I’m shifting my blog to: http://aveek.in/blog

## Category: Uncategorized

Almost every book on computer applications at the school level skip the beauty of the mathematics behind it

In fact basic counting principles are very easy to understand & should be part of every curricula

Excluding it leaves the interesting & easy but important basic part

**The concept of 2 **

Most of the computational data is stored & evaluated as binary numbers

Each digit of a binary number(base 2) is either 0 or 1(one less than the base of the system)

**Why just 2 ? **

A computer or any other electronics device generally uses logically 0 & 1 to represent either if any 2 states-one for 0; the other for 1

It is not necessary that 0 always represents low/off/false. That depends on the predefined logic

Most common situations are such that there are only two possible answers/outcomes/values for it

For example, a CFL can either glow(ON) or not(OFF) depending on the switch position

A coin generally when tossed either gives a head or a tail; in many movies we have seen a funny situation arising when the coin lands on its rim(neither head nor tail)

If we also consider this outcome, how many possibilities are there? Simply 3

Taking the base of the number system to be equal to the number of possibilities we reduce the chances of redundant data & wastage of memory

**WASTAGE OF MEMORY. HOW? **

Here I will go into very basic counting problems to explain the memory allocation. It is part of the +2 mathematics syllabus as well

**#1. A coin on being tossed either results in a head or a tail. How many outcomes are possible?**

**2**

**#2. Two coins are tossed. A coin on being tossed either results in a head or a tail. How many outcomes are possible?**

**4**

**how?**

Representing head by H & tail by T, I point out the possibilities

HH

HT

TH

TT

Now you must be thinking that this is such a lengthy process ! In face there is a theorem in mathematics that states that no matter how many independent processes are carried one after the other the outcome is their product.

Now the process of tossing a coin doesn’t affect the results we obtain on tossing the other coin; hence they are independent processes.

**#3. A two digit binary storage unit can store how many numbers?**

**4**; this is a situation analogous to #2

the possibilities are-

00

01

10

11

**#4. A 100 digit binary storage unit can store how many numbers?**

**2^100, its a huge number**

**quite boring. I too feel the same. Answer the next question & you will not feel the same.**

**#5. How many mobile numbers are possible in India at present? Assume that the first digit is always 9, the rest can be anything(0 to 9).**

**10^9**

Recently it was reported in the news papers that TRAI is considering adding an extra 9 to the beginning

of all mobile numbers. Any idea why??

In our case it was a ten digit mobile number beginning with 9, now its a eleven digit mobile number beginning with 9. **So how many mobile numbers are possible now? 10^10; 10 times the previous**

**NOTE : you may ask why not simply let the first digit start with any number(0-9). Then there can be 10^10 number of possible 10-digit mobile numbers. True**

**I don’t know the reason & will update this part of the text after finding it out**

**#6. Now this final question will illustrate the memory wastage on using say, a base-7 number system, to store values that have 2 possible outcomes.**

**How many possible values can a 10-digit base 7 number have? This is exactly its storage capacity.**

Obviously, 7*7*7…..=7^10

** In how many possible ways, can a combination of a serial-array of ten bulbs be lighted? This is exactly the storage that will be used.**

Ten bulbs A, B, C ,D, E, F, G, H, I, J are arranged in a line ABCDEFGHIJ. The various ways they can be lighted equals 2*2*2…=2^10, each bulb can either be on or off.

So if the base-7 system is used to store values then the wasted memory=?

7^10 – 2^10, a huge number.

**#7. then why are hexadecimal & octal numbers used by computers?**

This is the basic concept, that once understood , will not ever create confusion.

The last question, asked for a storage of a 10-digit binary linear array into a 7-digit octal linear array.

However, a binary number can be converted to any base. Not just binary numbers, any number in a given base-n can be converted to its corresponding equal number in another base-m.

What is the binary equivalent of the decimal number 10? 1010

how? It can be found in any standard textbook

10=1*(2^3) + 0*(2^2)+ 1*(2^1)+0*(2^0)

noticed any pattern? Each digit of the decimal number is multiplied by 2 raised to its positional-index(numbered from 0 & not 1).

noticed anything else?

The same number required 4-digits in the binary system but required only 2 in the decimal system.

In the hexadecimal system, the number of digits would be even less-one for the decimal number 10, represented by the hexadecimal number A.

So what exactly is our benefit if the number of digits s less or more?

**Less number of digits implies less number of electronics signals have to be transmitted**

**next-cylinders, storage units(mb,gb,etc), meta data, why does a 250 GB hard disk have less available space, etc..**

I have the same problem. i got a pop-up suggestion in Firefox itself(enclosing screenshot). I am also providing the link to the Mozilla help page I was led to-http://support.mozilla.com/en-US/kb/The+bookmarks+and+history+system+will+not+be+functional?style_mode=inproduct

I have still not used it due to lack of time but will do it soon & also update the post then.

What should I do if Fedora 11 shows “Hard Disc Failing”?

Is it anything serious?

I am attaching the screen-shots here on my blog-http:// aveek.wordpress.com/ & also uploading to the NIT Durgapur GLUG-named aveek1.png & aveek2.png.

If you go through the links provided by Indranil Das Gupta on the NIT Durgapur LUG mailing list(link above), we would see its NOTHING to worry about in most cases.

I got my BSNL EVDO card today itself. I used it for some time on my friend’s laptop with Windows XP. I had to install a driver. The attached disc with the EVDO(manufacturer-ZTE), had a file on Linux that stated that I had to modify the Kernel source code & all. However, all I did on my Fedora 11 was to edit network connections & add a “Mobile broadband”–>CDMA. I don’t know why the vendor’s default option didn’t work(i got 3 options-vendor’s, GSM & CDMA). I saved my username & password & I was instantly connected.

I used Google’s translation utility to translate everything- options, et. al for the translated Google group of NIT Agartala GNU/Linux Users group in Hindi.

Here are a few screenshots:

Before using Google translator, I was unable to translate the options atop the menu buttons.

Freenode no longer supports Mibbit. Discoverd it today, while helping a friend in a cyber cafe via gtalk.

Just use this & solve your problems- http://webchat.freenode.net/

If you do not have a registered “nick”(user id), then try out any you wish & if already registered try another choice. do register your “nick” later if you are regular on the IRC. Nick setup help.

Making your own radio-station?

Try GNU Radio-http://gnuradio.org/

I am doing the same for my college radio at NIT Agartala, India.

Being Open Source, it is cheap & much more reliable. It has been extensively tested for bugs by various users. It has a vibrant community & they are willing to help you for any problems that you face for free.

The USRP2 costs around $1,500(USD) outside of the USA for organizations but is extremely robust.

For details visit-http://www.ettus.com/sales

I found the youtube downloader too slow. So, I found another way out.

I opened youtube, let the full video be streamed. Then I went to the temp(temporary) directory & copied the video file after the full video got streamed.

Upto 50% quicker!! Works same ways with Windows. All files are copied to the directory, even the pictures you view on a webpage. They are erased as soon as you close the webpage.

In Linux, the directory is /temp. Find out the flash video file(.flv) or try to find the file whose size is increasing & is of size suitable t be the video file. Try playing it by VLC player.

For Windows XP, the directory is C:\Documents and Settings\User\Local Settings\Application Data\Mozilla\Firefox\Profiles\8axcg82l.default\Cache for Firefox. …./User/….may also have your own username. Just find the file of increasing size. Rename as <filename>.flv if you don’t wish to select the program used to open it repeatedly.

Sadly, the cache of Google Chrome is cached & you cannot copy easily from there.

I used my printer on both my laptop & desktop so easily. It is a HP psc 1210, an all-in-one printer & scanner.

I added it without need to use any CD/DVD as is required in Windows to install drivers. All the drivers are pre-loaded. I just clicked on add printer. Just a one minute job.

FOSS rocks!!