If it's not available in your Linux distribution try: Serial Software for Linux software for the serial ports
including getty and port monitors. Serial Communications for communication programs.
irqtune will give serial port interrupts higher
priority to improve performance. Using hdparm for hard-disk tuning
may help some more.
Low-Level Terminal Interface part of "GNU C Library Reference
manual" (in libc (or glibc) docs package). It covers the detailed
meaning of "stty" commands, etc.
Modem-HOWTO: modems on the serial port
PPP-HOWTO: help with PPP (using a modem on the serial port)
Printing-HOWTO: for setting up a serial printer
Serial-Programming-HOWTO: for some aspects of serial-port programming
Text-Terminal-HOWTO: how they work and how to install and configure
UPS-HOWTO: setting up UPS sensors connected to your serial port
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