Dr Rajiv Desai

An Educational Blog


Prologue: Millions of people read my comments on internet and yet,majority of them have very little knowledge of computer/internet and hence I am posting this comments to educate them.
Today,we live in computer age,the computers are found everywhere and it has created global awareness.
Computer is defined as a programmable machine that computes(stores,processes and retrieves) information(data)according to a set of instructions(program). Church-Tuning theory of mathematical versatility suggests that any computer with certain minimum capacity,in principle, can perform the same task that any other computer can perform.
Computers are of 2 kinds,analog and digital.
Analog computer is slower,having continuous inputs and uses mechanical devices like gear/rachet/lever to perform mathematical task, for example,speedometer in a car or electricity meter in house etc.It translates variables in a given problem into analogous variations in electrical quantity like current/voltage and solve original problem by solving an equivalent problem(analog) in electrical circuits.It is obsolete.
Digital computer also known as computer is fast,having intermittent inputs and uses digital electronic circuits to perform mathematical tasks.It differs from a calculator by being able to store,process and retrieve data without human help.The oscillator synchronizes various digital electronic circuits at the rate of millions of cycles per second performing millions of arithmetical/logical operations per second, making impossible for human to solve the problem at that speed.It varies from cell phone to personal computer(PC) to supercomputer.
Computers are of 4 generations.
1’st generation from 1951 to 1959 used vacuum tubes.
2’nd generation from 1959 to 1965 used transistors.
3’rd generation from 1965 to 1971 used integrated circuits(IC).
4’th generation from 1971 onwards uses microprocessor-silicon chips.
4’th generation computers with microprocessors as brain are known as microcomputers because of their compact size which could be a personal computer or work station.
Personal computer(PC) is defined as any general purpose microcomputer which is used by end user without the help of computer operator. PC could be a desktop,laptop or palmtop depending on size.
Today, 1 billion PC are used in the world and by the year 2014, 2 billion PC will be used in the world.
Computer processes data in numerical form and its digital electronic circuits perform mathematical operations using Binary System. Binary system means using only 2 digits for arithmetic processing, namely, 0 and 1 known as bits (binary digits).
0 means absence of current/voltage in electronic circuit = off
1 means presence of current/voltage in electronic citcuits = on
A series of 8 consecutive bits is known as a byte which permits 256 different on/off combinations.
Bits combinations = arithmetic number
0 (off) = 0
1 (on) = 1
10 (on-off) = 2
11 (on-on) = 3
100 (on-off-off) = 4
101 (on-off-on) = 5
People can see that such permutations and combinations of ‘on-off’ circuits in computer processes all data.
Unit of Data : 8 bits = 1 byte
1024 bytes = 1 kilobyte(KB)
1024 KB = 1 megabyte(MB) = 1048576 bytes
1024 MB = 1 gigabyte(GB) = 1073741824 bytes
1’st generation computer had 1 vacuum tube correspond to 1 bit.
Integrated circuits(IC) used in modern computer contain thousands of semi-conductors and each semi-conductor can store 1 MB and computer memory in GB.
Computer program may contain few instructions or millions of instructions. Modern computer can execute billions of instructions per second and rarely make a mistake after many years of use.
Computer hardware means those parts of computer that have a material form (machinery) like circuits,power cord,display,mouse,printer,key board etc. Computer software means those parts of computer that do not have a material form like data,program,instructions to hardware etc. External storage of data/program on optical disk is known as compact disc(CD) and digital versatile disc(DVD). Operative system software provides a ‘user interface’ to the computer user that manages data/program on computer, for example, microsoft windows.
Quantum computer uses a novel concept of superposition which allows a single bit of information(qubit) to represent both 0 and 1 at the same time,in contrast to a classical bit representing only 0 or 1 at a time. Quantum computer can solve a problem having trillions of variables.
Desktop can use up to 250 watts and laptop can use up to 40 watts of electricity. 1 google/yahoo search uses 1 kilojoule of energy and emits 0.2 grams of carbon, mainly from energy used by server and keeping server room cool.
Continuous use of computer by humans can lead to eye strain and muscle spasm.
With evolution of internet, PC has become as common as telephone/TV in household.
Internet( the Net) is defined as a global communication system of data connectivity between computers using transmission control protocol(TCP) and internet protocol(IP) to serve billions of users in the world.
In the year 2009, 25 % of world’s population is using internet services. In the september 2009, 27 billion hours were spent on internet by 1.2 billion users worldwide. Net traffic grows by 50 % per year but the system will not be overwhelmed due to technological advancements. Average consumer uses 10 to 15 gigabytes of information on internet every month. Total web traffic on internet is 40 petabytes.
Internet was invented in the year 1969 in America for military purpose.It is the most outstanding technological innovation in the history of man kind.It is a convergence of telecommunication,computers and media.
Internet has created new environment, new culture of abolishing barriers of race/religion/region/language/age/distance in communication making the world a better place to live in. When you are on internet, your computer is connected with other computers through network of telephone wires, fiber-optic cables or wireless(using radio waves).
Server is a network computer which processes requests from client computer. Modem allows a computer to communicate with other computers using phone lines. Ethernet allows internet access to computer using local area network(LAN). Wi-Fi means any wireless local area network based on the standard of the institute of electrical and electronic engineers giving internet access using radio waves.
World Wide web (www) is one of the services communicated via internet whereby data travels from client to server and back using the protocol of hypertext tranfer protocol(http). Web browsing ( net surfing) is done using a web browser like microsoft internet explorer. Internet also supports infrastructure for electronic mail(e-mail). Also, internet is used for online chat,search information,commerce,games,social networking,video conference,telecommunication,audio/video talk,file tranfer,publishing,steaming video etc etc.
Every computer on internet has a number(IP address) which consists of 4 sequences of up to 3 numbers with each sequence ranging from o to 255.Hence IP address ranges from to However it is difficult to remember IP address number and so domain name system(DNS) was created to provide mnemonic equivalent of each numeric IP address.
Data transfer rate(speed) of internet is usually in bits per second but can be converted in bytes per second.
1000 bits per second = 1 kilobit per second(Kbps) = 125 bytes per second.
1000000 bits per second = 1 megabit per second(Mbps) = 1000 Kbps
People must avoid unnecessary confusion in measurement of data speed/store.
1 kilobit = 1000 bits but 1 kilobyte = 1024 bytes.
This is because of unholy mixture of SI decimal system and binary digit system. SI system kilo means 1000 and mega means 1000000 but binary system kilo means 2 raised to 10 which is 1024 and binary mega means 2 raised to 20 which is 1048576. Since computer is using binary system,computer kilo also known as kilobinary(kibi) is 1024. This simultaneous double measurement standard used by IT industry and telecommunication industry has created confusion about quantification of data store/tranfer.
Broadband means download internet speed of more than 768 Kbps and upload internet speed of more than 200 Kbps. Newer technology with fiber-optic cables can give internet speed of 100 Mbps. Internet speed can be affected by network overhead,network overload, signal quality,bad weather,computer virus etc.
The speed of transmission of data from computer to computer through wireless technology (air) is the same as the speed of radio waves (speed of light) which is  300,000  kilometers per second. The internet data speed Kbps or Mbps refers to the speed of the data converted into radio waves and not the speed of data when traveling through the air. 

Advantages of internet:
1) You can communicate with another person sitting in another part of world in a fraction of a second anytime with little cost.
2) Unlimited source of information on any subject any time.
3) Various internet services including banking,railway reservation,hotel reservation,college admission,job searching,paying online bills etc.
4) E-commerce including any kind of shopping,product advertisement,tranfer of information for business deal etc. American companies conducted business worth 3 trillion dollars on internet.
5) Entertaining people by online live chats,cultivate hobbies, music, games, downloading video etc.
6) Internet satisfies human need of socializing by finding friends or life partner on social networking.
7) Internet can provide news,weather,sports information etc.
8) My comments are a classical example of online education read by students all over world.
9) Medical problems are solved by online advice given by a panel of expert doctors.
10) Online results are available of various university/board exams.
11) A study found that internet surfing is a brain exercise that improves cognition in elderly.
12) Internet is open and neutral as compared to media because media tries to control information and gives preferential treatment based on corruption,prejudice and blind patriotism.
Disadvantages of internet:
1) Security problem including theft of personal information like bank account,credit card number,identity etc and data damage by hackers.
2) Receiving spam-a spam is an unsolicited e-mail, one which is not requested.
3) Computer virus invasion
4) Children’s access to pornographic material
5) Access to information that is not authentic and getting misled.
6) Many students waste time in searching unnecessary information compromising studies.
7) Most information available in english language but only 50 % internet users know english language as their first language.
8) Internet addiction is a controversial issue but computer rehabilitation programs are available in America and Britain.
9) Movie and music industry suffered losses as movies and songs are available on internet.
10) Computer abilities of school children are misused by them to break into school computer to erase absence,change grades or leak exam paper.
11) Computer/internet work faster and more efficiently than humans and therefore may leads to unemployment.
People can see that advantages of internet far outweigh disadvantages and tough cyber crime laws can prevent many disadvantages.
Cyber crime includes cyber terrorism,Wi-fi hacking,sending offensive e-mail,data theft,child pornography,video voyeurism,identity theft,spam,leaking data breaching confidentiality,fraud by impersonation,publishing sexually explicit material etc.
Also, it is parent’s responsibility that the child does not view pornography anywhere including internet. Also, some countries have censored internet for political/moral considerations including blocking pornographic sites.
Intranet is a private computer network owned by an organisation run on internet protocol giving access only to member/employee of that organisation and having firewalled internet to prevent access to any outsider. Extranet is an extension to intranet whereby firewall is opened to a specific person outside organisation giving controlled access to intranet.
FBI’s recommendations for internet safety:
1) Never meet in person someone you have met online.
2) Never upload your picture to a stranger.
3) Never download pictures from unknown sources.
4) Do not give your name,address or phone number to a stranger.
5) Do not respond to messages from stranger or posts that are obscene/harassing.
6) Do not forget that people you meet online are usually dishonest about their identity.
Electronic mail(e-mail) is a method of exchanging digital messages through internet using simple mail tranfer protocol(SMTP). During the year 2009, 35 trillion e-mails were exchanged between 1 billion computers. An average corporate worker spends 40 % of time on e-mail work and receives 200 e-mails per day. E-mail has advantage of cheap and fast communication between participants without disturbing their schedule. E-mail has disadvantage of privacy compromised,information overload and spreading spam/virus.
Computer virus is a small software program that spreads from one computer to another computer and interferes with the operation of a computer.It is not merely a nuisance to the computer user but it caused loss of 8.6 billion dollars to consumers in the year 2008.It can wipe out information on hard disk,delete/corrupt data,block traffic on computer network and replicate itself and spreads to another computer via internet.Computer can get infected by virus through e-mail attachment or corrupted web links.
Symptoms of computer virus infection includes slowdown of computer,computer stops responding,data loss,incorrect computer applications etc. Every computer must have up to date anti-virus software installed along with firewall to tackle the menace of computer virus.
Computer hacking is a practice of modifying the hardware and software of a computer to achieve goals outside the original purpose of computer programmer and/or computer user. It is in some ways, online burglary and unauthorised access to computer. The motive could be intellectual curiosity which leads to development of technological advancement but the motive could be less noble resulting in stealing personal information, changing company’s financial data, getting unauthorised access to classified files etc which can land a hacker in jail. Some companies actually employ hackers as a part of technical support staff to use their skills to find flaws in the company’s security.
Internet TV is a television service distributed via internet. Also, digital LCD TV has a direct internet access without PC and mobile internet is available on cell phones.
Computer science is helping medical researchers to test how proteins fold, how genes(DNA) interact and how pandemic spreads in complex digital simulation of natural environment. Computer simulation technology is helping scientists to study black-holes and unfold mysteries of universe.
Next step to internet is the Grid. The grid is a global computer service for sharing computer power and data storage capacity over internet. The grid is a system of parallel computing where plenty of complete computers are connected through internet, in contrast to supercomputer where plenty of microprocessors are connected through a computer bus. The grid used by the CERN has storage capacity of 15 million gigabytes which connects millions of computers,supercomputers,cell phones,telescopes and meteorological sensors for the scientific community all over the world to solve problems like disease cure,disaster management,earthquake simulation,climate change,financial modeling etc.
In future, the grid internet will be available to common people which is 10000 times faster than broadband having internet speed in Gbps and no need to use CD/DVD/pen drive to transfer data.
1) Internet is the greatest invention in communication breaking barriers of age/distance/language/religion/race/region and making the world a better place to live in.
2) If you do not have internet access in 21’st century, you are illiterate.
3) Internet scores over media due to internet’s openness and neutrality.
4) Every school must teach basics of computer and internet to students.
Dr.Rajiv Desai.MD.
I earn my livelihood from my medical practice and post my comments in my spare time without anybody’s help. Had I devoted my full time to my comments, then, the comments would have been even better in quality but the issue of livelihood unresolved.



Update for learning binary arithmetic vis-à-vis IP address:


Binary arithmetic and IP address:

The act of creating large numbers from groups of binary units or bits is called binary arithmetic. Learning binary arithmetic helps you understand how your computer sees IPs (or any numbers greater than one). In binary arithmetic, each bit within a group represents a power of two. Specifically, the first bit in a group represents 20 [mathematicians stipulate that any number raised to the power of zero equals 1], the second bit represents 21, the third bit represents 22, and so on. It’s easy to understand binary because each successive bit in a group is exactly twice the value of the previous bit. The following table represents the value for each bit in a byte (remember, a byte is 8 bits). In binary math, the values for the bits ascend from right to left, just as in the decimal system you’re accustomed to:


8th bit 7th bit 6th bit 5th bit 4th bit 3rd bit 2nd bit 1st bit
128 (27) 64 (26) 32 (25) 16 (24) 8 (23) 4 (22) 2 (21) 1 (20)


Now that we know how to calculate the value for each bit in a byte, creating large numbers in binary is simply a matter of turning on certain bits and then adding together the values of those bits. So what does an 8-bit binary number like 01101110 represent? The following table dissects this number. Remember, a computer uses 1 to signify “on” and 0 to signify “off”:


128 (27) 64 (26) 32 (25) 16 (24) 8 (23) 4 (22) 2 (21) 1 (20)
0 1 1 0 1 1 1 0


In the table above, you can see that the bits with the values 64, 32, 8, 4 and 2 are all turned on. Calculating the value of a binary number means totalling all the values for the “on” bits. So for the binary value in the table, 01101110, we add together 64+32+8+4+2 to get the number 110. Binary arithmetic is pretty easy once you know what’s going on.


How computers see IP addresses:

To your computer, an IP address is a 32-bit number subdivided into four bytes.

For example IP address is

Using binary arithmetic, we can convert this IP address to its binary equivalent.

This is how your computer sees this IP: 11001100.10000100.00101000.10011011

Understanding binary also provides you with some of the rules pertaining to IPs. You wondered why the four segments of an IP were called octets. Well, now that you know that each octet is actually a byte, or eight bits, it makes a lot more sense to call it an octet. And you remember how the values for each octet in an IP are within the range of 0 to 255, but why? Using binary arithmetic, it’s easy to calculate the highest number that a byte can represent. If you turn on all the bits in a byte (11111111) and then convert that byte to a decimal number (128 + 64 + 32 + 16 + 8 + 4 + 2 + 1), those bits total 255.


The designers of the Internet Protocol defined an IP address as a 32-bit number and this system, known as Internet Protocol Version 4 (IPv4), is still in use today. However, because of the growth of the Internet and the predicted depletion of available addresses, a new version of IP (IPv6), using 128 bits for the address, was developed in 1995. The address size was increased from 32 bits (4 octets) to 128 bits (16 octets).  Mathematically, the new address space provides the potential for a maximum of 2128, or about 3.403×1038 addresses.  IP addresses are usually written and displayed in human-readable notations, such as (IPv4), and 2001:db8:0:1234:0:567:8:1 (IPv6).


Dr. Rajiv Desai. MD

June 16, 2015


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