PC Computer Hardware

Desktop Memory Upgrade

2016-03-22T00:00:00.000+05:30

Desktop Memory Upgrade Problem.?

I just went and bought a new memory stick for my computer, but when I put it in my monitor would not come on. The memory stick that originally game with the computer is DDR2 PC-4200 and the one I bought was Kingston DDR2 PC-5300, but it said compatible with DDR2 PC-4200. What could be the problem.

Best Answer - Chosen by Voters

It is compatible. But may be unserviceable . without checking in other system you can not assure that is 100% serviceable it may be new but, it may be damaged during transportation or handling when fixing . so try in other system

Sometimes i hear ''click'' from my pc

2012-08-03T22:59:00.001+05:30

Sometimes i hear ''click'' from my pc?

HI, sometimes i hear ''click'' from my pc but only once , and it happened to me about 2-3 times in this month, i havent noticed it before. Could it be something serious ? I dont have any crashes , my fans are working fine , and all hardware is detected. I can't afford for a new hardware , plz help

thnx

Additional Details

So i suppose i dont have to worry about it??

thnx

Best Answer - Chosen by Asker

in SMPS Powerful capacitor placed these holds power after sutdown also , if you touch these you may get heavy shock even system is unpluged . so when capacitors get discharge they may click sound. its normal, dont worry.

Having a problem using my portable hard drive?

2012-08-03T22:51:00.002+05:30

Having a problem using my portable hard drive?

Its a new hard drive, about 1 week old and has been working fine until now. I connect it through the USB and my computer seems to recognize it. I see it in my Device Manager and under Disk Management also. However, When I first got the drive I Re-named it to "Rons2" but It's calling itself Local Disk now. Im assuming there is some problem with the computer reading off of the drive. Any ideas for help? I can give anyone more details about this if they wish to know.

P.S. I have already moved quite a bit of files onto the drive so I REALLY don't want to re-format it. I know that if I want my files back I might have to take it back to a data recovery group but that will cost alot of cash and there might be another way to fix this.

Please anyone help me I would really like to get those files out.

Best Answer - Chosen by Voters

Its normal , once remove restart system there will not show local,
actually what happened Operating system check its size and file system if it found more GBs it assue as Local Hard Disk and gives a letter Like D, C ,F drive
Nothig to worry

BIOS ROM Checksum Error

2012-08-03T22:47:00.002+05:30

BIOS ROM Checksum Error?

EVERY time i boot my PC it shows it checking my GFX card (a 64mb card in this case-an old one for testing.) that goes, then this error appears, and it tries to find the A: Drive. I don't have a floppy drive..... I do have a USB drive though. Although it fails to detect it with (or even without) the BIOS repair diskette in it. I have tried resetting the CMOS with the on-board jumper, i have tried removing the 2032 battery next to the chip. i thought it may have been the RAM, i have two sticks of DDR2 533mHz 512mb RAM. I have tried the two sticks together, swapped round, one in one slot, the same in the other, all combinations, no luck. The PSU seems ok, no smell or discolouring of the molex cables. I have tried everyhing and now am stuck......
New MoBo??

...i cannot access the BIOS, it isn't passing the POST.....
just beeps like mad.

Best Answer - Chosen by Voters

Once remove and again fix your GFX card in slot.
if problem continue remove permanently use VGA port for your monitor. If you dont have onboard VGA then use PCI VGA card or new GFX card. for other problem do this
Check battery charge it may be down ,
fixt it at proper place . start system go BIOS of CMOIS pressing F1 or Del key you will be inside BIOS setup .
Check all the option you will find Deskett A drive disable and one place you will get boot priority(normally in boot option)change first boot devices as hard disk press F10 to save change.
Restart
for last change your RAM then check

HDD Enclosure

2012-08-03T22:43:00.001+05:30

What type of hard-drive enclosure should I use?

I am gutting an 11-year old pc and I am going to buy an enclosure for the 20gb hard drive and use it as an external. If I decided to do this (I will if the price of an enclosure is cheap) what kind of enclosure would I use. It is only 20gb and I will only bother with an enclosure if it is significantly cheaper than just getting a flash drive of the same capacity.

Hard drive specs:
* Maxtor Hard Drive
* Model:2B020H1 (541DX)
* 20.0GB Capacity
* 5400 RPM Spindle Speed
* UDMA/100 (IDE) interface
* 2MB Buffer
* < 12 ms average seek time
* Form Factor: Standard 3.5-inch
* Drive Only

Best Answer - Chosen by Voters

You will cost more for enclosure, better purchase flash drive,

Trouble Shooting Series

2010-03-24T23:42:00.001+05:30

When i turn on my pc after 30 sec it become off,why?

Best Answer - Chosen by Voters
Check CPU fan if it is OK, Your RAM may be faulty. or you have strong virus which generate RPC call , System is trying to save from further damage so it is getting OFF.
Source(s):

How to change size of hard disk partitions

2009-05-20T12:53:00.001+05:30

Trouble shooting series

Q. How to change size of hard disk partitions

Ans. You can not change size of disk without deleting partion. if really want to change back UP all data beacuse your are going to delete both partion , everything will be lost in C and D drive .after backup insert bootable CD in DVD rom follows instrutions boot from CD PRESS ANY KEY after some time files will be start loading in RAM and further you will reach in repair option , dont repair go ahead you will reach at where all partion were showing , delete C and D , both will be merged if not merging then delete E drive also( situation may arise to delete all drive ) after delete. fresh create C drive as per requirement. same way other drive , you have create full HDD in partion otherwise you will not be able to use that unpartioned drive. after creating C drive install , it will ask to format press F and follow further instructions , system will reboot , then asking press any to boot from CD PLZ DONT PRESS ANY KEY OTHERWISE SAME STEPS WILL GO. SO DONT PRESS ANY KEY LET WINDOWS DO ITSELF and follows instructions

PC Computer Hardware

2009-03-08T23:01:00.003+05:30

PC Computer Hardware

Trouble Shooting Series

What is the speed of my computer?

i have a computer with the following configuration

Intel(R)Pentium(R) Dual CPU
E2140 @ 1.60GHz
1.60 GHz, 1.49 GB of RAM

what is the speed(GHz) of my PC??

Best Answer - Chosen by Voters

Speed is 1.6 Ghz but two processor working at 1.6Ghz . It is not same as one processor at 3.2 Ghz . Reason is if you add two glass of alcohol that are 20% alcohol and 80% water each . if you mix up both glass will you get 40% of alcohol , never it is wrong interpretation, parallel processing means you can process more jobs Parallel but speed will be same.

http://pccomputerhardware.blogspot.com/

Computer will not sleep or not going stand by mode

2009-03-02T23:25:00.005+05:30

PC Computer Hardware

Trouble shooting series

Q. Computer will not sleep or not going stand by mode

Ans. Install Graphics drivers

How to change size of hard disk partitions

2009-03-02T23:01:00.006+05:30

PC Computer Hardware

Trouble shooting series
Q. How to change size of hard disk partitions

Ans. You can not change size of disk without deleting partion. if really want to change back UP all data beacuse your are going to delete both partion , everything will be lost in C and D drive .after backup insert bootable CD in DVD rom follows instrutions boot from CD PRESS ANY KEY after some time files will be start loading in RAM and further you will reach in repair option , dont repair go ahead you will reach at where all partion were showing , delete C and D , both will be merged if not merging then delete E drive also( situation may arise to delete all drive ) after delete. fresh create C drive as per requirement. same way other drive , you have create full HDD in partion otherwise you will not be able to use that unpartioned drive. after creating C drive install , it will ask to format press F and follow further instructions , system will reboot , then asking press any to boot from CD PLZ DONT PRESS ANY KEY OTHERWISE SAME STEPS WILL GO. SO DONT PRESS ANY KEY LET WINDOWS DO ITSELF and follows instructions

Sound Not Playing

2009-03-01T23:08:00.004+05:30

PC Computer Hardware

Trouble shooting series

Sound Not Playing

My computer right click-properties-hardware-device maneger-sound vedio and game controller (check for any warning colors like yelow or red if yes reinstall your sound driver)Go to right below in desktop near time and date display expend arrow there may be a speaker image double click it check any one option is not mute clicked if yes uncheck that play sound

Storage Devices HDD

2009-03-01T22:36:00.004+05:30

PC Computer Hardware

Storage Devices

Magnetic Memory ( Secondary Memory)

The secondary memory is a mass storage memory. Also the information stored in the secondary memory is never read directly by CPU. It is first transferred to primary memory before being read .Also it can only accept as well as output device .

Magnetic Tapes

magnetic tapes memories are similar to the commonly used audio tape recorders . It has been already discussed in Input devices.

Magnetic Hard disks

When the power to a PC is switched off , the contents of memory are lost . It is the PCs hard disk serves as non volatile, bulk storage medium and as the repository for a user 's documents, files and application .
Magnetic disk are used as an input or output device , and for computers auxiliary memory. A magnetic disk is similar to gramophone record but is coated with ferromagnetic materials and rotes at very high speed up to 5400 or 7200 rpm . in the magnetic disk we can have direct access to any information, irrespective of its location on disk.

Hard disks are rigid platters, composed of substrate and a magnetic medium, The substrate - the platter's base material- must be non magnetic and capable of being machined to a smooth finish. It is made either of aluminum alloy or a mixture of glass and ceramic. To allow data storage , both sides of each platter are coated with a magnetic medium - formerly magnetic oxide , but now , almost exclusively , a layer of metal called a thin film medium. This stores data in magnetic patterns, with each platter capable of storing a billion or so bits per square inch(bpsi) of platter surface,
In disk pack with 10 platters there are 20surfaces . out of 20 surfaces , the top most surface and the bottom most surface are not used for recording. Thus there is 18surface on which information is recorded . Cylinder thus consists of 18 tracks in such a disk pack. A track is divided into sectors . Read and write operation on a disk start at sector boundaries. Typically 512 byte are stored per sector. There are 50 sector per track, 400 track per surface and 18 surface
The total capacity of disk is
512 x 50 x 400 x 18 = 18,43,20,000 bytes
or
512 x 50 x 400 x 18 x 8 = 1,47,45,60, 000 bits ( 1 byte= 8bits)

The density of a recording on a tracks is of the order of
(50 x 512 x 8) / (12 x p) = 5500 bits inch

for a disk pack of diameter 12 inches.
There's read / write head for each side of each platter , mounted on arms which can move them towards the central spindle or towards the edge. The arms are moved by the head actuator, which contains a voice- coil- an electromagnetic coil that can move magnet very rapidly. Loudspeaker cones are vibrated using a similar mechanism.

The heads are designed to touch the platters when the disk stops spinning . that is when the drive is powered off,. During the spin down period, the airflow diminishes until it stops completely, when the head hand gently on the platter surface, to a dedicated spot called the landing zone(LZ). T he LZ is dedicated to providing a parking spot for the read/ write heads, and never contains data . The time taken to reach the specified cylinder from the landing zone is known as the seek time (T). The seek time varies depending upon the position of the arm assembly when the read- write command is received by the controller. It is normally measured in millisecond . The maximum seek time is the time taken by the head assembly to reach the innermost cylinder from the outermost cylinder or vice versa. The average seek time is usually specified on the disk and it is of the order of 30 milliseconds.

Once the hard assembly is positioned on the specified cylinder, the head corresponding to the specified surface is switched. After selecting the head, there is further delay because the specified sector has to reach the read write head. This rotation delay is variable. The average rotational delay equals half the time taken by the disk to rotate once. This time is known as latency time(Tl). E.g for a disk rotating at 4800 rpm

Tl=0.5 x 60/ 4800=6.25 milliseconds

The sum of average latency and seek time is known as average access time.
Now after reaching the exact location of data, data is read by the head . The rate at which information is read from the disk is known as transfer rate. In calculating the transfer rate , the speed of the rotation of disk play an important role . for a disk rotating at 4800 rpm , one full revolution take 1/4899 minute , in one revolution, one track, which has say 50 sectors , is read. (one sector contains 512 bytes). Thus the number of bytes read per revolution is thus
50 x12 = 25600 bytes
=25600 x 8 bits

Thus transfer rate =25600 x 4800 /60 per second
= 2048000 bytes per second
=2000MB per second

Time to read one sector =512/2000 x 1024 second
= 0.25 millisecond

Thus Average Access time =30+6.25 millisecond
=36.25 millisecond.

PC Computer Hardwaee Output Devices Pt 3

2009-02-13T00:31:00.007+05:30

Page Printer

These print complete page itself at a time as it done by Xerox like photocopying electrostatic process. These mat be
Laser Printer
Inkjet Printer

Electrostatic Printer

Photographic film Output

Laser Printer

Laser printer are non impact printer. They print one page at time . These printers use laser or other light to produce an image on a photo sensitive drum. The computer controls the laser beam to turn it on and off when it cut back and forth across the drum.
An image is produced on raster scan principal. The laser exposed area attract toner (an ink powder). Thereafter the drum transfer the toner to the paper . The paper then moves to a fusing station where toner is permanently fused on the paper with heat or pressure. After this the drum is discharged and cleaned. Now the drum is ready for processing the next information on the page.
Laser beam is the technology of transmitting powerful beam of light rays in a line without any reflection and refraction and loosing its power . The full form of laser is Light(frequency) Amplification of Stimulated Emission of Radiation.
The laser printers are quiet and they produce high quality output. These printer are expensive and require lots of maintenance. The low speed laser printer prints 10 page per minute or more these are used with microcomputer. High speed laser printers producing up to 300 page per minute are manufactured for mini and large computers . The laser printers have become popular for large printing work. They are used for desk top publishing work also.. the difference between Xerox machine and laser printer is that a Xerox machine the image of the original text is formed on the photosensitive drum with a camera lens whereas is laser printer image is formed by scanning laser beam using computer’ control. The computer sends the characters of a page of the text to be printed in the printer’s buffer memory.

Inkjet Printer

In inkjet printer system produces characters by spraying small ink droplets onto paper. A high frequency electrical generator causes a pyroelecttric crystal to vibrate and throws of tiny droplets supplied from a reservoir. T he droplets then charged by an electrode and guided by horizontal and vertical deflection plate in the precise manner to form the desired character on paper
The speed of the printers lies in the range of 40-300 pages. The average life of an inkjet printer head is about 10 million characters which is 5 times more than that of the print head of an impact type dot matrix printer. The inkjet printer uses ink cartridge containing a column of tiny separators . The print quality of these printer is very near to letter quality.

Electrostatic Printers
Printer of this type forms characters by impressing static charges of electricity on special paper. These charges attract a toner to the charged spots for coloration .The needles apply charges on the paper in a serial fashion.
These printers are capable of very fast speed , up to 20,000 lines per minute. A variety of alphabets , graphics and very large drawing can be produced in a very short times . These devices can draw better than a line plotter and even produced images similar to black and white photographs , with several hundred dots per square inch.

Photographic Film Outputs
These mean are used to store mass amount of data in a very small space . These are type
Micro film
Microfiche

Micro film
The output from computer instead being or pinted is displayed on high resolution CRT VDU. Then it is photographed on 16mm or 35 mm film. A camera is controlled to make films successive output pages on the screen of CRT. A special micro film reader is used to read the output. Some micro film readr also produce a hard copy using xerographic process. Another method is known as COM(Computer Output on Microfilm/ Microfiche). In this first computer’s output is recorded on to magnetic tape which is then fed into a machine called MICROFORM READER. It reads the magnetic tape and copies the data obn to microforms. The copied data can be inspected by using a viwer which projects the copied information on to a screen . Full size copies can be printed.

Microfiche is a sheet of film of size 100 mm x 75 mm on which information worth 80 pages can be recorded . The advantage of using microfiche is that it records information at the rate of 1 milion character per minute and that too in a small space Microfiche is generally used to record display catalogues, archieval documents.

PC Computer Hardware Output Devices Pt 2

2009-02-08T01:23:00.017+05:30

PC Computer Hardware Output Devices

Printers

Printer is an out put device which provide a hard copy on piece of paper and may resemble like type writer. The printer of different types has different speeds and qualities of printing. Their basic classification is this is:

Character Printer
Line printer

Page printer (Image printer) Print a complete page or photograph at a time.
The printers have been classified above as to how they print. There are one more classification which depends on technology used in their manufacture. According to this consideration printer are classified into following two broad
Categories

Impact printers
Non Impact printers

Impact printer are used electromechanical mechanism that causes hammers or pins to strike against a ribbon and paper to print the text. Non impact printers do not use electromechanical printing head to strike against ribbon and paper. They use thermal, chemical, electrostatic, laser beam or ink jet technology for printer the text. Usually, a non impact type printer is faster than an impact type printer. The disadvantage of non impact type printer is that they produce single copy of the text whereas impact printers can produce multiple copies of text.
Thermal printers use a thermal (heating) process. Heat applied by the head on to special paper of which surface turns into a different color, creating characters where the heat was applied. Others use an electrostatic process in which top layer of a special type of paper is actually burned away, allowing a darker second layer to show through . Both processes require special paper that generally costs more that standard typing paper.
The main type of printer that are used widely are summarized below:

Impact Printer
Non Impact Printer
Serial Character Printer
Line Printer
Line Printer
Page Printer
Dot Matrix Printer
Daisy wheel Printer
Chain Printer
Drum Printer
Character Printer
Laser Printer
Ink jet Printer
Thermal Printer
Electrostatic Printer

If you want a printed copy of a very long program or a report that is fifteen or twenty pages long, the normal procedure is to tell the computer to list or print the material on printer. The computer then sends data to printer at a speed; the printer can handle usually 18 characters per second to 200 characters per second. At this speed, the computer will has to wait for a long time. This problem is solved by interfacing the device known as printer buffer which is sometimes called printer spooler. The buffer generally takes only a second or two to accept all the material to be printed out. It then frees thee computer for other work and sends the material in the buffer on to the printer at a speed the printer can handle.

Serial Character Printers
These printers are of following four types

Dot matrix Printer
Ink jet electrostatic Printer
Daisy Wheel printer
Thermal Printer
Dot Matrix Printers

Dot matrix printer produces letters and shapes by pushing a matrix of tiny into a ribbon which strikes the paper. Thus each letter consists of a pattern of tiny ink dots on the paper. Some printers form number letters and graphics with the help of a 5x7 matrix formed by dots. The printer head has seven needles arranged in a vertical line and five rows horizontally. Electronic pulses instruct the print head to choose the correct pattern of dots which are fired on to a typewriter ribbon and then on to paper as the print head moves across.
The print out from 5x7 matrix printer is cruder than a print out from 9x9 matrix. A few of the dot matrix printer uses an overlapping dot pattern to create higher quality output which is almost similar to electronic type writer. In that case the printer is called letter quality printer.
To print on 5x7 matrix es there are 9pins contained in the print head. They are about one inch long and are driven by several hammers which force each pin into contact with the ink ribbon (and paper) at a certain time. The force on these hammers comes from the magnetic pull of small wire coils (solenoids) which are energized at a particular time, depending on the character to be printed. Timing of the signals sent to the solenoids is programmed into the printer for each character, and translate from information sent by the computer about which character to print.

Daisy wheel Printer

They have spinning wheels having several radial arms. Each arm is meant for carrying a character at its end touching the periphery. As the wheel spins a hammer punches them against the ribbon at right moment. This wheel can be easily changed with a similar wheel within a moment if you want different styles of letters or unusual symbols, you can change the daisy wheel. When the right letter hover over on the page, a hammer comes down and slums the letter against the ribbon on to the paper. Daisy printer makes sharper image on the page, but they cost more and print a slower s rate than dot matrix printers around 45 to 60 character per second. The output in the form bits, that computer produces, are turned into character of different type by the printer.

Thermal Printer

A thermal printer uses a hot needles pressed against heat sensitive paper to form character. It is not possible to produce multiple copies simultaneously, like impact printers
The advantage of this type of printer over dot matrix type is that the thermal unit is much quieter. The disadvantages are that a special type of paper must be used and is not possible to produce multiple copies.

Line Printer

These are high speed printer which prints a complete line at time. The printing speed is at the rate of 20 line to 80 line per second . Typical bar printer can print about 150 lines per minute for numbers and 100 lines per minute for alphanumeric character . Line printers are normally designed for heavy printing application and can operate for few hours. The main disadvantage of using line printer is that hammer movement and movement of drum, chain or band must be synchronized very accurately, otherwise lines gets blurred.
Speed of such machine is limited by the speed of paper movement. A special type of paper is used which holds electro-static charge in the form of spot. The printing process involves placing of spot to form the character. The paper then passes through a powered ink bath whence powder ink sticks to position of spots. The ink is melted by high temperature so as to make a permanent record.
Line Printer are three types
Drum Printer
Chain Printers
Band printers

Drum Printers

A drum printer has a cylindrical drum having the various character embossed on its surface. Each character position along the text line contains a band of raised character set. There is a magnetic driven hammer in each character position of the line . The drum rotes rapidly and one revolution is required to print each line a fast acting hammer opposite each and strike the paper against proper character as it passes. Thus , in one rotation, hammers of several position may ‘fire” when A appears . At the end of the rotation the line has been printed.

Chain printer

A chain printer has a steel band on which the various characters are embossed. The chain moves at a high but constant speed past the printing position. Magnetically controlled hammers force the paper against the appropriate print head. Each chain may contain 4 set of different styles for each of 64 or 120 characters. For printing a line , all character s in the lines are sent from memory to the printer buffer register. As the band rotes , a hammer is activated when desired character as specified by buffer register comes in front of it . Speeds of 50 lines per second can be achieved. Using continuous stationary with inter leaved carbons seven copies may be obtained. The noise level of printer is high. Its speeds lines in the range of 400-2400 lines per minute.

Band Printer

The band printer works on the similar manner to the chain printer, but here are bands of steels are used instead of chain and can be easily replaced quite often. Thus different scripts may be used with the same printer

Computer How To Build

2009-02-01T02:03:00.006+05:30

Friends How are you

Now i am going to write very simple , step to follow for assembling a PC>
PC Computer Hardware Requirement.

Motherboard (for example Intel model PR31GL )

Processor (Intel Core 2 Duo 2.2 Ghtz)

RAM One GB DDR II

Hard Disk SATA Seagate 160GB

DVD RW LG

ATX cabinet with SMPS of any company like VIP, INTEX

Two Power Chord

Some Screw (available with SMPS)

One IDE cable for DVD Writer( There are SATA DVD writer are also avaible )

One SATA data Cable for Hard disk

Fit main board by screw in such a way that Mouse port, Key Board Port, VGA Port, Rear USB Port, Rear headphone(Audio port) etc. set in a correct manner.
Do not force to fit the main board it will fit gently .
Fit Hard disk in place provided at front rear side.
Fit the RAM at proper slot (this will not fit in other place due to cut place)

PC Computer Hardware Output Devices Pt 1

2009-01-27T17:06:00.024+05:30

PC Computer Hardware Output Devices

Visual Display Unit (VDU) The Screen or Monitor

Till third generation of computer it was not possible to verify whether the program being typed into computer‘s memory is correct or correctly entered. It was possible only when microcomputer was introduced. The micro computer consisting of one visual display unit as essential part on which the user can directly see, whatever he or she typing on keyboard. When key is pressed corresponding character is displayed on VDU. The result of the calculation or manipulation can also be seen directly on visual display unit and that to instantaneously. By addition of this unit you can be interactive with computer, i.e. Can talk to comport by typing query and computer will answer your query.
Visual display unit looks likes a color television and is fabricated as integral part of microcomputer. Sometimes it may be an independent unit and connected to keyboard and CPU by flexible chords. Quite often the VDU houses the floppy disk drive. The home computer can be attched to color television itself but thruogh a interfacing device. Some television have this interfacing device in built with them

VDUs screen is made up Cathode Ray Tube (CRT) due to which it is also called CRT terminal. When the data input is fed through the key board of the computer, electrical signals are generated; the CPU converts these signals into alphanumeric or graphic display. So the output is obtained as optical display. It contains about 20 to 40 rows of horizontal lines with each lines divided into 80 space. Some computers are provided with the facility of changing the modes of operation. In that case the number of columns and rows will change. The mode of dividing the screen to the several small squire grid areas for visual display is known as resolutions. One squire area is meant for displaying one dot. A group of several dots makes up a pixel. Every character is made up for several pixels. When the entire screen is divided into high number of squire areas , then that particular mode are VDU is said have high resolution. With high resolution screen the information more accurately represented.

The screen is coated with dots for phosphors called pixel from inside. The more is number of pixels from inside. The more is number of pixels or dots. In a screen, the better will be capability of computer to display the information. The phosphors can be made to glow red, green or blue by firing electons at them from behind.

The electrons have to be guided to the right spot through the vertical and horizontal deflection systems. This is ensures that the beam lights up the right phosphors to produce the correct image on the screen.

All the times , the screen deals with tiny points of light, grouped together , form letters or numbers . It is moves so fast that you never notice all the steps involved inputting together a screen full of information. To make it even faster, microcomputers often have ROM (Read Only Memory) the monitors can be broadly classified as :

MONOCHROME MONITORS

COLORED MONITORS

MONOCHROME MONITOR

These are generally black and white monitors or green phosphor monitors they do not receive TV signals.

COLOR MONITORS

The colors are the human perception of the different wavelengths of light. It is possible

to create almost all visible colors using two systems of primary colors. On a color monitors, colors are displayed as varying intensities of red, green and blue dots. When red, green and blue are turned on high, white is produced. As the intensities are equally lowered, shades of grey are produced. When all dots are turned off, the base color of the screen appears.

LIQUID CRYSTAL DISPLAY (LCD)

In LCD’s liquid crystalline material is sandwiched between glass or plastic plates. The front plate is transparent and the back plate is reflective. There is a coating a of thin film on the front plate. The coating transparent and conductive. It is selection (segments) are in the shape of desired characters LCD’s don not emit their own light therefore, a light source is to be used. LCD’s simply changed the reflection of available light.

LCD TECHNOLOGY

A liquid crystal display is a thin, light weight display device with no moving parts. It consists of eclectically – controlled light- polarizing liquid trapped in cells between two transparent polarizing sheets. Polarizing axes of the two sheets are aligned in the same direction. Each cell is supplied with electrical contacts that allow an electric field to be applied to the liquid. Before an electric field is applied, the molecules in the liquid are in a relaxed state. Light can pass through the liquid without any effect o its direction of polarization , so entire assembly appears transparent . When an electric field is applied, the molecules in the liquid twist in to an excited state, causing the axis of polarization of the light to rotate. Thus the light has been polarized by passing through the first sheet , then rotated by passing trough the liquid , now has the wrong polarization of penetrate the second sheet . The result is that the activated part of the display appears dark .

TRANSMISSIVE AND REFLECTIVE DISPLAYS

LCD can be used in transmissive and reflective modes. A transmissive LCD is illuminated from one side and viewed from the opposite side. An activated cell therefore appears dark while inactive cells appear bright. This type is high brightness application such pocket television receivers. The lamp is used to illuminate the LCD in such product usually consumes more battery power that the LCD itself.

A reflective LCDs, are used in pocket calculators and digital watches, is viewed by ambient light reflected in a mirror behind the display. This type has lower contrast than the transmissive type, because the ambient light passes twice trough the display before reaching the viewer. The advantage of this type is that no lamp to consume power, so the battery life is long. A small LCD consumes so little power that can run a photovoltaic cell.

COLOR DISPLAYS

The liquid crystal used in LCD rotates all visible wavelength equally, but additional refinements have been added to the basic LCD to produce a color display.

In a color LCD each pixel is divided into three sections, one with red filter, one with green filter and one with blue filter the pixel can be made to appear an arbitrary color by varying the relative brightness of its three colored sections.

THIN FILM TRANSISTOR DISPLAY

An LCD is made with either a passive matrix display grid. The active matrix LCD is known as TFT (thin film transistors) display. The passive matrix has a grid of conductors with pixels located at each intersection in the grid a current is end across two conductors on the grid to control the light of any pixel. An active matrix has transistor located at each pixel intersection, requiring less current to control the luminance of a pixel. For this reason the current is on active matrix display can be switched on and off more frequently, improving the screen refresh time.

Medium sized displays, such as those in monochrome personal organizers and pocket television set, have a passive matrix structure. This type has one set of contacts for each row and column of the display, rather than one for each pixel. However the disadvantage is that only one pixel can be address at any instant. The other pixels have to remember their last state until the control circuit has time to revisit them. This results in reduced contrast and poor response to fast moving images. As the number of pixels increases, this type of displays becomes less and less attractive.

For high resolution color displays such as large LCD monitors, an active matrix system is used. The LCD panel contains, besides the polarizing sheets and cells of liquid crystal, a matrix of transistors. These devices store the electrical state of each pixel on the display while all the other pixel are being updated. This method provides much better brighter, sharper displays.

PC Computer Hardware Input Devices Part 2

2009-01-26T03:25:00.016+05:30

DIGITIZER

A digitizer is an input device that converts graphic and pictorial data to digital (binary) form which can be direct fed and stored inside a computer. There are two types of digitizers: rectangular- coordinate or flatbed digitizer and image- scan digitizer. In case of a flatbed digitizer, the drawing to be digitized is spread and fixed over a rectangular flatbed table. A mechanism is now moved over the surface of the drawing that scan the drawing and produces signals related to X and Y coordinates of the table. Image scan digitizers scan and reproduce entire drawing and photographs automatically. They are costlier and more powerful than the flatbed digitizers and are capable of digitizing not only the shape and size of the drawing but also the varying intensities on a gray to black scale at different points of the drawing. Thus, flatbed digitizers are mainly use to digitize simple drawing, graphs, charts, etc. and image- scan digitizers are used to digitize more complex pictures and photographs.

VOICE RECOGNITION SYSTEM

This is an input device; consist of a microphone or telephone that converts human speech into electrical signals. A signal pattern obtained in this manner is transmitted to the computer where it is matched against pre stored patterns to identify the input. When a close match is found, a word is recognized by the system. T he set of pre stored patterns is known as the vocabulary of the system. T o build up this vocabulary, the system has to be trained to recognize the words and phrases that are to present in the vocabulary. Hence the system is initially operated in a “training mode “when the user speaks the words and phases (to be sorted in the vocabulary) several times to train the system to recognize his / her particular voice pattern. In this mode, the patterns are created and stored for future matching. Because the accent of different speakers varies, most recognize system, are speaker dependent. How ever, a system may be trained to recognize the voice of more than one operator in which case a different vocabulary is maintained for each operator. These systems are used where a person wants to input data to a computerized system in situations where his hands are busy, or his eyes must be fixed on a measuring instrument or some other object.

OPTICAL MARKS READER (OMR)

It is a device for checking the documents and question papers. Now a days it is quite a common practice to the knowledge and IQ level of candidate by multiple choice objective type questions. The candidates are required write there answer by putting a standard dot in front of the correct answer with help of specially designed soft pencils. While evaluating the answer paper , OMR directs a thin beam of light is transmitted through the dot as compared to nearby surface due to which answer is recognized by the computer.. The OMR can evaluate only those documents which are printed with marked positions in the specified areas. OMR can read about 10,000 document per hour, and thus can print the result within the same day without any favoritism or mistake.

OPTICAL CHARACTER READER (OCR)

This is also a device for reading the documents. It can read alphanumeric characters created in a particulars style or good quality paper using special ink. The shape of character is recognized by OCR with help of light source in conjunction with photo electric cells. Optical characters are being extensively used for billing purposes, i.e. preparation of electricity bills and insurance premium renewals.

BAR CODE READERS

This method uses a number of bars (lines) of varying thickness and spacing between them to indicate the desired information. Bar code reader can read such bars and converts them into electrical pulses to be processed by a computer. The most common used bar code is Universal Product Code (UPC). The UPC code uses a series of vertical bars of varying width. These bars are detected as ten digits. The first five digits identify the supplier or manufacturer of item. The second five digits identify individual product code. The code also contains a check digit to ensure that the information read is correct or not.

MAGNETIC INK CHARACTER READER (MICR)

It uses a special ink that can be magnetized so that the individual characters can be recognized by the reader from the shape of the wave form of the electrical pulses induced in the magnetism. Such a system uses special inks containing magnetic particles of iron oxide. The characters are printed in a very distinctive style. When such documents are passed through a strong magnetic field, the ink coded characters become magnetized. MICRs have got reading speed about 24000 documents per minute. Such a character recognition system is now being used by all commercial banks even in India a MICR coded cheque.

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2009-01-24T16:50:00.002+05:30

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Contact US

2009-01-24T16:35:00.019+05:30

PC Computer Hardware Input Devices Part 1

2009-01-23T00:15:00.023+05:30

PC COMPUTER HARDWARE

INPUT DEVICES

Data and instruction must enter the computer system before any computation can be performed on the supplied data. This task is performed by the input unit that links the external environment with the computer system. An input device converts input data and instruction into suitable binary form which can be accepted by computer. The commonly used input device is keyboard. A number of input devices are there which do not required typing for inputting information e. i. mouse, light pen, joy stick track ball, touch screen etc. However regardless of their inputs all input devices must provide a computer with data that are transformed into the binary code that the primary memory of computer is designed to accept. This transformation is done by unit called input interfaces..

In short, the following functions are performed by input unit

It accepts [or reads] the list of instructions and data from the outside world.
It converts these instruction and data in computer acceptable form (electronic pulses).
It supplies the converted instructions and data to the computer system for further processing

The input unit may be any one or combination of two or mare units out of following.

Punched card
Punched Paper Tape
Keyboard
Light pen
Mouse
Joy Stick
Digitizer
Voice recognition System
Optical marker reader
Optical Character reader
Magnetic ink Character Recognition System

PUNCHED CARDS

This was earliest method of feeding data into computer. First punched card system was introduced by Dr. Hermann Hollerith in year 1887 for US census. The most popular design of punched chard was introduced by computer company IBM. The punch card is little longer and less broader than Indian Post Card, It contains total eighty column and twelve rows. Each column is meant for punching a pattern of square type holes for each character. The punching is done with the help of card punching machine which is very similar to a typewriter. When you press a key marked A, the card puncher will punch two holes as per code.

PUNCHED PAPER TAPE

A strip of paper 12.5 mm to 75mm wide and 90 to 300 m long was used for feeding data into computers in previous years.

The data is punched on these tapes with the help of a tape puncher using eight channel code or five channel 29 code . Corresponding to each character, a pattern of circular hole is generated according to certain code.

KEYBOARD

Each micro computer consists of a key board as input unit . In addition, the key board contains several command keys and function keys. Beneath each key . There is set of electrical contacts, which are closed when the key is pressed. By closing the electronic circuit, a signal (corresponding to character contained by key) is produced which is sensed by computer. This signal makes the character pressed to appear on the screen. Multi lingual key boards have been also devised.

Keyboards of special design are used for musical computer. In such key, piano type keys are provided through which any tune can be played . The standard IBM PC keyboard can be divided into three general areas:

Typewriter area , having the standard set of alphabet letters and number keys.
Function keys F1 through F12- which have different functions depending on the software in use. F1 is mostly used for getting help

Numeric keypad, having cursor control and number keys. Some on this pad have dual roles and the required number is obtained by either pressing along with shift key or by first pressing NUMLOCK key . The number keypad is used for entering large amount of numeric data.

GRAPHIC INPUT

Any information in the form drawing can be put into computer’s memory on visual display unit. The graphic pad has a magnetically sensitive surface that allows shapes to be drawn with the help of an electronic pen. The movement of pen is sensed by the electronic circuit below the pad which converts the movement signals into binary electrical pulses. These pulses travel into CPU of computer that displays the information on screen of VDU.

LIGHT PEN

Light pen is a device which enables us to write anything directly on the screen of computer. We can draw sketches and diagrams also. The light pen has got a tip which is very much sensitive to light. Actually it is a photosensitive detector. A bright spot of light known as raster spot moves in a orderly way across the back of computer‘s screen which alerts the tip of light pen.

MOUSE

A mouse is also a pointing device. It is held in one hand and moved across a flat surface. About the size of the normal cake of bath soap, it usually rolls on a small rubber ball and has two or three buttons on the top. When the user rolls the mouse across the flat surface the cursor on the screen moves in the direction of mouse movement, giving the user a sense of pointing at something on screen.

Positioning a cursor with a mouse is easier for non typists than pressing various key combinations. With proper software, a mouse can also be used to draw pictures on screen and edit text , as is done with software like Ventura, CorelDraw, etc. in DTP system.

JOYSTICK

A joystick is also used to move the cursor position on screen its function is similar to that of a mouse. Children can play with computers in a simple way by the use of joystick. While paying video games like SPACE- INVANDERS, user need to move space craft quickly across the screen. This can be done by pressing key on keyboard but it is neither convenient nor comfortable for small children to use the key board . This type of action can be better done with the help of joystick. As move the stick around in its socket the movements are translated into binary instructions with the help of electrical contacts.

Part

PC Computer Hardware Overview

2009-01-10T12:02:00.019+05:30

A DESCRIPTIVE OVERVIEW OF PC COMPUTER HARDWARE

Is general term used to represent the physical and tangible component of the computer i.e. those component which can be seen and touched . It includes:

Input Unit
output Unit
Central processing unit
Backing storage and auxiliary memory devices.

The electronic circuits consisting of resistors, capacitors, ICs main computer equipment( visually the keyboard, visual display unit and central processing unit) and its peripherals like floppy drives, joystick, printer, tracker ball ,graphic pad, plotters, digitizer, card reader, paper and magnetic tapes and disks, modems, interfaces terminals etc. are all examples of computer hardware . All input and output devices connected to computer are collectively known as peripherals.

INPUT UNIT

Input unit is actually a device which provides man to machine communication with computer. Input of any form is first converted into binary electronic signals which can be understood by CPU. This process is called digitizing.

Input may be linguistic, graphical, mechanical, audio, visual or audiovisual .Linguistic input is written program in computer’s programming languages which is inputted to computer either by typing on keyboard, or by floppy, magnetic tapes or CD, DVDs.

OUTPUT UNIT

Output unit works just in reverse manner of input units. We feed data into computer by typing on to the keyboard of computer. Similarly, information coming out of computer can be typed on the sheet of paper by an output unit known as printer, in a similar manner, as it happens is happens in teleprinters. Output coming from the CPU is in the form of electronic binary signals that needs conversion in a form, that can be easily understood by human being, i.e. graphical alphanumeric, audiovisual or in the form of human language. This function is performed by output units include, VDU, Plotter, printers, speech synthesizers, decoders, robots etc.

CENTRAL PROCESSING UNIT

CPU is totally electronic based and its function are to:

Receive and store data into main storage memory.
Control sequence of operations.
Give command to all parts of the computer system.
Carry out data processing and output the result.

The CPU assumes many different sizes in different computers. The CPU of mainframe computers are like large cup board and carry out millions of instructions in seconds The CPU of a microcomputer is much less powerful and is contained in a single chip.

This is actually the brain and heart of a computer. Data is processed here . It takes information from the input unit and process it accordingly to instructions . The instruction are given by programs. programs are written in languages which a computer can under stand. These are actually coded languages.

By data processing we means

Making arithmetic calculation like addition , subtraction, multification, division and exponentiation etc.
Making logical decision like comparing two values to find out which one geater.
Manipulating alphanumeric

ARITHMETIC AND LOGIC UNIT (ALU)

The ALU is a section where all the arithmetic and logical functions are carried out. We know that every arithmetic operation required twooperands. The operation then process a result. This ALU, therefore, must be able to handle two data words and the result. This concept is dependent on the storage and processing techniques, which may vary , from model to model. Logical operation usually involve comparisons. Circuits an the ALU compare two values by subtracting one from another. For example, to determine whether number A is greater than number B , B is subtracted fro A and the sign of the result is determined . Depending on the sign of the result , the ALU does further operation. Alphabetic data also compared according to their assigned order sequence.
ALU comprises a number of accumulators and registers. It derives all the data from the main memory as directed by control unit based on program given to it. This data gets loaded into accumulators in ALU. For example , if numbers A and B are to be added the control unit selects number A from its address in memory and loads it into arithmetic unit, Then the value of B is selected and added to A in the arithmetic unit. The results are placed in the main storage(again under the direction of control unit ) or may be retained in the accumulators themselves for further calculation. Some logical operation of the ALU enable the computer to have the decision making quality.

CONTROL UNIT

The control unit direct all the operation inside the computer. It is known as nerve centre of the computer, because it controls and coordinates all hardware operation, i.e, those of the CPU and input-output devices. It performs following actions
It gives command to transfer data from input device to memory of arithmetic and logic unit. It also transfer result from ALU to memory and on to the output device for printing.
It stores the program in the memory, takes instruction one by one , understand them and issue appropriate commands to other units.
It fetches the required instructions from the main memory storage via memory data register(MDR) and places it in the control instruction register (CIR). Then it interprets the instruction in CIR and gets it executed by sending a command signal to the concerned hardware device. Memory data register is a special register which holds all data instructions temporarily, as they pass in and out of the main memory, Control instruction register is also a special register which holds machine instructions currently being interpreted by control unit.

MEMORY

Digital computer use the binary number system, which has two digit : 0 and 1. A binary digit is called a bit . Information is represented in digital computer I n groups of bits.
The bit is an elementary of Memory.
A group of 8 bit is called a byte and a group of 4 bit is called nibble.

One byte is the smallest unit which represents data. Other bigger units of memory are KB , MB and GB which has following relation:
1KB=1024Byte(210 Byte)
1MB=1024KB=024x1024bytes
1GB=1024 MB =1024 x 1024 x1024 bytes.
Memory of storage devices are two types:

Internal Primary . or Main Storage or Immediate Access Storage (IAS).
Auxiliary memory storage or backing storage.

INTERNAL MEMORY OR IMMEDIATE ACCESS STORAGE (IAS)

It is also called computer ‘s main or primary memory because like human it is able to store information which can be recalled or accessed when required . The program of instruction s has to be stored in the main memory in order to make it work automatically. This memory forms an integral part of ALU and is synthesized wholly by electronic components due to which its operation is extremely fast.

Any item of data or any instruction stored in the memory can be retrieved (called back) by the computer at lightning speed. Modern computer does this in few nanoseconds. Only a limited storage is provided as it is very costly. The rest of the program and data are kept in secondary storage devices also known as backing storage devices.

Internal memory of a modern computer is contained in silicon chips which are of two types

Read only memory (ROM)
Random Access Memory (RAM)

RAM CHIPS

RAMs are designed to act as short term memory, and therefore also known as volatile memory. A RAM holds information which is needed for particular operation. New information can be recorded, read and then rubbed out when no longer needed. But once the computer switched off, a RAM forgets everything.

ROM CHIPS

ROMs are Read Only Memories holds sets of instruction which tell the microprocessor to do. For instance, a ROM will tell the computer, how to recognize keys and which key is to be pressed and how to light up the screen.
Information stored in ROM can only be read. It can not be rubbed out or added to. It is permanently built in computer at the time of its production and therefore also known as firmware. ROM also holds the permanent data like trigonometric functions several variations of ROM are available.

Please check other pages for more information in PC Computer Hardware

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