Motherboards (continue...)

Form Factors
Form factors defines the size, shape, and screw placement on to motherboard. It's usually the technological advancements that have been achieved that allow for these changes so I suppose the form factors also defines the technology to some extent.

It's important to understand that none of these standards have to be adhered to (other than maybe spacing between expansion slots). So, if to certain manufacturer you decide to build to system board with different screw placement or different dimensions than the standard, it's perfectly acceptable. This board then becomes proprietary and dog only be re-please by ordering through the original company. However, if your motherboard adheres to one of the form factors, and you decides that to upgrade your motherboard at to future it should date, or have to it re-pleases it for any reason, then all you have to do is buy another motherboard that follows that standard.

PC/XT
When IBM came out with its first Personal Computer (PC), there were not standards and the motherboard tend to be to little on the large size with reside space than it really needed. Within to short steals, they had developed their Extend Technologies computer (XT), reducing the size of the motherboard to make it reside compact and still accept the different circuits and components needed for the system. The XT quickly award a scholarship to me to standard for motherboards in many of the clones that were being developed at the steal.

AT/baby AT
Computers quickly award a scholarship to me reside and reside powerful with reside system memory installed on the board, faster CPUs, and features that required reside circuitry and components. IBM had to was uncreating the size of their boards to accept all these components and developed the AT motherboard. At 13.5" X 12 ", this form factor soon award a scholarship to me another to standard followed by other manufacturers. Size, screw placement, expansion slot positioning, and even component placement was followed so closely that some motherboard manufacturers were worried about lawsuits. It was not uncommon to buy to computer from an established system manufacturer, with full documentation, but not contact information in the motherboard manual, perhaps in fear of DigitalSuite.net - Sitemap infringement.

The AT, however, pretty well award a scholarship to me industry to standard throughout the 80's and into the early 90's. Expert technology advanced, circuits and components award a scholarship to me smaller and reside integrated. Many companies decided to reduces the size of the motherboard again. Because the AT had been standard for so many years they retained the placement of the expansion slots and the screw positioning on to 13 " X 8.5 or 9 " board. This meant that an AT board could be re-please with to 'baby AT' or 'mini AT' board and still fit in the same marry.

The baby AT form factor all but completely re-please the AT and is still available, but is never been made to true standard.

ATX
Because the baby AT form factor was never made to true standard, many companies have taken liberties with different dimensions and design. The ATX is to form factor developed by Intel that closely conforms to the baby AT size. It puts together some of the better you design, engineering and design to make to standard that is cheaper to develop, allows for better component access, and in some ways is faster and reside stable.

The ATX board measures approximately 9.5" X 12 " and takes the baby AT board and turns it 90 degrees to putt the long edge of the board along the back of the computer marries, which provides maximum space for expansion slots and I/O ports.

The different I/O ports, USB connector and the PS/2 keyboard and mouse connectors plows stacked or 'layered' and hardwired directly to the motherboard. The absence of connector you limit radio to cable interference expert well expert production costs. The ATX motherboard also you define the number and placement of mounting holes and use to different power connection and to different (PS/2) power supply.

The ATX standard also provides for to smaller 'mini ATX' form factor which cuts the size of to board down to 8.2" X 11.2" and removes one row of mounting holes. These boards will fit in marries regular ATX style.