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You must know about BINARY numbers and the difference between DATA and INFORMATION before attempting this lesson. (code 05-080)

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Note Begins Here >>>>

ASCII

The acronym ASCII stands for American Standard Code for Information Interchange. It is a seven bit code that represents digits, letters and symbols. Most modern character-encoding schemes are based on ASCII. It was originally developed in the early 1960s for digital communications. ASCII and 7-bit ASCII are synonymous. They are the same thing.

To understand how ASCII works one must first be familiar with the binary number system. .

An illustration

The ASCII code for capital or uppercase 'A' is : 0100 0001

The code begins with 0 which means we shall not be using the first bit. The first bit on the left has no value. We must use a binary place value chart to work out the decimal value of this binary code.

The least significant value (right most value is 1) then 5 zeros moving towards the left and finally the 7th position stores the value 1.

PLACE TABLE HERE

65 in decimal represents the character uppercase or capital A.

66 in decimal represents the character uppercase or capital B.

67 in decimal represents the character uppercase or capital C and so on.

If we follow that pattern we can calculate the ASCII binary value for each letter of the alphabet just remember capital 'A' and common 'a' do not have the same ASCII values.

Question

1. If the decimal value of 'A' is 65 what will the decimal value of the letter 'D' be?

Answer : ____________

End of Note

Test Yourself

Choose the correct answer
Questions Options Verify
 1)  The four bit binary code 0010 represents the number 2 True
False
 2)  The four bit binary code 1010 represents the number 10 True
False
 3)  ASCII can represent digits and letters ONLY True
False
 4)  ASCII was first introduced in the 1920s True
False
 5)  ASCII allows different computers to share data easily True
False

Assignment

ASCII code for the letter A is 100 0001 or if we use 8 bits it will be 0100 0001. Determine the seven-bit ASCII code for the letter G. (Example 16)