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73-415: The original PC/104 form factor is somewhat smaller than a desktop PC motherboard at 3.550 × 3.775 inches (90 × 96 mm). Unlike other popular computer form factors such as ATX , which rely on a motherboard or backplane , PC/104 boards are stacked on top of each other like building blocks. The PC/104 specification defines four mounting holes at the corners of each module, which allow

146-423: A BIOS , as did the boot ROM on the original IBM PC, or UEFI . UEFI is a successor to BIOS that became popular after Microsoft began requiring it for a system to be certified to run Windows 8 . When the computer is powered on, the boot firmware tests and configures memory, circuitry, and peripherals. This Power-On Self Test (POST) may include testing some of the following things: Interrupt request In

219-935: A Board Support Package is usually provided by the manufacturer for the supported operating system(s). When printing "PC/104" or its variants, it is common for the forward slash or dashes to be omitted. PC/104 may be abbreviated as PC104, PCI-104 abbreviated as PCI104, etc. Additionally, it is common for PC/104- Plus to be abbreviated with a plus sign (e.g. PC104+). Such abbreviations are not officially recognized in any PC/104 Consortium specifications or literature, however they have been in use for some time. PC/104 systems often require small, non-volatile storage, such as that afforded by compact flash and solid state disk (SSD) devices. These are often more popular than mechanical (rotating) hard drives. Compared to rotating disks, flash-based storage devices have limited lifetimes in terms of write cycles, but they are faster and draw less power. Additionally, their compactness and physical durability

292-428: A CPU board , power supply board, and one or more peripheral boards, such as a data acquisition module, GPS receiver, or Wireless LAN controller. A wide array of peripheral boards are available from various vendors. Users may design a stack that incorporates boards from multiple vendors. The overall height, weight, and power consumption of the stack can vary depending on the number of boards that are used. PC/104

365-426: A computer , an interrupt request (or IRQ ) is a hardware signal sent to the processor that temporarily stops a running program and allows a special program, an interrupt handler , to run instead. Hardware interrupts are used to handle events such as receiving data from a modem or network card , key presses, or mouse movements. Interrupt lines are often identified by an index with the format of IRQ followed by

438-615: A water cooling system instead of many fans. Some small form factor computers and home theater PCs designed for quiet and energy-efficient operation boast fan-less designs. This typically requires the use of a low-power CPU, as well as a careful layout of the motherboard and other components to allow for heat sink placement. A 2003 study found that some spurious computer crashes and general reliability issues, ranging from screen image distortions to I/O read/write errors, can be attributed not to software or peripheral hardware but to aging capacitors on PC motherboards. Ultimately this

511-609: A 156-pin surface mount connector for the PCI Express signals. The new connector occupies the same board location as the legacy PC/104 ISA connector. In addition to PCI Express, the specifications also defines pins on the connector for additional modern computer buses, such as USB , SATA , and LPC . The PCI/104-Express specification currently defines two possible pinouts for the PCIe connector: CPU boards and peripherals may be designed as Type 1, Type 2, or Universal (which only uses

584-441: A CPU board, power supply board, and one or more peripheral boards. The maximum number of boards supported by a PC/104 stack will depend on which buses are used by the peripheral boards. Regardless of the buses used, the maximum number of boards of a PC/104 stack may be limited due to size, weight, and power restrictions for the target application. When stacking PC/104 boards together, mechanical interference between adjacent boards

657-529: A PC/104 connector (ISA) plus a PCI connector. The standard defines a 120-pin connector for the PCI bus, located on the opposite side of the board from the PC/104 connector. PC/104- Plus CPU boards provide active communication on both buses, and are capable of communicating with both ISA and PCI peripheral cards. On PC/104- Plus peripheral modules, the PC/104 connector is simply a passive connector for stackability;

730-481: A PC/104 system (Serial Ports, USB, Ethernet, VGA, etc.) are typically supported via the native drivers built into the operating system. Certain peripheral boards, such as data acquisition may require special drivers from the board manufacturer. From a software development perspective, there is little difference between compiling software for a desktop PC or compiling for an x86 PC/104 stack. Software can be developed using standard x86 compilers (e.g. Visual Studio if

803-401: A PCB with expansion capabilities. As the name suggests, this board is often referred to as the mother of all components attached to it, which often include peripherals, interface cards, and daughterboards : sound cards , video cards , network cards , host bus adapters , TV tuner cards , IEEE 1394 cards, and a variety of other custom components. Similarly, the term mainboard describes

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876-478: A PCI/104-Express peripheral module will communicate on the PCIe bus only; the PCI connector is simply a pass-through connector for stackability. A PC/104-Express peripheral module may not be used with a PCI-104 or PC/104- Plus CPU board (unless an ISA bridge device is used). PCI/104-Express incorporates link shifting, which eliminates the need for the PCI slot selection switches/jumpers found on PCI-104 and PC/104- Plus peripherals. Some peripheral boards re-populate

949-445: A Type 1 bottom PCIe connector and a Type 2 top PCIe connector. Such a CPU board would be compatible with Type 1 and/or Universal peripherals on the bottom, and compatible with Type 2 and/or Universal peripherals on the top. Similar to PC/104- Plus , a PCI/104-Express CPU boards will provide active communication on both PCI and PCIe buses. A PC/104-Express CPU board may be used with PCI-104 and PC/104- Plus peripheral modules. However,

1022-471: A device with a single board and no additional expansions or capability, such as controlling boards in laser printers, television sets, washing machines, mobile phones, and other embedded systems with limited expansion abilities. Prior to the invention of the microprocessor , the CPU of a digital computer consisted of multiple circuit boards in a card-cage case with components connected by a backplane containing

1095-406: A different number of connections depending on its standard and form factor . A standard, modern ATX motherboard will typically have two or three PCI-Express x16 connection for a graphics card, one or two legacy PCI slots for various expansion cards, and one or two PCI-E x1 (which has superseded PCI ). A standard EATX motherboard will have two to four PCI-E x16 connection for graphics cards, and

1168-423: A lifetime of 3 to 4 years can be expected. However, many manufacturers deliver substandard capacitors, which significantly reduce life expectancy. Inadequate case cooling and elevated temperatures around the CPU socket exacerbate this problem. With top blowers, the motherboard components can be kept under 95 °C (203 °F), effectively doubling the motherboard lifetime. Mid-range and high-end motherboards, on

1241-594: A number. For example, on the Intel 8259 family of programmable interrupt controllers (PICs) there are eight interrupt inputs commonly referred to as IRQ0 through IRQ7 . In x86 based computer systems that use two of these PICs , the combined set of lines are referred to as IRQ0 through IRQ15 . Technically these lines are named IR0 through IR7 , and the lines on the ISA bus to which they were historically attached are named IRQ0 through IRQ15 (although historically as

1314-507: A peripheral board when it is installed. This is commonly set by a rotary switch , DIP switch , or jumpers on the peripheral board. Each PCI peripheral board in the system must have the PCI Slot Number set to a unique value. Failure to do so may cause erratic system behavior. The peripheral closest to the CPU should be set for the first slot, the next board should be set for the second slot, etc. The PCI-104 form factor includes

1387-499: A peripheral board. This is usually accomplished via the use of jumpers or DIP switches on the peripheral board. Failure to configure the peripheral correctly can cause a resource conflict and lead to erratic behavior. The PC/104- Plus standard adds support for the PCI bus , in addition to the ISA bus of the PC/104 standard. The name is derived from its origin: a PC/104- Plus module has

1460-555: A peripheral device. If no peripheral device containing an operating system was available, then the computer would perform tasks from other ROM stores or display an error message, depending on the model and design of the computer. For example, both the Apple II and the original IBM PC had Cassette BASIC (ROM BASIC) and would start that if no operating system could be loaded from the floppy disk or hard disk. The boot firmware in modern IBM PC compatible motherboard designs contains either

1533-656: A second Intel 8259 PIC. The first PIC, the master, is the only one that directly signals the CPU. The second PIC, the slave, instead signals to the master on its IRQ 2 line, and the master passes the signal on to the CPU. There are therefore only 15 interrupt request lines available for hardware. On APIC with IOAPIC systems, typically there are 24 IRQs available, and the extra 8 IRQs are used to route PCI interrupts, avoiding conflict between dynamically configured PCI interrupts and statically configured ISA interrupts. On early APIC systems with only 16 IRQs or with only Intel 8259 interrupt controllers, PCI interrupt lines were routed to

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1606-448: A separate component. Business PCs, workstations, and servers were more likely to need expansion cards, either for more robust functions, or for higher speeds; those systems often had fewer embedded components. Laptop and notebook computers that were developed in the 1990s integrated the most common peripherals. This even included motherboards with no upgradeable components, a trend that would continue as smaller systems were introduced after

1679-424: A set of interconnected sockets into which the circuit boards are plugged. In very old designs, copper wires were the discrete connections between card connector pins, but printed circuit boards soon became the standard practice. The central processing unit (CPU), memory, and peripherals were housed on individually printed circuit boards, which were plugged into the backplane. In older microprocessor-based systems,

1752-412: A set of low-speed peripherals: PS/2 keyboard and mouse , floppy disk drive , serial ports , and parallel ports . By the late 1990s, many personal computer motherboards included consumer-grade embedded audio, video, storage, and networking functions without the need for any expansion cards at all; higher-end systems for 3D gaming and computer graphics typically retained only the graphics card as

1825-704: A variety of sizes and shapes called form factors , some of which are specific to individual computer manufacturers. However, the motherboards used in IBM-compatible systems are designed to fit various case sizes. As of 2024 , most desktop computer motherboards use the ATX standard form factor — even those found in Macintosh and Sun computers, which have not been built from commodity components. A case's motherboard and power supply unit (PSU) form factor must all match, though some smaller form factor motherboards of

1898-515: A varying number of PCI and PCI-E x1 slots. It can sometimes also have a PCI-E x4 slot (will vary between brands and models). Some motherboards have two or more PCI-E x16 slots, to allow more than 2 monitors without special hardware, or use a special graphics technology called SLI (for Nvidia ) and Crossfire (for AMD ). These allow 2 to 4 graphics cards to be linked together, to allow better performance in intensive graphical computing tasks, such as gaming, video editing, etc. In newer motherboards,

1971-418: Is a concern. The mechanical interference issues listed above can often be addressed with a Bus Spacer, which allows additional room between the boards. However, Bus Spacers increase overall stack height, and may not be suitable for space-constrained applications. It may also be possible to re-arrange the boards in the stack to remove the interference. Another option is to modify the offending boards to remove

2044-563: Is often better-suited to rugged PC/104 applications; the size of magnetic hard drives can be cumbersome and their many delicate parts are more susceptible to failure in harsh environments. Motherboard A motherboard (also called mainboard , main circuit board , MB , base board , system board , or, in Apple computers, logic board ) is the main printed circuit board (PCB) in general-purpose computers and other expandable systems. It holds and allows communication between many of

2117-476: Is sometimes referred to as a "stackable PC", as most of the architecture derives from the desktop PC. The majority of PC/104 CPU boards are x86 compatible and include standard PC interfaces such as Serial Ports , USB , Ethernet , and VGA . A x86 PC/104 system is usually capable of standard PC operating system such as DOS, Windows, or Linux. However, it is also quite common to use a real-time operating system , such as VxWorks . The PC/104 bus and form factor

2190-406: Is usually more expensive than a desktop motherboard. A CPU socket (central processing unit) or slot is an electrical component that attaches to a printed circuit board (PCB) and is designed to house a CPU (also called a microprocessor). It is a special type of integrated circuit socket designed for very high pin counts. A CPU socket provides many functions, including a physical structure to support

2263-488: The procinfo utility. In early IBM-compatible personal computers , an IRQ conflict is a once common hardware error, received when two devices were trying to use the same interrupt request (or IRQ) to signal an interrupt to the Programmable Interrupt Controller (PIC). The PIC expects interrupt requests from only one device per line, thus more than one device sending IRQ signals along

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2336-704: The Apple II and IBM PC include only this minimal peripheral support on the motherboard. Occasionally video interface hardware was also integrated into the motherboard; for example, on the Apple II and rarely on IBM-compatible computers such as the IBM PCjr . Additional peripherals such as disk controllers and serial ports were provided as expansion cards. Given the high thermal design power of high-speed computer CPUs and components, modern motherboards nearly always include heat sinks and mounting points for fans to dissipate excess heat. Motherboards are produced in

2409-477: The Apple II and IBM PC used ROM chips mounted in sockets on the motherboard. At power-up, the central processor unit would load its program counter with the address of the Boot ROM and start executing instructions from the Boot ROM. These instructions initialized and tested the system hardware, displayed system information on the screen, performed RAM checks, and then attempts to boot an operating system from

2482-429: The M.2 slots are for SSD and/or wireless network interface controller . Motherboards are generally air cooled with heat sinks often mounted on larger chips in modern motherboards. Insufficient or improper cooling can cause damage to the internal components of the computer, or cause it to crash . Passive cooling , or a single fan mounted on the power supply , was sufficient for many desktop computer CPU's until

2555-505: The printer port ( LPT1 ). The serial ports are frequently disabled to free an IRQ line for another device. IRQ 2/9 is the traditional interrupt line for an MPU-401 MIDI port, but this conflicts with the ACPI system control interrupt (SCI is hardwired to IRQ9 on Intel chipsets); this means ISA MPU-401 cards with a hardwired IRQ 2/9, and MPU-401 device drivers with a hardcoded IRQ 2/9, cannot be used in interrupt-driven mode on

2628-476: The "104" name to distinguish the form factor from the legacy PC/104 bus. EBX (Embedded Board eXpandable) is a single board computer form factor, 5.75 × 8 in (146 × 203 mm). The EBX form factor applies to the CPU board , but supports PC/104 form factor peripheral boards for expansion. The original EBX specifications allowed for the PC/104, PC/104- Plus , and PCI-104 buses. EBX Express adds

2701-649: The 16 IRQs using a PIR (PCI interrupt routing) table integrated into the BIOS. Operating systems such as Windows 95 OSR2 may use PIR table to process PCI IRQ steering; later, the PIR table has been superseded by the ACPI _PRT (PCI routing table) protocol. On APIC with MSI systems, typically there are 224 interrupts available. The easiest way of viewing this information on Windows is to use Device Manager or System Information (msinfo32.exe). On Linux , IRQ mappings can be viewed by executing cat /proc/interrupts or using

2774-518: The CPU and some support circuitry would fit on a single CPU board, with memory and peripherals on additional boards, all plugged into the backplane. The ubiquitous S-100 bus of the 1970s is an example of this type of backplane system. The most popular computers of the 1980s such as the Apple II and IBM PC had published schematic diagrams and other documentation which permitted rapid reverse engineering and third-party replacement motherboards. Usually intended for building new computers compatible with

2847-420: The CPU series and speed. With the steadily declining costs and size of integrated circuits , it is now possible to include support for many peripherals on the motherboard. By combining many functions on one PCB , the physical size and total cost of the system may be reduced; highly integrated motherboards are thus especially popular in small form factor and budget computers. A typical motherboard will have

2920-471: The CPU, support for a heat sink, facilitating replacement (as well as reducing cost), and most importantly, forming an electrical interface both with the CPU and the PCB. CPU sockets on the motherboard can most often be found in most desktop and server computers (laptops typically use surface mount CPUs), particularly those based on the Intel x86 architecture. A CPU socket type and motherboard chipset must support

2993-616: The I/O connector area. The extended PCB "wings" is not addressed in the specification, generally does not cause mechanical issues as long as the overall PCB + I/O connector overhang is within the maximum allowable dimensions of 4.550 × 4.393 inches (116 × 112 mm). The dimensions were originally defined in the PC/104 Specification, and as a result the form factor is still commonly referred to as "PC/104". The PCI/104-Express and PCIe/104 Specification introduced

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3066-517: The IBM XT and consists of 64 pins. The 16-bit version corresponds to the IBM AT and adds 40 additional pins, bringing the total to 104 (hence the name "PC/104"). The signals marked J1/P1 are found on both versions, while the signals of J2/P2 are found only on the 16-bit version. Since PC/104 is based on the ISA bus, it is often necessary to set the base address , IRQ , and DMA channel when installing

3139-433: The ISA, PCI, and PCI Express buses found in a desktop PC. The original PC/104 bus derives from the ISA bus . It includes all the signals found on the ISA bus, with additional ground pins added to ensure bus integrity. Signal timing and voltage levels are identical to the ISA bus, with lower current requirements. The PC/104 specification defines two versions of the bus, 8-bit or 16-bit. The 8-bit version corresponds to

3212-561: The PC/104 Bus Structures for expandability. Note the term "PC/104" is often used interchangeably to refer to either the Bus Structure or Form Factor. This can be a source of confusion. For example, a product datasheet may refer to a board as "PC/104" due to its size and shape when it in fact has a PCI-104 expansion bus. The PC/104 Consortium specifications define a variety a computer buses, all of which derive from

3285-529: The PC/104 Consortium. There are currently 47 members of the Consortium. All specifications published by the Consortium are freely available. Membership in the Consortium is not required to design and manufacture a PC/104 board. The specifications released by the PC/104 Consortium define multiple of Bus Structures (ISA, PCI, PCI Express) and Form Factors (104, EBX, EPIC). Bus Structure defines

3358-503: The PC/104 system is running Windows). There is typically no need for specialized development tools, such as cross compilers , Board Support Packages , or JTAG debuggers . This is a significant departure from non-x86 embedded system platforms, which often require a development toolchain from the board manufacturer. Non-x86 PC/104 CPU boards based on ARM or PowerPC are also commercially available. However, such boards are not capable of running off-the-shelf PC software. In these cases,

3431-463: The PCI bus. Most PC/104- Plus boards can be manufactured as PCI-104 by simply not populating the PC/104 connector. PCI-104 utilizes the same PCI Slot Number selection scheme as PC/104- Plus . Each device must be assigned to a unique slot number. The PCI/104-Express specification incorporates the PCI Express bus (PCIe) in addition to the previous-generation PCI bus. The specification defines

3504-434: The PCI connector, but not the PC/104 connector, in order to increase the available board real estate. Even though the PCI connector has 120 pins instead of 104, the established name was kept. The PCI connector location and pinout is identical to PC/104- Plus . Since the ISA bus is omitted, a PCI-104 board is incompatible with PC/104 peripheral module. However, PCI-104 and PC/104- Plus are compatible, since they both utilize

3577-717: The PCI-104/Express and PCIe/104 buses. EPIC (Embedded Platform for Industrial Computing) is a single-board computer form factor which, like EBX, supports PC/104 peripheral boards but is smaller than EBX at 6.5 × 4.5 in (165 × 114 mm). It allows I/O connections to be implemented as either pin headers or PC-style ("real world") connectors. The standard provides specific I/O zones to implement functions such as Ethernet, serial ports, digital and analog I/O, video, wireless, and various application-specific interfaces. EPIC Express adds PCI Express expandability. In general, every PC/104 stack will contain

3650-466: The PCIe links, which allows the stack to have additional peripheral boards beyond the initial set of PCI Express links provided by CPU board. Link repopulation is not a requirement in the specification, and must be implemented on the peripheral board with a PCI Express packet switch. PCIe/104 is similar to the PCI/104-Express standard, but omits the legacy PCI bus to increase available space on

3723-423: The board (similar to the relationship between PC/104- Plus and PCI-104). The PCI Express connector location and pinout options the same as PCI/104-Express (both Type 1 and Type 2). Because the PCI bus connector is omitted, a PCIe/104 board is incompatible with PC/104- Plus and PCI-104 systems (unless a PCIe-to-PCI bridge device is used). The PC/104 Consortium's specifications cover three form factors which define

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3796-406: The boards to be fastened to each other using standoffs . The stackable bus connectors and use of standoffs provides a more rugged mounting than slot boards found in desktop PCs. The compact board size further contributes to the ruggedness of the form factor by reducing the possibility of PCB flexing under shock and vibration. A typical PC/104 system (commonly referred to as a "stack") will include

3869-401: The common subset of signals between the two types, PCIe x1 and/or USB 2.0). The Type 2 pinout was not introduced until Version 2.0 of the specification (released in 2011). PCI/104-Express products introduced prior to 2011 will be either Type 1 or Universal, but may not be explicitly labeled as such. A Type 1 bus is incompatible with Type 2 peripherals, or vice versa. The specification requires

3942-425: The crucial electronic components of a system, such as the central processing unit (CPU) and memory , and provides connectors for other peripherals . Unlike a backplane , a motherboard usually contains significant sub-systems, such as the central processor, the chipset 's input/output and memory controllers, interface connectors, and other components integrated for general use. Motherboard means specifically

4015-530: The early years of personal computing, IRQ management was often of user concern. With the introduction of plug and play devices this has been alleviated through automatic configuration. When working with personal computer hardware, installing and removing devices, the system relies on interrupt requests. There are default settings that are configured in the system BIOS and recognized by the operating system. These default settings can be altered by advanced users. Modern plug and play technology has not only reduced

4088-414: The exemplars, many motherboards offered additional performance or other features and were used to upgrade the manufacturer's original equipment. During the late 1980s and early 1990s, it became economical to move an increasing number of peripheral functions onto the motherboard. In the late 1980s, personal computer motherboards began to include single ICs (also called Super I/O chips) capable of supporting

4161-568: The interference (e.g. depopulate a connector), but this may require the vendor to supply a customized version of the board. In theory, PC/104 boards are interoperable. It is possible to assemble a system using boards from several different vendors, subject to the fundamental Bus Structure compatibility issues listed above. However, compatibility issues sometimes appear. The majority of PC/104 CPU boards are x86 compatible , and are capable of running commercially available off-the-shelf PC software without modification. The standard PC I/O interfaces of

4234-460: The late 1990s; since then, most have required CPU fans mounted on heat sinks , due to rising clock speeds and power consumption. Most motherboards have connectors for additional computer fans and integrated temperature sensors to detect motherboard and CPU temperatures and controllable fan connectors which the BIOS or operating system can use to regulate fan speed. Alternatively computers can use

4307-532: The location and pinout of the bus connector(s). Form Factor refers to size and shape of the board. It is possible to find one of the PC/104 stackable expansion buses on a number of different form factors. While most commercially available products using the Bus Structures will comply with the Form Factors listed below, it is possible for a non-standard or proprietary form factor to incorporate one of

4380-411: The module actively communicates on the PCI bus only. As a corollary, a PC/104- Plus peripheral module may not be used with a PC/104 CPU board. However, a PC/104- Plus CPU board may be used with a PC/104 peripheral module. Since PC/104- Plus is based on PCI, there is no need to set a Base Address, IRQ, or DMA channel on the peripheral boards. However, it is necessary to specify the PCI Slot Number of

4453-433: The motherboard cooling and monitoring solutions are usually based on a super I/O chip or an embedded controller . Motherboards contain a ROM (and later EPROM , EEPROM , NOR flash ) that stores firmware that initializes hardware devices and boots an operating system from a peripheral device . The terms bootstrapping and boot come from the phrase "lifting yourself by your bootstraps". Microcomputers such as

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4526-419: The motherboard. Other components such as external storage , controllers for video display and sound , and peripheral devices may be attached to the motherboard as plug-in cards or via cables; in modern microcomputers, it is increasingly common to integrate some of these peripherals into the motherboard itself. An important component of a motherboard is the microprocessor's supporting chipset , which provides

4599-478: The need for concern for these settings, but has also virtually eliminated manual configuration. Early PCs using the Intel 8086/8088 processors only had a single PIC, and are therefore limited to eight interrupts. This was expanded to two PICs with the introduction of the 286 based PCs. Typically, on systems using the Intel 8259 PIC, 16 IRQs are used. IRQs 0 to 7 are managed by one Intel 8259 PIC, and IRQs 8 to 15 by

4672-637: The number of hardware devices increased, the total possible number of interrupts was increased by means of cascading requests, by making one of the IRQ numbers cascade to another set or sets of numbered IRQs, handled by one or more subsequent controllers). Newer x86 systems integrate an Advanced Programmable Interrupt Controller (APIC) that conforms to the Intel APIC Architecture. Each Local APIC typically support up to 255 IRQ lines, with each I/O APIC typically support up to 24 IRQ lines. During

4745-443: The other hand, use solid capacitors exclusively. For every 10 °C less, their average lifespan is multiplied approximately by three, resulting in a 6-times higher lifetime expectancy at 65 °C (149 °F). These capacitors may be rated for 5000, 10000 or 12000 hours of operation at 105 °C (221 °F), extending the projected lifetime in comparison with standard solid capacitors. In desktop PCs and notebook computers,

4818-406: The same family will fit larger cases. For example, an ATX case will usually accommodate a microATX motherboard. Laptop computers generally use highly integrated, miniaturized, and customized motherboards. This is one of the reasons that laptop computers are difficult to upgrade and expensive to repair. Often the failure of one laptop component requires the replacement of the entire motherboard, which

4891-428: The same line will generally cause an IRQ conflict that can freeze a computer . For example, if a modem expansion card is added into a system and assigned to IRQ4, which is traditionally assigned to the serial port  1, it will likely cause an IRQ conflict. Initially, IRQ 7 was a common choice for the use of a sound card , but later IRQ 5 was used when it was found that IRQ 7 would interfere with

4964-430: The size and shape of the board. Each form factor may utilize one of the Bus Structures listed above. The 104 Form Factor is defined to be 3.550 × 3.775 inches (90 × 96 mm), with mounting holes at all four corners of the board. The specifications also allow for a 0.5 inches (13 mm) area beyond the edge of the PCB for I/O connectors. Some PC/104 products have oversized PCBs which extended into

5037-405: The supporting interfaces between the CPU and the various buses and external components. This chipset determines, to an extent, the features and capabilities of the motherboard. Modern motherboards include: Additionally, nearly all motherboards include logic and connectors to support commonly used input devices, such as USB for mouse devices and keyboards . Early personal computers such as

5110-399: The system to remain in reset and not boot in the case of a Type mismatch (no physical damage will occur). Universal peripheral boards may be used with either Type 1 or Type 2 pinouts. Because the PCIe bus connector is surface-mount, not through-hole, it is also possible for a board to use different bus pinouts on the top side of the board vs the bottom side. For example, a CPU board may have

5183-507: The turn of the century (like the tablet computer and the netbook ). Memory, processors, network controllers, power source, and storage would be integrated into some systems. A motherboard provides the electrical connections by which the other components of the system communicate. Unlike a backplane, it also contains the central processing unit and hosts other subsystems and devices. A typical desktop computer has its microprocessor , main memory , and other essential components connected to

5256-407: Was originally devised by Ampro in 1987 (led by CTO Rick Lehrbaum), and later standardized by the PC/104 Consortium in 1992. An IEEE standard corresponding to PC/104 was drafted as IEEE P996.1, but never ratified. In 1997, the PC/104 Consortium introduced a newer standard based on the PCI bus . A PCI Express -based standard was introduced in 2008. PC/104-related specifications are controlled by

5329-679: Was shown to be the result of a faulty electrolyte formulation, an issue termed capacitor plague . Modern motherboards use electrolytic capacitors to filter the DC power distributed around the board. These capacitors age at a temperature-dependent rate, as their water based electrolytes slowly evaporate. This can lead to loss of capacitance and subsequent motherboard malfunctions due to voltage instabilities. While most capacitors are rated for 2000 hours of operation at 105 °C (221 °F), their expected design life roughly doubles for every 10 °C (18 °F) below this. At 65 °C (149 °F)

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