Technically, a computer is a programmable machine. This means it can execute a programmed list of instructions and respond to new instructions that it is given. Today, however, the term is most often used to refer to the desktop and laptop computers that most people use. When referring to a desktop model, the term "computer" technically only refers to the computer itself -- not the monitor, keyboard, and mouse. Still, it is acceptable to refer to everything together as the computer. If you want to be really technical, the box that holds the computer is called the "system unit."
Some of the major parts of a personal computer (or PC) include the motherboard, CPU, memory (or RAM), hard drive, and video card. While personal computers are by far the most common type of computers today, there are several other types of computers. For example, a "minicomputer" is a powerful computer that can support many users at once. A "mainframe" is a large, high-powered computer that can perform billions of calculations from multiple sources at one time. Finally, a "supercomputer" is a machine that can process billions of instructions a second and is used to calculate extremely complex calculations.
Difference Between Input and Output Devices of a Computer
Overview:
This study note differentiate between input and output devices of a computer.
Input Devices:
Input is the first stage of computing, referring to any means that moves data (information) from the outside world into the processor or from one component of the computer to another.
- Keyboard
The primary input device for a computer, allowing users to type information just as they once did on a typewriter.
- Mouse
Used with graphical interface environments to point to and select objects on the system's monitor. Can be purchased in a variety of sizes, shapes, and configurations.
- Scanner
Converts printed or photographic information to digital information that can be used by the computer. Works similar to the scanning process of a photocopy machine.
- Microphone
Works like the microphone on a tape recorder. Allows input of voice or music to be converted to digital information and saved to a file.
- CD-ROM/DVD drive
Compact disc–read only memory: stores large amounts of data on a CD that can be read by a computer.
Processing Devices:
The central processing unit (CPU) is the heart and brain of the computer. This one component, or "chip," is responsible for all primary number crunching and data management. It is truly the centerpiece of any computer. It is so important that whole generations of computer technology are based and measured on each "new and improved" version of the CPU. When we refer to the CPU, we are usually speaking of the processor. However, the CPU requires several other components that support it with the management of data to operate. These components, when working in harmony, make up the primary elements of the PC we know today.
- Motherboard
The large circuit board found inside the computer. Without it, a computer is just a metal box. The motherboard contains all the remaining items in this table; for all practical purposes, it is the computer.
- Chip set
A group of computer chips or integrated circuits (ICs) that, when working together, manage and control the computer system. This set includes the CPU and other chips that control the flow of data throughout the system.
- Data bus
A group of parallel conductors (circuit traces) found on the motherboard and used by the CPU to send and receive data from all the devices in the computer.
- Address bus
A group of parallel conductors (circuit traces) found on the motherboard and used by the CPU to "address" memory locations. Determines which information is sent to, or received from, the data bus.
- Expansion slots
Specialized sockets that allow additional devices called expansion cards or, less commonly, circuit boards, to be attached to the motherboard. Used to expand or customize a computer, they are extensions of the computer's bus system.
- Clock
Establishes the maximum speed at which the processor can execute commands. Not to be confused with the clock that keeps the date and time.
- Battery
Protects unique information about the setup of the computer against loss when electrical power fails or is turned off. Also maintains the external date and time (not to be confused with the CPU's clock).
- Random Access Memory (RAM)
Stores temporary information (in the form of data bits) that the CPU and software need to keep running.
Output Devices:
All the input and processing in the world won't do us any good unless we can get the information back from the computer in a comprehensible and usable form.
- Printer
Generates a "hard copy" of information. Includes dot matrix, ink jet, and laser varieties.
- Monitor
The primary output device. Visually displays text and graphics.
- Plotter
Similar to a printer, but uses pens to draw an image. Most often used with graphics or drawing programs for very large drawings.
- Speakers
Reproduce sound. Optional high-quality speakers can be added to provide improved output from games and multimedia software.
Input and Output Devices:
Some devices handle both input and output functions. These devices are called input/output (I/O) devices, a term you will encounter quite often.
- Floppy disk drive
Mechanism for reading and writing to low-capacity, removable, magnetic disks. Used to store and easily transport information.
- Hard disk drive
High-capacity internal (and sometimes external) magnetic disks for storing data and program files. Also called fixed disks.
- Modem
Converts computer data to information that can be transmitted over telephone wires and cable lines. Allows communication between computers over long and short distances.
- Network card
An expansion card that allows several computers to connect to each other and share information and programs. Also called network interface card (NIC).
- CD recorder
Also called CD-R. You can copy data to a CD with this device, but you can only write to a section of the disc once. Variations on this type of device include compact disc–rewritable (CD-RW) drives. These drives allow you to read, write, and overwrite a special CD-ROM-type disc.
- Tape drive
Large-capacity, magnetic, data storage devices. Ideal for backup and retrieval of large amounts of data. Works like a tape recorder and saves information in a linear format.
What is Software?
Computer software, or just software is a general term used to describe a collection of computer programs, procedures and documentation that perform some tasks on a computer system.
The term includes:
- Application software such as word processors which perform productive tasks for users.
- Firmware which is software programmed resident to electrically programmable memory devices on board mainboards or other types of integrated hardware carriers.
- Middleware which controls and co-ordinates distributed systems.
- System software such as operating systems, which interface with hardware to provide the necessary services for application software.
- Software testing is a domain independent of development and programming. It consists of various methods to test and declare a software product fit before it can be launched for use by either an individual or a group. Many tests on functionality, performance and appearance are conducted by modern testers with various tools such as QTP, Load runner, Black box testing etc to edit a checklist of requirements against the developed code. ISTQB is a certification that is in demand for engineers who want to pursue a career in testing.
- Testware which is an umbrella term or container term for all utilities and application software that serve in combination for testing a software package but not necessarily may optionally contribute to operational purposes. As such, testware is not a standing configuration but merely a working environment for application software or subsets thereof.
Software includes websites, programs, video games, etc. that are coded by programming languages like C, C++, etc.
"Software" is sometimes used in a broader context to mean anything which is not hardware but which is used with hardware, such as film, tapes and records.Relationship to computer hardware:
Computer software is so called to distinguish it from computer hardware, which encompasses the physical interconnections and devices required to store and execute (or run) the software. At the lowest level, software consists of a machine language specific to an individual processor. A machine language consists of groups of binary values signifying processor instructions that change the state of the computer from its preceding state. Software is an ordered sequence of instructions for changing the state of the computer hardware in a particular sequence. It is usually written in high-level programming languages that are easier and more efficient for humans to use (closer to natural language) than machine language. High-level languages are compiled or interpreted into machine language object code. Software may also be written in an assembly language, essentially, a mnemonic representation of a machine language using a natural language alphabet. Assembly language must be assembled into object code via an assembler.
The term "software" was first used in this sense by John W. Tukey in 1958. In computer science and software engineering, computer software is all computer programs. The theory that is the basis for most modern software was first proposed by Alan Turing in his 1935 essay Computable numbers with an application to the Entscheidungsproblem.
Types of software:
Practical computer systems divide software systems into three major classes: system software, programming software and application software, although the distinction is arbitrary, and often blurred.System software
System software helps run the computer hardware and computer system. It includes:
- device drivers,
- operating systems,
- servers,
- utilities,
- windowing systems,
The purpose of systems software is to unburden the applications programmer from the details of the particular computer complex being used, including such accessory devices as communications, printers, readers, displays, keyboards, etc. And also to partition the computer's resources such as memory and processor time in a safe and stable manner.
Programming software
Programming software usually provides tools to assist a programmer in writing computer programs, and software using different programming languages in a more convenient way. The tools include:
- compilers,
- debuggers,
- interpreters,
- linkers,
- text editors,
An Integrated development environment (IDE) is a single application that attempts to manage all these functions.
Application software
Application software allows end users to accomplish one or more specific (not directly computer development related) tasks. Typical applications include:
- industrial automation,
- business software,
- computer games,
- telecommunications, (i.e., the internet and everything that flows on it)
- databases,
- educational software,
- medical software,
Tips to Avoid Getting a Computer Virus or Worm on Your Windows PC
With every passing day the Computers are made more Secure and on the Other hand they are becoming unsecure.
There ae two kind of people: (1) Those who are making our computers secure and (2) the Deadly the Hackers and The Virus/Torjans/Spywares/Adwares creators.
Both are working very efficently in their fields. In such a situations we the End users are left with only one choice to make sure that we are protected.
There are many viruses and worms out there that could infect your computer. Not all of them are going to completely destroy your data, but they are always a hassle to deal with.
Steps
1. Be careful about using MS Outlook. Outlook is more susceptible to worms than other e-mail programs, unless you have efficient Anti-Virus programs running. Use Pegasus or Thunderbird (by Mozilla), or a web-based program such as Hotmail or Yahoo or 'Outlook Express'.
2. Install an Anti-Virus program(ex. Norton, F-Secure, Sophos or McAfee.) Also available is the free AntiVir virus scanner. Make sure you keep your virus definitions updated and run a full system scan weekly.
3. Install an Anti-Spyware program(ex. Adaware SE, Microsoft Defender), that operates against internet malware and spyware. Just like Anti-Virus, keep it updated, and do a full system scan weekly.
4. If someone sends you an attachment in e-mail or instant messaging, do not open it. If it is a picture, text or sound file (these attachments end in the extensions .txt, .jpeg, .gif, .bmp, .tif, .mp3, .htm, .html, and .avi), you are probably safe. If someone you know very well sends you a Word attachment or other type of file, e-mail them to ask them if they meant to send it to you. If they say yes, you can open it, but you might still be at risk if they are not good about running Anti-Virus scans or careful about what they download. Be wary of attachments with a double extension, such as .txt.vb or .jpg.exe, as the system will only recognize the extension to the extreme right, and run the file as such. Double extensions are often a good indicator that the file is malicious.
5. Do not use disks that other people gave you, even from work. The disk could be infected with a virus. Of course, you can run a virus scan on it first to check it out, but AV programs are not 100% effective.
6. Do not download software from just any old website. If it is a reputable site that you trust, you are probably safe. The threat is not only from software; don't download Word documents or other non-HTML files that have something other than one of the extensions listed above, either.
7. Set up your Windows Update to automatically download patches and upgrades. This will allow your computer to automatically download any updates to both the operating system in Internet Explorer. These updates fix security holes in both pieces of software.
8. Consider switching to a different web browser. Other web browsers (such as Firefox or Opera and now the Google Chrome) are considered to have better security than Internet Explorer; some people also see them as more flexible and extensible browsers.
9. Be careful when surfing. You can get a malicious script from a webpage and not know it. If you have your IE set up for the maximum security settings, you are probably safe. You can try disabling javascript, but I'm not sure if this will entirely help, and it will make your web browsing pretty boring. If you ever get a window asking if you want to allow an automatic install, say "No" unless you know the site requesting the install.
10. Read about the latest virus threats so you are aware of the potential danger. Go to Symantec's or any other AntiVirus website to read about them daily.
11. Try to balance paranoia with common sense. Some people get really weird about viruses, spyware, etc. It's just a computer! Back up your data and follow these steps and it shouldn't be a big problem. Some people would suggest that you make sure you have a firewall and run anti-spyware programs as well. I'm not sure either of those will protect you from viruses, but they will protect you from hacking and from spyware. Microsoft's Antispyware and Ad-Aware are the best anti-spyware/virus programs I have found.
12. Use a software firewall! Even if you have a hardware firewall, always use a software firewall (ex. Norton, Mcafee, there's also free ones- ZoneLabs ZoneAlarm).
13. Scan things you download! Now don't be a total nut with this. But if you download something from a site that you don't know/trust, then scan it before opening it. Anything you get from P2P software you should scan, as you are getting it from a stranger. Balance scanning things with number 11, don't go nuts scanning everything you download.
Tips
PC World and other computer magazines will help you keep aware of the latest info about viruses and other things going on the Internet.
http://www.cnet.com CNET is a good place to find current updates on new viruses and security issues.
You can prevent many bugs(and ads) by blocking many sites using a host file. Like the one found here. This site also explains hosts file.
Some Anti-Virus/Anti-Spam/Anti-Malware programs are resource intensive and unless you have high system resources can slow your system during the scan process.
Many websites use ActiveX controls, which means you will have to use either Microsoft's Internet Explorer or install the Mozilla ActiveX plugin for Firefox. Many of these ActiveX controls can be malicious, so make sure you trust the author of the web page before installing any ActiveX controls.
A good free anti-spyware is Spybot Search&Destroy. This program is better than Adaware SE, the scans bring up things Adaware SE didn't detect and delete them or keep them, depending on what you want to do with the program.
Use other than Internet Explorer, as most hackers, viruses and spyware try to find computers that do and try to hack them. Try Opera, since it is so little known, nobody tries to hack it. Opera is developed by an European company. Firefox is Open Source and free and developed by Mozilla, fewer malware attacks it, however because it is well known, make sure you install updates because there are a few security holes.
Warnings
There are worms that use exploits in popular programs, email in particular, to execute code and infect a system. In most cases this is the most prevalent method of worm replication using Outlook or Outlook Express. The easiest way to avoid this is to keep current with Windows Updates, and also to disable the Preview Window.
Your safety is in your own hands be Careful be safe!.....
