Network is a computer and difference between primary and secondary?

Q:- Do you agree with the statement Network is a computer?Why or Why not?

Ans:
I agree with that statement because
A computer network is a group of computers that are connected to each other for the purpose of communication. Networks may be classified according to a wide variety of characteristics.
If the hardware is not working then you have no network,if the software is not configured to operate the hardware the network will not work.So basically all network problems are caused by one or the other.I put network cables as part of the hardware.


Q:-What is Difference Between primary and secondary storage Explain?
Ans:Primary & Secondary storage devices -
Index
 Primary and Secondary Storage
 Random Access Memory (RAM)
 Floppy Disk
 Hard Disk Drive
 Pen Drive
 CDs
 DVDs
 Summary

Primary and Secondary Storage
The term primary storage referees to the main memory of the computers, where both data and instructions are held for immediate access and use by the computer central processing. Although technology is changing, most primary storage today is considered a Volatile form of storage, meaning that the data and the instruction are lost when the computer is turned off. Secondary storage (or auxiliary storage) is any storage device designed to retain data and instructions in a more permanent form. Secondary storage is nonvolatile, meaning that the data and instructions remain intact when the computer is turned off.

Primary Storage Unit
Random Access Memory (RAM).
Ram stands for Random Access Memory. As the name suggests data or instruction could be accessed quickly/randomly from the RAM. It is a temporary/volatile memory i.e. what ever data or instruction is in RAM would be lost when the computer is switched off. Also when
the program is been completely executed it is automatically removed from the RAM .The information stored in RAM could be read, written, modified or erased. RAM stores the user’s data, instruction, intermediate and final result temporally.

Read-only memory (ROM)
Read-only memory (usually known by its acronym, ROM) is a class of storage media used in computers and other electronic devices. Because data stored in ROM cannot be modified (at least not very quickly or easily), it is mainly used to distribute firmware (software that is very closely tied to specific hardware, and unlikely to require frequent updates).
Modern semiconductor ROM chips are not immediately distinguishable from similar chips like RAM modules, except by the part numbers printed on the package.


Primary Storage Unit
RAM:
The key benefit of RAM over types of storage which require physical movement is that retrieval times are short and consistent. Short because no physical movement is necessary, and consistent because the time taken to retrieve a piece of data does not depend on its current distance from a physical head; it requires practically the same amount of time to access any piece of data stored in a RAM chip. Most other technologies have inherent delays for reading a particular bit or byte. The disadvantage of RAM over physically moving media is cost, and the loss of data when power is turned off.

Because of this speed and consistency, RAM is used as 'main memory' or primary storage: the working area used for loading, displaying and manipulating applications and data. In most personal computers, the RAM is not an integral part of the motherboard or CPU—it comes in the easily upgraded form of modules called memory sticks or RAM sticks about the size of a few sticks of chewing gum. These can quickly be removed and replaced should they become
damaged or too small for current purposes. A smaller amount of random-access memory is also integrated with the CPU, but this is usually referred to as "cache" memory, rather than RAM.

Modern RAM generally stores a bit of data as either a charge in a capacitor, as in dynamic RAM, or the state of a flip-flop, as in static RAM. Some types of RAM can detect or correct random faults called memory errors in the stored data, using RAM parity and error correction codes.

Secondary Storage Devices
Most Business information and particularly Transactions require semi-permanent Storage i.e. we need to store a transaction for either further processing or references. It should also be possible to edit and update such transactions. Primary Storage such as the RAM though fast
cannot be used for this purpose due to the sheer size of the information that an organization needs to store over a period of time. Further primary storage is volatile in nature. I.e. all information in the primary storage is lost as soon the power is turned off or the programme which has generated or is processing the information completes it job.
Some of the commonly used secondary storage devices include:
 Floppy Disks and Drives
 Hard Disks
 CDs/DVDs and CD/DVD drives
 Pen Drives.

Floppy Disk
What is Floppy Disk and Disk Drive?
 The first diskettes were introduced in 1971.
 They had a capacity of one megabyte i.e. roughly 1Million Bytes or characters
 The diskettes are placed in a drive, which has read and write heads.
 Later in 1976, 5.25” diskettes were introduced.
 They were inexpensive and easy to work with.
 Like the 8” diskettes, he 5.25” was soft and flexible. Therefore they were named floppy disks.
 In 1987 IBM’s revolutionary PS/2 PC’s were introduced and with them the 3.5” hard diskette we know today.

Hard Disk Drives

 IBM developed the idea of a Winchester or Hard Disk
 A Hard disk is a device and a storage medium which is permanently fixed into the computer.
 Hard disks of the available as well desired for storage have to be bought along with computer.
 Capacities of the order of 20GB, 30GB, 40GB, and 60 GB are typical on many desktops.

Pen Drive
What is a Pen Drive?
 A pen drive is a small removable FLASH MEMORY DRIVE usually connected to the USB port of a computer.
 It provides storage ranging from 16MB, to several Gigabytes.
 Data can be stored for as long as required even up to 10 years.
 It is a Plug and Play device.
 Typical Dimensions are approx. 77mm*25mm*9mm and weight of approx 20 grams.- It is thus compact and easy to carry around even in your pocket.

How does it Work
 The pen drive is really a memory chip. It therefore does not have any moving electro mechanical parts. The computer reads/writes to the Pen Drive as it would to the RAM. This is possible since the Flash Memory card (pen Drive) is directly connected to the USB – bus just as the memory is connected to the bus.
 The drive can be connected and in an instance a Windows based computer recognizes the presence of the drive, loads the necessary driver (special software required to read or write.
 The Pen Drive also has a write protect tab just like a floppy drive has.
 This prevents the computer from writing to the driver if the user so wishes.

CDs.

What are CDs?

A Compact Disc or CD is an optical disc used to store digital data, originally developed for storing digital audio. The CD, available on the market since late 1982, remains the standard playback medium for commercial audio recordings to the present day, although it has lost ground in recent years to MP3 players, which have greater storage capability (albeit with lower sound quality).

An audio CD consists of one or more stereo tracks stored using 16-bit PCM coding at a sampling rate of 44.1 kHz. Standard CDs have a diameter of 120 mm and can hold approximately 80 minutes of audio. There are also 80 mm discs, sometimes used for CD singles, which hold approximately 20 minutes of audio. The technology was later adapted for use as a data storage device, known as a CD-ROM, and to include record-once and re-writable media (CD-R and CD-RW respectively). CD-ROMs and CD-Rs remain widely used technologies in the computer industry as of 2007. The CD and its extensions have been extremely successful: in 2004, the worldwide sales of CD audio, CD-ROM, and CD-R reached about 30 billion discs. By 2007, 200 billion CDs had been sold worldwide.

DVDs
What are DVDs?
DVD (also known as "Digital Versatile Disc" and "Digital Video Disc") is a popular optical disc storage media format used for data storage. Its main uses are for movies, software, and data archiving. Most DVDs are of the same dimensions as compact discs (CDs) but store more than 6 times the data.
The term DVD is used in describing three ways that data is stored on the disks — DVD-ROM has data which can only be read and not written, DVD-R can be written once and then functions as a DVD-ROM, and DVD-RAM holds data that can be re-written multiple times.

Summary

Various forms of storage, based on various natural phenomena, have been invented. So far, no practical universal storage medium exists, and all forms of storage have some drawbacks. Therefore a computer system usually contains several kinds of storage, each with an individual purpose.

Processor without a memory would not be a computer, merely a simple digital signal processing device, able to perform a fixed operation and immediately output the result. It would have to be re-built to change its behaviour, like in case of a calculator. The ability to store and change both instructions and data, the important von Neumann's idea, makes computers versatile. It basically introduces the concept of computer programming, as opposed to re-building the hardware.

A computer can exist that uses the single type of storage for all the data. However, to provide acceptable computer performance at a lower cost, computers usually use a whole storage hierarchy. The traditional division of storage to primary, secondary, tertiary and off-line storage is based on the speed and cost per bit. The lower a storage is in hierarchy, the bigger is its distance from the CPU.

Primary storage, presently known as memory, is the only one directly accessible to the CPU. CPU continuously reads instructions stored there and executes them. Any data actively operated on is also stored there in uniform manner. RAM is zeroed after computer powers on. If a computer contained only RAM, the CPU would not have a place to read any instructions from. Hence a non-volatile primary storage is used, containing small initial program, both to perform hardware power-on self test, and to bootstrap, that is, to read the larger program from non-volatile secondary storage to RAM and execute it. A non-volatile technology known as read-only memory (ROM) is used for this purpose.

Secondary storage most business information and particularly Transactions require semi-permanent Storage i.e. we need to store a transaction for either further processing or references. It should also be possible to edit and update such transactions. Primary Storage such as the RAM though fast cannot be used for this purpose due to the sheer size of the information that an organization needs to store over a period of time. Further primary storage is volatile in nature. I.e. all information in the primary storage is lost as soon the power is turned off or the programmed which has generated or is processing the information completes it job.

Some of the commonly used secondary storage devices include:
 Floppy Disks and Drives
 Hard Disks
 CDs/DVDs and CD/DVD drives
 Pen Drives.