Output
There are a number of ways to get data back out of the computer. One of them is right there in front of your face, and that's the monitor. It has a screen that shows you information from the computer, so it is an output device. The monitor and the parts of the computer that run it are known as video. Another common output device is a printer, which of course puts the computer's output on paper for you.
Some devices are both input and output, like the floppy diskette mentioned earlier. If you have a modem or network connection, information can go both ways over the line so it's both input and output. In many cases it is practical to consider input and output together, in which case they are called Input/Output and abbreviated as I/O.
Thursday, January 1, 2009
Input
Input
The most obvious device for getting information (also called data) into a computer system is the keyboard. Another common input device is the mouse. Almost any time we use a computer we use one or both of these to get text data or instructions into the system. To get large amounts of information into the computer we would probably use a CD (compact disc), a floppy diskette, a modem connected to a phone line, or a network card connected to a network.
With the right sound equipment, a microphone or musical instrument can be used to bring in sound, and a digital camera can download visual information, so these are all being used as input.
The most obvious device for getting information (also called data) into a computer system is the keyboard. Another common input device is the mouse. Almost any time we use a computer we use one or both of these to get text data or instructions into the system. To get large amounts of information into the computer we would probably use a CD (compact disc), a floppy diskette, a modem connected to a phone line, or a network card connected to a network.
With the right sound equipment, a microphone or musical instrument can be used to bring in sound, and a digital camera can download visual information, so these are all being used as input.
Random Access Memory
Random Access Memory or RAM is the memory that the computer uses to temporarily store the information as it is being processed. The more information being processed the more RAM the computer needs.
One of the first home computers used 64 kilobytes of RAM memory (Commodore 64). Today's modern computers need a minimum of 64 Mb (recommended 128 Mb or more) to run Windows or OS 10 with modern software.
RAM memory chips come in many different sizes and speeds and can usually be expanded. Older computers came with 512 Kb of memory which could be expanded to a maximum of 640 Kb. In most modern computers the memory can be expanded by adding or replacing the memory chips depending on the processor you have and the type of memory your computer uses. Memory chips range in size from 1 Mb to 4 Gb. As computer technology changes the type of memory changes as well making old memory chips obsolete. Check your computer manual to find out what kind of memory your computer uses before purchasing new memory chips.
One of the first home computers used 64 kilobytes of RAM memory (Commodore 64). Today's modern computers need a minimum of 64 Mb (recommended 128 Mb or more) to run Windows or OS 10 with modern software.
RAM memory chips come in many different sizes and speeds and can usually be expanded. Older computers came with 512 Kb of memory which could be expanded to a maximum of 640 Kb. In most modern computers the memory can be expanded by adding or replacing the memory chips depending on the processor you have and the type of memory your computer uses. Memory chips range in size from 1 Mb to 4 Gb. As computer technology changes the type of memory changes as well making old memory chips obsolete. Check your computer manual to find out what kind of memory your computer uses before purchasing new memory chips.
Digital cameras & Cards
Digital cameras you to take digital photographs. The images are stored on a memory chip or disk that can be transferred to your computer. Some cameras can also capture sound and video.
Cards - Cards are components added to computers to increase their capability. When adding a peripheral device make sure that your computer has a slot of the type needed by the device.
Sound cards -allow computers to produce sound like music and voice. The older sound cards were 8 bit then 16 bit then 32 bit. Though the human ear can't distinguish the fine difference between sounds produced by the more powerful sound card they allow for more complex music and music production.
Colour cards - allow computers to produce colour (with a colour monitor of course). The first colour cards were 2 bit which produced 4 colours [CGA]. It was amazing what could be done with those 4 colours. Next came 4 bit allowing for 16 [EGA and VGA ] colours. Then came 16 bit allowing for 1064 colours and then 24 bit which allows for almost 17 million colours and now 32 bit is standard allowing monitors to display almost a billion separate colours.
Video cards - allow computers to display video and animation. Some video cards allow computers to display television as well as capture frames from video. A video card with a digital video camera allows computers users to produce live video. A high speed or network connection is needed for effective video transmission.
Network cards - allow computers to connect together to communicate with each other. Network cards have connections for cable, thin wire or wireless networks. For more information see the section on Networks.
Cards - Cards are components added to computers to increase their capability. When adding a peripheral device make sure that your computer has a slot of the type needed by the device.
Sound cards -allow computers to produce sound like music and voice. The older sound cards were 8 bit then 16 bit then 32 bit. Though the human ear can't distinguish the fine difference between sounds produced by the more powerful sound card they allow for more complex music and music production.
Colour cards - allow computers to produce colour (with a colour monitor of course). The first colour cards were 2 bit which produced 4 colours [CGA]. It was amazing what could be done with those 4 colours. Next came 4 bit allowing for 16 [EGA and VGA ] colours. Then came 16 bit allowing for 1064 colours and then 24 bit which allows for almost 17 million colours and now 32 bit is standard allowing monitors to display almost a billion separate colours.
Video cards - allow computers to display video and animation. Some video cards allow computers to display television as well as capture frames from video. A video card with a digital video camera allows computers users to produce live video. A high speed or network connection is needed for effective video transmission.
Network cards - allow computers to connect together to communicate with each other. Network cards have connections for cable, thin wire or wireless networks. For more information see the section on Networks.
Scanner
Scanners- Scanners allow you to transfer pictures and photographs to your computer. A scanner 'scans' the image from the top to the bottom, one line at a time and transfers it to the computer as a series of bits or a bitmap. You can then take that image and use it in a paint program, send it out as a fax or print it. With optional Optical Character Recognition (OCR) software you can convert printed documents such as newspaper articles to text that can be used in your word processor. Most scanners use TWAIN software that makes the scanner accessable by other software applications.
Modem
Modem - A modem is used to translate information transferred through telephone lines or cable.
The term stands for modulate and demodulate which changes the signal from digital, which computers use, to analog, which telephones use and then back again. A high speed connection also requires a modem but because the information is transferred digitally it isn't required to change the signal from digital to analog but is used to create the connection between your computer and the computer you are connecting with.
Modems are measured by the speed that the information is transferred. The measuring tool is called the baud rate. Originally modems worked at speeds below 2400 baud but today analog speeds of 56,000 are common. Cable, wireless or digital subscriber lines (DSL) modems can transfer information much faster with rates of 300,000 baud and up.
Modems also use Error Correction which corrects for transmission errors by constantly checking whether the information was received properly or not and Compression which allows for faster data transfer rates. Information is transferred in packets. Each packet is checked for errors and is re-sent if there is an error.
Anyone who has used the Internet has noticed that at times the information travels at different speeds. Depending on the amount of information that is being transferred the information will arrive at it's destination at different times. The amount of information that can travel through a line is limited. This limit is called bandwidth.
There are many more variables involved in communication technology using computers, much of which is covered in the section on the Internet.
Printers
Printers - The printer takes the information on your screen and transfers it to paper or a hard copy. There are many different types of printers with various levels of quality. The three basic types of printer are; dot matrix, inkjet, and laser.
* Dot matrix printers work like a typewriter transferring ink from a ribbon to paper with a series or 'matrix' of tiny pins.
* Ink jet printers work like dot matrix printers but fires a stream of ink from a cartridge directly onto the paper.
* Laser printers use the same technology as a photocopier using heat to transfer toner onto paper.
* Dot matrix printers work like a typewriter transferring ink from a ribbon to paper with a series or 'matrix' of tiny pins.
* Ink jet printers work like dot matrix printers but fires a stream of ink from a cartridge directly onto the paper.
* Laser printers use the same technology as a photocopier using heat to transfer toner onto paper.
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