A computer output device is used to extract information from a computer. There are visual, audio, print and data output devices. Different types of specific hardware include monitors, speakers and headphones, printers and external hard drives.
Monitors
Flat-screen monitors are more energy efficient than cathode ray-tube monitors. Monitor image by Kavita from Fotolia.com
There are two major categories of monitors: Cathode ray-tube or CRT and liquid crystal display, also known as flat-screen or LCD. Both measure screen size diagonally and connect to the computer via USB port or a conventional printer cord. The flat-screen monitor uses up less power and causes less eye strain.
Speakers and Headphones
Headphones are used to turn your computer into a telephone, stereo, or video game. headphones image by Nevena Kozekova from Fotolia.com
Part of the sound card system that produces multimedia, speakers and headphones produce audio output. The range of audio equipment available to the average computer user is tailored to Skype users, gamers, movie and video enthusiasts, and musicians. Most headphones also include a microphone for input as well.
Printers
Modern printers are advanced enough to publish detailed graphic arts and photos. The printer image by vin5 from Fotolia.com
Printers are used to make hard copies of computer output. There are three different kinds of printers. Dot matrix is the oldest and since it is slow and rather noisy compared to laser and ink-jet printers it is no longer widely used. Laser printers are the most expensive, but are fast and quiet and ink jet printers are inexpensive to buy, but the paper and toner consumption makes up for the cheap retail price.
Disks and External Drives
Portable memory sticks may have rendered CDs obsolete as output devices. usb stick image by Slobodan Djajic from Fotolia.com
CDs (which include rewritable CDs, DVDs, floppy disks and external hard drives are used as storage devices for data output. Data can be text, video, audio or graphics files. External memory drives are often portable depending on the size. Both disk drives and CDs can also be used as input devices.
.LCD Monitors-LCD stands for Liquid Crystal Display, referring to the technology behind these popular flat panel monitors. An LCD monitor is distinguishable from a traditional CRT monitor as the latter has a bulky footprint with a depth of several inches and a weight of 30 - 50 pounds (13 - 23 kilograms) or more, while LCDs are commonly 1 - 3 inches (2.5 - 7.5 cm) thick and weigh less than 10 pounds (4.5 k).
.LCD screens-
.plasma monitors-is a type of flat panel display common to large TV displays 30 inches (76 cm) or larger. They are called "plasma" displays because the technology utilizes small cells containing electrically charged ionized gases, or what are in essence chambers more commonly known as fluorescent lamps.
.HDTVs-High-definition television (or HDTV) is video that has resolution substantially higher than that of traditional television systems (standard-definition TV, or SDTV, or SD). HDTV has one or two million pixels per frame, roughly five times that of SD. Early HDTV broadcasting used analog techniques, but today HDTV is digitally broadcast using video compression.
Some personal video recorders (PVRs) with hard disk storage but without high-definition tuners are described as "HD", for "Hard Disk", which can be a cause of confusion.
3.What are the components inside the systems units.
.The Motherboard-sometimes called a system board is the main circuit board of the system unit. Many electronic components attach to the motherboard; others are built into it.
- Chip-is a small piece of semiconducting material, usually silicon, on which integrated circuits are etched. An integrated circuit contains many microscopic pathways capable of carrying electrical current.
- Microprocessor- is used to refer to a personal computer processor chip.
-The Arithmetic Logic Unit-another component of the processor, performs arithmetic, comparison, and other operations. Arithmetic operations include basic calculations such as addiction, subtraction, multiplication, and division.
-Machine Cycle- For every instruction, a processor repeats a set of four basic operations, which comprise a machine cycle.
1)fetching- is the process of obtaining a program instruction or data item for memory.
2)Decoding- refers to the process of translating the instruction into signals the computer can execute.
3)Executing-is the process of carrying out the commands.
4)Storing- in this context, means writing the result to memory (not to a storage medium).
-The system clock-The processor relies on a small quartz crystal circuit called the system clock to control the timing of all computer operations.
- clock speed-is measured by the number of ticks per second. Current personal computers have clock speeds in the gigahertz range. Giga is the prefix that stands for billion, and hertz is one cycle per second. Thus, one gigahertz equals one billion ticks of the system clock per second.
-Multi-core processor- is a chip with two or more separate processors.
-Data Representation-
- Most computers recognize only two discrete states: on and off. The two digits, 0 and 1, easily can represent these two states. The digit 0 represents the electronic state of off (absence of an electronic charge). The 1 represents the electronic state of on (presence of an electronic charge).
- The binary system-is a number system that has just two unique digits, 0 and 1, called bits.
- bits- is the smallest unit of data the computer can process.
- Byte- is 8 bits grouped together as a unit. This provides enough different commbinations of 0s and 1s to represent 256 individual characters.
- Coding Scheme- is the combination of 0s and 1s that represent characters that are defined by patterns.
- Memory stores three basic categories of items:
2)Application programs that carry out a specific task such as word processing.
3)The data being processed by the application programs and resulting information.
-Memory Size
- Kilobyte (KB or K)-Approx. 1 thousand bytes or 1,024. (Half page of text)
- Megabyte (MB)-Approx. 1 million bytes or exactly 1,048,576. (500 pages)
- Gigabyte (GB)-Approx. 1 billion bytes or exactly 1,073,741,824.(500,000 pages)
- Terabyte (TB)-Approx. 1 trillion bytes or exactly 1,099,511,627,776. (500,000,000 pages of text)
- Volatile memory-loses its contents when the computers power is turned off. This is a temporary memory.
- Nonvolatile memory-does not lose its contens when the power is removed from the computer. This is a permanent memory. Example: RAM(Most common type), flash memory, and CMOS.
-Three Basic Types of RAM Chips
- Dynamic RAM-chips must be re-energized constantly or they lose their contents.
- Static RAM-chips are faster and more reliable than any variation of DRAM chips. These chips do not have to be re-energized as often as DRAM chips, thus, the term static.
- Magnetoresistive RAM(Newer Type)-stores data using magnetic charges instead of electrical charges. Manufacturers claim that MRAM has greater storage capacity, consumes less power and has faster access times than electonic RAM.
-Cache-Is how computers improve processing times
- Memory Cache-helps speed the process of the computer because it stores frequetly used instuctions and data. Memory Cache has two types. L1 cache which is built directly in the processor chip. L1 cache usually has a very small capacity, ranging from 8KB to 128KB. L2 cache is slightly slower thatn L1 but has a much larger capacity, ranging from 64KB to 16MB. Current processors include advanced transfer cache, a type of L2 cache built directly on the procesor chip. Processors that use advanced transfer cache perform at a much faster rate than those that do not.
- Firmware-contains permanently written data, instuctions, or information.
-CMOS(Complementary metaloxide semiconductor)-Some RAM chips, flash memory chips, and other types of complemetary metaloxide semiconductor technology because it provides higher speeds and consumes little power.
-Memory Access time- is the amount of time it takes the processor to read data, instuctions, and information from memory.
- millisecond-one-thousandth of a second
- microsecond-one-millionth of a second.
- nanosecond-one-billionth of a second.
- picosecond-one-trillionth of a second.
- Adapter card-sometimes called an expansion card, is a circuit board that enhances functions of a component of the system unit and/or provides connections to peripherals.
- Peripheral-is a device that connects to the system unit and is controlled by the processor in the computer. EX:Modems, disk drives, printers, and keyboards.
- Sound card-enhances the sound-generating capabilities of a personal computer by allowing sound to be input through a microphone and output through external speakers or headphones.
- Video card-also called a graphics card, converts computer output into a video signal that travels through a cable to the monitor, which displays an image on the screen.
- A special type of USB flash drive is called a U3 smart drive which includes preinstalled software accessed through a Windows-type interface.
- PC card- is a thin, credit card-sized removable flash memory device that primarily is used today to enable notebook computers to access the internet wirelessly.
- ExpressCard module-which can be used as a removable flash memory device, is about one-half the size of a PC card and adds memory, communications, multimedia, and security capabilities to the computers.
-Connector-joins a cable to a peripheral. One end connects to the connector on the system unit and another one attaches to the connector on the peripheral.
-Serial Ports- is a type of interface that connects a device to the system unit by transmitting data one bit at a time.
-Parallel Ports-unlike a serial port a parallel port is an interface that connects devices by transferring more than one bit at a time.
-USB Ports-short for univeral serial bus port, can connect up to 127 different peripherals together with a single connector.
-USB Hub- is a device that plugs in a USB port on the system unit and contains multiple USB ports in which you plug cables from USB devices.
-Firewire Ports-are similar to a USB port in that it can connect multiple types of devices that require faster data transmission speeds, such as digital video cameras, digital VCRs, color printers, scanners, digital cameras, and DVD drives to a single connector.
-Special-purpose ports-
- MIDI Port-is a specialy type of sperial port that connects the system unit to a musical instument such as an electronic keyboard.
- ESATA Port-or external SATA port, allows you to connect a high-speed external SATA(Serial Advanced Technology Attachment) hard disk to a computer.
- SCSI Port-Is a high speed parallel port that allows you to attach SCSI peripherals such as disk drives and printers.
- IRDA Port-is a port that both the computer and the device have to have for some devices to transfer data via infrared light waves.
-Buses-allows various devices both inside and attached to the system unit to communicate with each other.
- System bus-is part of the mother board that connects the processor to main memory.
- expansion bus-allows the processor to communicate with peripherals.
- Drive bays- are rectangular openings that typically hold disk drives.
. Register -- a storage location inside the processor.
5.Define a bit and describe how a series of bits represents data :
(a contraction of binary digit) is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states. These may be the two stable states of a flip-flop, two positions of an electrical switch, two distinct voltage or current levels allowed by a circuit, two distinct levels of light intensity, two directions of magnetization or polarization, etc.
6.Identify the categories of application software.
Application software is the general designation of computer programs for performing user tasks. Application software may be general purpose (word processing, web browsers, ...) or have a specific purpose (accounting, truck scheduling, ...). Application software contrasts with (2} system software, a generic term referring to the computer programs used to start and run computer systems and networks; and (3) programming tools, such as compilers and linkers, used to translate and combine computer program source code and libraries into executable programs (programs that will belong to one of the three said categories).
7.Identify the key features of widely used business programs.
A word processor is a computer application used for the production (including composition, editing, formatting, and possibly printing) of any sort of printable material.
Word processor may also refer to a type of stand-alone office machine, popular in the 1970s and 1980s, combining the keyboard text-entry and printing functions of an electric typewriter with a dedicated processor (like a computer processor) for the editing of text. Although features and design varied between manufacturers and models, with new features added as technology advanced, word processors for several years usually featured a monochrome display and the ability to save documents on memory cards or diskettes. Later models introduced innovations such as spell-checking programs, increased formatting options, and dot-matrix printing. As the more versatile combination of a personal computer and separate printer became commonplace, most business-machine companies stopped manufacturing the word processor as a stand-alone office machine. As of 2009 there were only two U.S. companies, Classic and AlphaSmart, which still made stand-alone word processors.[1] Many older machines, however, remain in use. Since 2009, Sentinel has offered a machine described as a word processor, but in actuality it is more accurately a highly specialised microcomputer, used for accounting and publishing. [2]
Word processors are descended from early text formatting tools (sometimes called text justification tools, from their only real capability). Word processing was one of the earliest applications for the personal computer in office productivity.
Although early word processors used tag-based markup for document formatting, most modern word processors take advantage of a graphical user interface providing some form of what-you-see-is-what-you-get editing. Most are powerful systems consisting of one or more programs that can produce any arbitrary combination of images, graphics and text, the latter handled with type-setting capability.
Microsoft Word is the most widely used word processing software. Microsoft estimates that over 500,000,000 people use the Microsoft Office suite,[3] which includes Word. Many other word processing applications exist, including WordPerfect (which dominated the market from the mid-1980s to early-1990s on computers running Microsoft's MS-DOS operating system) and open source applications OpenOffice.org Writer, AbiWord, KWord, and LyX. Web-based word processors, such as Google Docs, are a relatively new category.
8. What are the advantages of using application software on the Web.
- an application that is accessed over a network such as the Internet or an intranet. The term may also mean a computer software application that is hosted in a browser-controlled environment (e.g. a Java applet)[citation needed] or coded in a browser-supported language (such as JavaScript, combined with a browser-rendered markup language like HTML) and reliant on a common web browser to render the application executable.
Web applications are popular due to the ubiquity of web browsers, and the convenience of using a web browser as a client, sometimes called a thin client. The ability to update and maintain web applications without distributing and installing software on potentially thousands of client computers is a key reason for their popularity, as is the inherent support for cross-platform compatibility. Common web applications include webmail, online retail sales, online auctions, wikis and many other functions.
- Web applications do not require any complex "roll out" procedure to deploy in large organizations. A compatible web browser is all that is needed;
- Browser applications typically require little or no disk space on the client;
- They require no upgrade procedure since all new features are implemented on the server and automatically delivered to the users;
- Web applications integrate easily into other server-side web procedures, such as email and searching.
- They also provide cross-platform compatibility in most cases (i.e., Windows, Mac, Linux, etc.) because they operate within a web browser window.
9. History of the Internet. The history of the Internet starts in the 1950s and 1960s with the development of computers. This began with point-to-point communication between mainframe computers and terminals, expanded to point-to-point connections between computers and then early research into packet switching. Packet switched networks such as ARPANET, Mark I at NPL in the UK, CYCLADES, Merit Network, Tymnet, and Telenet, were developed in the late 1960s and early 1970s using a variety of protocols. The ARPANET in particular led to the development of protocols for internetworking, where multiple separate networks could be joined together into a network of networks.
In 1982 the Internet Protocol Suite (TCP/IP) was standardized and the concept of a world-wide network of fully interconnected TCP/IP networks called the Internet was introduced. Access to the ARPANET was expanded in 1981 when the National Science Foundation (NSF) developed the Computer Science Network (CSNET) and again in 1986 when NSFNET provided access to supercomputer sites in the United States from research and education organizations. The ARPANET was decommissioned in 1990. Commercial internet service providers (ISPs) began to emerge in the late 1980s and 1990s and the Internet was commercialized in 1995 when NSFNET was decommissioned, removing the last restrictions on the use of the Internet to carry commercial traffic.
Since the mid-1990s the Internet has had a drastic impact on culture and commerce, including the rise of near instant communication by electronic mail, instant messaging, Voice over Internet Protocol (VoIP) "phone calls", two-way interactive video calls, and the World Wide Web with its discussion forums, blogs, social networking, and online shopping sites. The research and education community continues to use advanced networks such as NSF's very high speed Backbone Network Service (vBNS) and Internet2. Increasing amounts of data are transmitted at higher and higher speeds over fiber optic networks operating at 1-Gbit/s, 10-Gbit/s, or more. The Internet continues to grow, driven by ever greater amounts of online information and knowledge, commerce, entertainment and social networking.
10.Different storage devices:
Hard Drive (Internal)
Internal Hard Drive
You computer's hard drive is the first most important type of storage. Anything that you download, applications that you install, your pictures, videos and music are all stored directly to your hard drive. Basically, anything that is on your computer is stored to your internal hard drive. Internal hard drive capacity is measured in gigabytes. For example, you may have a 500GB SATA hard drive on your computer. Also, internal computer hard drives have different speeds such as 5400RPM and 7200RPM. This reading is the speed that the hard drive disk spins. A faster hard drive will have higher RPM. The faster the hard drive spins, the faster your hard drive can read data, as well as write data.
External Hard Drives
External Hard Drive
External hard drives are exactly the same as internal drives, with one exception. Rather then being enclosed inside your computer, external hard drives have their own separate casing and sit externally to your computer. External hard drives can connect to your computer in a variety of ways. Some common connection types are: USB 2.0, ESATA, Firewire 400 and Firewire 800. External hard drives measure capacity in gigabytes and have different speeds as well. For the most part, external hard drives are used for backup and storing files that a computer user may want to transport.
Network Attached Storage
NAS Server
Another common form of computer storage is network attached storage or NAS. Network attached storage is a method commonly used by businesses to share files between computers. A NAS is simply a storage device connected to a computer network. This is beneficial because many computers can read and write to a NAS. Network attached storage capacity is measured in gigabytes. Also, NASs are available with different hard drive speeds.Many at home computer users often create their own NAS devices by connecting an external hard drive to their router. This allows them to access it wirelessly, as well as share it with other computers.
Optical Media Storage
Optical Drive
Optical media storage is basically writing data to a CD or DVD. When your burn a CD, you are storing songs and music on the CD so that you can listen to it later. If you are burning a DVD, you are storing a video on it so that you can watch it later. CD-RW and DVD-RW media has the capability to be recorded on and erased later if necessary. This makes optical media storage ideal for transporting relatively small amounts of data.
Flash Drives
Flash Drive
Flash drives, or thumb drives, are one of the newest forms of computer storage. These drives connect to any computer by way of USB. Often times, students as well as business professionals, use flash drives as a simple way to transport text documents to and from work, and to and from school. When flash drives were first released, storage capacity was rather limited. However, companies are now manufacturing flash drives with huge storage capacities, up to 64GB.
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