Category Archives: Computer Hardware

Motherboard

A motherboard is the central printed circuit board of a computer. It is also known as the system board, baseboard, planar board, or the mainboard, while a lot of techies even call it “mobo” (slang). In Apple computers, it is called a logic board.

Uses of a Motherboard

A motherboard provides all the necessary electrical connections through which all the systems in the unit communicate. It also houses the Central Processing Unit, or CPU, and other computer subsystems, like peripheral interfaces and the real time clock.

Components of a Motherboard

A Motherboard contains the main memory, the microprocessor, and edge connectors that facilitate its connection to other external components. The external components are listed below.

External Components of a Motherboard

  • storage
  • video display controllers
  • sound controllers, and
  • peripheral tools (e.g. DVD-ROM, CD-ROM and USB Flash drive).

How a Motherboard Works

A motherboard’s functionality is directly proportional to a computer’s functionality. The heart of a motherboard is a chipset that contains the Northbridge and Southbridge chips. The Northbridge chip also known as the MCH, or Memory Control Hub, contains the RAM (Random Access Memory) and the AGP (Accelerated Graphics Port) video card. The Southbridge chip, on the other hand, contains the PCI (Peripheral Component Interconnect) bus, Real Time Clock, and the USB port. Both chips define the extent of a motherboard’s capabilities.

Form Factor

The form factor refers to the shape and layout of the motherboard and this determines the placement of its components and the design of its case. Today, almost all commercial motherboards designs are for IBM-compatible computers. This is because these types of computers have captured 90% of the global computer market.

Laptop motherboards are compressed, customized, and very integrated. This is the reason why laptop computer repairs and software upgrading cost a lot.

Motherboard Maintenance

Air-cool the motherboards properly. Failure to do so will cause the motherboard to degrade in performance. Before the 1990s, passive cooling by one mounted fan on the power supply was enough for desktop CPUs. Since then, CPU fans have to be on heat sinks because of increased power consumption by computers.

Today, additional fans are mounted and many motherboards have temperature sensors for themselves and the CPU. Fan connectors from the motherboard to the BIOS regulate the fan speeds.

PCMCIA

The acronym PCMCIA stands for Personal Computer Memory Card International Association. As the industrial organization’s name implies, it promotes and creates standards for PC memory cards. However, they are not merely confined to memory devices but also have cards for modem, wireless connectivity, and other related functions for the PC or laptop where there are areas of concern.

Overview

This trade association has been in existence since 1989 and has over 100 member companies. The body has been able to establish Integrated Circuit card standards and promotes the usability of mobile computers. As there are an increasing number of mobile computer users over recent years, the PCMCIA has to adapt as well.

Meanwhile, here are the general objectives of the association:

  • Use of mobile application for computers, digital audio or video equipment, cameras, and vehicles;
  • Provide ease for the user’s experience;
  • Create more market for these modular peripherals by increasing knowledge for its members and the community as a whole.

Breakthroughs for the Body

Initially, a 68-pin connector was used for memory cards but this was revised by PCMCIA in 1991 when they revealed a new I/O interface for that same connector. Meanwhile, the new Socket Services Specification and Card Services Specification were also developed to address the individual problems of common software and enhance their overall function.

Then, the high-speed and multimedia networking tools were soon introduced to the market. Along with this, the 100 Mbit Ethernet and MPEG video were enhanced with the introduction of the CardBus 32-bit interface and a new specification for Zoomed Video. These new speed enhancements certainly changed the phase of software applications and paved the way for more mobile-oriented breakthroughs.

PCMCIA also promoted the use of PC cards to be not restricted to mobile computers. They can also be used for other devices such as cable TV, digital cameras, and automobiles. These new capability expansion efforts have also facilitated the growth of mobile devices.

PCMCIA is still continuing its efforts to develop the standards for the ExpressCard, which will improve performance for whatever type of computer. Recently, a small form factor card that allows you to store data from on a handset using this card was also introduced. PC cards may now also be able to hold memory and be transported to other devices.

PDA

A Personal Digital Assistant (PDA) is a small mobile device offering data storage, computing, and retrieval capacities. PDAs are also known as palmtops or handhelds. Some users interchange the term PDA with (Hewlett-Packard’s) Palmtop or (3Com’s) PalmPilot.

Recent releases of PDAs have colored screens and high-quality audio features. These PDAs function as mobile phones, portable media players, smartphones, and Web browsers. Many PDAs are able to access the Internet via Wi-Fi, as well as intranets or extranets via Wireless Wide-Area Networks (WWANs).

PDAs may use small keyboards or touch-screens (electronically sensitive areas for input). Some may even ‘understand’ handwriting through the touch-screen interface. Many applications have been developed for PDAs, including games, e-books, and even links to telephone and paging systems. Many current PDAs can allow synchronization of data with personal computers.

Palm and Pocket PC are a couple of the main operating systems for PDAs. Some even use a variant of the Microsoft Windows OS called Windows CE.

The PDA has these basic features:

  • Datebook – an integral portion of the organizer which allows input of information for appointments, birthdays, meetings, reminders, etc.
  • Memo Pad – for notes, ‘to do’ lists, etc.
  • Calculator – for basic calculating functions
  • Address Book – for keeping track of all contacts and subsequent information
  • Keyboard – for typing (with the touch-screen and stylus or the basic keyboard)
  • Grafitti (Palm)/Character Recognizer (Pocket PC) – for handwritten input
  • E-mail – for composing, sending, and receiving e-mail
  • Backlight – for PDA use in dim or no lighting

Popular PDAs:

  • Blackberry
  • HTC Touch Series
  • iPhone
  • iPod Touch
  • Palm (Tungsten, Treo, TX, Zire)
  • Sidekick

Sales of smartphones have been on the rise from roughly 60 million yearly, heralding in more mobile phone users purchasing PDAs with telephonic capability.

Basic Types of Scanning Devices

What are scanning devices?

Scanning devices are devices that use a magnetic or photo-electric source to scan and convert images into electric signals that can be processed by an electronic apparatus, such as a computer. Images that can be scanned and converted include colored or black and white texts, graphics, and pictures.

Uses of Scanning Devices

Scanning devices are commonly used to:

  • Convert a text document into an electronic file;
  • Convert a photograph into an electronic graphic file;
  • Sense an image to be sent over a voice frequency
  • Circuit, such as a fax machine;
  • Reproduce text and images, as with a copier.

Types of Scanning Devices

Scanning devices are generally of two types:

  • flat-bed scanner
  • This type of scanner operates by placing the text or image on the scanning device and a motor-driven scanner makes a pass or several passes over the document in order to scan it.

  • manually operated scanning device
  • With this type of scanning device, a hand-held scanner is moved over a text document or an image by an operator. The scan head, located at the base of the apparatus, scans an image as the device is drawn over the document or image.

    These types of scanning devices are typically fitted with horizontal and vertical grids on the top surface of the apparatus. These marks function as reference points to direct the operator to the location of the scan head device and the document being scanned. Often, the operator must precisely maintain the horizontal and vertical grids on the image.

Hyperthreading

Hyperthreading is a technique that enables computer users to make one CPU act like multiple CPUs. Hyperthreading allows different parts of the CPU to carry out several concurrent tasks. This makes the CPU appear as though it is more than one unit. Hyperthreading is also known as simultaneous multi-threading.

How can a CPU achieve hyperthreading? First, it needs to have two sets of circuits that monitor the CPU’s state. These states include the CPU’s instruction pointer and registers.

The CPU uses the circuits as temporary storage facilities to keep track of what tasks it is currently performing. During the actual hyperthreading process, the circuits of the CPU are duplicated to around five percent. At this point, the performance of the CPU increases to about six times its previous rate.

Apart from the above-mentioned pieces of hardware, a CPU also needs software that support hyperthreading. The most important of these is the operating system. The computer’s operating system should support the use of multiple CPU’s. Examples of operating systems that support hyperthreading include Windows NT 4.0 and Windows XP Professional. Most of the UNIX variants also support hyperthreading.

Hyperthreading is implemented in systems that perform heavy tasks. Online businesses use servers that apply the said technique. Hyperthreading allows web-based companies to be available on the Internet all the time. It also increases the security of data stored in their servers.

Gaming systems also use computers that run in hyperthread mode. This lets the computers display the graphics and provide faster processing using the same resources.

EM64T (Intel 64)

Extended Memory 64 Technology is more commonly known as em64t or Intel 64. Today, this 64-bit extension is used in several Intel processors including the following:

  • Pentium 4
  • Pentium D
  • Pentium Extreme Edition
  • Xeon
  • Celeron D
  • Core 2 processors
  • Pentium Dual-Core

EM64T was first introduced to the market way back in 2004. First known as Yamhill, this technology underwent several name changes before finally settling on EM64T in time for its formal announcement in 2004.

Starting 2006 however, Intel no longer referred to this technology by that name and is now using Intel 64. The change of name was supposed to be for competitive measures in the market over its rival AMD64.

This technology was first tested on the E revision of Pentium 4 in June 2004. For Intel products, Nocona (also known as Xeon) was the first to adopt the Intel 64 technology. Thus, it gives testament to the idea that Intel 64 technology is also supported by Pentium 64 unlike results shown in the Prescott design.

Moreover, for desktop processors, EM64T was initially tried on the N0 Stepping Prescott-2M. The revised version of the technology now includes support for Execute Disable (XD). Lastly, for the mobile processors, Intel 64 for Merom of Core 2 processors was released on July 2006.

Advantages

First things first, you can only use the EM64T with a 64-bit operating system. However, if you do run this technology, you can avail of the following benefits:

  • You can install a maximum of 16 exabytes of RAM
  • You can execute 8-bit operations since most 64-bits follow the same scheme
  • There is a new 64-bit pointer in place for the EIP (for the 32-bits), which is the RIP and that in itself also now has its own relative address.

Other Features

There are also peculiarities involved with using such large amounts of memory for your processors. For instance, because the EM64T processor corresponds to the x86-64 ABI, the objects stored are filed according to three: small, medium, or large.

  • Objects stored in a small memory model have only 2GB of total space to use (for both code and data).
  • Models with medium memory have 2GB for the code section and there is 64-bit addressing for the data.
  • Lastly, the large model allows both data and code into a memory larger than 2GB.

Baud Rate and Bit Rate in Data Communication Systems

Baud Rate

A baud rate is the measurement of the number of times per second a signal in a communications channel changes its state. For instance, a 2400 baud rate indicates that the channel can change its state 2400 times per second. When changing its state, the channel can change from 0 to 1 or from 1 to 0, up to x, which is 2400 in this case.

Baud rate could also refer to the actual stage of the connection, such as frequency, voltage, and phase level.

Bit Rate

A bit rate is the measure of number of data bits, represented by 0s and 1s, transmitted within one second in a communication channel. For instance, 2400 bits, represented by 2400 0s or 1s, can be transmitted in one second. Individual characters, such as letter or number characters, are made of several bits.

Baud versus Bits per Second

The baud unit took its name from an officer of the French Telegraph Service named Jean Maurice Emile Baudot. In the late 19th century, he developed the first uniform-length 5-bit code for the characters of the alphabet. It was essentially the modulation rate or the number of times a line changes its state per second.

This change is not always equivalent to bits per second (BPS). As a symbol may have more than two states, it may represent more than one binary bit. Binary bits always represent precisely two states.

The baud rate and the bit rate are equivalent when connecting two serial devices with direct cables. With this setup, running at 19200 BPS means that the line is changing state 19200 times per second.

Recent modems usually do not have equal baud rates and bit rates. As modems transmit signals over a telephone line, the baud rate is limited to a maximum of 2400 baud. The use of complicated phase modulation and data compression methods augment this physical restriction of the lines.

For instance, a modem from Bell (212A modem) transmits 1,200 bps of information, using a symbol rate of 600 baud. It uses ph.ase shift keying (PSK) modulation, and each symbol features one of the four phase shifts of 270, 180, 90, and 0. As the baud rate will often not equal the bit rate, the bit per second unit is often used in referring to the data rate of a modem.

BGA

BGA, or Ball Grid Array, is a type of surface-mount package used in making electronic circuits. It is often used when electronic components are mounted directly on the Printed Circuit Board’s (PCB) surface. The BGA is derived from the PGA (Pin Grid Array), an older type of surface-mount package.
What is the Use of BGA? (or How is BGA mounted?)
The PGA mounts with pins on a circuit board. The pins emit electrical signals that appear from integrated circuits and goes to the PCB on which they are mounted.
In BGA, solder balls at the base of its package substitute pins. The apparatus is, therefore, on the PCB that holds copper pads in a blueprint that matches the solder balls. Its assembly heats in reflow ovens or in the infrared heater, and this causes the solder balls to melt. Exterior tension then causes the liquefied balls to align the package to the circuit board, on its correct distance of separation, as the solder begins to cool as it solidifies.

Advantages of BGA

  1. High Density – BGA is one answer to the production of a mini package for the integrated circuit with many pins. PGA and SOIC or Dual-in-line surface mount are produced pins. When more pins are required, the space between them is reduced. This causes difficulty for the soldering process. As its package pins go closer, the incidence of accidents in the bridging of pins with the solder grows. BGAs do not have this problem, as the solder used are factory-applied package at the precise amount.
  2. Heat Conduction – Another advantage of a BGA package is the low thermal resistance it has between its package and its PCB. This allows heat made by the integrated circuit inside its packages to flow with ease to the PCB, thereby preventing it from overheating.
  3. Low-Inductance Leads – Shorter electrical conductors mean it has a lower inductance, a property that causes unwelcome distortion signals in high-speed circuits. A BGA, with its short distance between packages and the PCB, have very low inductances.

Disadvantages of BGA

  1. Noncompliant leads – Solder balls that cannot flex are a problem for BGA. As with surface mount devices, bending due to the difference in the coefficient of its thermal expansion from the PCB substrates and the BGA, or its flexing and vibration, can cause the joints to fracture.
  2. Expensive Inspection – Once the package is soldered, checking solder faults becomes very difficult. X-ray machines and other special microscopes are being developed to overcome this troublesome process, but the costs are very high. If the BGA is badly soldered, it is transferred to the rework station and inspected with the use of an infrared lamp.

PCI

PCI, otherwise known as the PCI Standard, stands for Peripheral Component Interconnect. It is a computer bus that attaches peripheral devices to a computer motherboard. It can take the form of an integrated circuit called a planar device fitted onto the motherboard itself or as an expansion card that fits into a socket.

PCI was developed by Intel and was first introduced to computers in 1993. For several years, both PCI and the ISA bus were used. Eventually, it replaced ISA and VESA and become the standard local computer bus. Nowadays, most computers only have PCI slots and an AVG slot for a display adapter.

It is the most common local I/O bus used today, because it conveniently shares a common data path between the CPU and peripheral controllers in any computer model. Examples of common PCI Cards used today are network cards, sound cards, modems, USB ports, serial ports, TV tuner cards, and Disk controllers.

PCI Specifications specifications include the physical size of the bus such as wire spacing, bus timing, electrical characteristics, and protocols. The specifications can be bought from the PCI Special Interest Group (PCISIG).

PCI Configuration

PCI affords two separate 32-bit or 64-bit address spaces corresponding to the memory and the I/O ports of the x86 group of processors. The PCI Configuration Space is a third address space that allows the software to determine the amount of memory and I/O address space required by each device. Each of these devices can request a maximum of six areas of memory space.

During start-up, the Operating System queries all PCI buses through PCI Configuration Space to identify the devices attached to the computer and the system resources needed by each device. These resources are then determined and allocated to each device. These devices can also have an additional ROM that includes an executable x86 or PA-RISC code and an EFI driver.

Instead of using jumpers on the card, interrupts are often allocated to the device by the Operating System during configuration. These interrupts are assigned to improve their performance. Most PCI devices need special hardware to support sharing. They also need interrupt ports to aid the device in determining whether an interrupt is for itself or for another device sharing the I/O port.

PCI Variants

1. PCI 2.2 allows 66 MHz signaling at 3.3 signal voltage with a peak transfer rate of 533 MB/s. The 5 and 3.3 signal voltages are allowed at 33 MHz.

2. PCI 2.3 allows the use of 3.3 volts and universal keying. However, it does not allow 5-volt keyed add-in cards.

3. PCI 3.0 is the final official standard of the bus. It completely comes without the 5-volt capability.

4. PCI-X amplifies the maximum signaling frequency to 133 MHz with a peak transfer rate of 1066 MB/s.

5. PCI-X 2.0 allows a 266 MHz rate with a peak transfer rate of 2133 MB/s as well as a 533 MHz rate with a peak transfer rate of 4266 MB/s.

6. Mini PCI is the latest form factor of PCI 2.2 which is chiefly used for laptops.

7. CardBus is a PC card form factor for 32-bit 33 MHz PCI.

8. PC/104-Plus is an industrial bus that uses PCI signal lines with different connectors.

PCI Express

PCI Express (formerly known as 3GIO/Arapaho) is the latest interface using PCI programming concepts. It features a serial physical-layer protocol and various connectors. It is projected to replace PCI and PCI derived AGP buses.

SMBus

The System Management Bus (SMBus) is a simple two-wire interface wherein basic power-related chips interconnect with other parts of a system, such as within a computer motherboard. SMBus is mostly used in low-bandwidth devices.

Created by Intel in 1995, SMBus was mainly developed to both receive and control data from motherboards in a practical yet highly efficient manner. SMBus is an extremely simple and inexpensive piece of hardware, utilizing analog technology and limited digital capability. The functional design merits simple logic commands.

SMBus technology is based on Philips’ Inter-Integrated Circuit (I²C) serial bus protocol, a multi-master serial computer bus used to connect low-speed peripherals. The SMBus’ clock frequency ranges from 10 kHz to 100 kHz. Its timings and voltage levels are more specific than those of the I²C, although devices from the two different systems operate successfully in the same bus.

An SMBus device can transmit clock and data instructions from the motherboard to the system. Many electronic devices such as the rechargeable battery system of a laptop, a personal computer, and various types of electronics with lid switches and temperature sensors use SMBus.

SMBus can convey specific types of basic data. A device with SMBus can identify the version or model of the device, for example. SMBus also reports errors or events within a system, receives control parameters, and saves and returns its status.

Note that SMBus, even within a desktop or laptop computer, is commonly inaccessible and therefore cannot be configured. SMBus devices are usually unable to identify some of its function details; however, a recent PMBus combination has enableed SMBus to allow that.

SMBus is supported by various Operating Systems such as Linux, Windows 2000, Windows XP, and Windows Vista.

Molex

Molex is to a type of connector that is normally used in computers. It consists of a two-piece interconnection of a pin and a socket. This connector was developed by Molex Products Company. It was first used in home appliances in the 1950’s and 1960’s, and it soon became a standard in electronics.

The design of Molex connectors consists of several parts. First are the cylindrical spring pins and cylindrical spring sockets. The pins and sockets may be arranged in any combination as long as they are in a single connector.

These pins and sockets are fitted together and are held within a rectangular matrix. This rectangular matrix is housed in a nylon shell. Molex usually has 2 to 6 circuits, although in some cases, it can have 9, 12, or 15 circuits. Molex housings have separate male and female genders.

Molex is used in several computer aspects. This technology is used by certain types of computers to connect the power supply to the motherboard. It is also used as a means of providing power to floppy disk drives. Other PCs use Molex connectors to connect the power supply to the fans.

Molex has a set of features to provide reliability and safety. Molex connectors are designed to be polarized. This prevents the user from incorrectly inserting the pins to the sockets. Also, these connectors are locked firmly into position with the use of a latch. This ensures that the connection will not be cut off even if there would be sudden movement in the machine.

L2 Cache

What is an L2 Cache?

L2 cache refers to “Level 2” cache. It is a set of memory circuits designed to store recently accessed information that had not been caught by the L1 cache. As it is secondary to the Level 1 cache, the L2 cache is also referred to as secondary cache. It often appears larger than L1 cache and performs at a slightly slower rate.

Function

The L2 cache’s main function is to speed up access to information that had been used already by bridging the processor/memory performance gap. L2 Cache is also used to buffer program instructions and data that the processor is about to access from the memory, thus reducing data access time.

Typical Location

The L2 cache may be placed in the following locations:

  1. On the motherboard or daughterboard that inserts into the motherboard; – L2 caches found on the motherboard are either set in a Card Edge Low Profile (CELP) socket or on a coast module. The latter setting looks like a short SIM and plugs into a coast socket located close to the processor;
  2. On the processor core, either integrated or on-die cache; and
  3. In the same packet or cartridge as the processor, but set separate from the processor core.

Pentium Pro, Pentium II, early Pentium III, and slot A Athlon processors have all used this setting for the L2 cache. Pentium Pro processors have the L2 cache sighted on the processor chip itself, but it is not sighted in the same circuit where the processor and L1 cache are located.

Features

The processor’s bus interface employs a particular transfer standard called burst mode in order to facilitate the speedy transfer of data from the L2 cache to the processor. One burst cycle is composed of 4 data transfers where the first 64 addresses in a series are produced by the address bus.

An L2 cache commonly uses a pipeline burst. This type of synchronous cache pre-fetches memory contents before they are requested. It also pre-fetches pipelining, which allows the access of memory value in the cache at the same time another memory value is accessed in DRAM. These techniques reduce processor wait states.