 9.1 Can’t Set a High Enough Speed
• 9.2 Higher Serial Throughput

10. Locking Out Others

11. Communications Programs And Utilities

• 11.1 List of Software
• 11.2 kermit and zmodem

12. Serial Tips And Miscellany

13. Troubleshooting

14. Interrupt Problem Details

15. What Are UARTs? How Do They Affect Performance?

16. Pinout and Signals

17. Voltage Waveshapes

18. Other Serial Devices (not async EIA-232)

19. Other Sources of Information

20. Appendix: Obsolete Hardware (prior to 1990) Info

• 20.1 Replacing obsolete UARTS

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