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Without an Operating System, your computer would just sit there and do nothing. If switched on, you would see an error message such as "No Operating System".
The OS's job is to turn the hardware into a functional system. Operating systems also run applications, an application is a program like a text editor, or a spreadsheet, firefox is another app used to browse the internet.
Just about everyone will have heard of Microsoft Windows and Apple Computers Mac, but there are alternatives, most of which are free. Of alternative operative systems, Linux, FreeBSD and Solaris are most popular. However many others exist like Syllable, Haiku and OS2.
OS Requirements:The first requirement of an OS is that it correctly recognises and works with your available hardware. If you choose wisely in the hardware section, then from internet and forums advice, you will have already sought out individual components that collectively work well together. A secondly consideration is the applications that you will use. Windows comes with a simple word processor and several games, a paint program and mail program. Any dedicated software requires to be purchased. Linux has a growing database of around 28,000 packages. It is quite likely that there are already free alternatives to software you already use.
Partitioning and FileSystems
Before a hard drive can be used it has to be divided into sections called partitions, and a partition table created. This is done automatically or manually by the operating system when installing a new OS.
After a partition has been made, a filesystem is created. The format command will create the new filesystem on the partition. If you only want a single OS, for example, windows, then you can create a single partition using 100% of the hard drive and format it. Windows computers uses either FAT32 or NTFS filesystems. Other OS, e.g. linux can use a variety of filesystems, ext3, ext4, resiser and btrfs being popular examples.
The Master Boot Record MBR
When powering up your computer the last check your BIOS does is check for a valid MBR signiture, before passing control to the operating system. Once control is passed, then the operating system will take over, initialising all hardware and loading the OS.
The MBR is the first 512 bytes of the hard disk and contains the partition table and boot code. The boot code is standard for windows, but can change if other OS's write their code to the mbr. For example, Linux commonly uses grub as a bootloader and FreeBSD and Mac will uses Darwin as a bootloader. A corrupt partition table, or MBR will result in a non-booting system. If this should happen then you must use a recovery disk that does not read the MBR to boot, linux live CD's are particularly good at recovery.
Partitioning and Installing WindowsIf you install windows XP or Windows 7 for the first time, the windows CD or DVD will detect your hard drive and ask if you would like to partition your hard disk. You should answer yes and then decide how much space to use. (If you only plan to install a single version of windows then choose 100%.) After deciding on space, windows will ask you to confirm your choice and then format the hard drive; this can be a lengthy process, 45 minutes or even longer depending on the size of your drive. The filesystem on windows XP and later, defaults to NTFS, and once created, the windows CD (or DVD if installing windows 7) will install all required files. A couple of reboots later, you will have a working windows system. You may have to install various drivers for hardware, such as graphics card, sound card, printers etc, if the hardware is not recognised.
Partitions on Windows (all versions)
A partition is just a container or a section of a hard drive that will be used as storage. You can create partitions to be used as backup, storage for images, or a partition used to install windows.
Windows calls partitions "volumes" and assigns a single alphabet letter to a volume. For almost everyone, this will amount to the "C" drive being used as the windows volume, "A" and "B" are used for older floppy disk drives. Partitions may be created as primary or extended. A primary partition is one of the first 4 partitions on the hard drive. An extended partition is a container for logical drives, (see next paragraph).
On computers using an Intel partition table, you can only have 4 primary partitions. To create more than 4 partitions, then one of the primary partitions, must be used as an "extended partition". The extended partition acts as a container for all the partitions in the extended section. A partition formatted in the extended area, is called a "logical drive". Windows assigns a single alphabet letter to logical drives as well. Note that the single letter naming convention "C", "D", etc does not give any information about the partition itself, whether it is primary or logical, or even which drive it belongs to.
Viewing partitions on WindowsTo assist anyone posting in forums about windows XP and later, please do not post information about "C" or "D" drives. Instead open a command prompt and type the following commands:
list disk This will show the hard drives in your computer, the first hard drive starts at 0. Select disk 0 will use the first hard drive.
diskpart This runs the windows disk partition program to interrogate drives and volumes.
list partition Will list partitions on the selected disk in partition order. This means that partition 1 to 4 are primary, and 5 and above are logical drives. If an extended partition is displayed, there will be logical drives.
list volume This command will list the volumes and assigned drive letter, filesystem type, (NTFS or FAT32) and volume size.
The screenshot above shows one of my early partitioning schemes. Primary partition 3 was formatted for FreeBSD
and used a filesytem called A5. Any file system not recognised by windows will be shown as unknown. The 4th primary
partition is extended and partitions, 5, 6 and 7 are logical drives.
The volume information shows volume C as NTFS filesystem and size 128GB. Volume D is the CDROM and volume E is
Windows 7 on the same hard drive. Note that volume information is not the same as partition order, which is why it
is very useful to post the outputs of both list volume and list partition if posting on forums.
TechSupportForum Covers, windows, hardware and many other topics.
Dual Multi Boot Systems
Windows always requires the first partition. If installing Windows XP and Windows 7, then install XP first. After installing Windows 7, the windows 7 boot loader will find windows XP and next boot you will have a black and white text menu giving you a choice to boot XP or Windows 7.
Multi Boot with Linux
If you decide to install linux alongside windows, then install windows first, but make sure you have sufficient space to install linux. About 20G should be ample, but you can allow more space. Linux uses its own bootloader (the bootloader is a program allowing you to choose which OS to load at boot time) and will usually be written into the master boot record (MBR). Bootloaders for linux include, grub legacy, grub2 and burg. Each time you install linux it will overwrite the MBR and control booting of all installed operating systems. If you have windows installed, then install linux last of all, windows will be detected and included in the menu of the linux bootloader.
My Computer
Overall Performance
I am very pleased with my finished computer. There will always be new hardware and faster components but I have built a system that is fast, stable and so far given me no problems. The screenshot below is a benchmark from 3DMark06. This was running on windows XP and came out at 16078 marks:
It is of course, possible to improve and build a better,faster computer. Overall, your PC can only be as fast as the slowest component, so there's no point in buying the faster Intel i7 CPU, and putting in a slow graphics card. If you need a fast gaming computer, then every component needs to be optimum.
Final WordsBuilding a new computer is a bold challenge. Congratulations if you have successfully built yourself a new computer, after reading this tutorial. Assembly is not too difficult, a little more skill is required in partitioning, tuning and setting up multi operating systems.
If you have installed linux or freebsd, or an alternative to microsoft windows, then you have taken your first step into a much larger world of computing. To further your knowledge there are many internet forums, covering all aspects of hardware, software, and programming.
The Linux from Scratch project allows you to create a linux system to your own design, which will give you an even greater knowledge of how everything works together.