pirouette before summer

last episode before our radio-host summer stop, we return at 8 sep.

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Impact Printers And Its Type

Printers
Printers are the most commonly used output device. They are used to print output on the paper. The output may be in the form of characters, symbols and graphics information printed on paper is called hardcopy

Categories/Types of Printers
Printers are classified into two main acategories or types:
    1- Impact Printers
    2- Non-Impact Printers

Impact Printers
The types of printers that produce output on paper by striking the print hammer or wheel against  an inked ribbon are called impact printers. impact printers work like typewriter. They can print characters and graphics on the paper
Impact printers are slower in printing and produce low quality output. The printing speed of these printers is measured  in characters or lines per minute. They also produce more noise during printing. Today they are not commonly used.

The examples of impact printers are :
     1- Dot matrix printer
     2- Daisy Wheel printer
     3- Line printer

Dot Matrix Printers
A dot matrix printers is an impact character printer. It makes a hardcopy by printing one character at a time. Its printing speed is from 200 to 1000 or more characters per minute.

Dot matrix printer contains a print-head with a matrix of small pins arranged in rows and columns. Dot matrix printer produces output on paper by striking pins against an ink ribbon. Usually, a dot matrix printer uses 100 to 300 dots per inch (DPI) to print output on the paper. Print-heads are avialable with 9, 18 or 24 pins. The dot matrix printer with 24-pins provides best quality printout.

Dot matrix printers are usedd with personal computer. They are less expensive. The printout quality of these printers is not bad. They also produce more noise during printing.

Daisy Wheel Printer
Daisy wheel printer is also an impact character printer. It is similar to typewriter. It has a print wheel with a series of petals. This wheel is known as daisy wheel. Each petal of dasiy wheel contains a character at its end. A motor rotates the wheel. When the desired character reaches at the print position on the paper, a hammer strikes a petal against the ribbon. In this way, a character is printed on the paper. This printer is slower than dot-matrix printer. However, its print quality is better than dot matrix printer

Line Printer
Line printer is an impact printer. it is very fast printer. It prints a complete line of characters at a time. The printing speed of line printer is measured in lines per minute (lpm). It is upto 3000 lines per minute.
Line printers are normally used with mainframe and mini computers.

Two types of line printers are ;
    1- Chain Printer
    2- Band Printer

Primary Hardware Components

The primary Hardware components of computer system are shown in the following figure

                                                    CPU
                                                              ALU
                          Input Device             Control Unit              Output Device
                                                          Memory Unit
                                                       Secondary Storage

Input Device
The data and instructions are given to the computer as input. The input device is used to give input to the computer. It accepts input ( data & program instructions ) in a form that a computer can use. The most commonly used input devices are keyboard and mouse

Processor
Processor is the most important component of the computer. It is also known as Central Processing unit
(CPU). It is considered as the brain of the computer. It processes input data according to the given instructions, and converts it into useful information. It is is further divided into two main components. These are Control Unit (CU) and Arithmetic Logic Unit (ALU).

Memory Unit
The memory unit is another important part of computer. It is used to store data and instructions that are currently in use. The main memory or RAM is an example of memory unit.

Output Device
The Processed data is also known as output. The output device is used to get input from the computer. It gives processed data or results in form that a user can understand. The commonly used output devices are monitors and printers.

Secondary Storage Device
Secondary storage device is used to store data and programs permanently for later use. The commonly used secondary storage devices are hard disk, USB drive, floppy disk, and CD-ROM.

Computer Basic Introduction

Computer
A computer is an electronic machine.it can be programmed to accept data process data into useful information, and store it for later use. A computer System consists of hardware and software

Software
Computer processes data according to the set of instructions given to it. The set of instructions given to the computer to perform a specific task is known as software. Software is also called computer program

Hardware
The physical components of a computer are called hardware. You can touch, see and feel hardware. The input/output devices ( such as keyboard, mouse, printer, monitor ), CPU, memory unit. are examples of hardware