1.
Computer form factor
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In computing, the form factor is the specification of a motherboard – the dimensions, power supply type, location of mounting holes, number of ports on the back panel, etc. Traditionally, the most significant specification is for that of the motherboard, Small form factors have been developed and implemented. A PC motherboard is the circuit board within a typical desktop computer. For example, the introduction of AGP and, more recently, however, the standardized size and layout of motherboards have changed much more slowly and are controlled by their own standards. The list of components required on a motherboard changes far more slowly than the components themselves, although it is a slower process, form factors do evolve regularly in response to changing demands. IBMs long-standing standard, AT, was superseded in 1995 by the current industry standard ATX, the latest update to the ATX standard was released in 2007. A divergent standard by chipset manufacturer VIA called EPIA is based upon smaller form factors, differences between form factors are most apparent in terms of their intended market sector, and involve variations in size, design compromises and typical features. Most modern computers have similar requirements, so form factor differences tend to be based upon subsets and supersets of these. The smallest motherboards may sacrifice CPU flexibility in favor of a fixed manufacturers choice, ATX case compatible, Different form factors PC/104 is an embedded computer standard which defines both a form factor and computer bus. PC/104 is intended for embedded computing environments, single board computers built to this form factor are often sold by COTS vendors, which benefits users who want a customized rugged system, without months of design and paper work. The PC/104 form factor was standardized by the PC/104 Consortium in 1992, an IEEE standard corresponding to PC/104 was drafted as IEEE P996.1, but never ratified. The 5.75 ×8.0 in Embedded Board eXpandable specification, as compared with PC/104 modules, these larger SBCs tend to have everything of a full PC on them, including application oriented interfaces like audio, analog, or digital I/O in many cases. Also its much easier to fit Pentium CPUs, whereas its a tight squeeze to do so on a PC/104 SBC, mini PC is a PC small form factor very close in size to an external CD or DVD drive. Mini PCs have proven popular for use as HTPCs, aOpen XC mini Apple Mac mini Intel NUC Gigabyte Brix Zotac ZBOX Asus Vivopc Hard-disk-drive form factors Small form factor The official Intel Form factors website containing form factor descriptions
2.
Printed circuit board
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Components are generally soldered on the PCB. Advanced PCBs may contain components embedded in the substrate, PCBs can be single sided, double sided or multi-layer. Conductors on different layers are connected with vias, multi-layer PCBs allow for much higher component density. FR-4 glass epoxy is the primary insulating substrate, a basic building block of the PCB is an FR-4 panel with a thin layer of copper foil laminated to one or both sides. In multi-layer boards multiple layers of material are laminated together, printed circuit boards are used in all but the simplest electronic products. Alternatives to PCBs include wire wrap and point-to-point construction, PCBs require the additional design effort to lay out the circuit, but manufacturing and assembly can be automated. Manufacturing circuits with PCBs is cheaper and faster than other wiring methods as components are mounted and wired with one single part. A minimal PCB with a component used for easier prototyping is called a breakout board. When the board has no embedded components it is correctly called a printed wiring board or etched wiring board. However, the printed wiring board has fallen into disuse. A PCB populated with electronic components is called a printed circuit assembly, the IPC preferred term for assembled boards is circuit card assembly, and for assembled backplanes it is backplane assemblies. The term PCB is used both for bare and assembled boards. The world market for bare PCBs exceeded $60.2 billion in 2014, initially PCBs were designed manually by creating a photomask on a clear mylar sheet, usually at two or four times the true size. Starting from the diagram the component pin pads were laid out on the mylar. Rub-on dry transfers of common component footprints increased efficiency, traces were made with self-adhesive tape. Pre-printed non-reproducing grids on the mylar assisted in layout, to fabricate the board, the finished photomask was photolithographically reproduced onto a photoresist coating on the blank copper-clad boards. Modern PCBs are designed with dedicated software, generally in the following steps. Card dimensions and template are decided based on required circuitry and case of the PCB, the positions of the components and heat sinks are determined
3.
WTX (form factor)
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WTX was a motherboard form factor specification introduced by Intel at the IDF in September 1998, for its use at high-end, multiprocessor, multiple-hard-disks server and workstations. The specification had support from major OEMs and motherboard manufacturers and was updated in February 1999, as of 2008 the specification has been discontinued and the URL www. wtx. org no longer hosts a website and has not been owned by Intel since at least 2004. This form factor was geared specifically towards the needs of high-end systems and this allowed for standard form factor motherboards and chassis to be used to integrate processors with more demanding thermal management requirements. Bigger than ATX, maximum WTX motherboard size was 14 ×16.75 in and this was intended to provide more room in order to accommodate higher numbers of integrated components. WTX computer cases were backwards compatible with ATX motherboards, and sometimes equipped with ATX power supplies. EATX, a version of ATX which has a factor of 304.8 ×330.2 mm. SWTX
4.
AT (form factor)
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In the area of IBM compatible personal computers, the AT form factor referred to the dimensions and layout of the motherboard for the IBM AT. The IBM AT became a widely copied design in the home computer market of the 1980s. IBM clones made at the time began using AT compatible designs, in the 1990s many computers still used AT and its variants. Since 1997, the AT form factor has been supplanted by ATX. The original AT motherboard, later known as Full AT, is 13.8 ×12 inches, the boards size also means that it takes up space behind the drive bays, making installation of new drives more difficult. The power connectors for AT motherboards are two nearly identical 6-pin plugs and sockets, as designed by IBM, the connectors are mechanically keyed so that each can only be inserted in its correct position, but some clone manufacturers cut costs and used unkeyed connectors. Technicians developed mnemonic devices to assure proper installation, including black wires together in the middle and red and red. These motherboards have similar mounting hole positions and the same eight card slot locations as those with the AT form factor, the size 13 ×8.5 in and flexibility of this kind of motherboard were the key to success of this format. The development of bigger CPU coolers—and the fact that they blocked full-length PCI, while the AT standard is now considered to be mostly obsolete, some industrial computers still use it. In 1995, Intel introduced ATX, a factor which gradually replaced older Baby AT motherboards. During the late 1990s, a majority of boards were either Baby AT or ATX. Many motherboard manufacturers favored Baby AT over ATX as many cases and power supplies in the industry were still designed for AT boards. Also, the lack of a slot on ATX motherboards kept it from being used in some servers. After the industry shifted to ATX motherboard configurations, it common to design cases. The connector at the board is two Molex 15-48-0106 connectors and this mates with a Molex 90331. Motherboards of AT and Baby AT Baby AT Power Supply Baby AT Case Full AT Case Full AT Power Supply ATX Power Supply Links AT power supply connectors with pinouts PC Magazine
5.
BTX (form factor)
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BTX is a form factor for motherboards, originally intended to be the replacement for the aging ATX motherboard form factor in late 2004 and early 2005. It was designed to alleviate some of the issues that arose from using newer technologies on motherboards compliant with the circa 1996 ATX specification, the ATX and BTX standards were both proposed by Intel. The first company to implement BTX was Gateway Inc, followed by Dell, apples Mac Pro utilizes some elements of the BTX design system as well but is not BTX-compliant, rather using a proprietary form factor. Thermal design – The BTX layout establishes a straighter path of airflow with fewer obstacles, there is no dedicated CPU fan – instead, a large 12 cm case fan is mounted, drawing its air directly from outside the computer and cooling the CPU through an airduct. Another distinct feature of BTX is the mounting of the motherboard on the left-hand side. This results in the graphics card heatsink or fan facing upwards, pico BTX motherboards measure 8 ×10.5 in. This is smaller than many current micro-sized motherboards, hence the name pico and these motherboards share a common top half with the other sizes in the BTX line, but support only one or two expansion slots, designed for half-height or riser card applications. Other smaller BTX sizes include, micro BTX at 10.4 ×10.5 in, in the first months of production the ATX and BTX motherboards were so similar that moving a BTX motherboard to an ATX case was possible and vice versa. This was possible because the first BTX motherboards were ATX motherboards turned upside down, later the BTX form factor had a big change by turning it into a mirror image of the ATX standard. Since the new design, both standards are incompatible. Basically BTX motherboards are leftside-right compared to ATX and not upside-down as before, BTX power supply units can be exchanged with newer ATX12V units, but not with older ATX power supplies that dont have the extra 4-pin 12V connector, which was introduced with the ATX12V standard. The BTX form factor has not been widely adopted despite its improvements over ATX, as a result, the availability and variety of BTX-compatible components is limited. Another reason was the lack of OEM adopters, initially, only Gateway and Dell offered computers with the new format, later HP and Fujitsu-Siemens also offered some BTX-based computers. Whatever happened to BTX. org, an Intel-sponsored website dedicated to maintaining data and tools regarding the implementation of various form factors
6.
ATX
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ATX is a motherboard configuration specification developed by Intel in 1995 to improve on previous de facto standards like the AT design. It was the first major change in desktop computer enclosure, motherboard and power supply design in years, improving standardization. The specification defines the key dimensions, mounting point, I/O panel, power. ATX is the most common motherboard design, other standards for smaller boards usually keep the basic rear layout but reduce the size of the board and the number of expansion slots. Dimensions of a full-size ATX board are 12 ×9.6 in, the official ATX specifications were released by Intel in 1995 and have been revised numerous times since. The most recent ATX motherboard specification is version 2.2, the most recent ATX12V power supply unit specification is 2.31, released in February 2008. In 2004, Intel announced the BTX standard, intended as a replacement for ATX, as of 2016, the ATX design still remains popular, while BTX has been introduced by some manufacturers. On the back of the case, some major changes were made to the AT standard. Originally AT style cases had only a keyboard connector and expansion slots for add-on card backplates, any other onboard interfaces had to be connected via flying leads to connectors which were mounted either on spaces provided by the case or brackets placed in unused expansion slot positions. Cases are usually fitted with a panel, also known as an I/O plate or I/O shield. If necessary, I/O plates can be replaced to suit a motherboard that is being fitted, the computer will operate correctly without a plate fitted, although there will be open gaps in the case and the EMI/RFI screening will be compromised. Panels were made that allowed fitting an AT motherboard in an ATX case, ATX also made the PS/2-style mini-DIN keyboard and mouse connectors ubiquitous. AT systems used a 5-pin DIN connector for the keyboard and were used with serial port mice. Many modern motherboards are phasing out the PS/2-style keyboard and mouse connectors in favor of the more modern Universal Serial Bus, other legacy connectors that are slowly being phased out of modern ATX motherboards include 25-pin parallel ports and 9-pin RS-232 serial ports. In their place are onboard peripheral ports such as Ethernet, FireWire, eSATA, audio ports, video, standard ATX provides seven slots at 0.8 in spacing, the popular Micro-ATX size removes 2.4 inches and three slots, leaving four. Here width refers to the distance along the external connector edge, note each larger size inherits all previous colors area. Note, AOpen has conflated the term Mini ATX with a more recent 15 ×15 cm design, a number of manufacturers have added one, two or three additional expansion slots to the standard 12-inch ATX motherboard width. Server System Infrastructure Forums Compact Electronics Bay measures 12 ×10.5 in
