Monday, October 19, 2009

Communication and network

Twisted-pair

Twisted pair cabling is a type of wiring in which two conductors are twisted together.
The two wires carry equal and opposite signals and the destination detects the difference between the two.
Noise sources introduce signals into the wires by coupling of electric or magnetic fields.



Coaxial cable

Coaxial cable is an electrical cable with an inner conductor surrounded by a tubular insulating layer typically of a flexible material. The term coaxial comes from the inner conductor.
Coaxial cable is used as a transmission line for radio frequency signals.



Fiber optic cable

An optical fiber cable is a cable containing one or more optical fibers. fiber elements are typically individually coated with plastic layers.



Network Term


Node

Node is a connection point, either a redistribution point or a communication endpoint. node depends on the network and protocol layer.

A physical network node is an active electronic device that is attached to a network, and is capable of sending, receiving, or forwarding information.


Client

Client-server computing or networking is a distributed application architecture that partitions tasks or work loads between service.
Server
A network server is a computer designed to process requests and deliver data to other computers over a local network or the Internet. A server in this case could refer to the program that is managing resources rather than the entire computer.
Hub
A network hub or repeater hub is a device for connecting multiple twisted pair or fiber optic.Hubs are commonly used to connect segments of a LAN.
Network Interface Card
A wireless network interface controller (WNIC) is a network card which connects to a radio-based computer network, unlike a regular network interface controller (NIC) which connects to a wire-based network such as token ring or ethernet. This port accommodates an Ethernet cable, which resembles a thicker version of a standard telephone line.
Network Operating system
A networking operating system is an operating system that contains components and programs that allow a computer on a network to serve requests from other computer. It is also an operating system that includes special functions for connecting computers and devices into a local-area network.
Distributed Processing
A system consisting of a network of microcomputers performing certain functions and linked with a main computer used for more complex tasks. The computers interact with each other in order to achieve a common goal. . It also refers to any of a variety of computer systems that use more than one computer, or processor, to run an application.
Host Computer
Controlling computer connected to other computers or terminals to which it provides data or computing services via a network. The system that contains the data is called the host, while the computer at which the user sits is called the remote terminal.
Network Manager
NetworkManager is a software utility aimed at simplifying the use of computer networks on Linux and other Unix-like operating systems. A service which manages connections and reports network changes, and a graphical desktop applet which allows the user to manipulate network connections.

Monday, October 12, 2009

Secondary Storage

Disk Caching
Can be pronouce as cash. It is a high speed storage mechanism. There are two type of cache is commonly in used which is basically the Disk Caching and memory caching.
Memory caching is effective because the data can be reused again and again.
Rebundant arrays of inexpensive disks (RAID)
RAID combines two or more physical hard disks into a single logical unit by using either special hardware or software. Hardware solutions often are designed to present themselves to the attached system as a single hard drive.
File compression and decompression
Compression is minimizing the size in bytes of a graphics file without degrading the quality of the image.
It allows you compress and decompress data and files using standard well-known Gzip data compression engine.
Decompression is the process of retrieving compressed data.

Monday, October 5, 2009

Input and output


Magnetic Ink character Recognition (MICR)


Magnetic Ink Character Recognition (MICR), as defined by the American National Standards Institute (ANSI), is the common machine language specification for the paper-based payment transfer system. It consists of magnetic ink printed characters of a special design which can be recognized by high speed magnetic recognition equipment. This series of readable characters provides the receiving party with information needed for processing the check including: check number, bank routing number, checking account number and in some cases the amount of the check.

MICR characters are printed in the form of either an E-13B or CMC-7 Font. Each font series is made up of a series of numbers and symbols specifically designed for readability on check sorting machines which read at extremely high rates of speed. The symbols provide a beginning and ending point for each group of numbers allowing the machine to quickly determine what each series of number signifies.
Line placement, character placement, skew and quality are several critical components of printing MICR; the line must be precisely positioned in the MICR Clear Band area. To create consistency in the check clearing process it is critical that each character is readable and that the printing methods are reliable.



Optical Character Recognition


This is the technology long used by libraries and government agencies to make lengthy documents quickly available electronically. Advances in OCR technology have spurred its increasing use by enterprises.

Before OCR can be used, the source material must be scanned using an optical scanner (and sometimes a specialized circuit board in the PC) to read in the page as a bitmap (a pattern of dots). Software to recognize the images is also required.

The OCR software then processes these scans to differentiate between images and text and determine what letters are represented in the light and dark areas.
Older OCR systems match these images against stored bitmaps based on specific fonts. The hit-or-miss results of such pattern-recognition systems helped establish OCR's reputation for inaccuracy.
Today's OCR engines add the multiple algorithms of neural network technology to analyze the stroke edge, the line of discontinuity between the text characters, and the background. Allowing for irregularities of printed ink on paper, each algorithm averages the light and dark along the side of a stroke, matches it to known characters and makes a best guess as to which character it is. The OCR software then averages or polls the results from all the algorithms to obtain a single reading.


Optical Mark Recognition


Optical Mark Recognition (also called Optical Mark Reading and OMR) is the process of capturing human-marked data from document forms such as surveys and tests.

In contrast to the dedicated OMR device, desktop OMR software allows a user to create their own forms in a word processor and print them on a laser printer. The OMR software then works with a common desktop image scanner with a document feeder to process the forms once filled out.

Many of today's OMR applications involve people filling in specialized forms. These forms are optimized for computer scanning, with careful registration in the printing, and careful design so that ambiguity is reduced to the minimum possible. Due to its extremely low error rate, low cost and ease-of-use, OMR is a popular method of tallying votes


Dot Matrix Printer



A dot matrix printer or impact matrix printer is a type of computer printer with a print head that runs back and forth, or in an up and down motion, on the page and prints by impact, striking an ink-soaked cloth ribbon against the paper, much like a typewriter. Unlike a typewriter or daisy wheel printer, letters are drawn out of a dot matrix, and thus, varied fonts and arbitrary graphics can be produced. Because the printing involves mechanical pressure, these printers can create carbon copies and carbonless copies.
Each dot is produced by a tiny metal rod, also called a "wire" or "pin", which is driven forward by the power of a tiny electromagnet or solenoid, either directly or through small levers (pawls). Facing the ribbon and the paper is a small guide plate pierced with holes to serve as guides for the pins. The moving portion of the printer is called the print head, and when running the printer as a generic text device generally prints one line of text at a time. Most dot matrix printers have a single vertical line of dot-making equipment on their print heads; others have a few interleaved rows in order to improve dot density.
These machines can be highly durable. When they do wear out, it is generally due to ink invading the guide plate of the print head, causing grit to adhere to it; this grit slowly causes the channels in the guide plate to wear from circles into ovals or slots, providing less and less accurate guidance to the printing wires. Eventually, even with tungsten blocks and titanium pawls, the printing becomes too unclear to read.
Although nearly all inkjet, thermal, and laser printers print closely-spaced dots rather than continuous lines or characters, it is not customary to call them dot matrix printers.

Plotter



A plotter is a vector graphics printing device to print graphical plots, that connects to a computer. There are two types of main plotters. Those are pen plotters and electrostatic plotters.

Pen plotters print by moving a pen across the surface of a piece of paper. This means that plotters are restricted to line art, rather than raster graphics as with other printers. Pen plotters can draw complex line art, including text, but do so very slowly because of the mechanical movement of the pens. Pen Plotters are often incapable of creating a solid region of color; but can hatch an area by drawing a number of close, regular lines.

When computer memory was very expensive, and processor power was very limited, this was often the fastest way to produce color high-resolution vector-based artwork, or very large drawings efficiently.


Photo Printer


A photo printer is a printer (usually an inkjet printer) that is specifically designed to print high quality digital photos on photo paper. These printers usually have a very high number of nozzles and are capable of printing droplets as small as 1 picoliter.

What typically sets photo printers apart from standard inkjet printers is their use of additional cartridges, either speciality photo inks or just variations on the standard color cartridges. In order to produce more vivid and realistic pictures, photo printers use colors like photo cyan, light magenta, yellow, and light black. The increased range of colors produces better results, while the increased use of black or gray colors enhances black and white prints.

Fax


A "fax machine" usually consists of an image scanner, a modem, and a printer.
Although devices for transmitting printed documents electrically have existed, in various forms, since the 19th century (see "History" below), modern fax machines became feasible only in the mid-1970s as the sophistication increased and cost of the three underlying technologies dropped.

Digital fax machines first became popular in Japan, where they had a clear advantage over competing technologies like the teleprinter, since at the time (before the development of easy-to-use input method editors) it was faster to handwrite kanji than to type the characters. Over time, faxing gradually became affordable, and by the mid-1980s, fax machines were very popular around the world.
Although many businesses still maintain some kind of fax capability, the technology has faced increasing competition from Internet-based systems. In some countries, because electronic signatures on contracts are not recognized by law while faxed contracts with copies of signatures are, fax machines enjoy continuing support in business.
In many corporate environments, standalone fax machines have been replaced by "fax servers" and other computerized systems capable of receiving and storing incoming faxes electronically, and then routing them to users on paper or via an email (which may be secured). Such systems have the advantage of reducing costs by eliminating unnecessary printouts and reducing the number of inbound analog phone lines needed by an office.

Multifunctional Devices


A multifunctional device for use in an endoscopically performed operative procedure of the type where a narrow portal is established through the skin to provide access to an operative site and the multifunctional device is introduced to the operative site through the narrow portal.

The multifunctional device is formed of an absorbent material, preferably expandable, having a substantially rigid dry state prior to introduction to the operative site and a soft, flexible wet state after absorbing fluids. The absorbent material can be formed with a spine therein of either a continuous or a discontinuous, segmented construction, and the spine can be branched and tubular or solid.

The absorbent material can have portions or segments thereof expandable to different sizes to produce rounded protuberances to facilitate manipulation at the operative site and can have predetermined, non-straight configurations in the wet state, the predetermined configurations being controlled by the spine in the absorbent material or the method of forming the absorbent material. The multifunctional device can have a passage therethrough to accommodate laser, electrosurgical, biopsy or culturing instruments.


Internet Telephones


A gateway for an internet telephone system manages calls to and from personal computers and enables the personal computers to use the internet telephone system with an IP address assigned by a DHCP server or a private IP address.

Monday, September 28, 2009

System Unit

Expansion Card




Expansion Card is also called as an add-on card, internal card or interface adapter, an expansion card is an electronic board or card added in a desktop computer or other non-portable computer to give that computer a new ability. It has the ability to connect to another computer using a network cable. Below is a list of expansion cards that could be installed in a an available expansion slot in all computers.
Interface card (ATA / Bluetooth / EIDE / IDE / Parallel / RISC / SCSI /Serial / USB
)



Modem
MPEG Decoder

Network Card

Sound Card

Video Card
Video capture card

Note: Although each of the above devices are available as expansion cards, it is important to realize that they can also be on the motherboard.

Network Interface

The word for Network Interface Card is also known as NIC. It is also commonly referred to as a network adapter and is an expansion card that enables a computer to connect to a network such as a home network or the Internet using a Ethernet cable. The basic graphic example will be the SMC EZ Card 10/100 PCI network card, a type of network card commonly found in most desktop computers today that do not already have an integrated network on their motherboard.
The second bottom image on the right is another example of a network card, a PC Card SMC EZ Card 10/100 wireless network card. These types of cards are used in laptop computers
that do not have a built-in wireless network.


Cache Memory

Cache Memory can be also pronounced as Cash. Cache is a high-speed access area that can be either a reserved section of main memory or a storage device. The two main types of cache are: memory cache and disk cache. Memory cache is a portion on memory of high-speed static RAM (SRAM) and is effective because most programs access the same data or instructions over and over. By keeping as much of this information as possible in SRAM, the computer avoids accessing the slower DRAM.
Just like memory caching, disk caching is used to access commonly accessed data but instead of using high-speed SRAM, a disk cache uses conventional
main memory. The most recently accessed data from the disk is stored in a memory buffer. When a program needs to access data from the disk, it first checks the disk cache to see if the data is there.
Most computers today come with L3 cache and/or L2 cache, while older computers included only L1 cache. Disk caching can dramatically improve the performance of applications because accessing a byte of data in RAM can be thousands of times faster than accessing a byte on a hard disk.



Plug and Play

Short for Plug and Play, PnP is an ability of a computer to detect and configure a new piece of hardware automatically, without the requirement of the user to physically configure the hardware device with jumpers or dipswitches. Plug and Play was introduced on IBM compatible computers with the release of Microsoft Windows 95, where Apple Macintosh computers have always supported the ability to automatically detect and install hardware.
For Plug and Play to operate properly on IBM compatible computers the user must have the following:
BIOS supporting Plug and Play.
Windows 95, 98, 2000 or other operating systems supporting PnP.
Peripheral with PnP support.
Today, all new computers have PnP capabilities.



Computer Chips

Integrated circuit or small wafer of semiconductor material embedded with integrated circuitry. Chips comprise the processing and memory units of the modern digital computer (see microprocessor; RAM). Chip making is extremely precise and is usually done in a “clean room,” since even microscopic contamination could render the chip defective. As transistor components have shrunk, the number per chip has doubled about every 18 months (a phenomenon known as Moore's law), from a few thousand in 1971 (Intel Cord's first chip) to millions by 1989. Nanotechnology is expected to make transistors even smaller and chips correspondingly more powerful in the 21st century.



Slots


A type of computer processor connection designed to make upgrading the processor much easier, where the user would only have to slide a processor into a slot. The original slot, or slot 1, was first released by the Intel Corporation. Later, AMD released another type of slot known as the Slot A. Both slots look similar but are not compatible. Later, Intel released the slot 2, which was a bigger slot used with the later versions of the Pentium II processors. Today, slot processors are no longer found in new computers.



Serial Port


Serial port on the computer used to connect a serial device to the computer and capable of transmitting one bit at a time. Serial ports are typically identified on IBM compatible computers as COM (communications) ports. For example, a mouse might be connected to COM1 and a modem to COM2. With the introduction of USB, FireWire, and other faster solutions serial ports are rarely used when compared to how often they've been used in the past. To the right is a close up of a serial port on the back of a computer.

Below is a listing of various hardware components that can be purchased and used with your serial port.


Mouse - One of the most commonly used devices for all computers except laptop(if needed).
Modem
- It is another commonly used device for serial ports. Used commonly with older computers, however, is also commonly used for its ease of use.
Network
- One of the common uses of the serial port, which allowed two computers to connect together. On the same time, it allow large files to be transferred between the two.
Printer
- Today, this is not a commonly used device for serial ports. However, was frequently used with older printers and plotters.




Parallel Port


Parallel Port canreferred to as the Centronics interface or Centronics connector. Just after the company that originally designed it, the port was later pass down by Epson. The parallel port is found on the back of IBM compatible computers and is a 25-pin (type DB-25) computer interface commonly used to connect printers to the computer. It is used to connect to the printer in a way to initialize with the computer.





Universal Serial Bus

Short for Universal Serial Bus, USB is a standard that was introduced in 1995 by Intel, Compaq, Microsoft and several other computer companies. USB 1.x is an external bus standard that supports data transfer rates of 12 Mbps and is capable of supporting up to 127 peripheral devices. The image to the right is an example of a USB device, the SMC EZ Connect Wireless Bluetooth adapter adds Bluetooth connectivity for your computer.
USB 2.0, also known as "hi-speed USB", was developed by Compaq, Hewlett Packard, Intel, Lucent, Microsoft, NEC and Philips and was introduced in 2001. Hi-speed USB is capable of supporting a transfer rate of up to 480 Mbps and is backwards compatible, meaning it is capable of supporting USB 1.0 and 1.1 devices and cables.



Firewire Port



Firewire is also known as IEEE-1394. FireWire was developed by Apple in 1995 and is a bus that has a bandwidth of 400-800 Mbps, can handle up to 63 units on the same bus, and is hot swappable. Meaning, it can be plug into it with any cable with same sizes. Users more familiar with USB can relate FireWire to USB as it has a lot of the same similarities. Just like USB, FireWire has dozens of different devices such as removable drives and cameras that can be connected to it.

Monday, August 17, 2009

The Internet, The web and Electronic Commerce

HTML

Is a programmed which process information that directs the text format on the screen and is generally hidden from the user. HTML is the seperation of a broader language which it called Standard Generalized Markup Language(SGML) which is a system where it encode and formating the documents. From there, it will actually format what it is suppose too and show it on the screen.

It determine certain text which will be shown on the display page. Another important tag is a link, which may contain the Uniform Resource Locator (URL) of another document. The URL can be consider as an address which the user use to browse to the internet.


Jawascript

Jawascript enables novice programmers to easily design webpages and add interactive feature. Mainly it is a application which runs in the screen when your pointer move to the application. Simply nothing but to make the webpage to look nicer and much more simple for new user who wanted to scroll on things.


Applets

A single program which run a single task on a large application. A small application, such as a utility program or limited-function spreadsheet or word processor. Java programs that are run from the browser are always known as applets. An application which will comes pop-ing down when you point your mouse on the application.

Monday, August 3, 2009

Introduction to IT

Webmaster
Is a person who is responsible of creating, managing or maintaining one or more websites. It is also called as web architect, web developer or site author. This person have the skills, knowledge and integrity of customizing the website in a way to help reader's. He or she has the power to control the website in anyway he/she wanted. He is often required to updates information and solve the problem the people user problems in anyway he/she could possible do.


Computer support specialist
Most often user like to browse the internet and at times user people are more often have trouble with some stuff with their computer. And here is where 'Computer support specialist' come to place. Computer support specialist help people like us to use computer. When something goes wrong, they will try to figure it out and how to fix it.
Most often they answer through phones or e-mails. Some helps by face to face. To answer a problem over the phone or by e-mails, Support specialist will take it slowly by using steps by steps to help user overcome his/her situation.
Apart from just fixing people's problem. They also install software, printer and some other computer tools.To be consistent on the job, their daily work is to check computer system everyday to make sure they are good in shape to use.
They are often question by people. Not by the daily activities but the quality of the product. Hence, they always handle with software and hardware.


Technical writer
Every time you buy a electronical equipment like a phone or a DVD player, you receive a guidebook with it. This small book is user friendly and it helps you with various feature of the particular product you purchase.
A technical writer is person who understand technically of the product and explain it in a simple way, so that user with non-technical background can understand. Two very important things about Technical writer are, they must be good in technical knowledge and have a huge english base. When a newcomer comes to work, he/she are to be working under an expert and slowly gain your knowledge through it.


Software Engineer
Software engineer do research, design and develop software system to meet the requirement of the people. Once the job is done, the software engineer will then test and maintain the system.

Software engineer need to have knowledge of a variety of computer programming languages and applications and program this is due to the wide variety of work that they can be involved in.
They sometimes referred to as computer programmers or software developers which depending on the type of their organization. Software engineers can become specialists in either systems or applications.


Network Administrator
A network administrator check computer networks to ensure that they function smoothly and perfectly. A network administrator usually configures and manages an existing network. He or she are responsible to customize the network.


Database Administrator
Assignment, assignment and assignment is what makes us as a student in college and nothing more than just assignment. And of course after doing it, we safe it in a folder specific on what assignment were. Customers, inventory, and projects are found in nearly every college and business as well. Data must be stored, organized, and managed in a good way. But at times, computer too do mistakes and awful if the computer make mistake on the next day when your assignments got to hand out isn't. So this is where Database administrators comes in. They work with database software to find ways to do this.
They identify user needs, set up computer databases, and test systems. They ensure that the system perform as they should and add people to the system as needed. Database administrators often plan security measure. Data backup and security are critical parts of the job to prevent any lost of data.


System analyst
Latest electronical equipment has always caught many of teenagers. Not just you but even me is chasing over the latest and hottest item in the elctronical store. Every month, we spend huge amount of cash on the selected item even we may not know it is worth ot valuable to buy it. Nothing is much stylish than having the latest item on the street when nobody has it, so this is where system analyst come in place
They figure out how to use computers to get things done. They tell businesses and other organizations which computers and software to buy, and they decide how to get those tools to work together. This will help the company gain profit while having the best equiment working.
They start their work by asking the people what they need their computers to do. Slowly by there, they plan a simple computer system which can do the task well. Which means, computers working together with different kind of software and tools are being use.
They find various kind of steps and tool until they find the system which is the fastest, easiest and low in cost.


Programmer
Computer programmer write and test. Programmers also design and test logical structures for solving problems by computer. With the help of other programmer specialist, they figure out which instruction to use to make the computer do a specific task. Computer programmer work individually and their main job is programming. Since computer are so popular in demand in all over the country, therefore, computer programmer are to be able to understand various kind of language. Programmer also update, modify, repair and upgrade program.


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