How are alphabetic characters programmed into a computer?
It isn't stored anywhere. 01100001 could represent anything. It could be the ASCII character "a" or it could be the integer 97 or it could even be something different entirely. It's up to the programmer to tell the computer what to do with 01100001, for instance by supplying a font file that tells it how to map binary sequences to the instructions to draw a character on the screen. Often this is taken care of in libraries but the OS and motherboard have no idea that 01100001 represents "a".