LPI Linux Certification/Configure Modem & Sound Cards

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Configure Modem & Sound Cards

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Detailed Objective

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Weight: 1

Candidates should be able to configure modem and sound card settings.
  • Key knowledge area(s):
    • Ensure devices meet compatibility requirements (particularly that the modem is not an unsupported "win-modem").
    • Verify that correct resources are used by the cards.
    • Configure modem for outbound dial-up.
    • Set serial port speeds.
  • The following is a partial list of the used files, terms and utilities:
    • /proc/dma
    • /proc/interrupts
    • /proc/ioports
    • /proc/pci
    • lspci
    • lsusb


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A modem is a device that lets you send digital data through a telephone line. The four types of modem are:

  • External: Connected through the serial port.
  • USB: Connected through USB.
  • Internal: ISA or PCI board.
  • Built-in: Part of the motherboard.

Most new modems are Plug and Play and you have various ways to deal with it:

  • The serial driver does it all for you.
  • Use the isapnp program.
  • Let a PnP BIOS do the configuration.

To display the configuration of an ISA device, use pnpdump. This utility can dump information (IO ports, interrupts, and DMA channels) that the card uses. To configure any ISA devices, use isapnp. For more information check the man page of isapnp.conf file.

Serial ports

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An external modem can be configured with setserial.

setserial [options] device [parameters]

The available serial ports are:
/dev/ttyS0 (COM1), port 0x3f8, irq 4
/dev/ttyS1 (COM2), port 0x2f8, irq 3
/dev/ttyS2 (COM3), port 0x3e8, irq 4
/dev/ttyS3 (COM4), port 0x2e8, irq 3

Common options:
-a: report all available information on a connected device.

Common parameters:
-port: Port number.
-irq: IRQ number.
-uart: Type of UART permitted (none, 8250, 16450,...).
-autoconfig: Ask the kernel to determine the UART, IRQ number,...
-baud_rate: Communication bandwidth. (Maximum: 115200 bytes/sec)


setserial -g /dev/ttyS*

Dial Out and In

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In order to dial out with a modem, you can use the application setserial or minicom. A configuration file can be created with the -s option.

minicom -s

In order to be able to handle users dialing in, the system needs to be able to start a getty process to handle the dial-in session. The configuration must be done in the /etc/inittab file.

 D1:45:respawn:/sbin/agetty -mt60 19200,9600 ttyS0 vt100
 -m:          tells getty to try to extract the bps rate.
 19200,9600:  bps rate when it receives a BREAK character.
 t60:         timeout of 60 seconds.
 ttyS0:       Port on which the modem is connected.
 vt100:       Terminal type used in the TERM env variable.

Once /etc/inittab is modified, init needs to re-read it.

telinit -q

Sound Cards

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