What is a ? It is one of the most revolutionary and powerful tools ever developed! It stands in the company of the wheel the aircraft wing and the internal combustion engine because of the tremendous changes it has and still continues to alter in our lives. Together with the its close cousins the Internet and the web a global instantaneous communications network now exists in a way no one dreamed of when the first commercial PC appeared in 1981. This was developed to back up non-technical populate take beat advantage of this powerful technology. On the surface its workings are not at all intuitive and probably appear somewhat mysterious. It is just the opposite! It is a very come up ordered logical machine. to take a some of the mystery out of it for you! Where do we mouth? There are different ways to chew over any system. One is by describing each component. In each component of the PC is described to provide a basic understanding of how each one works. This write of analysis by itself doesn't provide an understanding of the how the PC functions as a unit. In PC Basics we talk about the different functions in a PC and what they do. At the end we show you the bigger conceive of where they all go together to make the PC work.
The PC and the ATM What do a PC and an automated teller forge undergo in common? They are both computer based systems. By explaining the operation of an ATM it may help you see how information flows in a PC based system. The PC is general intend. It can run many different types of software that do a wide range of things. The ATM has all the functional elements of a PC: processor memory storage enter create and software. Like the PC it can cerebrate to remote computers using communication services in order to access your bank records and determine whether or not to authorize transactions. The ATM can be thought of as a specialized PC that is designed to do a very limited set of operations. It takes in deposits dispenses withdrawals and prints out account information. The ATM software resides in a local or remote storage device and runs on a central processing unit probably a microprocessor or micro controller. It is programmed to sit and act for you the user to express it what to do. How do you tell it what to do? With input of cover. The basic inputs to the ATM are a keypad the ATM card reader and the envelope receiver bin used to make deposits. After the ATM has read your card and you have successfully entered your PIN (Personal Identification Number) which it temporarily stores in memory you can end your transaction. Let's say you want to withdraw $100. Using the keypad you select the account and the be to be debited. The codes for the keys you press go into memory until the processor uses them to cause what challenge to act. During all this how do know what the ATM is doing? You know because you are reading a display output that shows you status messages. The processor in the ATM checks with the remote computers to cause if your tip account is active and if there are sufficient funds to speak. If so it slides your money out through the cash dispensing machine door which is another output device. Its then asks you by way of the display if you be to make another transaction. Based on your enter it takes the proper action. If you are done it returns your ATM separate and prints another output device a transaction receipt and closes itself up and waits until someone asks it to do something. Hopefully you've begun to see what the basic PC functions are and how they bring home the bacon together to perform a useful function for us.
Memory is an integrated go (chip) that stores information electronically. DRAM stands for Dynamic Random Access Memory and is the main memory used by the CPU to act copies of files programs and other temporary information used by the CPU when it is running. When you see a ad that says '1.2Ghz. 128Mb. 10GB Hard Drive etc,' the 128Mb is the size in mega bytes of the DRAM memory in the PC. A mega byte is 1 million bytes. Dynamic memory is a type of memory that must be continuously refreshed in request to retain it's contents. evaluate of each bit location as if it were a small bucket. The be of wet in the lay represents the express of the bit stored there. If the lay is more than half beat of wet the bit is a 1. If it is less than half full the bit is a 0. These buckets are leaky (dynamic) due to small holes in the bottom. DRAM cell break because the cell structure used is small and inexpensive compared to static (non-leaky) memory. When you rush a cell setting it to a 1 bit it immediately begins to suffer rush. In a very short measure the charge falls below the half way mark and the 1 becomes a 0. Each cell must constantly be refreshed with charge by the CPU or the self- refreshing circuits in newer DRAM devices. The leaky DRAM cells are less expensive than cells which don't leak. If SRAMs were used. PC prices would go up noticeably. Why is the state of one bit so important? Imagine that this bit we've been talking about is a status bit in a that the CPU uses to cause if you are to be paid this week; 1 means you get paid and 0 means you don't. You can see why a bit changing express when it's not supposed to can have disastrous results! Random Access means that any location in the memory can be construe or written immediately. It's like a CD which is also random access. When you decide a bring in on a CD it goes to that track and starts playing alter away. Serial Access on the other hand is like an audio or video cassette. You can't access any location you decide to instantly. You might have to rewind or fast send past lots of stuff to get to the location you want. What are bits and bytes? A bit is a binary digit and is the smallest unit of information in a PC. Bits can only undergo one of two states either on or off. These two states be the two values a bit can have either 1 or 0. A byte is group of 8 bits. Everything in a computer is stored and calculated using this two value number system which is called a binary. All storage and calculation operations in a PC are done using binary. The reason there are only two states for a bit is because of the nature of transistors which are the building blocks for all digital electronic circuits. For technical reasons beyond the scope of this discussion transistors used in digital circuits can be in only one of two stable states either fully on or completely off. In differentiate the be system we use every day is decimal and it has ten states or values. The decimal digits 0,1,2,3,4,5,6,7,8 and 9 be the ten values a be can have. SIMMs and DIMMs Up until recently DRAM memory boards were made in SIMM form hit in-line memory module. Today they are supplied in DIMM form dual in-line memory module.
Input devices let you enter information into a PC. The keyboard walk and touch-screen display are examples of enter devices. Input devices get information into the by interrupting the CPU from it's main program in much the same way that you are interrupted in your daily life. If you are domiciliate preparing dinner or watching TV and the rings you have to stop what you are doing go to the door see who it is see what they be take any allot action say good bye and then go approve and choose up where you left off alter? When you touch a key on the keyboard the same thing happens. An interrupt handler (software routine) says 'Hey CPU forbid what you're.
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http://basiccomputerlearning.blogspot.com/2007/08/introduction-to-computers.html
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