Motherboards


The functions - BIOS and POST

As we mentioned earlier, the motherboard also houses the BIOS (the basic input/output system). An integral part of the PC, the BIOS controls the simplest configuration of your machine, and performs the POST (power on self-test) health check. This determines whether the computer's various components, such as the keyboard, memory, disk drives, and other hardware, are functioning properly.

If all the necessary hardware is detected and found to be running smoothly, the computer will start up. If, however, the hardware is not detected or is malfunctioning, the BIOS issues an error message, which may take the form of text on the display screen and/or a series of coded beeps, depending on the nature of the problem. These warning beeps or alerts will vary from board to board, depending on which type of BIOS is installed.

Some motherboard manufacturers for example, have introduced voice warnings into their POST reporters, while others will display error messages on-screen.


DualBIOS

A recent innovation to BIOS is DualBIOS technology. The purpose behind DualBIOS is to provide a backup to the primary BIOS. If the main BIOS chip fails, for whatever reason, the second BIOS chip automatically takes charge of the system and keeps it running.

For instance, if the BIOS data has become corrupted but the chip is still functioning electronically, the DualBIOS utility will issue a series of automatically activated features via the second BIOS chip, which allow you to restore the primary BIOS to health. This is particularly useful against viruses targeted at disabling your BIOS.

If the primary BIOS chip has an electronic fault, the second chip simply takes its place.

DualBIOS makes this possible through its built-in one-way flash utility, which can flash your system's BIOS from backup to main and vice versa. Because the second BIOS chip is your computer's BIOS backup, all of the good information will have been stored automatically.


RAID-controller

Another controller you may find on-board is RAID, which is short for Redundant Array of Independent Disks and basically refers to various methods used to store or span data across multiple hard disks.

The basic principle behind RAID is to combine multiple drives into what the operating systems will recognise as a single drive, improving performance, capacity and reliability of transferring data.

RAID achieves this by establishing multiple drives into an array of drives, which can be read and written to in parallel. This allows the system to retrieve large amounts of data from several sources at the same time. Retrieving several sections of data simultaneously increases the speed with which the data is transferred.

Six different types of RAID are available, ranging from the basic RAID 0 to RAID 5. They vary in the level of redundancy, data storage techniques and multiple drives they support.

RAID 0 employs the technique of striping, in which data is divided into a variety of units, ranging in size from 512 bytes up to sectors of several megabytes. These "stripes" are then interleaved around the drives, so that data is situated across multiple drives.

RAID 0 doesn't really fit with the concept of RAID as it offers no redundancy of data, i.e., if any of the drives in the chain fail, all data is lost. By using the striping technique, RAID 0 can improve the performance of the system and increase the speed with which data is transferred. This is great for applications that need very high-speed storage, such as image or photo programs.

RAID 1 does not use striping techniques but, instead, uses disc mirroring to improve the performance of your PC. Much like manually backing up your data from your hard drive to a storage disc, RAID 1 allows you to make a copy of data on one drive on another - in other words, mirroring the two drives. This can be beneficial, because if one drive fails, a complete copy of all your data is accessible on the other. This is known as fault tolerance. This mirroring process can also hasten the reading of information from your drives, as both drives can be read at once. It does, however, halve your storage capacity.

Higher levels of RAID, such as RAID 3, 4 or 5, also use parity techniques, which involve checking whether data has been lost or written over when moved from one place in storage to another or when transmitted between computers. Some RAID versions will store parity information on one dedicated drive, and others will rotate the information across all of the drives.

A range of motherboards on the market today offers built-in RAID controllers for desktop PCs, but they will generally only offer RAID 0 or RAID 1 support. Some will also support JBODS (just a bunch of disks), which unifies an arbitrary set of disks into a single logical "drive"; and RAID 0+1, which combines striping with mirroring. You won't find many motherboards in this space that come with built-in support for higher levels of RAID.

However, if you buy a board without RAID support but are keen on using RAID, hardware RAID controllers will communicate with the system and hard drives through either the SCSI or IDE/ATA interface. The more complicated and high-end RAID types, such as 3 or 4, are usually based on SCSI, so if you want to use these types of RAID, you will need to purchase a motherboard with a SCSI interface (again, a more expensive choice).

Hardware RAID is divided into internal and external RAID controllers. The internal RAID controllers are usually controller cards that are installed in the bus system of the computer - and look much like a SCSI or IDE adapter.

External RAID puts the controller into a case of its own. These are more often seen in high-end servers, which will employ a separate enclosure to house both the RAID controller and the hard drives. The interface used for external RAID is commonly SCSI.

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PC World Staff

PC World

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