ROM

1. This is read-only memory, memory that can only be read, but cannot be written to. ROM is used in situations where the data must be held permanently. This is due to the fact that it is non-volatile memory. This means the data is "hard-wired" into the ROM chip. You can store the chip forever and the data will always be there. Besides, the data is very secure. The BIOS is stored on ROM because the user cannot disrupt the information.
2. There are different types of ROM, too:
3. Programmable ROM(PROM). This is basically a blank ROM chip that can be written to, but only once. It is much like a CD-R drive that burns the data into the CD. Some companies use special machinery to write PROMs for special purposes.
4. Erasable Programmable ROM (EPROM). This is just like PROM, except that you can erase the ROM by shining a special ultra-violet light into a sensor atop the ROM chip for a certain amount of time. Doing this wipes the data out, allowing it to be rewritten.
5. Electrically Erasable Programmable ROM (EEPROM). Also called flash BIOS. This ROM can be rewritten through the use of a special software program. Flash BIOS operates this way, allowing users to upgrade their BIOS.

RAM

Random Access Memory (RAM) is what most of us think of when we hear the word memory associated with computers. It is volatile memory, meaning all data is lost when power is turned off. The RAM is used for temporary storage of program data, allowing performance to be optimum.

Like ROM, there are different types of RAM:
Static RAM (SRAM). This RAM will maintain it's data as long as power is provided to the memory chips. It does not need to be re-written periodically. In fact, the only time the data on the memory is refreshed or changed is when an actual write command is executed. SRAM is very fast, but is much more expensive than DRAM. SRAM is often used as cache memory due to its speed.

There are a few types of SRAM:

·         Async SRAM. An older type of SRAM used in many PC's for L2 cache. It is asynchronous, meaning that it works independently of the system clock. This means that the CPU found itself waiting for info from the L2 cache.

·         Sync SRAM. This type of SRAM is synchronous, meaning it is synchronized with the system clock. While this speeds it up, it makes it rather expensive at the same time.

Pipeline Burst SRAM. Commonly used. SRAM requests are pipelined, meaning larger packets of data re sent to the memory at once, and acted on very quickly. This breed of SRAM can operate at bus speeds higher than 66MHz, so is often used

Memory

             These days, no matter how much memory your computer has, it never seems to be quite enough. Not long ago, it was unheard of for a PC (Personal Computer), to have more than 1 or 2 MB (Megabytes) of memory. Today, most systems require 128MB to run basic applications. And up to 512MB or more is needed for optimal performance when using graphical and multimedia programs.

As an indication of how much things have changed over the past two decades, consider this: in 1981, referring to computer memory, Bill Gates said, "640K (roughly 1/2 of a megabyte) ought to be enough for anybody."

          For some, the memory equation is simple: more is good; less is bad. However, for those who want to know more, this reference guide contains answers to the most common questions, plus much, much more.

Concept of Health

Many people regard health as opposite of disease. However to define health in this narrow perspective is to miss many points of its study. Health means more than just being free from illness. Word Health Organization has defined health as a state of complete physical, mental and social well being and not merely the absence of disease of infirmity. This definition regards health as the combination of multi-dimensional characteristics. It has focused on all the aspect of health. It encompasses physical fitness, mental alertness and social adaptability.

            The definition of WHO attempts to view health as a broad and positive term. However, it is criticized for being too broad and idealistic. If healthy person is defined in this merit, no healthy. Similarly health should be seen as a dynamic process not as a state.

Hard Disk

Hard disks were invented in the 1950s. They started as large disks up to 20 inches in diameter holding just a few megabytes. They were originally called "fixed disks" or "Winchesters" (a code name used for a popular IBM product). They later became known as "hard disks" to distinguish them from "floppy disks." Hard disks have a hard platter that holds the magnetic medium, as opposed to the flexible plastic film found in tapes and floppies.

At the simplest level, a hard disk is not that different from a cassette tape. Both hard disks and cassette tapes use the same magnetic recording techniques. Hard disks and cassette tapes also share the major benefits of magnetic storage -- the magnetic medium can be easily erased and rewritten, and it will "remember" the magnetic flux patterns stored onto the medium for many years.

Input Device

Device which we use to enter the data information in to the computer is called input device. In a simple word which device we use to enter data and information in to the computer is input device. Input device use to enter data in to  the computer with out input computer can not operate. Computer has no its own brain so it can not work on it self. Computer need data and instruction ot operate. So to enter tdhe data and instruction in to the computer we need input device. With out inputd device we can not enter data into the computer. For example keyboard, mouse, loght pen, scanner, digital camara etc.
-Keyboard: Keyboard is an one of the board containning letters numbers etc. Through keyboard we can enter letters and numbers ond other instruction to the cinoyter.
-Mouse: Mouse is also input device. It is also called pointing device. We can enter instruction in to the computer by pointing by mouse curser.
-Light pen: It is also input device. we can enter data and instruction in to the computer by it's light.
-Digital camara: It is also input device. We can use digital camara to enter the photoes in to the computer.

Types of computer

There are different types of computer on different basis.
1 On the basic of size
      a) Super computer: It is most expensive and power ful computer. It is a big computer. It can work very fast. This types of computer used in scientific research.
       b) Mainframe Computer: This type of computer are smaller than super computer and bigger than mini computer. This type of computer used in big organization.
      c) Mini Computer: This types of computer is smaller than mainframe computer and bigger than micro computer. This computer can work faster than micro computer. This types of computer are used in servers.
     d) Micro Computer: The computer which we use in our home and offece is micro computer or personal computer. It is smal in size than mini computer. It is easy to handal for user. This types of computer are mostly used in word processing and graphic design.

My Village

    Hello I am Eak Lal Bhattarai. I live in Sivanagar 1, Chitwan Nepal. Now i am going to discribe my village. My village name is Shivanagar. It lies in west of Narayangarh. It is 15 KM far from Narayangarh. This village is very beauutiful and sweet place to visit. Chitwan National Park is 4 km south of dthis village. In my village there is one high school and one hospital. People of this village are very helpful. They help each other in dtheir work. They get enjoy fdrom their festivals and odther ocasition. Villager love each other. I love my village very much and i like to invite my friend to visit my village. I an sure that you can forget your problems when you come here. And i am sure that kyou can get full enjoyment when you come in my village. In my village there is one picnic sport. We go there to get enjoyment. Otdher people of odther village also come in this picnic sport. We collect money from that picnic sport and we spend that money in social work. And we have one youth club that allways works for our society. This club help in our society and people. At last i would like to invite my friend and other people to come in my village for visit and to get enjoyment.

Computer Hardware

All the physical parts of computer which we can see and touch are called computer hardware. That mean which parts we can see and touch are called computer hardware. In computer system there are many computer hardware.Such as keyboard mouse cpu monitor harddisk etc/ The parts either dthey are inside or outside of computer system. There are many types of hardware input device prdocessing unit output devce etc.
1 Input Device: Device which we use to enter data and information in to the computer are called Input device. For example keyboard mouse light pen digital camara etc.
2: Output Device: Device which we use to get reseult from the computer is called output device. For example monitor printer etc.
3: Storage Daevice: Device which we use to store data for permanent or temporary is called storage device. For example RAM ROM hard disk etc.
   In conclusion we can say that all physical parts of computer which are inside or soutside of cojmputer system are called computer haredware.

Computer

   Computer is an electronic device that takes data information from the user through the input device,processes these data under the set of instruction and gives a result to the user through output device. Computer is very important thing to human because it works very fast than people with out loosing any accuracy. Now a days compu8ter is popular among the people. We can use computer in many field such as school.campus.bank etc. It can solve our problem very fast with out loosing accuracy. It can calculate large scale of data which are complex for a people. Computer has many features such as Accuracy, Diligence, Versatility, Speed, Storage etc. Due these feature computer is popular in human to solve their problem. Computer works on IPO cycle that mean Input Processing Output.