ASCII - Whats the point of it?

Question

I always wanted to ask this, I know that ASCII uses numbers to represent characters like 65 = A

Whats the point? computer understand when i press A is A why we need to convert to 65?

Answer 1

You have it backwards: computers understand when you press an A because of codes like ASCII. Or rather, one part of the computer is able to tell another part of the computer that you pressed an A because they agree on conventions of binary signals like ASCII.

At its lowest level, each part of the computer "knows" that it is in one of two states - maybe off and on, maybe high voltage and low voltage, maybe two directions of magnetism, and so on. For convenience, we label these two states 0 and 1. We then build elaborate (and microscopic) sequences of machinery that each say "if this thing's a 1, then do this, if it's a 0 do this".

If we string a sequence of 1s and 0s together, we can write a number, like 1010; and we can make machinery that does maths with those numbers, like 1010 + 0001 = 1011. Alternatively, we can string a much longer sequence together to represent the brightness of pixels from the top left to bottom right of a screen, in order - a bitmap image. The computer doesn't "know" which sequences are numbers and which are images, we just tell it "draw the screen based on this sequence" and "calculate my wages based on this sequence".

If we want to represent not numbers or images, but text, we need to come up with a sequence of bits for each letter and symbol. It doesn't really matter what sequence we use, we just need to be consistent - we could say that 000001 is A, and as long as we remember that's what we chose, we can write programs that deal with text. ASCII is simply one of those mappings of sequences of bits to letters and symbols.

Note that A is not defined as "65" in ASCII, it's defined as the 7 bit sequence 1000001; it just happens that that's the same sequence of bits we generally use for the number 65. Note also that ASCII is a very old mapping, and almost never used directly in modern computers; it is however very influential, and a lot of more recent mappings are designed to use the same or similar sequences for the letters and symbols that it covers.