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 basic of hardware

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rajapriya

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PostSubject: basic of hardware   Sat Dec 05, 2009 2:17 pm

Boot Disk

A boot disk is actually not a computer disk in the shape of a boot. If it was, most disk drives would have a difficult time reading it. Instead, a boot disk is a disk that a computer can start up or "boot" from. The most common type of boot disk is an internal hard drive, which most computers use to start up from. The operating system installed on the hard drive is loaded during the boot process.

However, most computers allow you to boot from other disks, including external Firewire hard drives, CD-ROMs, DVD-ROMs, and floppy disks. In order to function as boot disks, these disks need to have an operating system installed that is understandable by the computer. This can either be a full-blown operating system like Windows or Mac OS X, or a small utility operating system, such as Norton Utilities or DiskWarrior.

CD and DVD boot disks are often used to start up a computer when the operating system on the internal hard drive won't load. This can happen when bad data blocks or other errors occur on the disk. By running a disk repair utility from the CD or DVD, you can often fix the hard drive and restart from it, using the full operating system.

Base Station


The term "base station" was first used to refer to the towers you see on the side of the road that relay cell phone calls. These stations handle all cellular calls made within their area, receiving information from one end of the call and transmitting it to the other.

In the computer world, however, a base station refers to the wireless access point for computers with wireless cards. It is basically a router that communicates with devices based on the Wi-Fi standard. Some common Wi-Fi configurations include 802.11b and 802.11g. Wireless base stations are made by companies such as Netgear, Linksys, D-Link, Apple Computer, and other manufacturers. Fortunately, as long as the hardware is based on the Wi-Fi standard, all wireless cards can communicate with base stations from any manufacturer.




Bridge


When a road needs to extend across a river or valley, a bridge is built to connect the two land masses. Since the average car cannot swim or fly, the bridge makes it possible for automobiles to continue driving from one land mass to another.

In computer networking, a bridge serves the same purpose. It connects two or more local area networks (LANs) together. The cars, or the data in this case, use the bridge to travel to and from different areas of the network. The device is similar to a router, but it does not analyze the data being forwarded. Because of this, bridges are typically fast at transferring data, but not as versatile as a router. For example, a bridge cannot be used as a firewall like most routers can. A bridge can transfer data between different protocols (i.e. a Token Ring and Ethernet network) and operates at the "data link layer" or level 2 of the OSI (Open Systems Interconnection) networking reference model.
Cable Modem


A cable modem is used for connecting to the Internet and is much faster than a typical dial-up modem. While a 56K modem can receive data at about 53 Kbps, cable modems support data transfer rates of up to 30 Mbps. That's over 500 times faster. However, most ISPs limit their subscribers' transfer rates to less than 6 Mbps to conserve bandwidth.

Another important way that a cable modem is different than a dial-up modem is that it doesn't connect to a phone line. Instead, the cable modem connects to a local cable TV line, hence the term "cable modem." This allows cable modems to have a continuous connection to the Internet. Therefore, there is no need to dial your ISP every time you want to check your e-mail.

Cable modems, which have a much more complex design than dial-up modems, are usually external devices, but some models can be integrated within a computer. Instead of connecting to a serial port like a external dial-up modem, cable modems attach to a standard Ethernet port so they can transfer data at the fastest speed possible.
Card Reader


"Card reader" is the generic term for an input device that reads flash memory cards. It can be a standalone device that connects to a computer via USB or it may be integrated into a computer, printer, or multifunction device. In fact, most multifunction printer/scanner/copiers now have built-in card readers.

Most card readers accept multiple memory card formats, including compact flash (CF), secure digital (SD), and Sony's Memory Stick. Some card readers accept various other formats such as XD, SmartMedia, Microdrive, and Memory Stick Pro Duo cards.

The purpose of a card reader is, not surprisingly, to read the data from a memory card. When you place a memory card into a card reader, it will often show up on your computer as a mounted disk. You can then view the contents of the memory card by double-clicking the card's icon. This icon typically appears on the desktop of Macintosh computers or inside "My Computer" on Windows machines.

Since memory cards most often contain pictures from digital cameras, a photo organization program may automatically open when you insert a memory card into you card reader. This provides an easy way of importing your pictures into your photo album. If you don't want to import photos using the program, you can simply close the program and the card will still be mounted on your computer.

Once you decide to remove the card, make sure you unmount or "eject" the disk before physically removing the card. This will help prevent the data on the card from becoming corrupted.

CISC (Complex Instruction Set Computing)


Stands for "Complex Instruction Set Computing." This is a type of microprocessor design. The CISC architecture contains a large set of computer instructions that range from very simple to very complex and specialized. Though the design was intended to compute complex instructions in the most efficient way, it was later found that many small, short instructions could compute complex instructions more efficiently. This led to a design called Reduced Instruction Set Computing (RISC), which is now the other major kind of microprocessor architecture. Intel Pentium processors are mainly CISC-based, with some RISC facilities built into them, whereas the PowerPC processors are completely RISC-based.

Controller Card


The controller card, or simply "controller," is a piece of hardware that acts as the interface between the motherboard and the other components of the computer. For example, hard drives, optical drives, printers, keyboards, and mice all require controllers to work. Most computers have all the necessary controllers built in the motherboard as chips, not full-sized cards. However, if you add additional components such as a SCSI hard drive, you may need to add a controller card as well. Controller cards are typically installed in one of the computer's PCI slots.
Chip


Technically speaking, a computer chip is a piece of silicon with an electonic circuit embedded in it. However, the word "chip" is often used as a slang term that refers to various components inside a computer. It typically describes an integrated circuit, or IC, such as a central processor or a graphics chip, but may also refer to other components such as a memory module.

While "chip" is a somewhat ambiguous term, it should not be confused with the term "card." For example, a laptop might have a graphics chip embedded in the motherboard, while a desktop computer may contain a graphics card connected to a PCI or AGP slot. A graphics card may contain a chip, but the chip cannot contain a card. Similarly, a CPU may contain a chip (the processor), but it may also contain several other components. Therefore, the term "chip" can be used to refer to specific components, but should not be used describe multiple components that are grouped together
CPU (Central Processing Unit)


Stands for "Central Processing Unit." This is the pretty much the brain of your computer. It processes everything from basic instructions to complex functions. Any time something needs to be computed, it gets sent to the CPU. Every day, it's compute this, compute that -- you'd think the CPU would need a break after awhile. But no -- it just keeps on processing. The CPU can also be referred to simply as the "processor."


Component


Computers are made up of many different parts, such as a motherboard, CPU, RAM, and hard drive. Each of these parts are made up of smaller parts, called components.

For example, a motherboard includes electrical connectors, a printed circuit board (PCB), capacitors, resistors, and transformers. All these components work together to make the motherboard function with the other parts of the computer. The CPU includes components such as integrated circuits, switches, and extremely small transistors. These components process information and perform calculations.

Generally speaking, a component is a element of a larger group. Therefore, the larger parts of a computer, such as the CPU and hard drive, can also be referred to as computer components. Technically, however, the components are the smaller parts that make up these devices.

Component may also refer to component video, which is a type of high-quality video connection. A component connection sends the video signal through three separate cables — one for red, green, and blue. This provides better color accuracy than composite video (typically a yellow connector), which combines all the color signals into a single cable.
DRAM (Dynamic Random Access Memory)


Stands for "Dynamic Random Access Memory." DRAM is a type of RAM that stores each bit of data on a separate capacitor. This is an efficient way to store data in memory, because it requires less physical space to store the same amount of data than if it was stored statically. Therefore, a DRAM chip can hold more data than an SRAM (static RAM) chip of the same size can. However, the capacitors in DRAM need to constantly be refreshed to keep their charge, so DRAM requires more power than SRAM.

Still, because DRAM can hold more data than SRAM and because it is significantly less expensive to manufacture, DRAM is the most common type of memory found in personal computer systems. While there are many types of DRAM available, the most common type is synchronous DRAM SDRAM, which is a faster version of standard DRAM. This is the type of memory most computers use for their main system memory.

If you choose to upgrade your computer's SDRAM, check your machine's requirements to see if the memory modules must be installed in pairs. If so, you will need to replace two modules at once and they must be the same size (i.e. two 1GB SDRAM memory modules).
CRT (Cathode Ray Tube)


Stands for "Cathode Ray Tube." CRT is the technology used in traditional computer monitors and televisions. The image on a CRT display is created by firing electrons from the back of the tube to phosphors located towards the front of the display. Once the electrons hit the phosphors, they light up and are projected on the screen. The color you see on the screen is produced by a blend of red, blue, and green light, often referred to as RGB.

The stream of electrons is guiding by magnetic charges, which is why you may get interference with unshielded speakers or other magnetic devices that are placed close to a CRT monitor. Flat screen or LCD displays don't have this problem, since they don't require a magnetic charge. LCD monitors also don't use a tube, which is what enables them to be much thinner than CRT monitors. While CRT displays are still used by graphics professionals because of their vibrant and accurate color, LCD displays now nearly match the quality of CRT monitors. Therefore, flat screen displays are well on their way to replacing CRT monitors in both the consumer and professional markets.


Ethernet


Just to be clear, the first syllable is pronounced "eath" as in "Heath Bar," not like "eth" as in Bethany. Some people find this out the hard way (ridiculing laughter), but at least you don't have to. Ethernet is the most common type of connection computers use in a local area network (LAN). An Ethernet port looks much like a regular phone jack, but it is slightly wider. This port can be used to connect your computer to another computer, a local network, or an external DSL or cable modem.

Two widely-used forms of Ethernet are 10BaseT and 100BaseT. In a 10BaseT Ethernet connection, data transfer speeds can reach 10 mbps (megabits per second) through a copper cable. In a 100BaseT Ethernet connection, transfer speeds can get up to 100 mbps. There is also a new technology called "Gigabit" Ethernet, where data transfer rates peak at 1000 mbps. Now that's fast.


DVD (Digital Versatile Disc)


Stands for "Digital Versatile Disc." It can also stand for "Digital Video Disc," but with the mulitple uses of DVDs, the term "Digital Versatile Disc" is more correct. Yep, the technology naming people just love to confuse us. A DVD is a high-capacity optical disc that looks like a CD, but can store much more information. While a CD can store 650 to 700 MB of data, a single-layer, single-sided DVD can store 4.7 GB of data. This enables massive computer applications and full-length movies to be stored on a single DVD.

The advanced DVD formats are even more amazing. There is a two-layer standard that doubles the single-sided capacity to 8.5 GB. These disks can also be double-sided, ramping up the maximum storage on a single disc to 17 GB. That's 26 times more data than a CD can hold! To be able to read DVDs in your computer you'll need a DVD-ROM drive. Fortunately, DVD players can also read CDs. To play DVD movies on your computer, you'll need to have a graphics card with a DVD-decoder, which most computers now have.
Fiber-Optic Cable


This is a cable made up of super-thin filaments of glass or other transparent materials that can carry beams of light. Because a fiber-optic cable is light-based, data can be sent through it at the speed of light. Using a laser transmitter that encodes frequency signals into pulses of light, ones and zeros are sent through the cable. The receiving end of the transmission translates the light signals back into data which can be read by a computer.

Because fiber-optics are based entirely on beams of light, they are less susceptible to noise and interference than than other data-transfer mediums such as copper wires or telephone lines. However, the cables are fragile and are usually placed underground, which makes them difficult and expensive to install. Some fiber-optic cables are installed above ground, but if they break, they often need to be completely replaced, which is not cheap. While copper wires can be spliced and mended as many times as needed, it is much harder to fix glass fiber-optic cables.
External Hard Drive


Nearly all personal computers come with an internal hard drive. This drive stores the computer's operating system, programs, and other files. For most users, the internal hard drive provides enough disk space to store all the programs and files. However, if the internal hard drive becomes full or if the user wants to back up the data on the internal hard drive, and external hard drive may be useful.

External hard drives typically have one of two interfaces ? USB or Firewire. USB hard drives commonly use the USB 2.0 interface because it supports data transfer rates of up to 480 Mbps. USB 1.1 only supports transfers of up to 12 Mbps, which would make the hard drive seem slow to even the most patient people. Firewire drives may use either Firewire 400 or Firewire 800, which support data transfer rates of up to 400 and 800 Mbps respectively.

The most likely users to need external hard drives are those who do audio and video editing. This is because high-quality media files can fill up even the largest hard drives. Fortunately, external hard drives can be daisy chained, which means they can be connected one after the other and be used at the same time. This allows for virtually unlimited amounts storage.

Users who do not require extra storage may still find external hard drives useful for backing up their main hard drive. External hard drives are a great backup solution because they can store an exact copy of another hard drive and can be stored in a safe location. Using the drive to restore data or perform another backup is as simple as connecting it to the computer and dragging the necessary files from one drive to another.

While most external hard drives come in heavy, protective cases, some hard drives are designed primarily for portability. These drives usually don't hold as much data as their larger desktop counterparts, but they have a sleek form factor and can easily be transported with a laptop computer. Some portable drives also include security features such as fingerprint recognition that prevent other people from accessing data on the drive in case it is lost.
FPU (Floating Point Unit)


Stands for "Floating Point Unit." The first computer processors were far better at dealing with integers than with real numbers (a.k.a. floating point numbers). So a separate FPU processor was developed to handle the floating point calculations. That way, when the CPU encountered a floating-point expresion (ie. 1.62 * 0.87359), it would send the calculation to the FPU. Since the FPU is specifically designed to handle floating-point math, it computes expressions involving real numbers more efficiently. While the first floating point units used to be manufactured as individual chips, they are now typically integrated into the CPU.


Expansion Card


An expansion card is a printed circuit board that can be installed in computer to add functionality to it. For example, a user may add a new graphics card to his computer to give it more 3D graphics processing power. An audio engineer may add a professional sound card to his machine to increase the computer's audio input and output connections. Users that need more Firewire or USB ports can add Firewire or USB expansion cards, which provide additional connections.

Most expansion cards are installed in PCI slots. This includes variations of PCI, such as PCI-X and PCI Express. Graphics cards may also be installed in an AGP slot, which is designed specifically for video cards. Since expansion cards require open slots, they can only be installed in computers that have available expansion slots. Therefore, computers like the Apple iMac and other all-in-one machines cannot accept expansion cards. Computer towers, however, often have two or three open expansion slots, and can accept multiple cards.

Laptops don't use traditional expansion cards because of their small form factor. However, some models can accept removable PCMCIA cards that add extra ports or other functionality to the computer.


DAC (Digital-to-Analog Converter)


Stands for "Digital-to-Analog Converter" and is often pronounced "dac." Since computers only recognize digital information, the output produced by computers is typically in digital format. However, some output devices only accept analog input, which means a digital-to-analog converter, or DAC, must be used.

The most common use for a DAC is to convert digital audio to an analog signal. This conversion typically takes place in the sound card, which has a built-in DAC. The digital signal, which is basically a stream of ones and zeros, is transformed into an analog signal that might take the form of an electrical charge. This electrical charge is recognized by most speaker inputs and therefore can be output to a speaker system.

DACs are also used for converting video signals. Historically, most video displays, such as TVs and computer monitors used analog inputs. Only in the last couple of years have digital displays with DVI and HDMI connections become commonplace. Therefore, in order for a computer to output to an analog display, the digital video signal must be converted to an analog signal. This is why all video cards with an analog output (such as a VGA connection) also include a DAC.

Any time a signal is converted from one format to another, there is a potential loss of quality. Therefore, it is important to have a high-quality DAC whether you are converting audio or video signals. The same holds true when performing the opposite conversion, which requires an analog-to-digital converter, or ADC.

Bus


While the wheels on the bus may go "round and round," data on a computer's bus goes up and down. Each bus inside a computer consists of set of wires that allow data to be passed back and forth. Most computers have several buses that transmit data to different parts of the machine. Each bus has a certain size, measured in bits (such as 32-bit or 64-bit), that determines how much data can travel across the bus at one time. Buses also have a certain speed, measured in megahertz, which determines how fast the data can travel.

The computer's primary bus is called the frontside bus and connects the CPU to the rest of the components on the motherboard. Expansion buses, such as PCI and AGP, allow data to move to and from expansion cards, including video cards and other I/O devices. While there are several buses inside a computer, the speed of the frontside bus is the most important, as it determines how fast data can move in and out of the processor.


GPU (Graphics Processing Unit)


Stands for "Graphics Processing Unit." Like the CPU (Central Processing Unit), it is a single-chip processor. However, the GPU is used primarily for computing 3D functions. This includes things such as lighting effects, object transformations, and 3D motion. Because these types of calculations are rather taxing on the CPU, the GPU can help the computer run more effienciently.

The first company to develop the GPU was NVidia, Inc. Its GeForce 256 GPU can process 10 million polygons per second and has over 22 million transistors. Compare that to the 9 million transistors found on the Pentium III chip. Wow -- that's a lot of processing power. There is also a workstation version of the chip called the Quadro, designed for CAD applications. This chip can process over 200 billion operations a second and deliver up to 17 million polygons per second. If only you could think that fast during those darn Calculus tests...


Blu-ray


Blu-ray is an optical disc format such as CD and DVD. It was developed for recording and playing back high-definition (HD) video and for storing large amounts of data. While a CD can hold 700 MB of data and a basic DVD can hold 4.7 GB of data, a single Blu-ray disc can hold up to 25 GB of data. Even a double sided, dual layer DVD (which are not common) can only hold 17 GB of data. Dual-layer Blu-ray discs will be able to store 50 GB of data. That is equivalent to 4 hours of HDTV.

Blu-ray discs can hold more information than other optical media because of the blue lasers the drives use. The laser is actually blue-violet, but "Blu-ray" rolls off the tounge a little easier than "Blu-violet-ray." The blue-violet laser has a shorter wavelength than the red lasers used for CDs and DVDs (405nm compared to 650nm). This allows the laser to focus on a smaller area, which makes it possible to cram significantly more data on a disc the same size as a CD or DVD. Proponents of the Blu-ray format say they expect Blu-ray devices to replace VCRs (thank goodness) and DVD recorders as more people make the transition to HDTV. For the latest Blu-ray news, check out Blu-ray.com.

Chipset


A chipset describes the architecture of an integrated circuit. This includes the layout of the circuitry, the components used within the circuit, and the functionality of the circuit board. For example, the chipset of a modem card is much much different than the chipset of a computer's CPU.

Processors themselves also have different chipsets. For example, A PowerPC processor, which uses RISC architecture, will have a much different chipset than an Intel processor that uses CISC technology. Even a Pentium II and Pentium III have slightly different chipsets, though they are both made by Intel. Regardless of what chipset a circuit uses, the important thing is that it works with other components inside the computer. Therefore, whenever you upgrade your computer's hardware, make sure you buy components that are compatible with the chipsets in your machine.


Dot Pitch


This is the measurement used to determine how sharp the display of a CRT (Cathode Ray Tube) monitor is. It is measured in millimeters and the smaller the number, the finer the picture. Most CRT monitors will have a dot pitch between .25 and .28. However, some large presentation monitors have dot pitches from .30 to .50 (which would make for really fuzzy images on a standard 17" desktop monitor). The difference between a "dot" (as in dot pitch) and a pixel is that a pixel is mapped onto the dots on the screen. When the monitor is set to lower resolutions, one pixel encompasses multiple dots. So pixels are typically larger than the "dots" on the actual screen.

In a CRT display with a shadow mask, the dot pitch is measured as the distance between the holes of the shadow mask, again in millimeters. "So what's a shadow mask?" you ask. It's basically a metal screen full of holes where three electron beams (red, green, and blue) pass through. These beams focus to a single point on the tube's phosphor surface. Thousands of these points make up the images on your screen. Neat, huh? In a CRT display that uses an aperture grill (like a Sony Trinitron monitor), the dot pitch is measured by the distance between adjacent slots where electron beams of the same color pass through.
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