Thanks for the detailed response. I was aware that early keyboards were uppercase only which results in the bitwise operation for ctrl key being applied to the

Thanks for the detailed response. I was aware that early keyboards were uppercase only which results in the bitwise operation for ctrl key being applied to the ASCII code of uppercase characters only. I too use ASCII codes of uppercase characters only in my post although I write the key sequence in lowercase, e.g., ctrl+g along with decimal 71 as the code of the modified character. However, I was not aware that '@' was shift+p in bit-paired keyboards. This revelation resolves a few other mysteries for me, so thank you for sharing this bit. Indeed https://en.wikipedia.org/wiki/File:TTY33ASR.jpg https://en.wikipedia.org/wiki/File:TTY33ASR.jpg shows '@' on shifted 'p'. I do see now how ctrl consistently toggling the 7th LSB explains all the control codes in the ASCII chart. So it is only ctrl+space that sticks out as a special case.