There are AT, Baby-AT, ATX, Micro ATX, LPX, NLX, Flex ATX, EATX, WATX, and BTX structures. Among them, AT and Baby-AT are the old motherboard structure many years ago, now has been eliminated; while LPX, NLX, Flex ATX is a variant of ATX, mostly found in foreign brand-name machines, not yet common in China; EATX and WATX are mostly used in the server/workstation motherboards; ATX is the most common motherboard structure on the market, with a large number of expansion slots and 4-6 PCI slots. -ATX is the most common motherboard structure on the market today, with more expansion slots and 4 or 6 PCI slots, most motherboards use this structure; Micro ATX, also known as Mini ATX, is a simplified version of the ATX structure, which is often referred to as "small board", with fewer expansion slots and 3 or less PCI slots, and is mostly used for branded machines and equipped with a small chassis; BTX is the latest generation of motherboard structure developed by Intel. The BTX is the latest generation of motherboard architecture developed by Intel.
1, PCAT motherboard
In the third year after the launch of the PC that is, in 1984, IBM announced the PCAT. AT motherboard dimensions of 13 "× 12", the board integrated with the control chip and eight I / 0 expansion slots. Because of the larger size of the AT motherboard, the system unit (chassis) was increased by 2 inches horizontally and 1 inch in height, a change that was also made to support the new larger size AT format adapter cards. The 8-bit data, 20-bit address XT expansion slot was changed to a 16-bit data, 24-bit address AT expansion slot. To maintain backward compatibility, it retains the 62-pin XT expansion slot and then adds 36-pin expansion slots in the same column. the XT expansion card still uses the 62-pin expansion slot (31 pins on each side), and the AT expansion card uses ***98 pins in two expansion slots in the same column. This evolutionary strategy for the PC AT bus architecture allows it to still function properly on any PC Pentium/PCI system today. The initial design of the PC AT was to have the expansion bus run at the same clock rate as the microprocessor, i.e., 6MHz for a 6MHz 286 and 8MHz for an 8MHz microprocessor. as the microprocessor speed increased, it was simple to increase the speed of the expansion bus. Later, some PC AT systems had expansion bus speeds of 10 and 12 MHz; unfortunately, some adapters did not work at these speeds or worked well enough. As a result, the vast majority of PC ATs still use 8 or 8.33 MHz as the expansion bus rate, and most adapters do not work consistently at this speed. AT motherboard size is larger, the board can place more components and expansion slots. However, as the degree of integration of electronic components increases, the same function of the motherboard no longer need the full size of the AT. As a result, the Baby/Mini AT motherboard specification, referred to as the Baby AT motherboard, was introduced in 1990.
2, Baby AT motherboard
From the earliest XT motherboards inherited, it is the size of 15 "× 8.5", than the AT motherboard is slightly longer than the width of the AT motherboard is much narrower than the AT motherboard. Baby AT motherboards inherited AT motherboards, such as the I / 0 expansion slots, keyboard sockets, and other peripheral interfaces and components of the placement of the position of the memory slots, such as the structure of the internal components of the tight, coupled with large-scale integrated circuits to make the AT motherboards. Tightening, coupled with large-scale integrated circuits to reduce the number of internal components, making Baby AT motherboards more compact than AT motherboards layout and functionality is not reduced. But with the further development of computer hardware technology, computer motherboard integrated features more and more, Baby AT motherboard is a little heavy load, while the AT motherboard is too large, so many motherboard vendors have taken another compromise program, that is, on the one hand, the cancellation of the use of fewer parts on the motherboard to compress the space (such as I / 0 expansion slots into seven or even six, on the other hand, the Baby AT motherboard) On the other hand, the Baby AT motherboards are widened to increase the usable area, which results in a large number of Baby AT motherboards with different specifications. Of course, these motherboards do not change the location of the basic I/0 slots, peripheral ports and motherboard mounting holes, allowing even the smallest Baby AT motherboards to be used in standard chassis. The most common Baby AT motherboard size is the 3/4Baby AT motherboard (26.5cm x 22cm i.e. 10.7" x 8.7") and utilizes 7 I/0 expansion slots. Because the Baby AT motherboard market is not standardized and the AT motherboard structure is too old, Intel announced the extended AT motherboard structure in January 95, that is, ATX (AT extended) motherboard standard. This standard is supported by the world's major motherboard manufacturers and has now become the most widely used industry standard. in February '97, ATX version 2.01 was released.
3, ATX structure of the motherboard
Baby AT structure of the standard first manifested in the motherboard lateral width is too narrow (generally 22cm), so that the interface directly from the motherboard space is too small. Significantly limit the number of external interfaces, which for the function of more and more strong, more and more external interfaces for the microcomputer, is an insurmountable shortcoming. Secondly, the placement of CPU and I/0 slots on the Baby AT motherboard is not reasonable. Early CPUs did not require much heat dissipation due to low performance and low power consumption. While today's CPUs have high performance and high power consumption, in order to make them work stably, it is necessary to have a good heat sink, add heatsinks or fans, thus greatly increasing the height of the CPU. In the AT architecture standard the CPU is located below the expansion slots, making it impossible to plug in many full-length expansion cards or preventing the CPU fan from running when plugged in. The location of the memory was also not reasonable. Early computer memory size is fixed, there is no special requirements for the installation of the location of the Baby AT motherboard in the structure of the customary memory slots placed in the chassis under the power supply, installation, replacement of memory sticks often have to remove the power supply or motherboard, very inconvenient. The heat dissipation condition of the memory stick is also not good. In addition, due to the soft disk controller and soft disk bracket does not have a specific location, which results in a soft disk cable is too long, increasing the computer's internal wiring confusion, reducing the reliability of the computer. Even the speed of many high-speed hard disk drives is affected due to the long hard disk cables.ATX motherboards have made the following improvements to address the shortcomings of the AT and Baby AT motherboards: The motherboard shape has been rotated 90 degrees from the Baby AT, and its geometric dimensions have been changed to 30.5cm x 24.4cm. Seven I/O slots are used, which makes the location of the CPU and the I/O slots, and the memory slots more reasonable. Optimized the location of the floppy hard disk drive interface. Improved motherboard compatibility and expandability. Adopts enhanced power management to truly realize software power on/off and green energy saving function of the computer. Micro ATX maintains the peripheral interface positions on the back panel of ATX standard motherboards for ATX compatibility.
4. MATX structured motherboards
Micro ATX motherboards reduce the number of expansion slots to 3-4, and the number of DIMM slots to 2-3, reducing the width of the motherboard horizontally, and decreasing its total area by approximately 0.92 square inches, making it a much more compact design than the standard ATX motherboards. According to the Micro ATX standard, graphics and audio processing should also be integrated on the board. Currently, many brand-name motherboards use the Micro ATX standard, and Micro ATX motherboards are often seen in the DIY market. BTX stands for Balanced Technology Extended, a new motherboard architecture proposed by Intel as a replacement for the ATX architecture, similar to how ATX replaced AT and Baby AT in previous years. The revolutionary change is that the new BTX specification is able to achieve the smallest size without sacrificing performance. The new architecture will have new requirements for interfaces, buses, and devices. The important thing is that all the current cluttered, wired-up, noise-filled PCs will soon be obsolete. Of course, the new architecture still offers some degree of backward compatibility to allow for a smooth transition to the technological revolution.
5. BTX has the following features:
Supporting Low-profile, or narrow-board, design, the system structure will be more compact; BTX structured motherboards
Optimized design of the motherboard's wiring layout for the movement of heat dissipation and airflow; Motherboards will be simpler to install, and the mechanical properties will be optimally designed. Moreover, BTX offers great compatibility. There are already several BTX derivatives available, divided into standard BTX (325.12mm), microBTX (264.16mm), low-profile picoBTX (203.20mm), and the future Extended BTX for servers, depending on the width of the board. In addition, new buses and interfaces that are currently popular, such as PCI Express and Serial ATA, will also be well supported in the BTX architecture motherboards. It is worth mentioning that the new BTX motherboards will optimize the cooling system, especially for the CPU, through the pre-installed SRM (Support and Retention Module). Also, the cooling system is known as a thermal module in BTX terminology. Generally, the module includes a heat sink and airflow channels. There are two types of thermal modules that have been developed so far, namely full-size and low-profile. Thanks to the continuous application of new technologies, future BTX motherboards will also completely eliminate the traditional serial, parallel, and PS/2 ports.
6. Mini-ITX motherboards:
Mini-ITX motherboards
Mini-ITX is a motherboard specification promoted by VIA Technologies, Inc. that can be used in microATX or ATX chassis, and measures 17 x 17 centimeters, which is just about right to include four mounting screws and an expansion slot. Mini-ITX is mainly used for embedded systems due to its low expandability. Intel has also released a desktop system motherboard using the Mini-ITX specification, measuring 171.45mm x 171.45mm, but labeled as "uATX" rather than Mini-ITX on the web site. ITX motherboards are much smaller than regular ATX and mATX motherboards, and are quite versatile. ITX motherboards are much smaller than regular ATX and mATX motherboards and are quite versatile. Integrated CPU ITX motherboard can greatly reduce the cost of the platform set up to Intel integrated ATOM ITX motherboard, for example, the motherboard is priced at 499 yuan, plus 2G of memory is about 150 yuan, the power supply is about 150 yuan or so, for different users of the hard disk requirements are different if it is a download user with a 1TB hard disk 599 yuan, the entire platform cost of 1398 yuan, far more than the cost of assembling a low-cost computer. Assembling a low-priced computer is much cheaper, and the price may be cheaper than the 1TB NAS sold on the market, the function is more powerful than NAS.