LPIC 1 Topic 101: System Architecture | 101.1

101.1 Determine and configure hardware settings

Enable and disable integrated peripherals

BIOS (Basic Input/Output System) can be used to enable or disable hardware/peripherals. Main hardware components that are managed by the BIOS are ATA HDD interfaces, I/O addresses, DMA addresses etc.

BIOS lives on Flash memory and is called upon as soon as the computer is turned on. BIOS works in this order after it is called in:
1. performs POST (Power On Self Test)
2. initializes Hardware
3. calls in the BootLoader
4. passes control to the BootLoader

IRQs (Interrupt Requests) are signals used to interrupt the current CPU activity as soon as an external event occurs (like mouse movement or keyboard input).
Some important IRQs that are good to know:

0 - System Timer
1 - Keyboard
9, 10 & 11 - Open interrupts
14 - Primary ATA controller
15 - Secondary ATA controller

To check IRQs on a running system:
# cat /proc/interrupts

I/O Addresses - unique locations in memory reserved for specific hardware


DMA Addresses - Direct memory addressing allows a device to directly transmit data to the memory, bypassing the CPU completely. This improves overall performance. 

To check DMA channels:
# cat /proc/dma

Configuring devices:

ISA and PCI
ISA devices are mostly onfigured today using the in-built functions in the kernel. These functions invoke the drivers from the kernel in order to configure most plug n play devices.
To retrieve the current configuration of the ISA PnP devices:
# pnpdump > isapnp.conf

This write the current configuration to the file isapnp.conf 
Once you've made changes to this file, you can load it back:
# isapnp /etc/isapnp.conf

PCI devices are configured automatically most of the times. 
setpci is a utility that can be used to change low-level configuration on hardware.

Modems
RS-232 serial port is what modems use 
#setserial /dev/ttyS0 - shows the basic info for the RS-232 port

setserial cmd can be used to set the speed of the modem etc.

USB devices
There are three types of controllers for USB in Linux:
UHCI - Universal Host Controller Interface (USB 1.x)
OHCI - Open Host Controller Interface (USB 1.x)
EHCI - Enhanced Host Controller Interface (USB 2)

USB is hot-pluggable technology - can be added while the computer is on.


Sound Cards

sndconfig (Red Hat) - program used to check sound-card related config files


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