Yet another in the LPI Certification. We’ve already covered a lot of this stuff before but no harm to review it again.
LPIC topic 1.101.6 — Configure Communication Devices 
Candidates should be able to install and configure internal and external communication devices such as modems, ISDN adapters, and DSL switches. This objective includes verification of compatibility requirements (especially important if that modem is winmodem), necessary hardware settings for internal devices (IRQs, DMAs, I/O ports), and loading and configuring suitable device drivers. It also includes communication device and interface configuration requirements, such as the correct serial port for 115.2 Kbps, and the correct modem settings for outbound PPP connection(s).
Key files, terms, and utilities include:
/proc/dma Direct memory accessing channels in use
/proc/interrupts Interrupts in use
/proc/ioports I/O ports in use
setserial(8) Configure serial port access for an internal modem