Can Linux Use More than 3 Serial Ports by Sharing Interrupts?

This article is from the Frequently Asked Questions for Linux, the Free/Open Source UNIX-like operating system kernel that runs on many modern computer systems. Maintained by David C. Merrill with numerous contributions by others. (v1.0).
A: Yes, but you won't be able to use simultaneously two ordinary ports which share an interrupt (without some trickery). This is a limitation of the ISA Bus architecture.

See the Serial HOWTO for information about possible solutions and workarounds for this problem.

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