Computer Input Processing Output

Computer Input Processing  Output

The most obvious device for getting information into a computer system is the keyboard another

The 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, 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


If we just put information into the computer and took it out again later, computers could be much simpler. Most of the time though, we want to do something with it or change it in some way. Doing something with it is called processing, or data processing. Most of this takes place in a part called the processor or Central Processing Unit. This is usually abbreviated to.

   1. CPU
The CPU is such an important part of the computer that we often refer to a system by the type of CPU it contains such as Pentium III or an Athlon system. Sometimes you will hear the entire computer cabinet called a CPU. To help the CPU there is another part that takes over a lot of the arithmetic. It is called the co-processor And also the Numerical Processing Unit or NPU.

The smallest piece of data that a computer can process is called a bit, and each bit will be either a one or a zero. For the sake of efficiency, the computer normally deals with a minimum of 8 bits at a time, and 8 bits together is called a byte. This is an important word to remember because in working with computers you will hear about bytes frequently, and also megabytes which is one million bytes. Megabyte is usually abbreviated MB, the details of conversion and format of data storage will be dealt with in detail in later chapters.

2. Storage
information is stored in a computer in several different ways, but the main two are Primary memory i.e RAM and Secondary memory i.e hard drive, also called a hard disk.
The hard drive can store huge amounts of information, and it can keep this information when the computer is turned off. The only problem with hard drives is that it takes too long to get the data from them because the system must wait as the disk Spins until the right part of the disk surface comes under the read heads, and then the driver transfers a block of data in sequence.
For information being used at the moment, the system needs to be able to get to any part of that information very quickly. The storage for this information is RAM, which stands for Random Access Memory. Random. access means the system can ask for any piece of stored data at random and get it immediately, without waiting for to come up in sequence.
Random access is faster than sequential access. The main reason that computers don‘t just store everything in RAM is that information in RAM is lost whenever the power is turned off. So, the computer needs both RAM and disk storage. Everything stored long-term is on the disk, and whatever is needed at the moment is copied into RAM. if changes are made to the data in RAM, the changes must be copied back to the disk before that computer is turned off so those changes are not lost.
When people talk about the memory of a computer, they almost always mean Primary Memory i.e RAM, and not the hard drive or other forms of storage that we haven't covered yet. Sometimes they will say ’main memory‘ just to be perfectly clear about it.


There are a number of ways to get data back out of the computer. one of them is right below, and that' the has a screen that is similar to a Television that shows you information from the computer, so it is 
an output device the monitor and the parts of the computer run it is 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 1/0.

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