101.1
From Initq
101.1 Determine and configure hardware settings (weight:2)
- Description
- Candidates should be able to determine and configure fundamental system hardware.
Enable and disable integrated peripherals
BIOS
BIOS is normally installed on a erasable programmable read only memory which is also considered flash. This eeprom thus is upgradeable and normally people get a firmware from their motherboard manufacturer. These updates come in ISO format, flash install or floppy disk files. Normally the motherboard manufacturer will give you one file and give you instructions on how to install that on a proper media, such as cd, flash or floppy. Once you have your media ready then you will boot your computer with that media and follow the instructions to install. This is always the case with all motherboards with the acception of routers and storage devices which might take a firmware update through a web interface but then will need a restart.
POST is power on self test which is done when you turn the power on. It checks the CPU, mem and looks for the first boot media. It then loads the boot loader from the boot device and passes control to the boot loader which loads the OS.
Linux kernel uses the BIOS to collect information about the hardware, once running, it does not use the BIOS services for I/O.
Date & Time
BIOS also controls the hardware clock or the internal clock of the system. The hw clock makes time available to the OS. The OS can also set the hwclock if an external clock is reliable. This is done with ntpd server. You should also look at date and hwclock commands.
Disk and boot devices
BIOS is also the place where all the storage media devices are set. These include Hard drives (sata, pata, scis), flash drives, floppy drives and CD/DVD devices. Once the computer is started it locates the boot devices and goes through the first boot device looking for the boot loader such as grub or lilo.
Configure systems with or without external peripherals such as keyboards
Halt On
Some PCs give you the ability to tell the BIOS specifically which types of errors will halt the computer during the power-on self test section of the boot process. Using this, you can tell the PC to ignore certain types of errors; common settings for this parameter are:
- All Errors: The boot process will halt on all errors. You will be prompted for action in the event of recoverable errors. This is the normally the default setting, and is also the recommended one.
- No Errors: The POST will not stop of any type of error. Not recommended except for very special cases.
- All But Keyboard: The boot process will stop for any error except a keyboard error. This can be useful for setting up a machine without a keyboard, for example for a file or print server.
- All But Diskette/Floppy: All errors will halt the system except diskette errors. In my opinion, if your floppy drive has recurring and known problems, it is most likely best just to replace (or disconnect) the drive rather than using this.
- Warning
- Telling the system not to halt for any error types is generally not wise. You may end up missing a problem with your system that you will want to know about.
Differentiate between the various types of mass storage devices
Set the correct hardware ID for different devices, especially the boot device
Know the differences between coldplug and hotplug devices
Determine hardware resources for devices
All BIOS have an area where IRQs, I/O addresses and DMA channels are assigned to hardware devices.
Interrupts
Interrupts are electrical signals sent to the PC's microprocessor, instructing it to stop its current activity and respond to an asynchronous event (a keyboard, for example).
I/O addresses
I/O address are locations in the microprocessor's memory map (a list of defined memory addresses) reserved for input/output devices such as network interfaces.
DMA
DMA allows some devices to work directly with memory through a DMA channel, freeing the microprocessor for other tasks.
| Device | I/O address | IRQ | DMA |
|---|---|---|---|
| ttyS0(COM1) | 3f8 | 4 | NA |
| ttyS1(COM2) | 2f8 | 3 | NA |
| ttyS2(COM3) | 3e8 | 4 | NA |
| ttyS3(COM4) | 2e8 | 3 | NA |
| lp0(LPT1) | 378-37f | 7 | NA |
| lp1(LPT2) | 278-27f | 5 | NA |
| fd0,fd1(floppies 1 and 2) | 3f0-3f7 | 6 | 2 |
| fd2,fd2(floppies 3 and 4) | 370-377 | 10 | 3 |
