How many Bits represent ONE character and How many Bits represent One Byte in ASCII?

Question

I know its simple but I still don't know it. Some people are saying that three are 7 Bits that represent a character while some are saying 8. So can anyone just tell me which one is right? If it is 8 Bits/Character then How many Bits represent a Byte? and If it's 7 then How many bits represent a Character and how many Bits represent ONE byte?

Answer 1

US-ASCII is indeed 7 bits per character. The highest code has value 127, which represents the DEL control character. Any character set that has codes with higher values is not US-ASCII (but may be an extension of it, such as Unicode).

Most microprocessors work with bytes (=smallest addressable unit of storage) of eight bits. If you want to use US-ASCII with these microprocessors, you have two options:

• Use 7 bytes (of 8 bits each) to store 8 characters (of 7 bits each), even though that makes programs very complicated.
• Use 1 byte (of 8 bits) to store 1 character (of 7 bits), even though you'll waste space.

The need for simple programs outweighs the need for efficient memory use in this case. That's why you usually use one 8-bit unit (an octet, for short) to store a character, even though each character is encoded in only 7-bit units. You just set the extra bit to zero (or, as was done in some cases, use the extra bit for error detection).