write short notes on the following memory devices?

write short notes on the following memory devices?

Random Access Memory (RAM) A type of memory on with CPU can perform read and write operations randomly is called Random Access Memory (RAM).... 04:31

Random Access Memory (RAM)
A type of memory on with CPU can perform read and write operations randomly is called Random Access Memory (RAM). it is read and write memory.it is because CPU can perform both read and write operations on RAM. in this memory, access time is the same for any memory location (address). it is very fast memory. most semiconductor memories and magnetic disk memories are random access memories.
RAM is divided into two types:
1-  DRAM(Dymatic Random Access Memory): This type of RAM is used in most of the computer. in order to maintain data in DRAM, it is refreshed with electric charge again; otherwise data stored into it can be lost.
2-  SRAM(Static Random Access Memory) it does not have to be refreshed with electric charge again  and again.
Sequential Access Memory
this type of memory on with CPU performs read and write operations sequentially is called sequential Access Memory. it is very slow memory. the information is read and stored in sequential order i.e. one after the other. the access time is different for different locations (addresses). Magnetic tape is an example of sequential access memory.
Dynamic Memory Device
the memory devices that must be refreshed with electric charge periodically (again and again) are called dynamics memory devices. these are semiconductor memory devices. if a dynamic memory device is not refreshed with electric charge, information stored into it can be lost.
Static Memory Device
the memory device that do not need to be refreshed with electric charge periodically are called static memory devices. these are semiconductor memory devices.the static memory devices are faster than dynamic memory devices. SRAM is an example of static memory device.
Read-Only Memory (ROM)
in the type of memory, instruction and information are permanently stored. the instructions and information are stored in ROM by the manufacturer at the time of its manufacturing. Once instructions and information re stored in ROM they cannot be changed or removed.

rbriefly explain the computer memory.How read and write operations are performed on memory?

rbriefly explain the computer memory.How read and write operations are performed on memory?

Memory A components of computer that stores data and programs is called its memory. digital computer has two types of memories: internal/ pr... 00:53

Memory
A components of computer that stores data and programs is called its memory. digital computer has two types of memories: internal/ primary memory and secondary memory.

internal memory is a temporary memory or primary memory. RAM is an example of internal memory. in this type of memory, following items are stored when computer working:-
1-   Operating system and other system software that control or maintain the computer and its devices. for example, Windows and device drivers.
2-     Application programs that are used to perform specific tasks.For example, word processing program, spreadsheet program etc.

3-     Data that is to be processed by application programs and results of the programs.
the role memory to store both data and programs is known as the stored program concepts.

the secondary memory or storage of computer is used to stored larged amount of data and programs permanently. it is also known as mass storage. Hard disk, CD-ROM's, and USB flash drive are examples of secondary storage's.

the read are write operation on memory is performed as follows:
1-  A particular address of memory is selected to perform read or write operation.
2-   Read or write operation is selected.
3-   In write operation, input data is supplied to be stored in memory. Similarly, in read operation, output data coming from memory is received.
4-  Enable (or disable) the memory so that it will (or will not) respond to the address inputs and read/write command.

describe the types of printers depending upon printing mechanism.OR what are the impact and non-impact printers?

describe the types of printers depending upon printing mechanism.OR what are the impact and non-impact printers?

impact and non-impact printers Different printers have different printing mechanisms. Therefore, printers are classified into two  main cate... 06:12

impact and non-impact printers
Different printers have different printing mechanisms. Therefore, printers are classified into two  main categories / types depending upon their printing mechanism.

1-     Impact printers                                 2-   Non-impact printers


1-   Impact printers
The printers that produce output on paper with striking the paper are known as impact printers. Impact printers work like typewriter. They use the eletro-mechanical mechanism to print the output on paper. They print characters and graphics on the paper by striking the print hammer or wheel against an inked ribbon.

impact printers are slower in printing and produce low quality output. They also produce more noise during printing. the examples of impact printers are character printers (such as dot matrix printer and wheel printer) and line printer (such as chain printer and drum printer).
2-     Non-impact printer
The printers that produce output on paper without striking the paper are known as Non-impact printers. They use electronic, inkjet, and thermal technologies for printing .

Non-impact printers are faster and produce high quality output then impact printers. They can print up to 24 pages per minute. They produce no noise during printing. these printers are costly than impact printers. the examples of Non-impact printers are laser printer, inkjet and thermal printers.

what are printers?briefly describe their categories/ types.

what are printers?briefly describe their categories/ types.

Printers Printers are the most commonly used output devices. they are used to produce the hard-copy of the output. the output printed on the... 00:36

Printers
Printers are the most commonly used output devices. they are used to produce the hard-copy of the output. the output printed on the paper is called hardcopy . the output may be in the form of characters, symbols and graphics(i.e.drawing or charts).
A printer is connected to a parallel port of system unit by a cable. the parallel port is also called LPT1 (LPT1 is short for line printer 1).
Different types of printers are available. the main difference between printers depends upon printing quality and printing speed.
Types of printer
the main types of printers are follows:
1-    Character printer                                      2-    Line printer
3-     Page printer
1-    Character printer:
The printers that make hardcopy by printing one character at a time are called character printers. A typewriter is an example of character printer. A character printer can print about 30 to 300 characters per scond (cps).
the advantage of character printer is that it is less expensive. However, there are many disadvantages of character printers. the main disadvantages are :
 they are slower in printing.
they produce low quality output.
they produce more noise during printing.
in the past, character printers were very popular. they were commonly used with personal computers to print the information on paper. Today they are rarely used. they examples of character printers are dot matrix printer and daisy wheel printer.
2-  Line Printers
The types of printers that print a complete line of characters at a time are called line printers. they are faster than character printers. the printing speed of line printer is measured in line per minute (lpm). it is about 200 lines per minutes. line printer are normally used with mainframe and mini computers. the examples of line printers are ; chain printers and drum printers.
3-  Page printer
The types of printers that print a complete page of output at a time are called page printers. Normally, printing speed of a page printer is about 4 to 32 pages per minute. laser printer is an example of pages printer.

what is flat panel monitors? describe different types of technologies used in flat panel monitors.

what is flat panel monitors? describe different types of technologies used in flat panel monitors.

Flat-panel monitor Falt-panel monitor is a lightweight, thin screen. it consumes less power then CRT monitor.it can operate with a charged b... 07:43

Flat-panel monitor
Falt-panel monitor is a lightweight, thin screen. it consumes less power then CRT monitor.it can operate with a charged battery. However, it is more expensive than CRT monitor.

Flat-panel Displays are made up of two plates of glass. these plates contain substance in between them. this substance is activated in different ways.

Flat panel monitor are available with different sizes such as 15, 17, 18, 20, 21 and 23 inches. the standard size of panel monitors for laptop computers is 15 or 16 inches. Flat panel monitors are commonly used in mobile devices such as laptops, tablet PCs, PAD and mobile phones. Today, Flat panel monitors are also used with personal computers.

some important types of technologies used in Falt-panel monitors are as follows:
ELD
ELD stands for Electroluminescent Display.it was the first flat screen that was used in portable computers. ELD technology works by placing a thin phosphorescent film between two plates. Each of the plates used are coated with a vertical or horizontal wire grid that align with each other where each crossing point forms a pixel.

Liquid-Crystal Display (LCD)

LCD uses liquid crystal between the glass plates. the output image is formed by liquid crystal. when an electric current passes through liquid crystal, its molecules twist.

what is CRT monitor?describe the refresh rate or refresh CRT and persistence.

what is CRT monitor?describe the refresh rate or refresh CRT and persistence.

CRT Monitor CRT stands for cathode-Ray tube. A type of monitor that uses CRT to display output on the screen is known as CRT monitor. CRT is... 22:51

CRT Monitor


CRT stands for cathode-Ray tube. A type of monitor that uses CRT to display output on the screen is known as CRT monitor. CRT is also used in TV set. a cathode ray tube is a vacuum tube. it creates the image of the output and displays on the screen the front of the tube is the screen. the back of the screen is coated with phosphor (chemical material that lights up when electron beam falls on it). the screen is organized into a grid of tiny dots of phosphor material. these dost are called pixels (picture elements).

CRT consists of one or more electronic guns. A stream of bits defining the image of output is sent from the computer ( from the CPU) to the CRT, where the bits are converted into beam of electrons passes through focusing and deflection systems. they direct the beam towards specified points on the phosphor-coated screen. when beam of electrons hits the screen, it lights up the selected pixels and an image of output is generated on the screen. Today, most of the PCs have color monitors. CRT in color monitor contains three electron guns; on for red color , second for green and third for blue color (RGB). other colors for output are generated with the combination of three colors. computer controls the three guns. color monitors consume relatively more power.

Refresh Rate or Refresh CRT
the refresh rate is the number of times per second the electron guns scan every pixel on the screen to redraw the images on the screen. it is measured in Hertz (Hz) or in cycles per second. refresh rate is also called refresh CRT.

Persistence
the screen of the CRT monitors may be coated with different types of phosphors. the light emitted by some type of phosphor fades rapidly, while other type fades slowly. the duration of emitting light by dots of phosphor after the electron beam is removed is called persistence (the word"persist" means "continue to be").