Computer - Random Access Memory

RAM (Random Access Memory) is used to store the result data, and program of the internal memory of the CPU. This is a read / write memory for storing data, until the machine is working. Once the machine is turned off, the data is erased.

In the RAM access time is independent of the number of other positions within the same memory address of each storage location is easy and the time required to reach. Data in RAM random access, but it is very expensive.

Is stored in the RAM when it loses volatile, i.e. the data, we turn off the computer, or if there is a power failure. Therefore, a backup power system (UPS), is often used and the computer. RAM is small, the amount of both in terms of its physical size and the data can be accommodated.

Are two types of RAM
Static RAM
Dynamic RAM

Static RAM (SRAM)

Digital still represent the contents of memory, as long as the power supply. However, the data when the power is down due to the volatile nature of the loss. Using 6-transistor static RAM chip and no capacitor matrix. Transistor does not require power to prevent leakage, so static RAM does not need to have to be refreshed periodically.

Because in the matrix of additional space, the same amount of storage space used by static RAM more than DRAM chip, so that the manufacturing cost is higher. Therefore,  static RAM  is used as a cache memory, and has a very fast access.

Dynamic RAM (DRAM)

In DRAM, unlike static RAM  must be constantly refreshed to keep the data. This is achieved by rewriting the data on a memory refresh circuitry done hundreds of times per second. DRAM memory is used in most systems, because it is inexpensive and small. All DRAM memory cell is a capacitor composed of them and a transistor.

Computer - Memory

Memory is like a human brain. It is used for storing data and instructions. Computer memory is a memory space of the computer, where the data is to be processed and the desired storage location of the process instruction. The memory is divided into a large number of small parts called cells. Each location has a unique address or cell varies from zero to the memory size minus 1. For example, if your computer has 64K words, then the storage unit has 64 * 1024 = 65536 memory location. Address these places, from 0 to 65535.

Three main types of memory is

Cache
Main memory / main memory
Auxiliary storage

Cache
Cache memory is a semiconductor memory of a very high speed, which can speed up the CPU. It is as a buffer between the CPU and main memory. It is used to store data and programs, which are those parts of the CPU of the most frequently used. Each part of the data and procedures from the disk is transferred to the cache memory by the operating system, CPU can access them from there.

Main memory (main memory)

The main memory to store data and instructions only working properly which computer. It has a capacity limit, and when the power is turned OFF data loss. It generally consists of a semiconductor device. These memories are not as fast as registers. Data and instructions to be processed resides in main memory. It is divided into two sub-RAM and a ROM.

Auxiliary storage

This type of memory is also called external memory or non-volatile. It is slower than main memory. These are used to permanently store data / information. CPU does not access directly the opposite of these memories, they are accessed through the input and output process. Two memory contents is first transferred to the main memory, the CPU can then access it. For example: disk, CD-ROM, DVD and so on.

Computer - Output Devices

Here are a few that are important to the output device for use in a computer.

Monitor

Plotter
Printer

Monitor

Monitor, commonly known as visual display unit (VDU), is the main output device of the computer. It forms an image from a fine dot, i.e., called pixels arranged in a rectangular shape. The sharpness of the image depends on the number of pixels.

There are two viewing screen for a display.
A cathode ray tube (CRT)
Flat panel displays

A cathode ray tube (CRT) display

The CRT monitor is a small picture elements called pixels. The smaller the pixels, image clarity, or the better the resolution. It takes more than one pixel lighting, the overall quality of the formation, such as helping the letter "E" word.
A limited number of characters can be displayed at one time on the screen. Screen can be divided into a series of character blocks - a fixed position on the screen, a standard character can be placed. Most of the screen is capable of displaying the data level 80 characters and 25 vertical lines. There are some disadvantages of the cathode ray tube:
Large
High-power
CRT monitors

Flat Panel Display Monitor

The flat-panel display refers to a class of video device, in comparison to CRT reduce the size, weight and power requirements. You can hang on the wall, or to wear on your wrist. Current flat panel display applications include calculators, game machines, monitors, notebook computers, graphic display.


Printer

Output means of the printer, which is used to print the information on paper.

There are two types of printers:
Dot matrix printer
Non-dot matrix printer

Computer - Input Devices

Following are few of the important input devices which are used in a computer:

• Keyboard
• Mouse
• Joy Stick
• Light pen
• Track Ball
• Scanner
• Graphic Tablet
• Microphone
• Magnetic Ink Card Reader(
• Optical Character Reader(OCR)
• Bar Code Reader
• Optical Mark Reader 

Keyboard

The keyboard is the most common and popular input device, it can help in entering data into the computer. The keyboard layout is such a traditional typewriter, although providing additional functionality to perform some additional keys are used.

84-key keyboard in two sizes or 101/102 key, but now 02-11-22104 keys or 108 keys are also available for Windows and the Internet.

Mouse

The mouse is the most popular pointing device. It is has a round ball at its base, it detects the movement of the mouse, and sends a corresponding signal, CPU when the mouse button is pressed a small palm-sized box of a very famous cursor control device.

Usually it has two buttons called the left and right buttons, a wheel between this button. Mouse can be used to control the position of the cursor on the screen, but it can not be used to enter text into the computer.

Advantages

Easy to use

Not very expensive

Move the cursor over the arrow keys on the keyboard to be fast.

Joystick

The joystick is also used to move the cursor position on the monitor screen to indicate the device. It is a rod having a spherical ball at its two lower and upper ends. The lower spherical ball in the socket move. You can move the joystick in all four directions.

Joystick function is similar to a mouse. It is mainly used for computer-aided design (CAD) and playing computer games.

Computer - CPU(Central Processing Unit)

The CPU contains the following features:

CPU is regarded as the brain of the computer.
CPU performs all types of data processing operations.
It stores data, intermediate results, and instructions (program)
It controls the operation of all components of the computer.

                      

There are three components of the CPU itself.

Memory or storage unit
Control unit
ALU (arithmetic logic unit)


Memory or storage unit
This unit may store instructions, data and intermediate results. When the unit is required to provide information to the other computer units. It is also known as the internal storage unit or the main memory or primary memory or a random access memory (RAM).

Its size will affect the speed, strength and ability. Main memory and secondary memory are two types of memory in a computer. Functional storage units are:

All its stored data, and processing instructions necessary.
It stores the intermediate results of processing.
The end result is stored before it is processed, the results are released to the output device.
All inputs and outputs are transmitted through the main memory.

Control unit
Operation of all components of the computer control unit, but does not perform any actual data processing operations.

Features of this machine are:
Other unit which is responsible for the transmission of control data and commands between computers.
It is the management and coordination of all units of the computer.
indicating that it obtained from the memory, interpret them, and the instructions of the computer.
With the input / output device for data transfer from memory or communicate results.
It does not handle or store data.

ALU (arithmetic logic unit)
The unit consists of two sections, namely

Arithmetic unit
Logical part


Arithmetic Division
Function calculation unit is to perform arithmetic operations like addition, subtraction, multiplication and division. All complex operations are accomplished by repeating the above action.

Logical part
Logic part of the function is to perform logical operations, such as comparing, merging selection, matching and data.

Computer - Components

Computer system consists mainly of four basic unit. an input unit, a storage unit, the central processing unit and an output unit. The central processing unit further comprises: an arithmetic logic unit and the control unit, as shown in the figure: the computer to perform the functions of five business regardless of its size or make of. These are
• It takes as input data or instructions
• It stores data and instructions
• It processes data in accordance with instructions
• It controls all operations within a computer
• It gives the results in the form of the output

Input unit
This unit with these help, we enter data into a computer device. This unit allows contact between the user and the computer. Input Devices translate information into a form understandable by the computer.

CPU (Central Processing Unit)

CPU is regarded as the brain of the computer. CPU performs all types of data processing operations. It stores data, intermediate results, and instructions (program). It controls the operation of all components of the computer.

CPU itself has the following three components
ALU (arithmetic logic unit)
Memory
Control unit


The output unit
Consisting of help output unit, where we information equipment from the computer. This unit is a link between the computer and the user. Computer output device to convert the output to the user's understanding of the form.

What is a computer?

A computer is an electronic device to manipulate information, or data. It has storage, retrieval, and processing data capabilities. You can enter a document with a computer, send e-mail and browse the Web. You can also use it to handle spreadsheets, accounting, database management, presentations, games, and more.

Superiority
The following list indicates the advantages of today's arena of computers.

High speed
Is a very fast computer equipment.
It is possible to perform the calculation of very large amounts of data.
The computer has speed in microseconds, nanoseconds or even picosecond units.
Compared to men who will spend a few months to do the same task, it can perform millions of calculations in a few seconds.

Accuracy
In addition to being very fast, the computer is very accurate.
This calculation is 100% error free.
Executed on a computer provided that the correct input has been given 100% accuracy rate of all jobs.

Storage capacity
Memory is a very important characteristic of the computer.
Computer has more storage capacity than humans.
it can store large amounts of data.
It can store any type of data, such as images, video, text, audio, and many others.

Diligence
Unlike humans, a computer is free from monotony, fatigue, lack of concentration.
It can work without any errors and boring.
It can do the same speed and accuracy of duplication of effort.

Versatility
A computer is a very versatile machine.
Computer is very flexible conduct work to be done.
The machine can be used to solve problems in various fields.
In one case, it can solve a complex scientific issues and the very next moment it can play the card game.

Reliability
A computer is a reliable machine.
Modern electronic components have a long life.
Computer design, easy maintenance.