dear students we have already learned about main memory and mass storages from today we will learn that how actually the real-time data is stored in computer so as we have already discussed in previous modules that computer can only understand the binary language that is the language of zeros and fun so how for example a letter in the real data for example a world hello how the world hello can be stored internally in computer so we will try to learn this concept in today's module so initially we have thought that each textual symbol should be represented with a unique bit pattern so you we have number of zeros and ones so for example we can say that 0 1 1 0 0 0 1 so this will be a I am just giving an example so such a unique pattern will be used to represent one symbol and there would be number of such symbols available in the world and for each symbol we will design a unique bit pattern that would be normally of 8 bits so if we want to store virtual University so we would be stored in 8 bits I would be stored in 8 bits and so on so we have 18 characters in virtual University including the space in between them space is also treated as a character so we will need 144 bits to store the world virtual University or you can say we will need 18 bytes to store virtual University internally so how such codes were developed in 1940s and 1950s many such codes were developed by different scientist of the world and then there is Authority known as American national standard Institute a and si that has formed American Standard Code for information interchange that is called a SC III and that is pronounced as ASCII so that Oski had seven bits for information representation and more significant bit was just zero so if we have seven bits you have learned in a previous modules that if we have seven bits we can form to raise to power 7 combinations which are 128 so this means 128 different kind of symbols could be represented as we have 128 different kind of patterns so those 128 symbols would be uppercase alphabets lowercase punctuation marks digits from 0 to 9 line feed carriage return and taps so line feed means you want to say that here is a next line symbol should be inserted and carriage return means that you want to return your carriage or you turn your cursor to the start of your line and tab you know it's available on your keyboard so if we want to see the ASCII codes which are available in your book so let's go on to page number 577 of your book and see what are those ASCII codes which are available there so here I have opened this five 77 number page which is Appendix A of your book and here these are the symbols and this is the hexer value so you already have learned that four things are joined together to form one symbol hexadecimal so these are eight so this mean that this would be translated to two hexadecimal symbols so we have line feed carriage return space for example for space you have this symbol and so on and you can also translate these symbols into their actual decimal places so for example the space will have 32 in the decimal system and then 0 to 9 then from A to Z these are the upper cases and then the lower cases so these are 128 symbols and for each symbol there is a ASCII value and that ASCII value is being used by the computers who are using ASCII codes so for example from this Appendix A from your book so you have learned that if we want to store hello . so I have picked the ASCII value of H from your book and then the ASCII value of e from your book and then the ASCII value of L L oh and point so actually on backhand side these values will represent hello so ASCII codes had some limitations as well so there's there are not 128 collectors in the world so in the world there are many many more characters available so International Organization for Standardization which is also called as ISO that has come up with many extensions to Oski codes so one for to sport of one Western language and another to sport another language but it has also issues for example if we even take 256 letters so these are still insufficient to donate all language symbols so in actually in the world there are many many symbols available and document having multiple languages could not be read as it should follow of one standard so as I mentioned that ISO had defined different patterns for different Western symbols so if one document has multiple patterns then that document cannot be read so it should be internationalized so it was internationalized using unique patterns of 21 bits and those are called unique codes and these are compliance with us ascii compliant with us he means that all of the symbols which ask you use those remain as it is in the unicode and unicode further define more symbols but with the 21 so it has now a large space of 2 raised to power 21 symbols to represent all of the chinese help you japanese and others languages so utf-8 has 24 or 32 bits so if we only take 24 bits it can represent 16 million of unique symbols and file consisting of long symbols encoded with ASCII or Unicode is normally called a text file so if we summarize today's module that we have learned at how text is actually represented within the computer using binary and what our ASCII and Unicode and how they have made our life easier to store data on the computer