Computer Memory

• Computer Memory:-

                   Computer memory refers to the physical devices used to store data or programs (sequences of instructions) on a temporary or permanent basis for use in an electronic digital computer also internal storage areas in the computer. Computers represent information in binary code, written as sequences of 0 and 1. Each binary digit (or ''bit'') may be stored by any physical system that can be in either of two stable states, to represent 0 and 1. Such a system is called bistable. The term memory identifies data storage that comes in the form of chips. 8bit=1byte

• Types of Memory:-

• RAM (Random Access Memory)
• ROM (Read only Memory)

• RAM (Random Access Memory):-

 

               Random access memory is used to store data temporarily. This is the same as main memory. When used by itself, the term RAM refers to read and write memory; that is, you can both write data into RAM and read data from RAM. This is contrast to ROM, which permits you only to read data. Most Ram is volatile, which means that is requires a steady flow of electricity to maintain its contents. As soon as that power is turned off, whatever the data was in RAM is lost. It read write data randomly so it is called random access memory.

• Types of RAM:-

1. SRAM (Static Random Access Memory)
2. DRAM (Dynamic Random Assess Memory)

• SRAM (Static Random Access Memory):-

     

                              Short for static random access memory and pronounces ess-ram. SRAM is a type of memory that is faster and more reliable then the more common DRAM (dynamic RAM). The term static is derived from the fact that it doesn't need to be refreshed like dynamic RAM.

• DRAM (Dynamic Random Access Memory):-

 

                        Pronounced Dee-ram, DRAM stands for dynamic random access memory, a type of memory used in most computers. Unlike to sram it need to be refreshed other wise data is lost after some time.

• ROM (Read only Memory):-

 

                            ROM is a computer memory on which data has been prerecorded. Once data has been written onto the ROM chip, it cannot be removed and can only be read.Unlike main memory (RAM), ROM retains its contents even when the computer is turned off. ROM is referred to as being nonvolatile, whereas RAM is volatile.

• Types of ROM:-

• PROM (Programmable Read Only Memory)
• EPROM (Erasable Programmable Read Only Memory)
• EEPROM (Electrically Erasable Programmable Read Only Memory)

• PROM (Programmable Read Only Memory):-

 

                    Short for programmable read only memory, a memory chip on which data can be written only once. Once a program has been written onto a PROM, it remains there forever. Unlike RAM, PROMs retain their contents when the computer is turned off.

• EPROM (Erasable Programmable Read only Memory):-

 

                  Acronym for erasable programmable read only memory, and pronounced ee-prom, EPROM is a special type of memory that retain its contents until it is exposed to ultraviolet light. The ultraviolet light clears its contents, making it possible tp reprogram the memory. To write to and erase an EPROM, you need a special device called a PROM programmer or PROM burner.

• EEPROM (Electrically Erased Programmable Read Only Memory):-

 

                 Pronounced double -ee-prom or e-eprom, short for electrically erasable programmable read only memory. EEPROM is a special type of PROM that can be erased by exposing it to an electrical charge. Like other type of PROM. EEPROM retains its contents even when the power is turned off. Also like other type of ROM, EEPROM is not as fast as RAM.

Central Processing Unit (CPU)

• Central Processing Unit:-

CPU is the abbreviation for Central Processing Unit. The CPU is the brain of computer. Sometimes referred to simply as the central processor, but more commonly called processor,the CPU is where most calculations take place.

         
                   In terms of computing power, the CPU is the most important element of a computer system. The CPU itself is an internal component of the computer. Modern CPUs are small and square contain multiple metallic connectors or pins on the underside. The CPU is inserted directly into a CPU socket, pin side down, on the motherboard.

• Parts of CPU:-

1. ALU (Arithmetic Logic Unit)
2. CU (Control Unit)

• ALU (Arithmetic Unit) :-

                                   ALU is the Abbreviation of arithmetic logic unit, the part of a computer that perform all arithmetic computations, such as addition and multiplication, and all the comparison operations. The ALU is the one component of the CPU (central processing unit). The ALU is a fundamental building block of the central processing unit (CPU) of a computer, and even the simplest microprocessors contain one for purposes such as maintaining timers.

• CU (Control Unit) :-

CU is the abbreviation of control unit, the part of computer which overall control all the mechanism of processor. It decodes the instruction coming from the device and send to the ALU for necessary action. It also keep track on all the activates of the computer parts.

• Types of CPU:-
• Complex instruction set computer (CISC):-

                   A complex instruction set computer (CISC) is a computer where single instruction can execute several low level operations (such as a load from memory, an arithmetic operation, and a memory store) and/or are capable for multi-step operations or addressing modes within single instructions.

• Reduced instruction set computing (RISC):-

                          RISC is a CPU design strategy  based on the insight that simplified (as opposed to complex) instructions can provide higher performance if this simplicity enables much faster execution of each instruction.

Uses of Computer

• Uses of Computer:-

                  
               Computer are used everywhere. They found their applications starting with playing games till processing satellite image to give weather information.

• In Education:-

   

                  Now a days computer play an important role in education. Teachers use computer as teaching aids. Now a days colleges are setting up such a system where student and faculty attendance, syllabubs, scheduled of tests are put on the web, students, parents and faculties can access it from anywhere and get update.

 

Students also use computer to complete their homework given at school or collage.  

• In Industries:-

 

                Computers play very important role in industries. All modern industries use computer for different tasks. In most advance industries all the task is control by computer. Computer used to automate the manual tasks. Computers control the production quality in industries. Although computer is much faster then a human being so it is used to control of a machines. Computers can be used to produce pattern in textile industries. and color combination of paint industries. In short all advance industries use computer for better production results.

• In Business:-

      

                In business computer are used for electrical and administrative purpose.

•  For Example:-

                                             

                       Tax counting, salary slips preparations etc, can be done by using computers. Stock market predictions can be done. Banks are using computer to maintain the account details and transactions. E-banking is picking up popularity because of flexibility. E-shopping is one more concept gain popularity in industry, when customer can buy the displayed items by paying using credit card on delivery options.

• By Government:-

                      A government use computer at their offices to keep track of attendance of an employee.

• For Example:-

                    Military applications satellite launching and collecting taxes etc.

So we can say computer also play a important role by Government.

• At Home:-

                  In home computers are mostly used for entertainment. They are used to checks mails or chat with family members or friends abroad. You can do video chatting where you can actually see the person you are talking to. Other applications gaming, listening music, watching movies and do some documentation tasks.

• In Entertainment:-

                   A Computer is also used for entertainment. Computer used in movie making and music. We can also watch movies and kind of entertaining videos and music with the help of computers. Kids enjoy playing games using computers.

Classification of Computer

Classification of Computer:-
                      There are many computer which are different from each other in various aspects.

• Micro Computers

Microcomputer is a complete computer on a smaller scale. These computers are also called personal computers or pc. Two major types of these computer are laptop or desktop computers. Only one user can use these computers at a time. A microcomputer contains a microprocessor, memory 1/10 ports and a bus, housed on a circuit called motherboard. These computer are much slower then the large computers. These computers are inexpensive and easy to use. These computers used in small business and school classrooms.

• Mini Computers:-

                 Minicomputers introduced in 1960. These computers are powerful computers. These can execute 5 million instructions in one second. These are much smaller then mainframe and also less expensive. These computers between the microcomputers and mainframe computers. These are stand alone computers. These computers are used in small or medium businesses purposes. 

• Mainframe Computers:-

            A main frame computer is a high performance computer used for large scale computing purposes. These are very large often filling on entire room. They can store enormous of information. They can perform many tasks at same time and communicate with many users at same time. These are very expensive and faster. These computers can execute 16 millions instructions per/sec. Terminals used to connect user to this computer. These are introduced in 1975. These computers used in large businesses. Government agents and Universities.

Types of Computer

• Computer:-

                 Computer is an electronic device operating under the control of instructions stored in its own memory. It accepts data, processes data into useful information and store result for future.

• Types of Computer:-

There are three main types of computer.

• Analog Computer
• Digital Computer
• Hybrid Computer

• Analog Computer:-

                                                     

               An Analog Computer is a form of computer that uses the continuously changeable aspects of physical quantity. These computers operate with analog signal. Its output is displayed on a meter or graph. It is difficult to use. Mainly used in Engineering and Medical field.

• For Example:-

• Analog Clock

• Speedometer:-

• Digital Computer:-

                   Digital computers are type of Computer that operates on digital signal. It store data in terms of digits. These computers us two states either on (1) or (0). In digital computers, even letters, words and texts are represented digitally; these computers have big memory, variety of sizes speed and capacities. These computers used in offices and educational institutions.

• For Example:-

• Digital Clock:-

• Hybrid Computer:-

 

                  Hybrid Computers are computers that exhibit features of analog and digital computers. These are the combination of analog and digital computers. It combines the best characteristics of both analog and digital computers. It accept data in both analog and digital form.

• For Example:-

                     

Basics of Computer

• Computer:-

             Computer is an electronic device operating under the control of instructions stored in its own memory. It accepts data, processes data into useful information and store result for future.

• General task of Computer:-

1.       Computer receives data from user.

2.       Processes data into information.

3.    Produces output results.

And then store the results in its memory.

•  Characteristic of Computer:-

Computer has so many characteristics some are following:

1. Automation

2. Speed

3. Accuracy

4. Reliability

5. Storage

6. Flexibility

• Automation:

                                  The modern age is the age of automation. Everything and every device is automatic. If we talk about Computer, Computer is not only adding machine or Calculator. When a programs is in Computer’s memory, the CPU (Central Processing Unit) follows these instructions until last instruction execute. It mean when once the process had began, it would continue without the need for human intervention until completion.

• Speed:-

              We can use computer to perform quickly the necessary calculations and analyses. Electrical pulses travel at incredible speed because the computer is an electronic device; its internal speed is virtually great. A powerful computer is capable of adding together two 18-digits in 300-400 nanoseconds.

Note:-

                ''The speed of computer is measured in MHz and GHz"

• Accuracy:-

                 Accuracy is also a characteristic of Computer. Computer can perform complicated tasks with accuracy. An error occurs due to programmer, incorrect data or poorly designed systems otherwise computer has no chance of error. Computer executes millions of instruction in seconds and with accuracy.

• Reliability:-

                Computer is very reliable. Many personal computer have never needed a service cal. Communications are also very reliable and generally available. Computer can perform very complicated calculations without creating any problems.

• Storage:-

               A computer has internal storage memory as well as external or secondary storage. In secondary storage large amount of data can be stored for future use. The store data are available any time for processing. So computer storage memory helps us to keep store our important data.

• Flexibility:-

              Computer is a more flexible machine and it gives us flexibility in many tasks. We can conduct banking online instead of driving to the bank. Almost all banking and office

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