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Inside a PC

The motherboard is the main circuit board inside the PC which holds the processor, memory and expansion slots and connects directly or indirectly to every part of the PC. It's made up of a chipset (known as the "glue logic"), some code in ROM and the various interconnections or buses. PC designs today use many different buses to link their various components. Wide, high-speed buses are difficult and expensive to produce: the signals travel at such a rate that even distances of just a few centimetres cause timing problems, while the metal tracks on the circuit board act as miniature radio antennae, transmitting electromagnetic noise that introduces interference with signals elsewhere in the system. For these reasons, PC design engineers try to keep the fastest buses confined to the smallest area of the motherboard and use slower, more robust buses, for other parts.

This section focuses on basic functionality and layout - the motherboard's various interfaces, buses and chipsets being covered elsewhere.

The original PC had a minimum of integrated devices, just ports for a keyboard and a cassette deck (for storage). Everything else, including a display adapter and floppy or hard disk controllers, were add-in components, connected via
expansion slots.

Over time, more devices have been integrated into the motherboard. It's a slow trend though, as I/O ports and disk controllers were often mounted on expansion cards as recently as 1995. Other components - typically graphics, networking, SCSI and sound - usually remain separate. Many manufacturers have experimented with different levels of integration, building in some or even all of these components. However, there are drawbacks. It's harder to upgrade the specification if integrated components can't be removed, and highly integrated motherboards often require non-standard cases. Furthermore, replacing a single faulty component may mean buying an entire new motherboard.

Consequently, those parts of the system whose specification changes fastest - RAM, CPU and graphics - tend to remain in sockets or slots for easy replacement. Similarly, parts that not all users need, such as networking or SCSI, are usually left out of the base specification to keep costs down.

The basic changes in motherboard form factors over the years are covered later in this section - the diagrams below provide a detailed look at the various components on two motherboards. The first a Baby AT design, sporting the ubiquitous Socket 7 processor connector, circa 1995. The second is an ATX design, with a Pentium II Slot 1 type processor connector, typical of motherboards on the market in late 1998.

Motherboard development consists largely of isolating performance-critical components from slower ones. As higher speed devices become available, they are linked by faster buses - and the lower-speed buses are relegated to supporting roles. In the late 1990s there was also trend towards putting peripherals designed as integrated chips directly onto the motherboard. Initially this was confined to audio and video chips - obviating the need for separate sound or graphics adapter cards - but in time the peripherals integrated in this way became more diverse and included items such as SCSI, LAN and even RAID controllers. While there are cost benefits to this approach the biggest downside is the restriction of future upgrade options.

All motherboards include a small block of Read Only Memory (
ROM) which is separate from the main system memory used for loading and running software. The ROM contains the PC's Basic Input/Output System (BIOS). This offers two advantages: the code and data in the ROM BIOS need not be reloaded each time the computer is started, and they cannot be corrupted by wayward applications that write into the wrong part of memory. A Flash upgradeable BIOS may be updated via a floppy diskette to ensure future compatibility with new chips, add-on cards etc.

The BIOS comprises several separate routines, serving different functions. The first part runs as soon as the machine is powered on. It inspects the computer to determine what hardware is fitted and then conducts some simple tests to check that everything is functioning normally - a process called the power-on self test (POST). If any of the peripherals are plug and play devices, it's at this point that the BIOS assigns their resources. There's also an option to enter the Setup program. This allows the user to tell the PC what hardware is fitted, but thanks to automatic self-configuring BIOSes this isn't used so much now.

If all the tests are passed, the ROM tries to boot the machine from the hard disk. Failing that, it will try the CD-ROM drive, then the floppy drive, finally displaying a message that it needs a system disk. Once the machine has booted, the BIOS serves a different purpose by presenting DOS with a standardised API for the PC hardware. In the days before Windows, this was a vital function, but 32-bit "protect mode" software doesn't use the BIOS, so again it's of less benefit today.

Most PCs ship with the BIOS set to check for the presence of an operating system in the floppy disk drive first, then on the primary hard disk drive. Any modern BIOS will allow the floppy drive to be moved down the list so as to reduce normal boot time by a few seconds. To accommodate PCs that ship with a bootable CD-ROM, some BIOSes allow the CD-ROM drive to be assigned as the boot drive. Some also allow booting from a hard disk drive other than the primary IDE drive. In this case it would be possible to have different operating systems - or separate instances of the same OS - on different drives.

Windows 98 (and later) provides multiple display support. Since most PCs have only a single AGP slot, users wishing to take advantage of this will generally install a second graphics card in a PCI slot. In such cases, most BIOSes will treat the the PCI card as the main graphics card by default. Some, however, allow either the AGP card or the PCI card to be designated as the primary graphics card.

Whilst the PCI interface has helped - by allowing IRQs to be shared more easily - the limited number of IRQ settings available to a PC remains a problem for many users. For this reason, most BIOSes allow ports that are not in use to be disabled. With the increasing popularity of cable and ADSL Internet connections and the ever-increasing availability of peripherals that use the USB interface, it will often be possible to get by without needing either a serial or a parallel port.

CMOS RAM: Motherboards also include a separate block of memory made from very low power consumption CMOS (complementary metal oxide silicon) RAM chips, which is kept "alive" by a battery even when the PC's power is off. This is used to store basic information about the PC's configuration: number and type of hard and floppy drives, how much memory, what kind and so on. All this used to be entered manually, but modern auto-configuring BIOSes do much of this work, in which case the more important settings are advanced settings such as DRAM timings. The other important data kept in CMOS memory is the time and date, which is updated by a Real Time Clock (RTC). The clock, CMOS RAM and battery are usually all integrated into a single chip. The PC reads the time from the RTC when it boots up, after which the CPU keeps time - which is why system clocks are sometimes out of sync. Rebooting the PC causes the RTC to be reread, increasing their accuracy.

Form factor : Early PCs used the AT form factor and 12in wide motherboards. The sheer size of an AT motherboard caused problems for upgrading PCs and did not allow use of the increasingly popular slimline desktop cases. These problems were largely addressed by the smaller version of the full AT form factor, the Baby AT, introduced in 1989. Whilst this remains a common form factor, there have been several improvements since. All designs are open standards and as such don't require certification. A consequence is that there can be some quite wide variation in design detail between different manufacturers' motherboards.

The Baby AT (BAT) format reduced the dimensions of the motherboard to a typical 9in wide by 10in long, and BAT motherboards are generally characterised by their shape, an AT-style keyboard connector soldered to the board and serial and parallel port connectors which are attached using cables between the physical ports mounted on the system case and corresponding connectors located on the motherboard.

With the BAT design the processor socket is located at the front of the motherboard, and full-length expansion cards are intended to extend over it. This means that removing the processor requires the removal of some or all expansion cards first. Problems were exacerbated by the increasing speeds of Pentium-class processors. System cooling relied on the AT power supply blowing air out of the chassis enclosure and, due to the distance between the power supply and the CPU, an additional chassis fan or active heatsink became a necessity to maintain good airflow across the CPU. AT power supplies only provide 12V and 5V outputs to the motherboard, requiring additional regulators on the motherboard if 3.3V components (PCI cards or CPUs) are used. Sometimes a second heatsink was also required on these voltage regulators and together the various additional heat dissipation components caused serious obstruction for expansion slots.

Some BAT designs allow the use of either AT or ATX power supplies, and some ATX cases might allow the use of a Baby-AT motherboard.

The LPX format is a specialised variant of the Baby-AT used in low profile desktop systems and is a loose specification with a variety of proprietary implementations.

Expansion slots are located on a central riser card, allowing cards to be mounted horizontally. However, this arrangement can make it difficult to remove the motherboard, and the more complex engineering required adds to system costs. As the riser card prevents good airflow within the system case, additional chassis fans are almost always needed.

The Intel Advanced/ML motherboard, launched in 1996, was designed to solve these issues and marked the beginning of a new era in motherboard design. Its size and layout are completely different to the BAT format, following a new scheme known as
ATX. The dimensions of a standard ATX board are 12in wide by 9.6in long; the mini ATX variant is typically of the order 11.2in by 8.2in.   

The ATX design gets round the problem by moving the CPU socket and the voltage regulator to the right-hand side of the expansion bus. Room is made for the CPU by making the card slightly wider, and shrinking or integrating components such as the Flash BIOS, I/O logic and keyboard controller. This means the board need only be half as deep as a full size Baby AT, and there's no obstruction whatsoever to the six expansion slots (two ISA, one ISA/PCI, three PCI).

The ATX uses a new specification of power supply that can be powered on or off by a signal from the motherboard. This allows notebook-style power management and software-controlled shutdown and power-up. A 3.3V output is also provided directly from the power supply. Accessibility of the processor and memory modules is improved dramatically, and relocation of the peripheral connectors allows shorter cables to be used. This also helps reduce electromagnetic interference. The ATX power supply has a side vent that blows air from the outside directly across the processor and memory modules, allowing passive heatsinks to be used in most cases, thereby reducing system noise.

Mini-ATX is simply a smaller version of a full-sized ATX board. On both designs, parallel, serial, PS/2 keyboard and mouse ports are located on a double-height I/O shield at the rear. Being soldered directly onto the board generally means no need for cable interconnects to the on-board I/O ports. A consequence of this, however, is that the ATX needs a newly designed case, with correctly positioned cut-outs for the ports, and neither ATX no Mini-ATX boards can be used in AT-style cases.

Intel's NLX design, introduced in 1997, is an improvement on the LPX design for low-profile systems, with an emphasis on ease of maintenance. The NLX format is smaller, typically 8.8in wide by 13in long, so well suited for low-profile desktop cases.

All expansion slots, power cables and peripheral connectors are located on an edge-mounted riser card, allowing simple removal of the main motherboard, which is mounted on rails in the chassis. It uses a full-width I/O shield to allow for different combinations of rear-panel I/O. The design allows for use of an AGP card, but the slot must be on the motherboard, which reduces the ease of maintenance when such a card is implemented.

Introduced in the late 1990s, the MicroATX is basically a smaller version of Intel's ATX specification, intended for compact, low-cost consumer systems with limited expansion potential.

The maximum size of the board is 9.6in square, and its designed to fit into either a standard ATX case or one of the new micro-tower desktop designs. The double-decker I/O shield is the same as that on the ATX design, but there's only provision for up to four expansion slots as opposed to the seven that ATX allows. The microATX also allows use of a smaller power supply, such as the SFX design, which is reduced in both size and power output.

The FlexATX is a natural evolution of the Intel's microATX form factor which was first unveiled in late 1999. The FlexATX addendum to the microATX specification addresses the requirements of only the motherboard and not the overall system solution. As such, it does not detail the interfaces, memory or graphics technologies required to develop a successful product design. These are left to the implementer and system designer. The choice of processor is, however, limited to socket-only designs.

The principal difference between FlexATX and microATX is that the new form factor reduces the size of the motherboard - to 9in x 7.5in. Not only does this result in lower overall system costs, it also facilitates smaller system designs. The FlexATX form factor is backwards compatible with both the ATX and micro-ATX specifications - use of the same motherboard mounting holes as both of its predecessors avoids the need to retool existing chassis.

In the spring of 2000 VIA Technologies announced an even smaller motherboard than the FlexATX. At 8.5in x 7.5in, the company's ITX form factor is half and inch less wide than it's Intel competitor. The key innovation that allows the ITX to achieve such a compact form is the specially designed slimline power unit with built in fan. It's dimensions of 174mm long x 73mm wide x 55mm high compare with a standard ATX power supply unit measuring 140mm x 150mm x 86mm.

The table below compares the dimensions of the microATX, FlexATX and ITX form factors:

Form FactorMax. Width (mm)Max. Depth (mm)

Unsurprisingly Intel's FlexATX form factor uses it's CNR riser architecture, while the ITX uses the rival ACR architecture.

Riser architectures: In the late 1990s, the PC industry developed a need for a riser architecture that would contribute towards reduced overall system costs and at the same time increase the flexibility of the system manufacturing process. The Audio/Modem Riser (AMR) specification, introduced in the summer of 1998, was the beginning of a new riser architecture approach. AMR had the capability to support both audio and modem functions. However, it did have some shortcomings, which were identified after the release of the specification. These shortcomings included the lack of Plug and Play (PnP) support, as well as the consumption of a PCI connector location.

Consequently, new riser architecture specifications were defined which combine more functions onto a single card. These new riser architectures combine audio, modem, broadband technologies, and LAN interfaces onto a single card. They continue to give motherboard OEMs the flexibility to create a generic motherboard for a variety of customers. The riser card allows OEMs and system integrators to provide a customised solution for each customer's needs. Two of the most recent riser architecture specifications include CNR and ACR.

Intel's CNR Communication and Networking Riser) specification defines a hardware scalable OEM motherboard riser and interface that supports the audio, modem, and LAN interfaces of core logic chipsets. The main objective of this specification is to reduce the baseline implementation cost of features that are widely used in the "Connected PC", while also addressing specific functional limitations of today's audio, modem, and LAN subsystems.

PC users' demand for feature-rich PCs, combined with the industry's current trend towards lower cost, mandates higher levels of integration at all levels of the PC platform. Motherboard integration of communication technologies has been problematic to date, for a variety of reasons, including FCC and international telecom certification processes, motherboard space, and other manufacturer specific requirements.

Motherboard integration of the audio, modem, and LAN subsystems is also problematic, due to the potential for increased noise, which in-turn degrades the performance of each system. The CNR specifically addresses these problems by physically separating these noise-sensitive systems from the noisy environment of the motherboard.

With a standard riser solution, as defined in this specification, the system manufacturer is free to implement the audio, modem, and/or LAN subsystems at a lower bill of materials (BOM) cost than would be possible by deploying the same functions in industry-standard expansion slots or in a proprietary method. With the added flexibility that hardware scalability brings, a system manufacturer has several motherboard acceleration options available, all stemming from the baseline CNR interface.

The CNR Specification supports the five interfaces:

  • AC97 Interface - Supports audio and modem functions on the CNR card
  • LAN Connect Interface (LCI) - Provides 10/100 LAN or Home Phoneline Networking capabilities for Intel chipset based solutions
  • Media Independent Interface (MII) - Provides 10/100 LAN or Home Phoneline Networking capabilities for CNR platforms using the MII Interface
  • Universal Serial Bus (USB) - Supports new or emerging technologies such as xDSL or wireless
  • System Management Bus (SMBus) - Provides Plug and Play (PnP) functionality on the CNR card.

Each CNR card can utilise a maximum of four interfaces by choosing the specific LAN interface to support.

The rival ACR specification is supported by an alliance of leading computing and communication companies, whose founders include 3COM, AMD, VIA Technologies and Lucent Technologies. Like CNR, it defines a form factor and interfaces for multiple and varied communications and audio subsystem designs in desktop OEM personal computers. Building on first generation PC motherboard riser architecture, ACR expands the riser card definition beyond the limitation of audio and modem codecs, while maintaining backward compatibility with legacy riser designs through an industry standard connector scheme. The ACR interface combines several existing communications buses, and introduces new and advanced communications buses answering industry demand for low-cost, high-performance communications peripherals.

ACR supports modem, audio, LAN, and xDSL. Pins are reserved for future wireless bus support. Beyond the limitations of first generation riser specifications, the ACR specification enables riser-based broadband communications, networking peripheral and audio subsystem designs. ACR accomplishes this in an open-standards context.

Like the original AMR Specification, the ACR Specification was designed to occupy or replace an existing PCI connector slot. This effectively reduces the number of available PCI slots by one, regardless of whether the ACR connector is used. Though this may be acceptable in a larger form factor motherboard, such as ATX, the loss of a PCI connector in a microATX or FlexATX motherboard - which often provide as few as two expansion slots - may well be viewed as an unacceptable trade-off. The CNR specification overcomes this issue by implementing a shared slot strategy, much like the shared ISA /PCI slots of the recent past. In a shared slot strategy, both the CNR and PCI connectors effectively use the same I/O bracket space. Unlike the ACR architecture, when the system integrator chooses not to use a CNR card, the shared PCI slot is still available.

Although the two specifications both offer similar functionality, the way in which they are implemented are quite dissimilar. In addition to the PCI connector/shared slot issue, the principal differences are as follows:

  • ACR is backwards compatible with AMR, CNR isn't
  • ACR provides support xDSL technologies via its Integrated Packet Bus (IPB) technology; CNR provides such support via the well-established USB interface
  • ACR provides for concurrent support for LCI (LAN Connect Interface) and MII (Media Independent Interface) LAN interfaces; CNR supports either, but not both at the same time
  • The ACR Specification has already reserved pins for a future wireless interface; the CNR specification has the pins available but will only define them when the wireless market has become more mature.

Ultimately, motherboard manufacturers are going to have to decide whether the ACR specification's additional features are worth the extra cost.


CPU interfaces: The PC's ability to evolve many different interfaces allowing the connection of many different classes of add-on component and peripheral device has been one of the principal reasons for its success. The key to this has been standardisation, which has promoted competition and, in turn, technical innovation.


The heart of a PC system - the processor - is no different in this respect than any other component or device. Intel's policy in the early 1990s of producing OverDrive CPUs that were actually designed for upgrade purposes required that the interface by which they were connected to the motherboard be standardised. A consequence of this is that it enabled rival manufacturers to design and develop processors that would work in the same system. The rest is history.


In essence, a CPU is a flat square sliver of silicon with circuits etched on its surface. This chip is linked to connector pins and the whole contraption encased some form of packaging - either ceramic or plastic - with pins running along the flat underside or along one edge. The CPU package is connected to a motherboard via some form of CPU interface, either a slot or a socket. For many years the socket style of CPU was dominant. Then both major PC chip manufacturers switched to a slot style of interface. After a relatively short period of time they both changed their minds and the socket was back in favour!


The older 386, 486, classic Pentium and Pentium MMX processors came in a flat square package with an array of pins on the underside - called Pin Grid Array (PGA) - which plugged into a socket-style CPU interface on the motherboard. The earliest such interface for which many motherboards and working systems remain to this day - not least because it supported CPUs from so many different chip manufacturers - is Socket 7. Originally developed by Intel as the successor to Socket 5, it was the same size but had different electrical characteristics including a system bus that ran at 66MHz. Socket 7 was the interface used by most Pentium systems from the 75MHz version and beyond.


Socket 8 was developed for Intel's Pentium Pro CPU - introduced in late 1995 - and specifically to handle its unusual dual-cavity, rectangular package. To accommodate L2 cache - in the package but not on the core - this contained up to three separate dice mounted on a small circuit board. The complicated arrangement proved extremely expensive to manufacture and was quickly abandoned.


With the introduction of their Pentium II CPU, Intel switched to a much cheaper solution for packaging chips that consisted of more than a single die. Internally, the SECC package was really a circuit board containing the core processor chip and cache memory chips. The cartridge had pins running along one side which enabled it to be mounted perpendicularly to the motherboard - in much the same way as the graphics or sound card is mounted into an expansion slot - into an interface that was referred to as Slot 1. The up to two 256KB L2 cache chips ran at half the CPU speed. When Intel reverted - from the Pentium III Coppermine core - to locating L2 cache on the processor die, they continued to use cacheless Slot 1 packaging for a while for reasons of compatibility.

Pentium II Xeon's - unlike their desktop counterparts - ran their L2 cache at full clock speed. This necessitated a bigger heatsink which in turn required a taller cartridge. The solution was Slot 2, which also sported more connectors than Slot 1, to support a more aggressive multi-processor protocol amongst other features.


When Intel stopped making its MMX processor in mid-1998 it effectively left the Socket 7 field entirely to its competitors, principally AMD and Cyrix. With the co-operation of both motherboard and chipset manufacturers their ambitious plans for extending the life of the "legacy" form factor was largely successful.

AMD's determination to match Intel's proprietary Slot 1 architecture on Socket 7 boards was amply illustrated by their 0.25-micron K6-2 processor, launched at the end of May 1998, which marked a significant development of the architecture. AMD referred to this as the "Super7" platform initiative, and its aim was to keep the platform viable throughout 1999 and into the year 2000. Developed by AMD and key industry partners, the Super7 platform supercharged Socket 7 by adding support for 100MHz and 95MHz bus interfaces and the Accelerated Graphics Port (AGP) specification and by delivering other leading-edge features, including 100MHz SDRAM, USB, Ultra DMA and ACPI.


When AMD introduced their Athlon processor in mid-1999 they emulated Intel's move away from a socket-based CPU interface in favour of a slot-based CPU interface, in their case "Slot A". This was physically identical to Slot 1, but it communicated across the connector using a completely different protocol - originally created by Digital and called EV6 - which allowed RAM to CPU transfers via a 200MHz FSB. Featuring an SECC slot with 242 leads, Slot A used a Voltage Regulator Module (VRM), putting the onus on the CPU to set the correct operating voltage - which in the case of Slot A CPUs was a range between 1.3V and 2.05V.


Slot-based processors are overkill for single-chip dies. Consequently, in early 1999 Intel moved back to a square PGA packaging for its single die, integrated L2 cache, Celeron range of CPUs. Specifically these used a PPGA 370 packaging, which connected to the motherboard via a Socket 370 CPU interface. This move marked the beginning of Intel's strategy for moving its complete range of processors back to a socket-based interface. Socket 370 has proved to be one of the more enduring socket types, not least because of the popularity of the cheap and overclockable Celeron range. Indeed, Intel is not the only processor manufacturer which produces CPUs that require Socket 370 - the Cyrix MIII (VIA C3) range also utilising it.


The sudden abandonment of Slot 1 in favour of Socket 370 created a need for adapters to allow PPGA-packaged CPUs to be used in Slot 1 motherboards. Fortunately, the industry responded, with Abit being the first off the mark with its original "SlotKET" adapter. Many were soon to follow, ensuring that Slot 1 motherboard owners were not left high and dry. A Slot 1 to Socket 370 converter that enables Socket 370-based CPUs to be plugged into a Slot 1 motherboard was also produced. Where required, these converters don't just provide the appropriate connector, they also make provision for voltage conversion.


Unfortunately users were more inconvenienced by Intel's introduction of the FC-PGA (Flip Chip-Pin Grid Array) and FC-PGA2 variants of the Socket 370 interface - for use with Pentium III Coppermine and Tualatin CPUs respectively - some time later. The advantage with this packaging design is that the hottest part of the chip is located on the side that is away from the motherboard, thereby improving heat dissipation. The FC-PGA2 package adds an Integral Heat Spreader, improving heat conduction still further. Whilst FC-PGA and FC-PGA2 are both mechanically compatible with Socket 370, electrically they're incompatible and therefore require different motherboards. Specifically, FC-PGA processors require motherboards that support VRM 8.4 specifications while FC-PGA2 processors require support for the later VRM 8.8 specifications.

Like Intel's Slot 1, AMD's proprietary Slot A interface was also to prove to be relatively short-lived. With the advent of the Athlon Thunderbird and Spitfire cores, the chipmaker followed the lead of the industry leader by also reverting to a PPGA-style packaging for its new family of Athlon and Duron processors. This connects to a motherboard via what AMD calls a "Socket A" interface. This has 462 pin holes - of which 453 are used by the CPU - and supports both the 200MHz EV6 bus and newer 266MHz EV6 bus. AMD's subsequent Palomino and Morgan cores are also Socket A compliant.


With the release of the Pentium 4 in late 2000, Intel introduced yet another socket to its line-up, namely Socket 423. Indicative of the trend for processors to consume ever decreasing amounts of power, the PGA-style Socket 423 has a VRM operational range of between 1.0V and 1.85V.

Socket 423 had been in use for only a matter of months when Intel muddied the waters still further with the announcement of the new Socket 478 form factor. The principal difference between this and its predecessor is that the newer format socket features a much more densely packed arrangement of pins known as a micro Pin Grid Array (µPGA) interface, which allows both the size of the CPU itself and the space occupied by the interface socket on the motherboard to be significantly reduced. Socket 423 was introduced to accommodate the 0.13-micron Pentium 4 Northwood core, launched at the beginning of 2002.

The table below identifies all the major CPU interfaces from the time of Intel's Socket 1, the first "OverDrive" socket used by Intel's 486 processor in the early 1990s:

Socket 1169-pinFound on 486 motherboards, operated at 5 volts and supported 486 chips, plus the DX2, DX4 OverDrive.
Socket 2238-pinA minor upgrade from Socket 1 that supported all the same chips. Additionally supported a Pentium OverDrive.
Socket 3237-pinOperated at 5 volts, but had the added capability of operating at 3.3 volts, switchable with a jumper setting on the motherboard. Supported all of the Socket 2 chips with the addition of the 5x86. Considered the last of the 486 sockets.
Socket 4273-pinThe first socket designed for use with Pentium class processors. Operated at 5 volts and consequently supported only the low-end Pentium-60/66 and the OverDrive chip. Beginning with the Pentium-75, Intel moved to the 3.3 volt operation.
Socket 5320-pinOperated at 3.3 volts and supported Pentium class chips from 75MHz to 133MHz. Not compatible with later chips because of their requirement for an additional pin.
Socket 6235-pinDesigned for use with 486 CPU's, this was an enhanced version of Socket 3 supporting operation at 3.3 volts. Barely used since it appeared at a time when the 486 was about to be superseded by the Pentium.
Socket 732-pinIntroduced for the Pentium MMX, the socket had provision for supplying the split core/IO voltage required by this and later chips. The interface used for all Pentium clones with a 66MHz bus.
Socket 8387-pinUsed exclusively by the Intel Pentium Pro, the socket proved extremely expensive to manufacture and was quickly dropped in favour of a cartridge-based design.
Slot 1242-way connectorThe circuit board inside the package had up to 512KB of L1 cache on it - consisting of two 256KB chips - which ran at half the CPU speed. Used by Intel Pentium II, Pentium III and Celeron CPUs.
Slot 2330-way connectorSimilar to Slot 1, but with the capacity to hold up to 2MB of L2 cache running at the full CPU speed. Used on Pentium II/III Xeon CPUs.
Slot A242-way connectorAMD interface mechanically compatible with Slot 1 but which using a completely different electrical interface. Introduced with the original Athlon CPU.
Socket 370370-pinBegan to replace Slot 1 on the Celeron range from early 1999. Also used by Pentium III Coppermine and Tualatin CPUs in variants known as FC-PGA and FC-PGA2 respectively.
Socket A462-pinAMD interface introduced with the first Athlon processors (Thunderbird) with on-die L2 cache. Subsequently adopted throughout AMD's CPU range.
Socket 423423-pinIntroduced to accommodate the additional pins required for the Pentium 4's completely new FSB. Includes an Integral Heat Spreader, which both protects the die and provides a surface to which large heat sinks can be attached.
Socket 603603-pinThe connector for Pentium 4 Xeon CPUs. The additional pins are for providing more power to future CPUs with large on-die (or even off-die) L3 caches, and possibly for accommodating inter-processor-communication signals for systems with multiple CPUs.
Socket 478478-pinIntroduced in anticipation of the introduction of the 0.13-micron Pentium 4 Northwood CPU at the beginning of 2002. It's micro Pin Grid Array (µPGA) interface allows both the size of the CPU itself and the space occupied by the socket on the motherboard to be significantly reduced.

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Add "www." to the beginning and ".com" to the end of the text typed in the Address bar


Move forward through the list of AutoComplete matches


Move back through the list of AutoComplete matches

 Working with favorites

Press this

To do this


Add the current page to your favorites


Open the Organize Favorites dialog box


Move selected item up in the Favorites list in the Organize Favorites dialog box


Move selected item down in the Favorites list in the Organize Favorites dialog box


Press this

To do this


Remove the selected items and copy them to the Clipboard


Copy the selected items to the Clipboard


Insert the contents of the Clipboard at the selected location


Select all items on the current Web page


 Remap the Right-Alt Key to be the Windows Key

Create a Scancode entry in the Registry as follows:

  1. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Keyboard Layout
  2. Create a new binary entry called Scancode Map with the following values
  3. 00 00 00 00 00 00 00 00 02 00 00 00 5B EO 38 EO 00 00 00 00
  4. Reboot the computer

Disabling the Windows Key with NT or Windows2000

Added 5/14/01

To disable the use of the Windows Key for the two operating Systems,

  1. Start Regedit
  2. Go to HKEY_LOCAL_MACHINE \ System \ CurrentControlSet \ Control \ Keyboard Layout
  3. Add a Binary Value called Scancode Map
  4. Give it a value of 00000000000000000300000000005BE000005CE000000000
  5. Reboot the computer

Outlook 2000 Shortcut Keys

Added 2/2/00

Go to the Inbox


Go to the Outbox


Check for New Mail

F5 or CTRL+M

Start a New E-mail message


Open the address book


Start a New appointment


Start a New contact


Start a New meeting request


Start a New a task


Make the Find a Contact box active


Open the Advanced Find dialog box


Mark an e-mail message as read


Delete an e-mail message, contact, calendar item, or task


Front Page 2000 Shortcut Keys

Front Page has quite a few shortcut keys

Center a paragraph


Left align a paragraph


Right align a paragraph


Display HTML tags


Apply the Heading 1 style (ect.)


Apply the Normal style


Not listed in their help is:

Cycle through Normal / HTML / Preview

Ctrl-PgUp/ Down

If you are at the last row in a table, the TAB key will add a new row below the current one.


Fast Access to the Desktop

Submitted 7/19/99

To get an Explorer view of the Desktop

  1. Press Ctrl-Esc or click the Start button
  2. Press R to go to Run. Note: If you are using a Win keyboard, you can get to this point by pressing Win+R
  3. Type in a period

Opening Up the Task Manager in NT 4

Submitted 7/24/98

In Windows NT 4, to quickly bring up the task manager, press Ctrl-Shift-Esc

MS-Natural Keyboard Shortcuts

Toggles between minimizing/restoring


Open the start menu


Display the pop-up menu for the selected object


Start Explorer


Find Files or Folders


Find computer


Minimizes all windows


Undo Minimize All


Display Run Dialog box


Cycles through taskbar buttons


Displays System Properties


Getting to My Computer from the Control Panel

If you're in Control Panel, hitting the Backspace key will switch you into the My Computer folder.


Press CTRL + Z to undo things like renaming a file in Explorer

Minimizing All Windows

To minimize all windows:

  1. Press Ctrl-ESC to bring up the Task Bar
  2. Press Alt-M

This makes it a lot easier to minimize windows when all your open applications are full screen. With the Microsoft Keyboard, you can accomplish the same thing by pressing the Window-M key.

Shortcut to System Properties

To access the System Properties screen quickly, simply hold down the ALT key while double clicking on the My Computer icon.

While holding the windows key, press the Pause / Break key.
This will open up the System Properties box.
From here you can easily get to the Device Manager

Duplicating the Right Mouse Click

Pressing the Shift-F10 key will be the same as clicking the right-mouse button.

Accessing Programs from the Start Button

Submitted 9/13/97

To access your programs more quickly from your start button, with out aid of a mouse, hit ctrl+esc to open your start menu.
Then, type the letter for the directory you are looking for.
For example, to access the ever popular game of solitaire, CTRL+ESC, then "P" for programs, "A" for accessories, "G" for games, then "S" for Solitaire.
If there is more than one entry for the letter, keep hitting the letter until you reach your desired location. Then, hit enter.

Quickly Starting Explorer

You can quickly start an explorer session by holding down the Windows key on a Microsoft Keyboard and pressing the E.key

Internet Explorer Shortcuts

Here are a few IE keyboard shortcuts:

Go ‘Back’ to the previous page

Alt+Left Arrow

Go ‘Forward’ to the next page

Alt+Right Arrow

Add to Favorites on the current web page


Open the History folder


Open the Organize Favorites window


Lets you open a new web page


Open a new browser window


Reload the current page


Close the active Internet Explorer window


Bringing up the Properties Window

While holding the ALT key double click on an icon to bring up the properties.

Resizing and Moving a Window

To Resize or Move a window:

  1. Press Alt-Space
  2. Press the S key - To Resize
  3. Press the M key - To Move

You can now use the arrow keys to resize or move the window

Key stroking is faster than mouse moving

  1. In desktop you can press "m", "My Briefcase is highlighted, press "enter" will open this applet.
  2. If you do not press "enter",
  3. The next "m" key stroke will highlight "My Computer".
  4. "Ctrl"-"Esc", press "P" for Programs, "enter","M""enter", you get to the first program or folder that starts with "M"
  5. Other applets will also be opened the same way.

Explorer Shortcut Keys

  • F4 - Displays the Combo Box
  • F5 - Refresh the display
  • Ctrl+Z - Undo last action
  • Backspace - Go up one directory

Quickly Search for Files

To quickly open up the Find all Files window

  1. Press Ctrl+ESC ESC
  2. Press F3

To copy a file with a Mouse/Keyboard combo

Drag the file while holding down the CTRL key - A + will appear on the icon

To move a file with a Mouse/Keyboard combo

Drag file while holding down SHIFT key - Nothing appears on the icon

If moving a icon with the mouse and an arrow appears, it will create a shortcut.
You can press shift or ctrl at anytime during the drag
and it will change this little part of the icon.