Tuesday, October 23, 2012

Install missing drivers to any computer in just few minutes

Sometime when you install or reinstall a windows XP, Vista or Seven you had some missing drivers such as:
Ethernet Controller
Network Controller
Multimedia Audio Controller
Audio Device on High Definition Audio Bus
Video Controller
Video Controller ( VGA Compatible)
PCI Serial Port
PCI Simple Communications Controller
PCI Device
Biometric Coprocessor
Universal SerialBus (USB) Controller
System interrupt controller
Base System Device
Broadcom USH w/swipe sensor
USB device
SM Bus controller
Unknown device

To resolve this problem you need the DriverPack Solution DVD

DriverPack Solution is the most popular program that makes the job of finding and automatically installing drivers a pleasure

DriverPack Solution simplifies the process of installing missing drivers on any computer.
To download DriverPack Solution from the official site Click here 

Youtube videos are black screen on my firefox browser.

Problem: You can’t play any youtube videos on firefox browser, yesterday you had no problems viewing any youtube videos but today all the videos on youtube website appear as a black screen, you don’t have any problems with intenret explorer or google chrome.

1) Solution 1: Disable Shockwave Flash plugin in firefox and restart firefox.

2) Solution 2: Delete the history and all cockies on firefox and restart it.

3) Solution 3: If you have Adblock Disable it and restart firefox.

4) Solution 4: Disabled all the extensions and the add-on in firefox and restart it.

Repairing Power Supply COMPAQ HP PDP-124P 185W

Preferably using a low electric current in the test, less than 220 volts, It is better to have 80 volts, so as not to damage the others components of the power supply.

Repairing Power Supply COMPAQ HP PDP-124P 185W

After you opened the power supply box, start the measurement of the following pieces, they are most damaged pieces in the COMPAQ HP PDP-124P 185W power supply:
  1. Fuse 5 Am
  2. Resistor value MOV1_2_3 V10K
  3. Resistor value 1 kilo ohms (Brown. Black. Red. Gold) R9
  4. Resistor value 1 Kilo Ohm  (Brown. Black. Red. Gold) R5
  5. Resistor value 330 ohms (Orange. Orange. Black. Gold) R7
  6. Resistor value 1 ohms 1 Watt R11
  7. Integrated circuit U1 UC3845
  8. Integrated circuit U5 TOP 244P
  9. Transistor  Q1 PN 2907A
  10. Transistors MOSFET Q1 FQA9N90C
  11. Transistors Q2 B1116
  12. PHOTOCOUPLER 6 U1 U3 B337T
Replace defective components

Repairing Power Supply COMPAQ PDP-115P 120W

Preferably using a low electric current in the test, less than 220 volts, It is better to have 80 volts, so as not to damage the others components of the power supply.

Repairing Power Supply COMPAQ PDP-115P 120W

After you opened the power supply box, start the measurement of the following pieces, they are most damaged pieces in the COMPAQ PDP-115P 120W  power supply:
  1. Fuse 5 Am
  2. Resistors  1,2,3 and 4 value  V10K VDR
  3. Resistor R3 value 120 kilo ohms
  4. Integrated circuit IC1 and IC2 type: KA 358S
  5. Integrated circuit IC3 type: UCC 3581 N
Replace defective components

Friday, October 12, 2012

What is MOSFET

MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is a semiconductor device used to control and amplify current. MOSFET is four electronically active regions that are marked: gate (G), source (S), and drain (D), and the bulk terminal (B) to which the gate, drain, and source voltages are typically referenced. The rectangular gate region lies on top of the bulk separated by a thin silicon oxide dielectric with thickness. Two other important dimensions are the transistor gate length and width. The drain and source regions are embedded in the substrate but have an opposite doping to the substrate.

There are two types of MOSFET transistors, the nMOS transistor and the pMOS transistor, that differ in the polarity of carriers responsible for transistor current. The charged carriers are holes in pMOS transistors and electrons in nMOS transistors.

MOSFET Operate: A MOSFET has a gate that is insulated from the channel. A voltage that is applied to the gate will attract charge from the channel toward the gate. This charge cannot move through the gate because of the insulation. But, this “moved” charge does change the conductivity of the channel.

A simple description treats the MOSFET operate. When the gate has a high voltage, the transistor closes like a wall switch, and the drain and source terminals are electrically connected. Just as a light switch requires a certain force to activate, the transistor gate terminal needs a certain voltage level to switch and connect the drain and source terminals. This voltage is called the transistor threshold voltage Vt and is a fixed voltage for nMOS and for pMOS devices in a given fabrication process.

The most common MOSFET is the enhancement mode MOSFET. In an n-channel enhancement mode MOSFET the resistance from the source to drain is relatively high; therefore, very little current can flow. However, a positive voltage at the gate causes the channel to induce negative charges which allows more electrons to flow from the source to the drain. This means that the resistance of the channel is easily controlled by the gate.

Practical form of the MOSFET

CMOS: Complementary MOSFET

Complementary Metal Oxide Semiconductor Field Effect Transistor is a technology for constructing integrated circuits. In this circuit, two MOSFETs P-channel and N-channel are connected in series so that source of P-channel device is connected to a positive voltage supply + VDD and the source of N-channel device is connected to the ground. Gates of both the devices are connected as a common input and drain terminals of both the devices are connected together as a common output.

When the input is low on the gate, the P-channel MOSFET will be ON, the drain and source terminals are electrically connected and the N-channel MOSFET is OFF.
In other case when the input is high on the gate, the N-channel MOSFET will be ON, the drain and source terminals are electrically connected and the P-channel MOSFET is OFF.

What is Transistor

Transistor is an active electronic component composed of semiconductor material with three terminals that can function as electronic switches or as signal amplifiers.

 Modern transistors are divided into two main categories: bipolar junction transistors (BJTs) and field effect transistors (FETs). Application of current in BJTs and voltage in FETs between the input and common terminals increases the conductivity between the common and output terminals, there by controlling current flow between them. The transistor characteristics depend on their type.

Transistors are made from the n-type and p-type semiconductor materials as diodes and employ the same principles. Transistors have two PN junctions instead of just one like a diode has. The two PN junctions allow a transistor to perform more functions than a diode, such as acting as a witch or an amplifier.

The bipolar transistor is made up of three parts: the emitter, the base and the collector. There are two types of bipolar transistors: the PNP transistor and the NPN transistor.

In the PNP transistor the emitter made from p-type semiconductor material, the base is made from n-type semiconductor material and the collector is p-type semiconductor material. For the PNP transistor to operate, the emitter must connect to positive, the base to negative and the collector to negative.

In the NPN transistor the emitter made from n-type semiconductor material, the base is made from p-type semiconductor material and the collector is n-type semiconductor material. For the NPN transistor to operate, the emitter must connect to negative, the base to positive and the collector to positive.

What is Semiconductor

The semiconductors are just average conductors, a higher resistance than metal conductors, but a lower resistance than insulators. The two most commonly used semiconductor elements are Silicon and Germanium. Their +4 valence electrons mean that they have a very stable covalent bond structure.

Intrinsic semiconductors are pure semiconductors that contain no impurities. When temperature increases, the conduction property of the intrinsic type also increases. This is because, at high temperatures, electrons are excited to higher energy levels and create holes. These holes are positively charged and flow in the direction opposite to that of electrons thus causing electricity. In an intrinsic semiconductor, the number of holes and electrons are equal. Other causal agent of electricity in this type is crystal defects.

Extrinsic semiconductors when impurities are added to intrinsic semiconductors, extrinsic semiconductors are formed, meaning they are not in their natural form. The process of adding impurities to the semiconductor is called doping.

Doping a pure semiconductor with a small amount of material with a valence electron of  +5 (which inclues Phosphorus, Arsenic, and Anitmony) creates an n-type semiconductor. It is referred to this because of the excess of free electrons in the material.
Similiarly, doping a pure semiconductor with a small amount of material with valence electron of +3 (Boron, Aluminum, Gallium, and Indium) creates a p-type semiconductor. This results because of a hole that is left by the absence of an electron in the covalent bond structure.

Note that doping a semiconductor does not add or remove any charge. The resulting product is still electrically neutral. Doping simply redistributes valence electrons so more or less free charges are available for conduction.

The PN Junction is formed by joining n-type and p-type semiconductor. The extra electrons in the n-type semiconductor attempt to move over into available holes in the p-type semiconductor. At the same time, some of the holes in the p-type seiconductor end up moving over to the n-type to meet up with electrons.When this happens, we end up with an excess of electrons on the p-type side and extra electrons on the n-type side, creating an electrical imbalance. This electrical imbalance is known as the barrier potential.

Forward Bias
When we apply a positive voltage to the p-type semiconductor and a negative voltage to the n-type semiconductor, we are applying a forward bias to the semiconductor. First, the negative voltage at the n-type semiconductor is going to attempt to push electrons towards the junction in the middle. The positive voltage at the p-type semiconductor will push the holes towards the barrier as well. This reduces the barrier potential. If the barrier potential is reduced enough, the charge carriers can move through the barrier and out the other side. This means that current flows.

Reverse Bias
Applying a reverse voltage to our semiconductor material is known as reverse bias. In this condition, the electrons are pulled away from the barrier on the n-type side and the holes are pulled away from the barrier on the p-type side. This results in a larger barrier, which creates a much greater resistance for charges to flow through. The net result is that no current flows through the barrier.

What is Diode

Diode is a electrical device made from semiconductor material, usually silicon, which is doped with two impurities. One side is doped with a donor or n-type impurity which releases electrons into the semiconductor lattice. These electrons are not bound and are free to move about. Because there is no net charge in the donor impurity, the n-type semiconductor is electrically neutral. The other side is doped with an acceptor or p-type impurity which imparts free holes into the lattice. A hole is the absence of an electron which acts as a positive charge. The p-type semiconductor is also electrically neutral because the acceptor material adds no net charge. In simple terms, a diode is a device that restricts the direction of flow of charge carriers (electrons in this class) . Essentially, it allows an electric current to flow in one direction, but blocks it in the opposite direction.

The diode has two terminals or electrodes (di-ode), that act like an on-off switch. When the diode is “on”, it acts as a short circuit  and passes all current. When it is “off”, it behaves like an open circuit and passes no current. The two terminals are different and are marked as plus and minus. If the polarity of the applied voltage matches that of the diode (forward bias), then the diode turns “on”. When the applied voltage polarity is opposite (reverse bias), it turns “off”.


Diodes allow electricity to flow in only one direction. The arrow of the circuit symbol shows the direction in which the current can flow. Diodes are the electrical version of a valve and early diodes were actually called valves.

Reverse Voltage
When a reverse voltage is applied a perfect diode does not conduct, but all real diodes leak a very tiny current of a few µA or less. This can be ignored in most circuits because it will be very much smaller than the current flowing in the forward direction. However, all diodes have a maximum reverse voltage (usually 50V or more) and if this is exceeded the diode will fail and pass a large current in the reverse direction, this is called breakdown.

Forward Voltage Drop
The voltage across a semiconductor diode that is carrying current in the forward direction; it is usually approximately constant over the range of currents commonly used. Also known as diode drop; diode voltage; forward voltage drop.

Connecting and Soldering Diodes
Diodes must be connected the correct way round, and circuit diagrams may be labelled ‘a’ or ‘+’ for anode and ‘k’ or ‘-’ for cathode. The cathode is marked by a line painted on the body of the diode.

 Types of Diodes:
There is different types of diodes:

Zener diodes – This diode allows current to flow in the forward direction in the same manner as an ideal diode, but will also permit it to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage, “zener knee voltage” or “zener voltage”.

Light emitting diodes (LED) – This is the most popular kind of diode. When it works in the forward bias condition, the current flows through the junction to produce the light.

Photodiodes – The electrons and holes are generated as light strikes across the p-n junction causing the current to flow. Theses diodes can work as photodetector and are used to generate electricity.

Schottky diode - is a semiconductor diode with a low forward voltage drop and a very fast switching action.

Shockley diode – This is a four layer diode which is also known as PNPN diode. This didoe is similar to thyristor where the gate is disconnected.

Tunnel diodes - The tunnel diode has a region in its voltage current characteristic where the current decreases with increased forward voltage, known as its negative resistance region. This characteristic makes the tunnel diode useful in oscillators and as a microwave amplifier.

Vaccum diodes - This diode is two electrode vacuum tube which can tolerate high inverse voltages.

Varactor diodes – This didoe works in reverse bias condition and restricts the flow of current thorugh the junction. Depending on the amount of biasing, the width of the depletion region keeps varying. This diode comprises of two plates of a capacitor with the depletion region amidst them. The variation in capacitance depends upon the depletion region and this can varied by altering the reverse bias on the diode.

PIN diodes – This diode has intrinsic semiconductor sandwiched between P- type and N- type region. Doping does not occur in this type of diode and thereby the intrinsic semiconductor increases the width of the depletion region. They are used as ohtodiodes and radio frequency switches.

LASER diode – This diode produces laser type of light and are expensive as compared to LED. They are widely used in CD and DVD drives.

Transient voltage supression diodes – This diode is used to protect the electronics that are sensitive against voltage spikes.

Gold doped diodes – These diodes use gold as the dopant and can operate at signal frequencies even if the forward voltage drop increases.

Silicon controlled rectifier - As the name implies this diode can be controlled or triggered to the ON condition due to the application of small voltage. They belong to the family of Tyristors and is used in various fields of DC motor control, generator field regulation, lighting system control and variable frequency drive . This is three terminal device with anode, cathode and third controled lead or gate.

Super barrier diodes – These are also called as the rectifier diodes. This diodes have the property of low reverse leakage current as that of normal p-n junction diode and low forward voltage drop as that of Schottky diode with surge handling ability.

Peltier diodes – This diode is used as heat engine and sensor for thermoelectric cooling.

Gunn diode - is a form of diode used in high-frequency electronics. Its internal construction is unlike other diodes in that it consists only of N-doped semiconductor material, whereas most diodes consist of both P and N-doped regions. In the Gunn diode, three regions exist: two of them are heavily N-doped on each terminal, with a thin layer of lightly doped material in between. When a voltage is applied to the device, the electrical gradient will be largest across the thin middle layer. Conduction will take place as in any conductive material with current being proportional to the applied voltage. Eventually, at higher field values, the conductive properties of the middle layer will be altered, increasing its resistivity, preventing further conduction and current starts to fall. This means a Gunn diode has a region of negative differential resistance.

Crystal diode – These are a type of point contact diodes which are also called as Cat’s whisker diode. This didoe comprises of a thin sharpened metal wire which is pressed against the semiconducting crystal. The metal wire is the anode and the semconducting crystal is the cathode. These diodes are obsolete.

Avalanche diode – This diode conducts in reverse bias condition where the reverse bias volage applied across the p-n junction creates a wave of ionization leading to the flow of large current. These didoes are designed to breakdown at specific reverse voltage in order to avoid any damage.

Thursday, October 11, 2012

What is Capacitors

A capacitor (originally known as condenser) is a device which stores electric charge. Capacitors vary in shape and size, but the basic configuration is two conductors separated by a dielectric, with a charge +Q on one conductor (typically referred to as a “plate”) and an equal but opposite charge −Q stored on the other conductor. We find that the charge stored by a capacitor is proportional to the potential difference between the two conductors. In other words, Q = CV , Where,  Q is the charge stored by the capacitor, C is the capacitance value of  the capacitor, and V is the voltage applied across the capacitor.

The capacitance of a given set of conductors depends only upon their geometry (the shape of the conductors and the distance between them) and on the “stuff” placed between them. We refer to any insulating material placed between conductors in a capacitor as a dielectric.
The SI unit of capacitance is the farad (F):  1F = 1 farad = 1coulomb / volt= 1C / V.
Normal value of  capacitance is smaller and it is measured in microfarad, nanofarad,  and picofarad.

There are three principal capacitor geometries you should become familiar with:
• the parallel-plate capacitor.
• the cylindrical capacitor.
• the spherical capacitor.

Capacitors have many important applications in electronics. Some examples include storing electric potential energy, delaying voltage changes when coupled with resistors, filtering out unwanted frequency signals, forming resonant circuits and making frequency-dependent and independent voltage dividers when combined with resistors.
The symbol for a capacitor used in schematic diagrams of electronic circuits looks very much like a parallel-plate model.

 Symptoms of faulty motherboard associated to faulty capacitors:
1) The computer does not start up from the first time, you need a lot of try on the power key.
2) Motherboard failed to complete the post , it start up but no  Data.
3) Failure to complete RAM memory test at the beginning of the run motherboard or motherboard stop at the RAM memory test.
4) The fan processor run and  front LED lighting  without giving Data on the screen.
5) When motherboard try to download the Windows OS  fails to complete the download process.
6) CPU overheating unusually Although not loaded complex operations.
7) instability of the computer, particularly when running complex graphical programs.

What is Current

Current is moving charge, typically electrons. And just as the amount of water flowing in a river can be measured, so can the amount of flowing electrons through a medium. To make this measurement, we simply pick a reference point and count the number of electrons that flow past that point over time.

The standard measure of electrical current is the Ampere, often referred to just as “amp”. It is equal to 6.24e18 (that’s 6 quintillion!) electrons flowing past a reference point in 1 second. The amp is named after André-Marie Ampère, a French physicist credited with the discovery of electromagnetism.

Many times the term amp is abbreviated as just a capital A. For example, instead of seeing “5 amps” it may be more common to see “5A". This is especially true when SI prefixes are used, such as writing 5mA instead of 5 milliamps.

Finally, the terminology of current is often abbreviated with the letter I (probably because the letter C had already been used as an abbreviation for charge). Electrical schematics that need to show the presence of current in a portion of a circuit will often use the letter I as a symbol for current.

What is Voltage?

Voltage (also called electrical potential difference or electric tension or electromotive force) is the potential energy that makes the electrical current flow in a circuit by pushing the electrons around. Voltage is equal to the work which would have to be done, per unit charge, against a static electric field to move the charge between two points.
Voltage can be direct or alternating. A direct voltage maintains the same polarity at all times. In an alternating voltage, the polarity reverses direction periodically. The number of complete cycles per second is the frequency, which is measured in hertz (one cycle per second), kilohertz, megahertz, gigahertz, or terahertz. An example of direct voltage is the potential difference between the terminals of an battery. Alternating voltage exists between the terminals of a common utility outlet.

The unit of voltage is volt shown as 'v'.  One Volt is equal to one Joule of energy that can move one Coulomb of electrical charge. A voltmeter can be used to measure the voltage (or potential difference) between two points in a circuit.

Basic concept of electricity

Electricity is a form of energy. Electricity is the flow of electrons. Every material, be it solid, liquid, or gas contains two basic sub-atomic particles that house a fundamental property known as electrical charge. These particles are the protons and the electrons. The proton and electron each contain the same amount of electrical charge, however their type of charge is exactly opposite of each other. We distinguish the two by defining the proton’s charge as positive (+) and the electron’s charge as negative (-) . Electricity is simply the movement (or “flow”) of the electrons.

The electrons of different types of atoms have different degrees of freedom to move around. With some types of materials, such as metals, the outermost electrons in the atoms are so loosely bound that they chaotically move in the space between the atoms of that material by nothing more than the inffuence of room-temperature heat energy. Because these virtually unbound electrons are free to leave their respective atoms and float around in the space between adjacent atoms, they are often called free electrons.
In other types of materials such as glass, the atoms’ electrons have very little freedom to move around. While external forces such as physical rubbing can force some of these electrons to leave their respective atoms and transfer to the atoms of another material, they do not move between atoms within that material very easily.
This relative mobility of electrons within a material is known as electric conductivity. Conductivity is determined by the types of atoms in a material (the number of protons in each atom’s nucleus, determining its chemical identity) and how the atoms are linked together with one another. Materials with high electron mobility (many free electrons) are called conductors, while materials with low electron mobility (few or no free electrons) are called insulators.

Electric Current:
The Electric Current is a flow (movement) of electric charge (electron) through a conductive material (circuit) from a point with a higher electrical potential (voltage) to the other.

The value of current or the current intensity is equal to the volume of the flowing electrical charge in the unit of time, second, as shown in the formula below: I = Q/t
Were I is the electrical current, which we refer to as Current, Q is the positive electrical charge in Coulomb (the electrical charge unit) passing in the time t with the unit of seconds.

Voltage (also called electrical potential difference or electric tension or electromotive force) is the potential energy that makes the electrical current flow in a circuit by pushing the electrons around. Voltage is equal to the work which would have to be done, per unit charge, against a static electric field to move the charge between two points.
Voltage can be direct or alternating. A direct voltage maintains the same polarity at all times. In an alternating voltage, the polarity reverses direction periodically. The number of complete cycles per second is the frequency, which is measured in hertz (one cycle per second), kilohertz, megahertz, gigahertz, or terahertz. An example of direct voltage is the potential difference between the terminals of an battery. Alternating voltage exists between the terminals of a common utility outlet.

The unit of voltage is volt shown as ‘v’.  One Volt is equal to one Joule of energy that can move one Coulomb of electrical charge. A voltmeter can be used to measure the voltage (or potential difference) between two points in a circuit.

Wednesday, October 10, 2012

What is a Hard Disk Drive

The hard disk drive (HDD) is one of the most important and yet mysterious parts of a computer system. HDDs are sealed units used for nonvolatile data storage. Nonvolatile, or semipermanent, storage means that the storage device retains the data even when no power is supplied to the computer. Because HDDs store crucial programming and data, the consequences of any failures are usually very serious.

Hard disk drives contain rigid, disk-shaped platters, usually constructed of aluminum or glass Unlike floppy disks, the platters can’t bend or flex—hence the term hard disk. In most drives you can’t remove the platters, which is why they are sometimes called fixed disk drives. Removable hard disk drives are also available.

Obviously, the large storage capacities found on modern drives are useless unless you can also quickly transfer the data to and from the disk. The hard disk as found in the original IBM XT in 1983 had a constant data transfer rate from the media of about 100KBps. Today, most commonly used drives feature average transfer rates of 100MBps or more, an increase of over 1,000 times. Much like the increase in drive capacity, the speed of the interface has also come a long way since the MFM and RLL interfaces that were commonplace in the ’80s. As always, the interfaces are much faster than the actual drives. Modern interfaces offer data transfer rates of up to 133MBps for Parallel ATA, 150MBps and 300MBps for Serial ATA, 320MBps bandwidth for Ultra-320 SCSI, and 300MBps or 600MBps for SAS. All these interfaces are much faster than the drives they support, meaning that the true transfer rate you will see is almost entirely limited by the drive and not the interface you choose. The modern interfaces have bandwidth to spare for future developments and advances in hard disk technology.

What is PC Motherboard

The Motherboard is the most important component in a PC system. Virtually every internal component in a PC connects to the motherboard, and its features largely determine what your computer is capable of, not to mention its overall performance. Although I prefer the term motherboard, other terms such as main board, system board, and planar are interchangeable. This chapter examines the various types of motherboards available and those components typically contained on the motherboard and motherboard interface connectors.

Several common form factors are used for PC motherboards. The form factor refers to the physical dimensions (size and shape) as well as certain connector, screw hole, and other positions that dictate into which type of case the board will fit. Some are true standards (meaning that all boards with that form factor are interchangeable), whereas others are not standardized enough to allow for interchangeability. Unfortunately, these nonstandard form factors preclude any easy upgrade or inexpensive replacement, which generally means they should be avoided. The more commonly known PC motherboard form factors include the following:

Obsolete Form Factors
■ Baby-AT (PC and XT)
■ Full-size AT
■ LPX (semiproprietary)
■ BTX, microBTX, picoBTX

Modern Form Factors
■ ATX and variants; microATX, FlexATX, DTX/Mini-DTX, and ITX/Mini-ITX

PC motherboard form factors have evolved over the years from the Baby-AT form factor boards based on the original IBM PC and XT, to the current ATX form factor (and variants) used in most desktop and tower systems. ATX has a growing number of variants, mostly in smaller sizes designed to fit different market segments and applications. The short-lived BTX form factors relocated major components to improve system cooling and incorporate a thermal module.

Anything that does not fit into one of the industry-standard form factors should be considered proprietary. Unless there are special circumstances, I do not recommend purchasing systems based on proprietary board designs because they are difficult to upgrade and expensive to repair because components such as the motherboard, case, and power supply are not interchangeable with other systems. I often call proprietary form factor systems “disposable” PCs because that’s what you must normally do with them when they are too slow or need repair out of warranty.

What is RAM (Memory)

Memory is the workspace for the processor. It is a temporary storage area where the programs and data being operated on by the processor must reside. Memory storage is considered temporary because the data and programs remain there only as long as the computer has electrical power or is not reset. Before the computer is shut down or reset, any data that has been changed should be saved to a more permanent storage device (usually a hard disk) so it can be reloaded into memory in the futur

Memory often is called RAM, for random access memory. Main memory is called RAM because you can randomly (as opposed to sequentially) access any location in memory. This designation is somewhat misleading and often misinterpreted. Read-only memory (ROM), for example, is also randomly accessible, yet is usually differentiated from the system RAM because it maintains data without power and can’t normally be written to. Although a hard disk can be used as virtual random access memory, we don’t consider that RAM either.

Over the years, the definition of RAM has changed from a simple acronym to become something that means the primary memory workspace the processor uses to run programs, which usually is constructed of a type of chip called dynamic RAM (DRAM). One of the characteristics of DRAM chips (and therefore most types of RAM in general) is that they store data dynamically, which really has two meanings. One meaning is that the information can be written to RAM repeatedly at anytime. The other has to do with the fact that DRAM requires the data to be refreshed (essentially rewritten) every few milliseconds or so; faster RAM requires refreshing more often than slower RAM. A type of RAM called static RAM (SRAM) does not require the periodic refreshing. An important characteristic of RAM in general is that data is stored only as long as the memory has electrical power.
RAM can refer to both the physical chips that make up the memory in the system and the logical mapping and layout of that memory. Logical mapping and layout refer to how the memory addresses are mapped to actual chips and what address locations contain which types of system information.
Memory temporarily stores programs when they are running, along with the data being used by those programs. RAM chips are sometimes termed volatile storage because when you turn off your computer or an electrical outage occurs, whatever is stored in RAM is lost unless you saved it to your hard drive. Because of the volatile nature of RAM, many computer users make it a habit to save their work frequently. Many software applications perform periodic saves automatically in order to minimize the potential for data loss.
Physically, the main memory in a system is a collection of chips or modules containing chips that are usually plugged into the motherboard. These chips or modules vary in their electrical and physical designs and must be compatible with the system into which they are being installed to function properly.
To better understand physical memory in a system, you should understand what types of memory are found in a typical PC and what the role of each type is. Three main types of physical memory are used in modern PCs.
■ ROM—Read-only memory
■ DRAM—Dynamic random access memory
■ SRAM—Static RAM

The only type of memory you normally need to purchase and install in a system is DRAM. The other types are built in to the motherboard (ROM), processor (SRAM), and other components such as the video card, hard drives, and so on.

What is Processor

The brain or engine of the PC is the processor—sometimes called microprocessor or central processing unit (CPU). The CPU performs the system’s calculating and processing. The processor is often the most expensive single component in the system; in higher-end systems it can cost up to four or more times more than the motherboard it plugs into. Intel is generally credited with creating the first microprocessor in 1971 with the introduction of a chip called the 4004. Today Intel still has control over the processor market, at least for PC systems, although AMD has garnered a respectable market share. For the most part, PC-compatible systems use either Intel processors or Intel-compatible processors from a handful of competitors such as AMD and VIA/Cyrix

The first major change in processor architecture was the move from the 16-bit internal architecture of the 286 and earlier processors to the 32-bit internal architecture of the 386 and later chips, which Intel calls IA-32 (Intel Architecture, 32-bit). Intel’s 32-bit architecture dates to 1985, and it took a full 10 years for both a partial 32-bit mainstre am OS (Windows 95) as well as a full 32-bit OS requiring 32-bit drivers (Windows NT) to surface, and another 6 years for the mainstream to shift to a fully 32-bit environment for the OS and drivers (Windows XP). That’s a total of 16 years from the release of 32-bit computing hardware to the full adoption of 32-bit computing in the mainstream with supporting software. I’m sure you can appreciate that 16 years is a lifetime in technology. Now we are in the midst of another major architectural jump, as Intel, AMD, and Microsoft are in the process of moving from 32-bit to 64-bit architectures. In 2001, Intel had introduced the IA-64 (Intel Architecture, 64-bit) in the form of the Itanium and Itanium 2 processors, but this standard was something completely new and not an extension of the existing 32-bit technology. IA-64 was first announced in 1994 as a CPU development project with Intel and HP (code-named Merced), and the first technical details were made available in October 1997. The fact that the IA-64 architecture is not an extension of IA-32 but is instead a whole new and completely different architecture is fine for non-PC environments such as servers (for which IA-64 was designed), but the PC market has always hinged on backward compatibility. Even though emulating IA-32 within IA-64 is possible, such emulation and support is slow.
With the door now open, AMD seized this opportunity to develop 64-bit extensions to IA-32, which it calls AMD64 (originally known as x86-64). Intel eventually released its own set of 64-bit extensions, which it calls EM64T or IA-32e mode. As it turns out, the Intel extensions are almost identical to the AMD extensions, meaning they are software compatible. It seems for the first time that Intel has unarguably followed AMD’s lead in the development of PC architecture. To make 64-bit computing a reality, 64-bit operating systems and 64-bit drivers are also needed. Microsoft began providing trial versions of Windows XP Professional x64 Edition (which supports AMD64 and EM64T) in April 2005, but it wasn’t until the release of Windows Vista x64 in 2007 that 64-bit computing would begin to go mainstream. Initially, the lack of 64-bit drivers was a problem, but by the release of Windows 7 x64 in 2009, most device manufacturers provide both 32-bit and 64-bit drivers for virtually all new devices. Linux is also available in 64-bit versions, making the move to 64-bit computing possible for non-Windows environments as well.
Another important development is the introduction of multicore processors from both Intel and AMD. Current multicore processors have up to four or more full CPU cores operating off of one CPU package—in essence enabling a single processor to perform the work of multiple processors. Although multicore processors don’t make games that use single execution threads play faster, multicore processors, like multiple single-core processors, split up the workload caused by running multiple applications at the same time. If you’ve ever tried to scan for malware while simultaneously checking email or running another application, you’ve probably seen how running multiple applications can bring even the fastest processor to its knees. With multicore processors available from both Intel and AMD, your ability to get more work done in less time by multitasking is greatly enhanced. Current multicore processors also support 64-bit extensions, enabling you to enjoy both multicore and 64-bit computing’s advantages.
PCs have certainly come a long way. The original 8088 processor used in the first PC contained 29,000 transistors and ran at 4.77MHz. Compare that to today’s chips: The AMD Phenom II has an estimated 758 million transistors and runs at up to 3.4GHz or faster, and the Intel Core i5/i7 have up to 774 million transistors and run at up to 3.33GHz or faster. As multicore processors with large integrated caches continue to be used in more and more designs, look for transistor counts and real-world performance to continue to increase well beyond a billion transistors. And the progress won’t stop there, because according to Moore’s Law, processing speed and transistor counts are doubling every 1.5–2 years.

USB device Over Current Status Detected, System will shut down in 15 seconds.

ASUS motherboard Problem :  When you power on the computer, the system show you a message says there is a problem in USB device, the USB device Over Current Status Detected, System will shut down in 15 seconds .

The motherboard know this problems:

A8V Deluxe
1) Check USB ports on the front panel disconnected them from the motherboad and see if the problem persist. Sometime the USB pins are get connected to another pins in that USB. Which is transferring more current than usual to the mainboard. Your mainboard is now telling you that if the system runs then it can harm the system, so its better to shutdown the system.
2) If you made any update to the bios, you should to return to the old bios driver. the bios update make this problem sometime.
3) Check  USB fuse protection, if the fuse damaged replace it.

you should check all USB fuse protection.

Thursday, October 4, 2012

What is Resistor

A Resistor is an electrical component that resists the flow of electrical current in electronic circuits, in other term, where there is high resistance in a circuit the flow of current is small, where the resistance is low the flow of current is large. And so we can control the flow of current by changing the value of the resistance, which passes through the electronic circuits, when a resistor is introduced to a circuit the flow of current is reduced. The higher the value of the resistor the smaller/lower the flow of current, the resistance is measured in ohms.
Resistance, voltage and current are connected in an electrical circuit by Ohm’s Law:
R = V / I.
The most common schematic symbol for a resistor is a zig-zag line but in a circuit diagram the symbol used for a resistor varies:

The Ohm (symbol: Ω, called Omega) is the SI unit of electrical resistance, named after Georg Simon Ohm, Higher resistance values are represented by “k” (kilo-ohms) and M (meg ohms).
For example:
150 000 Ω = 150k,
1 500 000 Ω = 1M5
The resistors are typically constructed of metal wire or carbon, and engineered to maintain a stable resistance value over a wide range of environmental conditions.Unlike lamps, they do not produce light, but they do produce heat as electric power is dissipated by them in a working circuit. Typically, though, the purpose of a resistor is not to produce usable heat, but simply to provide a precise quantity of electrical resistance.

Resistor color codes

Resistors have colored stripes on them that represent their resistance value. They also have a colored stripe that represents a tolerance value.Three or four colored stripes in close proximity designate the resistance value. The first two or three bands represent a numerical value with the last band representing a multiplier of that value.

The resistors are the most common components are the basis for all electronic circuits, their ability to restrict the flow of electric current allows them to protect electronics components from circuit overload or destruction. Diodes, for example, are current sensitive and so are almost always coupled with a resistor when they are placed inside of a circuit. Resistors are also combined with other electrical components to form important fundamental circuits. They can be paired with capacitors to perform as filters or voltage dividers. Another role is that of the formation of oscillatory AC circuits when they are coupled with capacitors and inductors.